* added missed dependency PNGImage.

* moved FUNCTION InitializePaths(), from uFiles to
  uMain as this is a more sane location for it.
* updated files that used UFiles to point to UMain,
  and removed uFiles where its not needed.

git-svn-id: svn://svn.code.sf.net/p/ultrastardx/svn/trunk@385 b956fd51-792f-4845-bead-9b4dfca2ff2c

1 files changed, 5205 insertions, 0 deletions

diff --git a/Game/Code/lib/PngImage/pngimage.~pas b/Game/Code/lib/PngImage/pngimage.~pas
new file mode 100644
index 00000000..ec712737
--- /dev/null
+++ b/Game/Code/lib/PngImage/pngimage.~pas
@@ -0,0 +1,5205 @@
+{Portable Network Graphics Delphi 1.4361   (8 March 2003)     }

+

+{This is the latest implementation for TPngImage component    }

+{It's meant to be a full replacement for the previous one.    }

+{There are lots of new improvements, including cleaner code,  }

+{full partial transparency support, speed improvements,       }

+{saving using ADAM 7 interlacing, better error handling, also }

+{the best compression for the final image ever. And now it's  }

+{truly able to read about any png image.                      }

+

+{

+  Version 1.4361

+  2003-03-04 - Fixed important bug for simple transparency when using

+               RGB, Grayscale color modes

+

+  Version 1.436

+  2003-03-04 - * NEW * Property Pixels for direct access to pixels

+               * IMPROVED * Palette property (TPngObject) (read only)

+               Slovenian traslation for the component (Miha Petelin)

+               Help file update (scanline article/png->jpg example)

+

+  Version 1.435

+  2003-11-03 - * NEW * New chunk implementation zTXt (method AddzTXt)

+               * NEW * New compiler flags to store the extra 8 bits

+               from 16 bits samples (when saving it is ignored), the

+               extra data may be acessed using ExtraScanline property

+               * Fixed * a bug on tIMe chunk

+               French translation included (Thanks to IBE Software)

+               Bugs fixed

+

+  Version 1.432

+  2002-08-24 - * NEW *  A new method, CreateAlpha will transform the

+               current image into partial transparency.

+               Help file updated with a new article on how to handle

+               partial transparency.

+

+  Version 1.431

+  2002-08-14 - Fixed and tested to work on:

+               C++ Builder 3

+               C++ Builder 5

+               Delphi 3

+               There was an error when setting TransparentColor, fixed

+               New method, RemoveTransparency to remove image

+               BIT TRANSPARENCY

+

+  Version 1.43

+  2002-08-01 - * NEW * Support for Delphi 3 and C++ Builder 3

+               Implements mostly some things that were missing,

+               a few tweaks and fixes.

+

+  Version 1.428

+  2002-07-24 - More minor fixes (thanks to Ian Boyd)

+               Bit transparency fixes

+               * NEW * Finally support to bit transparency

+               (palette / rgb / grayscale -> all)

+

+  Version 1.427

+  2002-07-19 - Lots of bugs and leaks fixed

+               * NEW * method to easy adding text comments, AddtEXt

+               * NEW * property for setting bit transparency,

+                       TransparentColor

+

+  Version 1.426

+  2002-07-18 - Clipboard finally fixed (hope)

+               Changed UseDelphi trigger to UseDelphi

+               * NEW * Support for bit transparency bitmaps

+                       when assigning from/to TBitmap objects

+               Altough it does not support drawing transparent

+               parts of bit transparency pngs (only partial)

+               it is closer than ever

+

+  Version 1.425

+  2002-07-01 - Clipboard methods implemented

+               Lots of bugs fixed

+

+  Version 1.424

+  2002-05-16 - Scanline and AlphaScanline are now working correctly.

+               New methods for handling the clipboard

+

+  Version 1.423

+  2002-05-16 - * NEW * Partial transparency for 1, 2, 4 and 8 bits is

+               also supported using the tRNS chunk (for palette and

+               grayscaling).

+               New bug fixes (Peter Haas).

+

+  Version 1.422

+  2002-05-14 - Fixed some critical leaks, thanks to Peter Haas tips.

+               New translation for German (Peter Haas).

+

+  Version 1.421

+  2002-05-06 - Now uses new ZLIB version, 1.1.4 with some security

+               fixes.

+               LoadFromResourceID and LoadFromResourceName added and

+               help file updated for that.

+               The resources strings are now located in pnglang.pas.

+               New translation for Brazilian Portuguese.

+               Bugs fixed.

+

+ IMPORTANT: I'm currently looking for bugs on the library. If

+            anyone has found one, please send me an email and

+            I will fix right away. Thanks for all the help and

+            ideias I'm receiving so far.}

+

+{My new email is: gubadaud@terra.com.br}

+{Website link   : pngdelphi.sourceforge.net}

+{Gustavo Huffenbacher Daud}

+

+unit pngimage;

+

+interface

+

+{Triggers avaliable (edit the fields bellow)}

+{$DEFINE UseDelphi}              //Disable fat vcl units (perfect to small apps)

+{$DEFINE ErrorOnUnknownCritical} //Error when finds an unknown critical chunk

+{$DEFINE CheckCRC}               //Enables CRC checking

+{$DEFINE RegisterGraphic}        //Registers TPNGObject to use with TPicture

+{$DEFINE PartialTransparentDraw} //Draws partial transparent images

+{.$DEFINE Store16bits}            //Stores the extra 8 bits from 16bits/sample

+{.$DEFINE Debug}                 //For programming purposes

+{$RANGECHECKS OFF} {$J+}

+

+

+

+uses

+ Windows {$IFDEF UseDelphi}, Classes, Graphics, SysUtils{$ENDIF} {$IFDEF Debug},

+ dialogs{$ENDIF}, pngzlib, pnglang;

+

+{$IFNDEF UseDelphi}

+  const

+    soFromBeginning = 0;

+    soFromCurrent = 1;

+    soFromEnd = 2;

+{$ENDIF}

+

+const

+  {ZLIB constants}

+  ZLIBErrors: Array[-6..2] of string = ('incompatible version (-6)',

+    'buffer error (-5)', 'insufficient memory (-4)', 'data error (-3)',

+    'stream error (-2)', 'file error (-1)', '(0)', 'stream end (1)',

+    'need dictionary (2)');

+  Z_NO_FLUSH      = 0;

+  Z_FINISH        = 4;

+  Z_STREAM_END    = 1;

+

+  {Avaliable PNG filters for mode 0}

+  FILTER_NONE    = 0;

+  FILTER_SUB     = 1;

+  FILTER_UP      = 2;

+  FILTER_AVERAGE = 3;

+  FILTER_PAETH   = 4;

+

+  {Avaliable color modes for PNG}

+  COLOR_GRAYSCALE      = 0;

+  COLOR_RGB            = 2;

+  COLOR_PALETTE        = 3;

+  COLOR_GRAYSCALEALPHA = 4;

+  COLOR_RGBALPHA       = 6;

+

+

+type

+  {$IFNDEF UseDelphi}

+    {Custom exception handler}

+    Exception = class(TObject)

+      constructor Create(Msg: String);

+    end;

+    ExceptClass = class of Exception;

+    TColor = ColorRef;

+  {$ENDIF}

+

+  {Error types}

+  EPNGOutMemory = class(Exception);

+  EPngError = class(Exception);

+  EPngUnexpectedEnd = class(Exception);

+  EPngInvalidCRC = class(Exception);

+  EPngInvalidIHDR = class(Exception);

+  EPNGMissingMultipleIDAT = class(Exception);

+  EPNGZLIBError = class(Exception);

+  EPNGInvalidPalette = class(Exception);

+  EPNGInvalidFileHeader = class(Exception);

+  EPNGIHDRNotFirst = class(Exception);

+  EPNGNotExists = class(Exception);

+  EPNGSizeExceeds = class(Exception);

+  EPNGMissingPalette = class(Exception);

+  EPNGUnknownCriticalChunk = class(Exception);

+  EPNGUnknownCompression = class(Exception);

+  EPNGUnknownInterlace = class(Exception);

+  EPNGNoImageData = class(Exception);

+  EPNGCouldNotLoadResource = class(Exception);

+  EPNGCannotChangeTransparent = class(Exception);

+  EPNGHeaderNotPresent = class(Exception);

+

+type

+  {Direct access to pixels using R,G,B}

+  TRGBLine = array[word] of TRGBTriple;

+  pRGBLine = ^TRGBLine;

+

+  {Same as TBitmapInfo but with allocated space for}

+  {palette entries}

+  TMAXBITMAPINFO = packed record

+    bmiHeader: TBitmapInfoHeader;

+    bmiColors: packed array[0..255] of TRGBQuad;

+  end;

+

+  {Transparency mode for pngs}

+  TPNGTransparencyMode = (ptmNone, ptmBit, ptmPartial);

+  {Pointer to a cardinal type}

+  pCardinal = ^Cardinal;

+  {Access to a rgb pixel}

+  pRGBPixel = ^TRGBPixel;

+  TRGBPixel = packed record

+    B, G, R: Byte;

+  end;

+

+  {Pointer to an array of bytes type}

+  TByteArray = Array[Word] of Byte;

+  pByteArray = ^TByteArray;

+

+  {Forward}

+  TPNGObject = class;

+  pPointerArray = ^TPointerArray;

+  TPointerArray = Array[Word] of Pointer;

+

+  {Contains a list of objects}

+  TPNGPointerList = class

+  private

+    fOwner: TPNGObject;

+    fCount : Cardinal;

+    fMemory: pPointerArray;

+    function GetItem(Index: Cardinal): Pointer;

+    procedure SetItem(Index: Cardinal; const Value: Pointer);

+  protected

+    {Removes an item}

+    function Remove(Value: Pointer): Pointer; virtual;

+    {Inserts an item}

+    procedure Insert(Value: Pointer; Position: Cardinal);

+    {Add a new item}

+    procedure Add(Value: Pointer);

+    {Returns an item}

+    property Item[Index: Cardinal]: Pointer read GetItem write SetItem;

+    {Set the size of the list}

+    procedure SetSize(const Size: Cardinal);

+    {Returns owner}

+    property Owner: TPNGObject read fOwner;

+  public

+    {Returns number of items}

+    property Count: Cardinal read fCount write SetSize;

+    {Object being either created or destroyed}

+    constructor Create(AOwner: TPNGObject);

+    destructor Destroy; override;

+  end;

+

+  {Forward declaration}

+  TChunk = class;

+  TChunkClass = class of TChunk;

+

+  {Same as TPNGPointerList but providing typecasted values}

+  TPNGList = class(TPNGPointerList)

+  private

+    {Used with property Item}

+    function GetItem(Index: Cardinal): TChunk;

+  public

+    {Removes an item}

+    procedure RemoveChunk(Chunk: TChunk); overload;

+    {Add a new chunk using the class from the parameter}

+    function Add(ChunkClass: TChunkClass): TChunk;

+    {Returns pointer to the first chunk of class}

+    function ItemFromClass(ChunkClass: TChunkClass): TChunk;

+    {Returns a chunk item from the list}

+    property Item[Index: Cardinal]: TChunk read GetItem;

+  end;

+

+  {$IFNDEF UseDelphi}

+    {The STREAMs bellow are only needed in case delphi provided ones is not}

+    {avaliable (UseDelphi trigger not set)}

+    {Object becomes handles}

+    TCanvas = THandle;

+    TBitmap = HBitmap;

+    {Trick to work}

+    TPersistent = TObject;

+

+    {Base class for all streams}

+    TStream = class

+    protected

+      {Returning/setting size}

+      function GetSize: Longint; virtual;

+      procedure SetSize(const Value: Longint); virtual; abstract;

+      {Returns/set position}

+      function GetPosition: Longint; virtual;

+      procedure SetPosition(const Value: Longint); virtual;

+    public

+      {Returns/sets current position}

+      property Position: Longint read GetPosition write SetPosition;

+      {Property returns/sets size}

+      property Size: Longint read GetSize write SetSize;

+      {Allows reading/writing data}

+      function Read(var Buffer; Count: Longint): Cardinal; virtual; abstract;

+      function Write(const Buffer; Count: Longint): Cardinal; virtual; abstract;

+      {Copies from another Stream}

+      function CopyFrom(Source: TStream;

+        Count: Cardinal): Cardinal; virtual;

+      {Seeks a stream position}

+      function Seek(Offset: Longint; Origin: Word): Longint; virtual; abstract;

+    end;

+

+    {File stream modes}

+    TFileStreamMode = (fsmRead, fsmWrite, fsmCreate);

+    TFileStreamModeSet = set of TFileStreamMode;

+

+    {File stream for reading from files}

+    TFileStream = class(TStream)

+    private

+      {Opened mode}

+      Filemode: TFileStreamModeSet;

+      {Handle}

+      fHandle: THandle;

+    protected

+      {Set the size of the file}

+      procedure SetSize(const Value: Longint); override;

+    public

+      {Seeks a file position}

+      function Seek(Offset: Longint; Origin: Word): Longint; override;

+      {Reads/writes data from/to the file}

+      function Read(var Buffer; Count: Longint): Cardinal; override;

+      function Write(const Buffer; Count: Longint): Cardinal; override;

+      {Stream being created and destroy}

+      constructor Create(Filename: String; Mode: TFileStreamModeSet);

+      destructor Destroy; override;

+    end;

+

+    {Stream for reading from resources}

+    TResourceStream = class(TStream)

+      constructor Create(Instance: HInst; const ResName: String; ResType:PChar);

+    private

+      {Variables for reading}

+      Size: Integer;

+      Memory: Pointer;

+      Position: Integer;

+    protected

+      {Set the size of the file}

+      procedure SetSize(const Value: Longint); override;

+    public

+      {Stream processing}

+      function Read(var Buffer; Count: Integer): Cardinal; override;

+      function Seek(Offset: Integer; Origin: Word): Longint; override;

+      function Write(const Buffer; Count: Longint): Cardinal; override;

+    end;

+  {$ENDIF}

+

+  {Forward}

+  TChunkIHDR = class;

+  {Interlace method}

+  TInterlaceMethod = (imNone, imAdam7);

+  {Compression level type}

+  TCompressionLevel = 0..9;

+  {Filters type}

+  TFilter = (pfNone, pfSub, pfUp, pfAverage, pfPaeth);

+  TFilters = set of TFilter;

+

+  {Png implementation object}

+  TPngObject = class{$IFDEF UseDelphi}(TGraphic){$ENDIF}

+  protected

+    {Gamma table values}

+    GammaTable, InverseGamma: Array[Byte] of Byte;

+    procedure InitializeGamma;

+  private

+    {Temporary palette}

+    TempPalette: HPalette;

+    {Filters to test to encode}

+    fFilters: TFilters;

+    {Compression level for ZLIB}

+    fCompressionLevel: TCompressionLevel;

+    {Maximum size for IDAT chunks}

+    fMaxIdatSize: Cardinal;

+    {Returns if image is interlaced}

+    fInterlaceMethod: TInterlaceMethod;

+    {Chunks object}

+    fChunkList: TPngList;

+    {Clear all chunks in the list}

+    procedure ClearChunks;

+    {Returns if header is present}

+    function HeaderPresent: Boolean;

+    {Returns linesize and byte offset for pixels}

+    procedure GetPixelInfo(var LineSize, Offset: Cardinal);

+    procedure SetMaxIdatSize(const Value: Cardinal);

+    function GetAlphaScanline(const LineIndex: Integer): pByteArray;

+    function GetScanline(const LineIndex: Integer): Pointer;

+    {$IFDEF Store16bits}

+    function GetExtraScanline(const LineIndex: Integer): Pointer;

+    {$ENDIF}

+    function GetTransparencyMode: TPNGTransparencyMode;

+    function GetTransparentColor: TColor;

+    procedure SetTransparentColor(const Value: TColor);

+  protected

+    {Returns the image palette}

+    function GetPalette: HPALETTE; {$IFDEF UseDelphi}override;{$ENDIF}

+    {Returns/sets image width and height}

+    function GetWidth: Integer; {$IFDEF UseDelphi}override;{$ENDIF}

+    function GetHeight: Integer; {$IFDEF UseDelphi}override; {$ENDIF}

+    procedure SetWidth(Value: Integer);  {$IFDEF UseDelphi}override; {$ENDIF}

+    procedure SetHeight(Value: Integer);  {$IFDEF UseDelphi}override;{$ENDIF}

+    {Assigns from another TPNGObject}

+    procedure AssignPNG(Source: TPNGObject);

+    {Returns if the image is empty}

+    function GetEmpty: Boolean; {$IFDEF UseDelphi}override; {$ENDIF}

+    {Used with property Header}

+    function GetHeader: TChunkIHDR;

+    {Draws using partial transparency}

+    procedure DrawPartialTrans(DC: HDC; Rect: TRect);

+    {$IFDEF UseDelphi}

+    {Returns if the image is transparent}

+    function GetTransparent: Boolean; override;

+    {$ENDIF}

+    {Returns a pixel}

+    function GetPixels(const X, Y: Integer): TColor; virtual;

+    procedure SetPixels(const X, Y: Integer; const Value: TColor); virtual;

+  public

+    {Generates alpha information}

+    procedure CreateAlpha;

+    {Removes the image transparency}

+    procedure RemoveTransparency;

+    {Transparent color}

+    property TransparentColor: TColor read GetTransparentColor write

+      SetTransparentColor;

+    {Add text chunk, TChunkTEXT, TChunkzTXT}

+    procedure AddtEXt(const Keyword, Text: String);

+    procedure AddzTXt(const Keyword, Text: String);

+    {$IFDEF UseDelphi}

+    {Saves to clipboard format (thanks to Antoine Pottern)}

+    procedure SaveToClipboardFormat(var AFormat: Word; var AData: THandle;

+      var APalette: HPalette); override;

+    procedure LoadFromClipboardFormat(AFormat: Word; AData: THandle;

+      APalette: HPalette); override;

+    {$ENDIF}

+    {Calling errors}

+    procedure RaiseError(ExceptionClass: ExceptClass; Text: String);

+    {Returns a scanline from png}

+    property Scanline[const Index: Integer]: Pointer read GetScanline;

+    {$IFDEF Store16bits}

+    property ExtraScanline[const Index: Integer]: Pointer read GetExtraScanline;

+    {$ENDIF}

+    property AlphaScanline[const Index: Integer]: pByteArray read GetAlphaScanline;

+    {Returns pointer to the header}

+    property Header: TChunkIHDR read GetHeader;

+    {Returns the transparency mode used by this png}

+    property TransparencyMode: TPNGTransparencyMode read GetTransparencyMode;

+    {Assigns from another object}

+    procedure Assign(Source: TPersistent);{$IFDEF UseDelphi}override;{$ENDIF}

+    {Assigns to another object}

+    procedure AssignTo(Dest: TPersistent);{$IFDEF UseDelphi}override;{$ENDIF}

+    {Assigns from a windows bitmap handle}

+    procedure AssignHandle(Handle: HBitmap; Transparent: Boolean;

+      TransparentColor: ColorRef);

+    {Draws the image into a canvas}

+    procedure Draw(ACanvas: TCanvas; const Rect: TRect);

+      {$IFDEF UseDelphi}override;{$ENDIF}

+    {Width and height properties}

+    property Width: Integer read GetWidth;

+    property Height: Integer read GetHeight;

+    {Returns if the image is interlaced}

+    property InterlaceMethod: TInterlaceMethod read fInterlaceMethod

+      write fInterlaceMethod;

+    {Filters to test to encode}

+    property Filters: TFilters read fFilters write fFilters;

+    {Maximum size for IDAT chunks, default and minimum is 65536}

+    property MaxIdatSize: Cardinal read fMaxIdatSize write SetMaxIdatSize;

+    {Property to return if the image is empty or not}

+    property Empty: Boolean read GetEmpty;

+    {Compression level}

+    property CompressionLevel: TCompressionLevel read fCompressionLevel

+      write fCompressionLevel;

+    {Access to the chunk list}

+    property Chunks: TPngList read fChunkList;

+    {Object being created and destroyed}

+    constructor Create; {$IFDEF UseDelphi}override;{$ENDIF}

+    destructor Destroy; override;

+    {$IFNDEF UseDelphi}procedure LoadFromFile(const Filename: String);{$ENDIF}

+    {$IFNDEF UseDelphi}procedure SaveToFile(const Filename: String);{$ENDIF}

+    procedure LoadFromStream(Stream: TStream); {$IFDEF UseDelphi}override;{$ENDIF}

+    procedure SaveToStream(Stream: TStream); {$IFDEF UseDelphi}override;{$ENDIF}

+    {Loading the image from resources}

+    procedure LoadFromResourceName(Instance: HInst; const Name: String);

+    procedure LoadFromResourceID(Instance: HInst; ResID: Integer);

+    {Access to the png pixels}

+    property Pixels[const X, Y: Integer]: TColor read GetPixels write SetPixels;

+    {Palette property}

+    {$IFNDEF UseDelphi}property Palette: HPalette read GetPalette;{$ENDIF}

+  end;

+

+  {Chunk name object}

+  TChunkName = Array[0..3] of Char;

+

+  {Global chunk object}

+  TChunk = class

+  private

+    {Contains data}

+    fData: Pointer;

+    fDataSize: Cardinal;

+    {Stores owner}

+    fOwner: TPngObject;

+    {Stores the chunk name}

+    fName: TChunkName;

+    {Returns pointer to the TChunkIHDR}

+    function GetHeader: TChunkIHDR;

+    {Used with property index}

+    function GetIndex: Integer;

+    {Should return chunk class/name}

+    class function GetName: String; virtual;

+    {Returns the chunk name}

+    function GetChunkName: String;

+  public

+    {Returns index from list}

+    property Index: Integer read GetIndex;

+    {Returns pointer to the TChunkIHDR}

+    property Header: TChunkIHDR read GetHeader;

+    {Resize the data}

+    procedure ResizeData(const NewSize: Cardinal);

+    {Returns data and size}

+    property Data: Pointer read fData;

+    property DataSize: Cardinal read fDataSize;

+    {Assigns from another TChunk}

+    procedure Assign(Source: TChunk); virtual;

+    {Returns owner}

+    property Owner: TPngObject read fOwner;

+    {Being destroyed/created}

+    constructor Create(Owner: TPngObject); virtual;

+    destructor Destroy; override;

+    {Returns chunk class/name}

+    property Name: String read GetChunkName;

+    {Loads the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; virtual;

+    {Saves the chunk to a stream}

+    function SaveData(Stream: TStream): Boolean;

+    function SaveToStream(Stream: TStream): Boolean; virtual;

+  end;

+

+  {Chunk classes}

+  TChunkIEND = class(TChunk);     {End chunk}

+

+  {IHDR data}

+  pIHDRData = ^TIHDRData;

+  TIHDRData = packed record

+    Width, Height: Cardinal;

+    BitDepth,

+    ColorType,

+    CompressionMethod,

+    FilterMethod,

+    InterlaceMethod: Byte;

+  end;

+

+  {Information header chunk}

+  TChunkIHDR = class(TChunk)

+  private

+    {Current image}

+    ImageHandle: HBitmap;

+    ImageDC: HDC;

+

+    {Output windows bitmap}

+    HasPalette: Boolean;

+    BitmapInfo: TMaxBitmapInfo;

+    BytesPerRow: Integer;

+    {Stores the image bytes}

+    {$IFDEF Store16bits}ExtraImageData: Pointer;{$ENDIF}

+    ImageData: pointer;

+    ImageAlpha: Pointer;

+

+    {Contains all the ihdr data}

+    IHDRData: TIHDRData;

+  protected

+    {Resizes the image data to fill the color type, bit depth, }

+    {width and height parameters}

+    procedure PrepareImageData;

+    {Release allocated ImageData memory}

+    procedure FreeImageData;

+  public

+    {Properties}

+    property Width: Cardinal read IHDRData.Width write IHDRData.Width;

+    property Height: Cardinal read IHDRData.Height write IHDRData.Height;

+    property BitDepth: Byte read IHDRData.BitDepth write IHDRData.BitDepth;

+    property ColorType: Byte read IHDRData.ColorType write IHDRData.ColorType;

+    property CompressionMethod: Byte read IHDRData.CompressionMethod

+      write IHDRData.CompressionMethod;

+    property FilterMethod: Byte read IHDRData.FilterMethod

+      write IHDRData.FilterMethod;

+    property InterlaceMethod: Byte read IHDRData.InterlaceMethod

+      write IHDRData.InterlaceMethod;

+    {Loads the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    {Saves the chunk to a stream}

+    function SaveToStream(Stream: TStream): Boolean; override;

+    {Destructor/constructor}

+    constructor Create(Owner: TPngObject); override;

+    destructor Destroy; override;

+    {Assigns from another TChunk}

+    procedure Assign(Source: TChunk); override;

+  end;

+

+  {Gamma chunk}

+  TChunkgAMA = class(TChunk)

+  private

+    {Returns/sets the value for the gamma chunk}

+    function GetValue: Cardinal;

+    procedure SetValue(const Value: Cardinal);

+  public

+    {Returns/sets gamma value}

+    property Gamma: Cardinal read GetValue write SetValue;

+    {Loading the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    {Being created}

+    constructor Create(Owner: TPngObject); override;

+    {Assigns from another TChunk}

+    procedure Assign(Source: TChunk); override;

+  end;

+

+  {ZLIB Decompression extra information}

+  TZStreamRec2 = packed record

+    {From ZLIB}

+    ZLIB: TZStreamRec;

+    {Additional info}

+    Data: Pointer;

+    fStream   : TStream;

+  end;

+

+  {Palette chunk}

+  TChunkPLTE = class(TChunk)

+  private

+    {Number of items in the palette}

+    fCount: Integer;

+    {Contains the palette handle}

+    function GetPaletteItem(Index: Byte): TRGBQuad;

+  public

+    {Returns the color for each item in the palette}

+    property Item[Index: Byte]: TRGBQuad read GetPaletteItem;

+    {Returns the number of items in the palette}

+    property Count: Integer read fCount;

+    {Loads the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    {Saves the chunk to a stream}

+    function SaveToStream(Stream: TStream): Boolean; override;

+    {Assigns from another TChunk}

+    procedure Assign(Source: TChunk); override;

+  end;

+

+  {Transparency information}

+  TChunktRNS = class(TChunk)

+  private

+    fBitTransparency: Boolean;

+    function GetTransparentColor: ColorRef;

+    {Returns the transparent color}

+    procedure SetTransparentColor(const Value: ColorRef);

+  public

+    {Palette values for transparency}

+    PaletteValues: Array[Byte] of Byte;

+    {Returns if it uses bit transparency}

+    property BitTransparency: Boolean read fBitTransparency;

+    {Returns the transparent color}

+    property TransparentColor: ColorRef read GetTransparentColor write

+      SetTransparentColor;

+    {Loads/saves the chunk from/to a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    function SaveToStream(Stream: TStream): Boolean; override;

+    {Assigns from another TChunk}

+    procedure Assign(Source: TChunk); override;

+  end;

+

+  {Actual image information}

+  TChunkIDAT = class(TChunk)

+  private

+    {Holds another pointer to the TChunkIHDR}

+    Header: TChunkIHDR;

+    {Stores temporary image width and height}

+    ImageWidth, ImageHeight: Integer;

+    {Size in bytes of each line and offset}

+    Row_Bytes, Offset : Cardinal;

+    {Contains data for the lines}

+    Encode_Buffer: Array[0..5] of pByteArray;

+    Row_Buffer: Array[Boolean] of pByteArray;

+    {Variable to invert the Row_Buffer used}

+    RowUsed: Boolean;

+    {Ending position for the current IDAT chunk}

+    EndPos: Integer;

+    {Filter the current line}

+    procedure FilterRow;

+    {Filter to encode and returns the best filter}

+    function FilterToEncode: Byte;

+    {Reads ZLIB compressed data}

+    function IDATZlibRead(var ZLIBStream: TZStreamRec2; Buffer: Pointer;

+      Count: Integer; var EndPos: Integer; var crcfile: Cardinal): Integer;

+    {Compress and writes IDAT data}

+    procedure IDATZlibWrite(var ZLIBStream: TZStreamRec2; Buffer: Pointer;

+      const Length: Cardinal);

+    procedure FinishIDATZlib(var ZLIBStream: TZStreamRec2);

+    {Prepares the palette}

+    procedure PreparePalette;

+  protected

+    {Decode interlaced image}

+    procedure DecodeInterlacedAdam7(Stream: TStream;

+      var ZLIBStream: TZStreamRec2; const Size: Integer; var crcfile: Cardinal);

+    {Decode non interlaced imaged}

+    procedure DecodeNonInterlaced(Stream: TStream;

+      var ZLIBStream: TZStreamRec2; const Size: Integer;

+      var crcfile: Cardinal);

+  protected

+    {Encode non interlaced images}

+    procedure EncodeNonInterlaced(Stream: TStream;

+      var ZLIBStream: TZStreamRec2);

+    {Encode interlaced images}

+    procedure EncodeInterlacedAdam7(Stream: TStream;

+      var ZLIBStream: TZStreamRec2);

+  protected

+    {Memory copy methods to decode}

+    procedure CopyNonInterlacedRGB8(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedRGB16(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedPalette148(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedPalette2(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedGray2(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedGrayscale16(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedRGBAlpha8(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedRGBAlpha16(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedGrayscaleAlpha8(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyNonInterlacedGrayscaleAlpha16(

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedRGB8(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedRGB16(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedPalette148(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedPalette2(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedGray2(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedGrayscale16(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedRGBAlpha8(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedRGBAlpha16(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedGrayscaleAlpha8(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+    procedure CopyInterlacedGrayscaleAlpha16(const Pass: Byte;

+      Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+  protected

+    {Memory copy methods to encode}

+    procedure EncodeNonInterlacedRGB8(Src, Dest, Trans: pChar);

+    procedure EncodeNonInterlacedRGB16(Src, Dest, Trans: pChar);

+    procedure EncodeNonInterlacedGrayscale16(Src, Dest, Trans: pChar);

+    procedure EncodeNonInterlacedPalette148(Src, Dest, Trans: pChar);

+    procedure EncodeNonInterlacedRGBAlpha8(Src, Dest, Trans: pChar);

+    procedure EncodeNonInterlacedRGBAlpha16(Src, Dest, Trans: pChar);

+    procedure EncodeNonInterlacedGrayscaleAlpha8(Src, Dest, Trans: pChar);

+    procedure EncodeNonInterlacedGrayscaleAlpha16(Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedRGB8(const Pass: Byte; Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedRGB16(const Pass: Byte; Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedPalette148(const Pass: Byte;

+      Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedGrayscale16(const Pass: Byte;

+      Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedRGBAlpha8(const Pass: Byte;

+      Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedRGBAlpha16(const Pass: Byte;

+      Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedGrayscaleAlpha8(const Pass: Byte;

+      Src, Dest, Trans: pChar);

+    procedure EncodeInterlacedGrayscaleAlpha16(const Pass: Byte;

+      Src, Dest, Trans: pChar);

+  public

+    {Loads the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    {Saves the chunk to a stream}

+    function SaveToStream(Stream: TStream): Boolean; override;

+  end;

+

+  {Image last modification chunk}

+  TChunktIME = class(TChunk)

+  private

+    {Holds the variables}

+    fYear: Word;

+    fMonth, fDay, fHour, fMinute, fSecond: Byte;

+  public

+    {Returns/sets variables}

+    property Year: Word read fYear write fYear;

+    property Month: Byte read fMonth write fMonth;

+    property Day: Byte read fDay write fDay;

+    property Hour: Byte read fHour write fHour;

+    property Minute: Byte read fMinute write fMinute;

+    property Second: Byte read fSecond write fSecond;

+    {Loads the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    {Saves the chunk to a stream}

+    function SaveToStream(Stream: TStream): Boolean; override;

+  end;

+

+  {Textual data}

+  TChunktEXt = class(TChunk)

+  private

+    fKeyword, fText: String;

+  public

+    {Keyword and text}

+    property Keyword: String read fKeyword write fKeyword;

+    property Text: String read fText write fText;

+    {Loads the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    {Saves the chunk to a stream}

+    function SaveToStream(Stream: TStream): Boolean; override;

+    {Assigns from another TChunk}

+    procedure Assign(Source: TChunk); override;

+  end;

+

+  {zTXT chunk}

+  TChunkzTXt = class(TChunktEXt)

+    {Loads the chunk from a stream}

+    function LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+      Size: Integer): Boolean; override;

+    {Saves the chunk to a stream}

+    function SaveToStream(Stream: TStream): Boolean; override;

+  end;

+

+{Here we test if it's c++ builder or delphi version 3 or less}

+{$IFDEF VER110}{$DEFINE DelphiBuilder3Less}{$ENDIF}

+{$IFDEF VER100}{$DEFINE DelphiBuilder3Less}{$ENDIF}

+{$IFDEF VER93}{$DEFINE DelphiBuilder3Less}{$ENDIF}

+{$IFDEF VER90}{$DEFINE DelphiBuilder3Less}{$ENDIF}

+{$IFDEF VER80}{$DEFINE DelphiBuilder3Less}{$ENDIF}

+

+

+{Registers a new chunk class}

+procedure RegisterChunk(ChunkClass: TChunkClass);

+{Calculates crc}

+function update_crc(crc: {$IFNDEF DelphiBuilder3Less}Cardinal{$ELSE}Integer

+  {$ENDIF}; buf: pByteArray; len: Integer): Cardinal;

+{Invert bytes using assembly}

+function ByteSwap(const a: integer): integer;

+

+implementation

+

+var

+  ChunkClasses: TPngPointerList;

+  {Table of CRCs of all 8-bit messages}

+  crc_table: Array[0..255] of Cardinal;

+  {Flag: has the table been computed? Initially false}

+  crc_table_computed: Boolean;

+

+{Draw transparent image using transparent color}

+procedure DrawTransparentBitmap(dc: HDC; srcBits: Pointer;

+  var srcHeader: TBitmapInfoHeader;

+  srcBitmapInfo: pBitmapInfo; Rect: TRect; cTransparentColor: COLORREF);

+var

+  cColor:   COLORREF;

+  bmAndBack, bmAndObject, bmAndMem: HBITMAP;

+  bmBackOld, bmObjectOld, bmMemOld: HBITMAP;

+  hdcMem, hdcBack, hdcObject, hdcTemp: HDC;

+  ptSize, orgSize: TPOINT;

+  OldBitmap, DrawBitmap: HBITMAP;

+begin

+  hdcTemp := CreateCompatibleDC(dc);

+  // Select the bitmap

+  DrawBitmap := CreateDIBitmap(dc, srcHeader, CBM_INIT, srcBits, srcBitmapInfo^,

+    DIB_RGB_COLORS);

+  OldBitmap := SelectObject(hdcTemp, DrawBitmap);

+

+  // Sizes

+  OrgSize.x := abs(srcHeader.biWidth);

+  OrgSize.y := abs(srcHeader.biHeight);

+  ptSize.x := Rect.Right - Rect.Left;        // Get width of bitmap

+  ptSize.y := Rect.Bottom - Rect.Top;        // Get height of bitmap

+

+  // Create some DCs to hold temporary data.

+  hdcBack  := CreateCompatibleDC(dc);

+  hdcObject := CreateCompatibleDC(dc);

+  hdcMem   := CreateCompatibleDC(dc);

+

+  // Create a bitmap for each DC. DCs are required for a number of

+  // GDI functions.

+

+  // Monochrome DCs

+  bmAndBack  := CreateBitmap(ptSize.x, ptSize.y, 1, 1, nil);

+  bmAndObject := CreateBitmap(ptSize.x, ptSize.y, 1, 1, nil);

+

+  bmAndMem   := CreateCompatibleBitmap(dc, ptSize.x, ptSize.y);

+

+  // Each DC must select a bitmap object to store pixel data.

+  bmBackOld  := SelectObject(hdcBack, bmAndBack);

+  bmObjectOld := SelectObject(hdcObject, bmAndObject);

+  bmMemOld   := SelectObject(hdcMem, bmAndMem);

+

+  // Set the background color of the source DC to the color.

+  // contained in the parts of the bitmap that should be transparent

+  cColor := SetBkColor(hdcTemp, cTransparentColor);

+

+  // Create the object mask for the bitmap by performing a BitBlt

+  // from the source bitmap to a monochrome bitmap.

+  StretchBlt(hdcObject, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0,

+    orgSize.x, orgSize.y, SRCCOPY);

+

+  // Set the background color of the source DC back to the original

+  // color.

+  SetBkColor(hdcTemp, cColor);

+

+  // Create the inverse of the object mask.

+  BitBlt(hdcBack, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0,

+       NOTSRCCOPY);

+

+  // Copy the background of the main DC to the destination.

+  BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, dc, Rect.Left, Rect.Top,

+       SRCCOPY);

+

+  // Mask out the places where the bitmap will be placed.

+  BitBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcObject, 0, 0, SRCAND);

+

+  // Mask out the transparent colored pixels on the bitmap.

+//  BitBlt(hdcTemp, 0, 0, ptSize.x, ptSize.y, hdcBack, 0, 0, SRCAND);

+  StretchBlt(hdcTemp, 0, 0, OrgSize.x, OrgSize.y, hdcBack, 0, 0,

+    PtSize.x, PtSize.y, SRCAND);

+

+  // XOR the bitmap with the background on the destination DC.

+  StretchBlt(hdcMem, 0, 0, ptSize.x, ptSize.y, hdcTemp, 0, 0,

+    OrgSize.x, OrgSize.y, SRCPAINT);

+

+  // Copy the destination to the screen.

+  BitBlt(dc, Rect.Left, Rect.Top, ptSize.x, ptSize.y, hdcMem, 0, 0,

+       SRCCOPY);

+

+  // Delete the memory bitmaps.

+  DeleteObject(SelectObject(hdcBack, bmBackOld));

+  DeleteObject(SelectObject(hdcObject, bmObjectOld));

+  DeleteObject(SelectObject(hdcMem, bmMemOld));

+  DeleteObject(SelectObject(hdcTemp, OldBitmap));

+

+  // Delete the memory DCs.

+  DeleteDC(hdcMem);

+  DeleteDC(hdcBack);

+  DeleteDC(hdcObject);

+  DeleteDC(hdcTemp);

+end;

+

+{Make the table for a fast CRC.}

+procedure make_crc_table;

+var

+  c: Cardinal;

+  n, k: Integer;

+begin

+

+  {fill the crc table}

+  for n := 0 to 255 do

+  begin

+    c := Cardinal(n);

+    for k := 0 to 7 do

+    begin

+      if Boolean(c and 1) then

+        c := $edb88320 xor (c shr 1)

+      else

+        c := c shr 1;

+    end;

+    crc_table[n] := c;

+  end;

+

+  {The table has already being computated}

+  crc_table_computed := true;

+end;

+

+{Update a running CRC with the bytes buf[0..len-1]--the CRC

+ should be initialized to all 1's, and the transmitted value

+ is the 1's complement of the final running CRC (see the

+ crc() routine below)).}

+function update_crc(crc: {$IFNDEF DelphiBuilder3Less}Cardinal{$ELSE}Integer

+  {$ENDIF}; buf: pByteArray; len: Integer): Cardinal;

+var

+  c: Cardinal;

+  n: Integer;

+begin

+  c := crc;

+

+  {Create the crc table in case it has not being computed yet}

+  if not crc_table_computed then make_crc_table;

+

+  {Update}

+  for n := 0 to len - 1 do

+    c := crc_table[(c XOR buf^[n]) and $FF] XOR (c shr 8);

+

+  {Returns}

+  Result := c;

+end;

+

+{$IFNDEF UseDelphi}

+  function FileExists(Filename: String): Boolean;

+  var

+    FindFile: THandle;

+    FindData: TWin32FindData;

+  begin

+    FindFile := FindFirstFile(PChar(Filename), FindData);

+    Result := FindFile <> INVALID_HANDLE_VALUE;

+    if Result then Windows.FindClose(FindFile);

+  end;

+

+

+{$ENDIF}

+

+{$IFNDEF UseDelphi}

+  {Exception implementation}

+  constructor Exception.Create(Msg: String);

+  begin

+  end;

+{$ENDIF}

+

+{Calculates the paeth predictor}

+function PaethPredictor(a, b, c: Byte): Byte;

+var

+  pa, pb, pc: Integer;

+begin

+  { a = left, b = above, c = upper left }

+  pa := abs(b - c);      { distances to a, b, c }

+  pb := abs(a - c);

+  pc := abs(a + b - c * 2);

+

+  { return nearest of a, b, c, breaking ties in order a, b, c }

+  if (pa <= pb) and (pa <= pc) then

+    Result := a

+  else

+    if pb <= pc then

+      Result := b

+    else

+      Result := c;

+end;

+

+{Invert bytes using assembly}

+function ByteSwap(const a: integer): integer;

+asm

+  bswap eax

+end;

+function ByteSwap16(inp:word): word;

+asm

+  bswap eax

+  shr   eax, 16

+end;

+

+{Calculates number of bytes for the number of pixels using the}

+{color mode in the paramenter}

+function BytesForPixels(const Pixels: Integer; const ColorType,

+  BitDepth: Byte): Integer;

+begin

+  case ColorType of

+    {Palette and grayscale contains a single value, for palette}

+    {an value of size 2^bitdepth pointing to the palette index}

+    {and grayscale the value from 0 to 2^bitdepth with color intesity}

+    COLOR_GRAYSCALE, COLOR_PALETTE:

+      Result := (Pixels * BitDepth + 7) div 8;

+    {RGB contains 3 values R, G, B with size 2^bitdepth each}

+    COLOR_RGB:

+      Result := (Pixels * BitDepth * 3) div 8;

+    {Contains one value followed by alpha value booth size 2^bitdepth}

+    COLOR_GRAYSCALEALPHA:

+      Result := (Pixels * BitDepth * 2) div 8;

+    {Contains four values size 2^bitdepth, Red, Green, Blue and alpha}

+    COLOR_RGBALPHA:

+      Result := (Pixels * BitDepth * 4) div 8;

+    else

+      Result := 0;

+  end {case ColorType}

+end;

+

+type

+  pChunkClassInfo = ^TChunkClassInfo;

+  TChunkClassInfo = record

+    ClassName: TChunkClass;

+  end;

+

+{Register a chunk type}

+procedure RegisterChunk(ChunkClass: TChunkClass);

+var

+  NewClass: pChunkClassInfo;

+begin

+  {In case the list object has not being created yet}

+  if ChunkClasses = nil then ChunkClasses := TPngPointerList.Create(nil);

+

+  {Add this new class}

+  new(NewClass);

+  NewClass^.ClassName := ChunkClass;

+  ChunkClasses.Add(NewClass);

+end;

+

+{Free chunk class list}

+procedure FreeChunkClassList;

+var

+  i: Integer;

+begin

+  if (ChunkClasses <> nil) then

+  begin

+    FOR i := 0 TO ChunkClasses.Count - 1 do

+      Dispose(pChunkClassInfo(ChunkClasses.Item[i]));

+    ChunkClasses.Free;

+  end;

+end;

+

+{Registering of common chunk classes}

+procedure RegisterCommonChunks;

+begin

+  {Important chunks}

+  RegisterChunk(TChunkIEND);

+  RegisterChunk(TChunkIHDR);

+  RegisterChunk(TChunkIDAT);

+  RegisterChunk(TChunkPLTE);

+  RegisterChunk(TChunkgAMA);

+  RegisterChunk(TChunktRNS);

+

+  {Not so important chunks}

+  RegisterChunk(TChunktIME);

+  RegisterChunk(TChunktEXt);

+  RegisterChunk(TChunkzTXt);

+end;

+

+{Creates a new chunk of this class}

+function CreateClassChunk(Owner: TPngObject; Name: TChunkName): TChunk;

+var

+  i       : Integer;

+  NewChunk: TChunkClass;

+begin

+  {Looks for this chunk}

+  NewChunk := TChunk;  {In case there is no registered class for this}

+

+  {Looks for this class in all registered chunks}

+  if Assigned(ChunkClasses) then

+    FOR i := 0 TO ChunkClasses.Count - 1 DO

+    begin

+      if pChunkClassInfo(ChunkClasses.Item[i])^.ClassName.GetName = Name then

+      begin

+        NewChunk := pChunkClassInfo(ChunkClasses.Item[i])^.ClassName;

+        break;

+      end;

+    end;

+

+  {Returns chunk class}

+  Result := NewChunk.Create(Owner);

+  Result.fName := Name;

+end;

+

+{ZLIB support}

+

+const

+  ZLIBAllocate = High(Word);

+

+{Initializes ZLIB for decompression}

+function ZLIBInitInflate(Stream: TStream): TZStreamRec2;

+begin

+  {Fill record}

+  Fillchar(Result, SIZEOF(TZStreamRec2), #0);

+

+  {Set internal record information}

+  with Result do

+  begin

+    GetMem(Data, ZLIBAllocate);

+    fStream := Stream;

+  end;

+

+  {Init decompression}

+  InflateInit_(Result.zlib, zlib_version, SIZEOF(TZStreamRec));

+end;

+

+{Initializes ZLIB for compression}

+function ZLIBInitDeflate(Stream: TStream;

+  Level: TCompressionlevel; Size: Cardinal): TZStreamRec2;

+begin

+  {Fill record}

+  Fillchar(Result, SIZEOF(TZStreamRec2), #0);

+

+  {Set internal record information}

+  with Result, ZLIB do

+  begin

+    GetMem(Data, Size);

+    fStream := Stream;

+    next_out := Data;

+    avail_out := Size;

+  end;

+

+  {Inits compression}

+  deflateInit_(Result.zlib, Level, zlib_version, sizeof(TZStreamRec));

+end;

+

+{Terminates ZLIB for compression}

+procedure ZLIBTerminateDeflate(var ZLIBStream: TZStreamRec2);

+begin

+  {Terminates decompression}

+  DeflateEnd(ZLIBStream.zlib);

+  {Free internal record}

+  FreeMem(ZLIBStream.Data, ZLIBAllocate);

+end;

+

+{Terminates ZLIB for decompression}

+procedure ZLIBTerminateInflate(var ZLIBStream: TZStreamRec2);

+begin

+  {Terminates decompression}

+  InflateEnd(ZLIBStream.zlib);

+  {Free internal record}

+  FreeMem(ZLIBStream.Data, ZLIBAllocate);

+end;

+

+{Decompresses ZLIB into a memory address}

+function DecompressZLIB(const Input: Pointer; InputSize: Integer;

+  var Output: Pointer; var OutputSize: Integer;

+  var ErrorOutput: String): Boolean;

+var

+  StreamRec : TZStreamRec;

+  Buffer    : Array[Byte] of Byte;

+  InflateRet: Integer;

+begin

+  with StreamRec do

+  begin

+    {Initializes}

+    Result := True;

+    OutputSize := 0;

+

+    {Prepares the data to decompress}

+    FillChar(StreamRec, SizeOf(TZStreamRec), #0);

+    InflateInit_(StreamRec, zlib_version, SIZEOF(TZStreamRec));

+    next_in := Input;

+    avail_in := InputSize;

+

+    {Decodes data}

+    repeat

+      {In case it needs an output buffer}

+      if (avail_out = 0) then

+      begin

+        next_out := @Buffer;

+        avail_out := SizeOf(Buffer);

+      end {if (avail_out = 0)};

+

+      {Decompress and put in output}

+      InflateRet := inflate(StreamRec, 0);

+      if (InflateRet = Z_STREAM_END) or (InflateRet = 0) then

+      begin

+        {Reallocates output buffer}

+        inc(OutputSize, total_out);

+        if Output = nil then

+          GetMem(Output, OutputSize) else ReallocMem(Output, OutputSize);

+        {Copies the new data}

+        CopyMemory(Ptr(Longint(Output) + OutputSize - total_out),

+          @Buffer, total_out);

+      end {if (InflateRet = Z_STREAM_END) or (InflateRet = 0)}

+      {Now tests for errors}

+      else if InflateRet < 0 then

+      begin

+        Result := False;

+        ErrorOutput := StreamRec.msg;

+        InflateEnd(StreamRec);

+        Exit;

+      end {if InflateRet < 0}

+    until InflateRet = Z_STREAM_END;

+

+    {Terminates decompression}

+    InflateEnd(StreamRec);

+  end {with StreamRec}

+

+end;

+

+{Compresses ZLIB into a memory address}

+function CompressZLIB(Input: Pointer; InputSize, CompressionLevel: Integer;

+  var Output: Pointer; var OutputSize: Integer;

+  var ErrorOutput: String): Boolean;

+var

+  StreamRec : TZStreamRec;

+  Buffer    : Array[Byte] of Byte;

+  DeflateRet: Integer;

+begin

+  with StreamRec do

+  begin

+    Result := True; {By default returns TRUE as everything might have gone ok}

+    OutputSize := 0; {Initialize}

+    {Prepares the data to compress}

+    FillChar(StreamRec, SizeOf(TZStreamRec), #0);

+    DeflateInit_(StreamRec, CompressionLevel,zlib_version, SIZEOF(TZStreamRec));

+

+    next_in := Input;

+    avail_in := InputSize;

+

+    while avail_in > 0 do

+    begin

+      {When it needs new buffer to stores the compressed data}

+      if avail_out = 0 then

+      begin

+        {Restore buffer}

+        next_out := @Buffer;

+        avail_out := SizeOf(Buffer);

+      end {if avail_out = 0};

+

+      {Compresses}

+      DeflateRet := deflate(StreamRec, Z_FINISH);

+

+      if (DeflateRet = Z_STREAM_END) or (DeflateRet = 0) then

+      begin

+        {Updates the output memory}

+        inc(OutputSize, total_out);

+        if Output = nil then

+          GetMem(Output, OutputSize) else ReallocMem(Output, OutputSize);

+

+        {Copies the new data}

+        CopyMemory(Ptr(Longint(Output) + OutputSize - total_out),

+          @Buffer, total_out);

+      end {if (InflateRet = Z_STREAM_END) or (InflateRet = 0)}

+      {Now tests for errors}

+      else if DeflateRet < 0 then

+      begin

+        Result := False;

+        ErrorOutput := StreamRec.msg;

+        DeflateEnd(StreamRec);

+        Exit;

+      end {if InflateRet < 0}

+

+    end {while avail_in > 0};

+

+    {Finishes compressing}

+    DeflateEnd(StreamRec);

+  end {with StreamRec}

+

+end;

+

+{TPngPointerList implementation}

+

+{Object being created}

+constructor TPngPointerList.Create(AOwner: TPNGObject);

+begin

+  inherited Create; {Let ancestor work}

+  {Holds owner}

+  fOwner := AOwner;

+  {Memory pointer not being used yet}

+  fMemory := nil;

+  {No items yet}

+  fCount := 0;

+end;

+

+{Removes value from the list}

+function TPngPointerList.Remove(Value: Pointer): Pointer;

+var

+  I, Position: Integer;

+begin

+  {Gets item position}

+  Position := -1;

+  FOR I := 0 TO Count - 1 DO

+    if Value = Item[I] then Position := I;

+  {In case a match was found}

+  if Position >= 0 then

+  begin

+    Result := Item[Position]; {Returns pointer}

+    {Remove item and move memory}

+    Dec(fCount);

+    if Position < Integer(FCount) then

+      System.Move(fMemory^[Position + 1], fMemory^[Position],

+      (Integer(fCount) - Position) * SizeOf(Pointer));

+  end {if Position >= 0} else Result := nil

+end;

+

+{Add a new value in the list}

+procedure TPngPointerList.Add(Value: Pointer);

+begin

+  Count := Count + 1;

+  Item[Count - 1] := Value;

+end;

+

+

+{Object being destroyed}

+destructor TPngPointerList.Destroy;

+begin

+  {Release memory if needed}

+  if fMemory <> nil then

+    FreeMem(fMemory, fCount * sizeof(Pointer));

+

+  {Free things}

+  inherited Destroy;

+end;

+

+{Returns one item from the list}

+function TPngPointerList.GetItem(Index: Cardinal): Pointer;

+begin

+  if (Index <= Count - 1) then

+    Result := fMemory[Index]

+  else

+    {In case it's out of bounds}

+    Result := nil;

+end;

+

+{Inserts a new item in the list}

+procedure TPngPointerList.Insert(Value: Pointer; Position: Cardinal);

+begin

+  if (Position < Count) then

+  begin

+    {Increase item count}

+    SetSize(Count + 1);

+    {Move other pointers}

+    if Position < Count then

+      System.Move(fMemory^[Position], fMemory^[Position + 1],

+        (Count - Position - 1) * SizeOf(Pointer));

+    {Sets item}

+    Item[Position] := Value;

+  end;

+end;

+

+{Sets one item from the list}

+procedure TPngPointerList.SetItem(Index: Cardinal; const Value: Pointer);

+begin

+  {If index is in bounds, set value}

+  if (Index <= Count - 1) then

+    fMemory[Index] := Value

+end;

+

+{This method resizes the list}

+procedure TPngPointerList.SetSize(const Size: Cardinal);

+begin

+  {Sets the size}

+  if (fMemory = nil) and (Size > 0) then

+    GetMem(fMemory, Size * SIZEOF(Pointer))

+  else

+    if Size > 0 then  {Only realloc if the new size is greater than 0}

+      ReallocMem(fMemory, Size * SIZEOF(Pointer))

+    else

+    {In case user is resize to 0 items}

+    begin

+      FreeMem(fMemory);

+      fMemory := nil;

+    end;

+  {Update count}

+  fCount := Size;

+end;

+

+{TPNGList implementation}

+

+{Removes an item}

+procedure TPNGList.RemoveChunk(Chunk: TChunk);

+begin

+  Remove(Chunk);

+  Chunk.Free

+end;

+

+{Add a new item}

+function TPNGList.Add(ChunkClass: TChunkClass): TChunk;

+var

+  IHDR: TChunkIHDR;

+  IEND: TChunkIEND;

+

+  IDAT: TChunkIDAT;

+  PLTE: TChunkPLTE;

+begin

+  Result := nil; {Default result}

+  {Adding these is not allowed}

+  if (ChunkClass = TChunkIHDR) or (ChunkClass = TChunkIDAT) or

+    (ChunkClass = TChunkPLTE) or (ChunkClass = TChunkIEND) then

+    fOwner.RaiseError(EPngError, EPNGCannotAddChunkText)

+  {Two of these is not allowed}

+  else if ((ChunkClass = TChunkgAMA) and (ItemFromClass(TChunkgAMA) <> nil)) or

+     ((ChunkClass = TChunktRNS) and (ItemFromClass(TChunktRNS) <> nil)) then

+    fOwner.RaiseError(EPngError, EPNGCannotAddChunkText)

+  {There must have an IEND and IHDR chunk}

+  else if (ItemFromClass(TChunkIEND) = nil) or

+    (ItemFromClass(TChunkIHDR) = nil) then

+    fOwner.RaiseError(EPngError, EPNGCannotAddInvalidImageText)

+  else

+  begin

+    {Get common chunks}

+    IHDR := ItemFromClass(TChunkIHDR) as TChunkIHDR;

+    IEND := ItemFromClass(TChunkIEND) as TChunkIEND;

+    {Create new chunk}

+    Result := ChunkClass.Create(Owner);

+    {Add to the list}

+    if (ChunkClass = TChunkgAMA) then

+      Insert(Result, IHDR.Index + 1)

+    {Transparency chunk (fix by Ian Boyd)}

+    else if (ChunkClass = TChunktRNS) then

+    begin

+      {Transparecy chunk must be after PLTE; before IDAT}

+      IDAT := ItemFromClass(TChunkIDAT) as TChunkIDAT;

+      PLTE := ItemFromClass(TChunkPLTE) as TChunkPLTE;

+

+      if Assigned(PLTE) then

+        Insert(Result, PLTE.Index + 1)

+      else if Assigned(IDAT) then

+        Insert(Result, IDAT.Index)

+      else

+        Insert(Result, IHDR.Index + 1)

+    end

+    else {All other chunks}

+      Insert(Result, IEND.Index);

+  end {if}

+end;

+

+{Returns item from the list}

+function TPNGList.GetItem(Index: Cardinal): TChunk;

+begin

+  Result := inherited GetItem(Index);

+end;

+

+{Returns first item from the list using the class from parameter}

+function TPNGList.ItemFromClass(ChunkClass: TChunkClass): TChunk;

+var

+  i: Integer;

+begin

+  Result := nil; {Initial result}

+  FOR i := 0 TO Count - 1 DO

+    {Test if this item has the same class}

+    if Item[i] is ChunkClass then

+    begin

+      {Returns this item and exit}

+      Result := Item[i];

+      break;

+    end {if}

+end;

+

+{$IFNDEF UseDelphi}

+

+  {TStream implementation}

+

+  {Copies all from another stream}

+  function TStream.CopyFrom(Source: TStream; Count: Cardinal): Cardinal;

+  const

+    MaxBytes = $f000;

+  var

+    Buffer:  PChar;

+    BufSize, N: Cardinal;

+  begin

+    {If count is zero, copy everything from Source}

+    if Count = 0 then

+    begin

+      Source.Seek(0, soFromBeginning);

+      Count := Source.Size;

+    end;

+

+    Result := Count; {Returns the number of bytes readed}

+    {Allocates memory}

+    if Count > MaxBytes then BufSize := MaxBytes else BufSize := Count;

+    GetMem(Buffer, BufSize);

+

+    {Copy memory}

+    while Count > 0 do

+    begin

+      if Count > BufSize then N := BufSize else N := Count;

+      Source.Read(Buffer^, N);

+      Write(Buffer^, N);

+      dec(Count, N);

+    end;

+

+    {Deallocates memory}

+    FreeMem(Buffer, BufSize);

+  end;

+

+{Set current stream position}

+procedure TStream.SetPosition(const Value: Longint);

+begin

+  Seek(Value, soFromBeginning);

+end;

+

+{Returns position}

+function TStream.GetPosition: Longint;

+begin

+  Result := Seek(0, soFromCurrent);

+end;

+

+  {Returns stream size}

+function TStream.GetSize: Longint;

+  var

+    Pos: Cardinal;

+  begin

+    Pos := Seek(0, soFromCurrent);

+    Result := Seek(0, soFromEnd);

+    Seek(Pos, soFromCurrent);

+  end;

+

+  {TFileStream implementation}

+

+  {Filestream object being created}

+  constructor TFileStream.Create(Filename: String; Mode: TFileStreamModeSet);

+    {Makes file mode}

+    function OpenMode: DWORD;

+    begin

+      Result := 0;

+      if fsmRead in Mode then Result := GENERIC_READ;

+      if (fsmWrite in Mode) or (fsmCreate in Mode) then

+        Result := Result OR GENERIC_WRITE;

+    end;

+  const

+    IsCreate: Array[Boolean] of Integer = (OPEN_ALWAYS, CREATE_ALWAYS);

+  begin

+    {Call ancestor}

+    inherited Create;

+

+    {Create handle}

+    fHandle := CreateFile(PChar(Filename), OpenMode, FILE_SHARE_READ or

+      FILE_SHARE_WRITE, nil, IsCreate[fsmCreate in Mode], 0, 0);

+    {Store mode}

+    FileMode := Mode;

+  end;

+

+  {Filestream object being destroyed}

+  destructor TFileStream.Destroy;

+  begin

+    {Terminates file and close}

+    if FileMode = [fsmWrite] then

+      SetEndOfFile(fHandle);

+    CloseHandle(fHandle);

+

+    {Call ancestor}

+    inherited Destroy;

+  end;

+

+  {Writes data to the file}

+  function TFileStream.Write(const Buffer; Count: Longint): Cardinal;

+  begin

+    if not WriteFile(fHandle, Buffer, Count, Result, nil) then

+      Result := 0;

+  end;

+

+  {Reads data from the file}

+  function TFileStream.Read(var Buffer; Count: Longint): Cardinal;

+  begin

+    if not ReadFile(fHandle, Buffer, Count, Result, nil) then

+      Result := 0;

+  end;

+

+  {Seeks the file position}

+  function TFileStream.Seek(Offset: Integer; Origin: Word): Longint;

+  begin

+    Result := SetFilePointer(fHandle, Offset, nil, Origin);

+  end;

+

+  {Sets the size of the file}

+  procedure TFileStream.SetSize(const Value: Longint);

+  begin

+    Seek(Value, soFromBeginning);

+    SetEndOfFile(fHandle);

+  end;

+

+  {TResourceStream implementation}

+

+  {Creates the resource stream}

+  constructor TResourceStream.Create(Instance: HInst; const ResName: String;

+    ResType: PChar);

+  var

+    ResID: HRSRC;

+    ResGlobal: HGlobal;

+  begin

+    {Obtains the resource ID}

+    ResID := FindResource(hInstance, PChar(ResName), RT_RCDATA);

+    if ResID = 0 then raise EPNGError.Create('');

+    {Obtains memory and size}

+    ResGlobal := LoadResource(hInstance, ResID);

+    Size := SizeOfResource(hInstance, ResID);

+    Memory := LockResource(ResGlobal);

+    if (ResGlobal = 0) or (Memory = nil) then EPNGError.Create('');

+  end;

+

+

+  {Setting resource stream size is not supported}

+  procedure TResourceStream.SetSize(const Value: Integer);

+  begin

+  end;

+

+  {Writing into a resource stream is not supported}

+  function TResourceStream.Write(const Buffer; Count: Integer): Cardinal;

+  begin

+    Result := 0;

+  end;

+

+  {Reads data from the stream}

+  function TResourceStream.Read(var Buffer; Count: Integer): Cardinal;

+  begin

+    //Returns data

+    CopyMemory(@Buffer, Ptr(Longint(Memory) + Position), Count);

+    //Update position

+    inc(Position, Count);

+    //Returns

+    Result := Count;

+  end;

+

+  {Seeks data}

+  function TResourceStream.Seek(Offset: Integer; Origin: Word): Longint;

+  begin

+    {Move depending on the origin}

+    case Origin of

+      soFromBeginning: Position := Offset;

+      soFromCurrent: inc(Position, Offset);

+      soFromEnd: Position := Size + Offset;

+    end;

+

+    {Returns the current position}

+    Result := Position;

+  end;

+

+{$ENDIF}

+

+{TChunk implementation}

+

+{Resizes the data}

+procedure TChunk.ResizeData(const NewSize: Cardinal);

+begin

+  fDataSize := NewSize;

+  ReallocMem(fData, NewSize + 1);

+end;

+

+{Returns index from list}

+function TChunk.GetIndex: Integer;

+var

+  i: Integer;

+begin

+  Result := -1; {Avoiding warnings}

+  {Searches in the list}

+  FOR i := 0 TO Owner.Chunks.Count - 1 DO

+    if Owner.Chunks.Item[i] = Self then

+    begin

+      {Found match}

+      Result := i;

+      exit;

+    end {for i}

+end;

+

+{Returns pointer to the TChunkIHDR}

+function TChunk.GetHeader: TChunkIHDR;

+begin

+  Result := Owner.Chunks.Item[0] as TChunkIHDR;

+end;

+

+{Assigns from another TChunk}

+procedure TChunk.Assign(Source: TChunk);

+begin

+  {Copy properties}

+  fName := Source.fName;

+  {Set data size and realloc}

+  ResizeData(Source.fDataSize);

+

+  {Copy data (if there's any)}

+  if fDataSize > 0 then CopyMemory(fData, Source.fData, fDataSize);

+end;

+

+{Chunk being created}

+constructor TChunk.Create(Owner: TPngObject);

+var

+  ChunkName: String;

+begin

+  {Ancestor create}

+  inherited Create;

+

+  {If it's a registered class, set the chunk name based on the class}

+  {name. For instance, if the class name is TChunkgAMA, the GAMA part}

+  {will become the chunk name}

+  ChunkName := Copy(ClassName, Length('TChunk') + 1, Length(ClassName));

+  if Length(ChunkName) = 4 then CopyMemory(@fName[0], @ChunkName[1], 4);

+

+  {Initialize data holder}

+  GetMem(fData, 1);

+  fDataSize := 0;

+  {Record owner}

+  fOwner := Owner;

+end;

+

+{Chunk being destroyed}

+destructor TChunk.Destroy;

+begin

+  {Free data holder}

+  FreeMem(fData, fDataSize + 1);

+  {Let ancestor destroy}

+  inherited Destroy;

+end;

+

+{Returns the chunk name 1}

+function TChunk.GetChunkName: String;

+begin

+  Result := fName

+end;

+

+{Returns the chunk name 2}

+class function TChunk.GetName: String;

+begin

+  {For avoid writing GetName for each TChunk descendent, by default for}

+  {classes which don't declare GetName, it will look for the class name}

+  {to extract the chunk kind. Example, if the class name is TChunkIEND }

+  {this method extracts and returns IEND}

+  Result := Copy(ClassName, Length('TChunk') + 1, Length(ClassName));

+end;

+

+{Saves the data to the stream}

+function TChunk.SaveData(Stream: TStream): Boolean;

+var

+  ChunkSize, ChunkCRC: Cardinal;

+begin

+  {First, write the size for the following data in the chunk}

+  ChunkSize := ByteSwap(DataSize);

+  Stream.Write(ChunkSize, 4);

+  {The chunk name}

+  Stream.Write(fName, 4);

+  {If there is data for the chunk, write it}

+  if DataSize > 0 then Stream.Write(Data^, DataSize);

+  {Calculates and write CRC}

+  ChunkCRC := update_crc($ffffffff, @fName[0], 4);

+  ChunkCRC := Byteswap(update_crc(ChunkCRC, Data, DataSize) xor $ffffffff);

+  Stream.Write(ChunkCRC, 4);

+

+  {Returns that everything went ok}

+  Result := TRUE;

+end;

+

+{Saves the chunk to the stream}

+function TChunk.SaveToStream(Stream: TStream): Boolean;

+begin

+  Result := SaveData(Stream)

+end;

+

+

+{Loads the chunk from a stream}

+function TChunk.LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+  Size: Integer): Boolean;

+var

+  CheckCRC: Cardinal;

+  {$IFDEF CheckCRC}RightCRC: Cardinal;{$ENDIF}

+begin

+  {Copies data from source}

+  ResizeData(Size);

+  if Size > 0 then Stream.Read(fData^, Size);

+  {Reads CRC}

+  Stream.Read(CheckCRC, 4);

+  CheckCrc := ByteSwap(CheckCRC);

+

+  {Check if crc readed is valid}

+  {$IFDEF CheckCRC}

+    RightCRC := update_crc($ffffffff, @ChunkName[0], 4);

+    RightCRC := update_crc(RightCRC, fData, Size) xor $ffffffff;

+    Result := RightCRC = CheckCrc;

+

+    {Handle CRC error}

+    if not Result then

+    begin

+      {In case it coult not load chunk}

+      Owner.RaiseError(EPngInvalidCRC, EPngInvalidCRCText);

+      exit;

+    end

+  {$ELSE}Result := TRUE; {$ENDIF}

+

+end;

+

+{TChunktIME implementation}

+

+{Chunk being loaded from a stream}

+function TChunktIME.LoadFromStream(Stream: TStream;

+  const ChunkName: TChunkName; Size: Integer): Boolean;

+begin

+  {Let ancestor load the data}

+  Result := inherited LoadFromStream(Stream, ChunkName, Size);

+  if not Result or (Size <> 7) then exit; {Size must be 7}

+

+  {Reads data}

+  fYear := ((pByte(Longint(Data) )^) * 256)+ (pByte(Longint(Data) + 1)^);

+  fMonth := pByte(Longint(Data) + 2)^;

+  fDay := pByte(Longint(Data) + 3)^;

+  fHour := pByte(Longint(Data) + 4)^;

+  fMinute := pByte(Longint(Data) + 5)^;

+  fSecond := pByte(Longint(Data) + 6)^;

+end;

+

+{Saving the chunk to a stream}

+function TChunktIME.SaveToStream(Stream: TStream): Boolean;

+begin

+  {Update data}

+  ResizeData(7);  {Make sure the size is 7}

+  pWord(Data)^ := Year;

+  pByte(Longint(Data) + 2)^ := Month;

+  pByte(Longint(Data) + 3)^ := Day;

+  pByte(Longint(Data) + 4)^ := Hour;

+  pByte(Longint(Data) + 5)^ := Minute;

+  pByte(Longint(Data) + 6)^ := Second;

+

+  {Let inherited save data}

+  Result := inherited SaveToStream(Stream);

+end;

+

+{TChunkztXt implementation}

+

+{Loading the chunk from a stream}

+function TChunkzTXt.LoadFromStream(Stream: TStream;

+  const ChunkName: TChunkName; Size: Integer): Boolean;

+var

+  ErrorOutput: String;

+  CompressionMethod: Byte;

+  Output: Pointer;

+  OutputSize: Integer;

+begin

+  {Load data from stream and validate}

+  Result := inherited LoadFromStream(Stream, ChunkName, Size);

+  if not Result or (Size < 4) then exit;

+  fKeyword := PChar(Data);  {Get keyword and compression method bellow}

+  CompressionMethod := pByte(Longint(fKeyword) + Length(fKeyword))^;

+  fText := '';

+

+  {In case the compression is 0 (only one accepted by specs), reads it}

+  if CompressionMethod = 0 then

+  begin

+    Output := nil;

+    if DecompressZLIB(PChar(Longint(Data) + Length(fKeyword) + 2),

+      Size - Length(fKeyword) - 2, Output, OutputSize, ErrorOutput) then

+    begin

+      SetLength(fText, OutputSize);

+      CopyMemory(@fText[1], Output, OutputSize);

+    end {if DecompressZLIB(...};

+    FreeMem(Output);

+  end {if CompressionMethod = 0}

+

+end;

+

+{Saving the chunk to a stream}

+function TChunkztXt.SaveToStream(Stream: TStream): Boolean;

+var

+  Output: Pointer;

+  OutputSize: Integer;

+  ErrorOutput: String;

+begin

+  Output := nil; {Initializes output}

+  if fText = '' then fText := ' ';

+

+  {Compresses the data}

+  if CompressZLIB(@fText[1], Length(fText), Owner.CompressionLevel, Output,

+    OutputSize, ErrorOutput) then

+  begin

+    {Size is length from keyword, plus a null character to divide}

+    {plus the compression method, plus the length of the text (zlib compressed)}

+    ResizeData(Length(fKeyword) + 2 + OutputSize);

+

+    Fillchar(Data^, DataSize, #0);

+    {Copies the keyword data}

+    if Keyword <> '' then

+      CopyMemory(Data, @fKeyword[1], Length(Keyword));

+    {Compression method 0 (inflate/deflate)}

+    pByte(Ptr(Longint(Data) + Length(Keyword) + 1))^ := 0;

+    if OutputSize > 0 then

+      CopyMemory(Ptr(Longint(Data) + Length(Keyword) + 2), Output, OutputSize);

+

+    {Let ancestor calculate crc and save}

+    Result := SaveData(Stream);

+  end {if CompressZLIB(...} else Result := False;

+

+  {Frees output}

+  if Output <> nil then FreeMem(Output)

+end;

+

+{TChunktEXt implementation}

+

+{Assigns from another text chunk}

+procedure TChunktEXt.Assign(Source: TChunk);

+begin

+  fKeyword := TChunktEXt(Source).fKeyword;

+  fText := TChunktEXt(Source).fText;

+end;

+

+{Loading the chunk from a stream}

+function TChunktEXt.LoadFromStream(Stream: TStream;

+  const ChunkName: TChunkName; Size: Integer): Boolean;

+begin

+  {Load data from stream and validate}

+  Result := inherited LoadFromStream(Stream, ChunkName, Size);

+  if not Result or (Size < 3) then exit;

+  {Get text}

+  fKeyword := PChar(Data);

+  SetLength(fText, Size - Length(fKeyword) - 1);

+  CopyMemory(@fText[1], Ptr(Longint(Data) + Length(fKeyword) + 1),

+    Length(fText));

+end;

+

+{Saving the chunk to a stream}

+function TChunktEXt.SaveToStream(Stream: TStream): Boolean;

+begin

+  {Size is length from keyword, plus a null character to divide}

+  {plus the length of the text}

+  ResizeData(Length(fKeyword) + 1 + Length(fText));

+  Fillchar(Data^, DataSize, #0);

+  {Copy data}

+  if Keyword <> '' then

+    CopyMemory(Data, @fKeyword[1], Length(Keyword));

+  if Text <> '' then

+    CopyMemory(Ptr(Longint(Data) + Length(Keyword) + 1), @fText[1],

+      Length(Text));

+  {Let ancestor calculate crc and save}

+  Result := inherited SaveToStream(Stream);

+end;

+

+

+{TChunkIHDR implementation}

+

+{Chunk being created}

+constructor TChunkIHDR.Create(Owner: TPngObject);

+begin

+  {Call inherited}

+  inherited Create(Owner);

+  {Prepare pointers}

+  ImageHandle := 0;

+  ImageDC := 0;

+end;

+

+{Chunk being destroyed}

+destructor TChunkIHDR.Destroy;

+begin

+  {Free memory}

+  FreeImageData();

+

+  {Calls TChunk destroy}

+  inherited Destroy;

+end;

+

+{Assigns from another IHDR chunk}

+procedure TChunkIHDR.Assign(Source: TChunk);

+begin

+  {Copy the IHDR data}

+  if Source is TChunkIHDR then

+  begin

+    {Copy IHDR values}

+    IHDRData := TChunkIHDR(Source).IHDRData;

+

+    {Prepare to hold data by filling BitmapInfo structure and}

+    {resizing ImageData and ImageAlpha memory allocations}

+    PrepareImageData();

+

+    {Copy image data}

+    CopyMemory(ImageData, TChunkIHDR(Source).ImageData,

+      BytesPerRow * Integer(Height));

+    CopyMemory(ImageAlpha, TChunkIHDR(Source).ImageAlpha,

+      Integer(Width) * Integer(Height));

+

+    {Copy palette colors}

+    BitmapInfo.bmiColors := TChunkIHDR(Source).BitmapInfo.bmiColors;

+  end

+  else

+    Owner.RaiseError(EPNGError, EPNGCannotAssignChunkText);

+end;

+

+{Release allocated image data}

+procedure TChunkIHDR.FreeImageData;

+begin

+  {Free old image data}

+  if ImageHandle <> 0  then DeleteObject(ImageHandle);

+  if ImageDC     <> 0  then DeleteDC(ImageDC);

+  if ImageAlpha <> nil then FreeMem(ImageAlpha);

+  {$IFDEF Store16bits}

+  if ExtraImageData <> nil then FreeMem(ExtraImageData);

+  {$ENDIF}

+  ImageHandle := 0; ImageDC := 0; ImageAlpha := nil; ImageData := nil;

+end;

+

+{Chunk being loaded from a stream}

+function TChunkIHDR.LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+  Size: Integer): Boolean;

+begin

+  {Let TChunk load it}

+  Result := inherited LoadFromStream(Stream, ChunkName, Size);

+  if not Result then Exit;

+

+  {Now check values}

+  {Note: It's recommended by png specification to make sure that the size}

+  {must be 13 bytes to be valid, but some images with 14 bytes were found}

+  {which could be loaded by internet explorer and other tools}

+  if (fDataSize < SIZEOF(TIHdrData)) then

+  begin

+    {Ihdr must always have at least 13 bytes}

+    Result := False;

+    Owner.RaiseError(EPNGInvalidIHDR, EPNGInvalidIHDRText);

+    exit;

+  end;

+

+  {Everything ok, reads IHDR}

+  IHDRData := pIHDRData(fData)^;

+  IHDRData.Width := ByteSwap(IHDRData.Width);

+  IHDRData.Height := ByteSwap(IHDRData.Height);

+

+  {The width and height must not be larger than 65535 pixels}

+  if (IHDRData.Width > High(Word)) or (IHDRData.Height > High(Word)) then

+  begin

+    Result := False;

+    Owner.RaiseError(EPNGSizeExceeds, EPNGSizeExceedsText);

+    exit;

+  end {if IHDRData.Width > High(Word)};

+  {Compression method must be 0 (inflate/deflate)}

+  if (IHDRData.CompressionMethod <> 0) then

+  begin

+    Result := False;

+    Owner.RaiseError(EPNGUnknownCompression, EPNGUnknownCompressionText);

+    exit;

+  end;

+  {Interlace must be either 0 (none) or 7 (adam7)}

+  if (IHDRData.InterlaceMethod <> 0) and (IHDRData.InterlaceMethod <> 1) then

+  begin

+    Result := False;

+    Owner.RaiseError(EPNGUnknownInterlace, EPNGUnknownInterlaceText);

+    exit;

+  end;

+

+  {Updates owner properties}

+  Owner.InterlaceMethod := TInterlaceMethod(IHDRData.InterlaceMethod);

+

+  {Prepares data to hold image}

+  PrepareImageData();

+end;

+

+{Saving the IHDR chunk to a stream}

+function TChunkIHDR.SaveToStream(Stream: TStream): Boolean;

+begin

+  {Ignore 2 bits images}

+  if BitDepth = 2 then BitDepth := 4;

+

+  {It needs to do is update the data with the IHDR data}

+  {structure containing the write values}

+  ResizeData(SizeOf(TIHDRData));

+  pIHDRData(fData)^ := IHDRData;

+  {..byteswap 4 byte types}

+  pIHDRData(fData)^.Width := ByteSwap(pIHDRData(fData)^.Width);

+  pIHDRData(fData)^.Height := ByteSwap(pIHDRData(fData)^.Height);

+  {..update interlace method}

+  pIHDRData(fData)^.InterlaceMethod := Byte(Owner.InterlaceMethod);

+  {..and then let the ancestor SaveToStream do the hard work}

+  Result := inherited SaveToStream(Stream);

+end;

+

+{Resizes the image data to fill the color type, bit depth, }

+{width and height parameters}

+procedure TChunkIHDR.PrepareImageData();

+

+  {Set the bitmap info}

+  procedure SetInfo(const Bitdepth: Integer; const Palette: Boolean);

+  begin

+

+    {Copy if the bitmap contain palette entries}

+    HasPalette := Palette;

+    {Initialize the structure with zeros}

+    fillchar(BitmapInfo, sizeof(BitmapInfo), #0);

+    {Fill the strucutre}

+    with BitmapInfo.bmiHeader do

+    begin

+      biSize := sizeof(TBitmapInfoHeader);

+      biHeight := Height;

+      biWidth := Width;

+      biPlanes := 1;

+      biBitCount := BitDepth;

+      biCompression := BI_RGB;

+    end {with BitmapInfo.bmiHeader}

+  end;

+begin

+  {Prepare bitmap info header}

+  Fillchar(BitmapInfo, sizeof(TMaxBitmapInfo), #0);

+  {Release old image data}

+  FreeImageData();

+

+  {Obtain number of bits for each pixel}

+  case ColorType of

+    COLOR_GRAYSCALE, COLOR_PALETTE, COLOR_GRAYSCALEALPHA:

+      case BitDepth of

+        {These are supported by windows}

+        1, 4, 8: SetInfo(BitDepth, TRUE);

+        {2 bits for each pixel is not supported by windows bitmap}

+        2      : SetInfo(4, TRUE);

+        {Also 16 bits (2 bytes) for each pixel is not supported}

+        {and should be transormed into a 8 bit grayscale}

+        16     : SetInfo(8, TRUE);

+      end;

+    {Only 1 byte (8 bits) is supported}

+    COLOR_RGB, COLOR_RGBALPHA:  SetInfo(24, FALSE);

+  end {case ColorType};

+  {Number of bytes for each scanline}

+  BytesPerRow := (((BitmapInfo.bmiHeader.biBitCount * Width) + 31)

+    and not 31) div 8;

+

+  {Build array for alpha information, if necessary}

+  if (ColorType = COLOR_RGBALPHA) or (ColorType = COLOR_GRAYSCALEALPHA) then

+  begin

+    GetMem(ImageAlpha, Integer(Width) * Integer(Height));

+    FillChar(ImageAlpha^, Integer(Width) * Integer(Height), #0);

+  end;

+

+  {Build array for extra byte information}

+  {$IFDEF Store16bits}

+  if (BitDepth = 16) then

+  begin

+    GetMem(ExtraImageData, BytesPerRow * Integer(Height));

+    FillChar(ExtraImageData^, BytesPerRow * Integer(Height), #0);

+  end;

+  {$ENDIF}

+

+  {Creates the image to hold the data, CreateDIBSection does a better}

+  {work in allocating necessary memory}

+  ImageDC := CreateCompatibleDC(0);

+  ImageHandle := CreateDIBSection(ImageDC, pBitmapInfo(@BitmapInfo)^,

+    DIB_RGB_COLORS, ImageData, 0, 0);

+

+  {Clears the old palette (if any)}

+  with Owner do

+    if  TempPalette <> 0 then

+    begin

+      DeleteObject(TempPalette);

+      TempPalette := 0;

+    end {with Owner, if TempPalette <> 0};

+

+  {Build array and allocate bytes for each row}

+  zeromemory(ImageData, BytesPerRow * Integer(Height));

+end;

+

+{TChunktRNS implementation}

+

+{$IFNDEF UseDelphi}

+function CompareMem(P1, P2: pByte; const Size: Integer): Boolean;

+var i: Integer;

+begin

+  Result := True;

+  for i := 1 to Size do

+  begin

+    if P1^ <> P2^ then Result := False;

+    inc(P1); inc(P2);

+  end {for i}

+end;

+{$ENDIF}

+

+{Sets the transpararent color}

+procedure TChunktRNS.SetTransparentColor(const Value: ColorRef);

+var

+  i: Byte;

+  LookColor: TRGBQuad;

+begin

+  {Clears the palette values}

+  Fillchar(PaletteValues, SizeOf(PaletteValues), #0);

+  {Sets that it uses bit transparency}

+  fBitTransparency := True;

+

+

+  {Depends on the color type}

+  with Header do

+    case ColorType of

+      COLOR_GRAYSCALE:

+      begin

+        Self.ResizeData(2);

+        pWord(@PaletteValues[0])^ := ByteSwap16(GetRValue(Value));

+      end;

+      COLOR_RGB:

+      begin

+        Self.ResizeData(6);

+        pWord(@PaletteValues[0])^ := ByteSwap16(GetRValue(Value));

+        pWord(@PaletteValues[2])^ := ByteSwap16(GetGValue(Value));

+        pWord(@PaletteValues[4])^ := ByteSwap16(GetBValue(Value));

+      end;

+      COLOR_PALETTE:

+      begin

+        {Creates a RGBQuad to search for the color}

+        LookColor.rgbRed := GetRValue(Value);

+        LookColor.rgbGreen := GetGValue(Value);

+        LookColor.rgbBlue := GetBValue(Value);

+        {Look in the table for the entry}

+        for i := 0 to 255 do

+          if CompareMem(@BitmapInfo.bmiColors[i], @LookColor, 3) then

+            Break;

+        {Fill the transparency table}

+        Fillchar(PaletteValues, i, 255);

+        Self.ResizeData(i + 1)

+

+      end

+    end {case / with};

+

+end;

+

+{Returns the transparent color for the image}

+function TChunktRNS.GetTransparentColor: ColorRef;

+var

+  PaletteChunk: TChunkPLTE;

+  i: Integer;

+begin

+  Result := 0; {Default: Unknown transparent color}

+

+  {Depends on the color type}

+  with Header do

+    case ColorType of

+      COLOR_GRAYSCALE:

+          Result := RGB(PaletteValues[0], PaletteValues[0],

+        PaletteValues[0]);

+      COLOR_RGB:

+          Result := RGB(PaletteValues[1], PaletteValues[3], PaletteValues[5]);

+      COLOR_PALETTE:

+      begin

+        {Obtains the palette chunk}

+        PaletteChunk := Owner.Chunks.ItemFromClass(TChunkPLTE) as TChunkPLTE;

+

+        {Looks for an entry with 0 transparency meaning that it is the}

+        {full transparent entry}

+        for i := 0 to Self.DataSize - 1 do

+          if PaletteValues[i] = 0 then

+            with PaletteChunk.GetPaletteItem(i) do

+            begin

+              Result := RGB(rgbRed, rgbGreen, rgbBlue);

+              break

+            end

+      end {COLOR_PALETTE}

+    end {case Header.ColorType};

+end;

+

+{Saving the chunk to a stream}

+function TChunktRNS.SaveToStream(Stream: TStream): Boolean;

+begin

+  {Copy palette into data buffer}

+  if DataSize <= 256 then

+    CopyMemory(fData, @PaletteValues[0], DataSize);

+

+  Result := inherited SaveToStream(Stream);

+end;

+

+{Assigns from another chunk}

+procedure TChunktRNS.Assign(Source: TChunk);

+begin

+  CopyMemory(@PaletteValues[0], @TChunkTrns(Source).PaletteValues[0], 256);

+  fBitTransparency := TChunkTrns(Source).fBitTransparency;

+  inherited Assign(Source);

+end;

+

+{Loads the chunk from a stream}

+function TChunktRNS.LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+  Size: Integer): Boolean;

+var

+  i, Differ255: Integer;

+begin

+  {Let inherited load}

+  Result := inherited LoadFromStream(Stream, ChunkName, Size);

+

+  if not Result then Exit;

+

+  {Make sure size is correct}

+  if Size > 256 then Owner.RaiseError(EPNGInvalidPalette,

+    EPNGInvalidPaletteText);

+

+  {The unset items should have value 255}

+  Fillchar(PaletteValues[0], 256, 255);

+  {Copy the other values}

+  CopyMemory(@PaletteValues[0], fData, Size);

+

+  {Create the mask if needed}

+  case Header.ColorType of

+    {Mask for grayscale and RGB}

+    COLOR_RGB, COLOR_GRAYSCALE: fBitTransparency := True;

+    COLOR_PALETTE:

+    begin

+      Differ255 := 0; {Count the entries with a value different from 255}

+      {Tests if it uses bit transparency}

+      for i := 0 to Size - 1 do

+        if PaletteValues[i] <> 255 then inc(Differ255);

+

+      {If it has one value different from 255 it is a bit transparency}

+      fBitTransparency := (Differ255 = 1);

+    end {COLOR_PALETTE}

+  end {case Header.ColorType};

+

+end;

+

+{Prepares the image palette}

+procedure TChunkIDAT.PreparePalette;

+var

+  Entries: Word;

+  j      : Integer;

+begin

+  {In case the image uses grayscale, build a grayscale palette}

+  with Header do

+    if (ColorType = COLOR_GRAYSCALE) or (ColorType = COLOR_GRAYSCALEALPHA) then

+    begin

+      {Calculate total number of palette entries}

+      Entries := (1 shl Byte(BitmapInfo.bmiHeader.biBitCount));

+

+      FOR j := 0 TO Entries - 1 DO

+        with BitmapInfo.bmiColors[j] do

+        begin

+

+          {Calculate each palette entry}

+          rgbRed := fOwner.GammaTable[MulDiv(j, 255, Entries - 1)];

+          rgbGreen := rgbRed;

+          rgbBlue := rgbRed;

+        end {with BitmapInfo.bmiColors[j]}

+    end {if ColorType = COLOR_GRAYSCALE..., with Header}

+end;

+

+{Reads from ZLIB}

+function TChunkIDAT.IDATZlibRead(var ZLIBStream: TZStreamRec2;

+  Buffer: Pointer; Count: Integer; var EndPos: Integer;

+  var crcfile: Cardinal): Integer;

+var

+  ProcResult : Integer;

+  IDATHeader : Array[0..3] of char;

+  IDATCRC    : Cardinal;

+begin

+  {Uses internal record pointed by ZLIBStream to gather information}

+  with ZLIBStream, ZLIBStream.zlib do

+  begin

+    {Set the buffer the zlib will read into}

+    next_out := Buffer;

+    avail_out := Count;

+

+    {Decode until it reach the Count variable}

+    while avail_out > 0 do

+    begin

+      {In case it needs more data and it's in the end of a IDAT chunk,}

+      {it means that there are more IDAT chunks}

+      if (fStream.Position = EndPos) and (avail_out > 0) and

+        (avail_in = 0) then

+      begin

+        {End this chunk by reading and testing the crc value}

+        fStream.Read(IDATCRC, 4);

+

+        {$IFDEF CheckCRC}

+          if crcfile xor $ffffffff <> Cardinal(ByteSwap(IDATCRC)) then

+          begin

+            Result := -1;

+            Owner.RaiseError(EPNGInvalidCRC, EPNGInvalidCRCText);

+            exit;

+          end;

+        {$ENDIF}

+

+        {Start reading the next chunk}

+        fStream.Read(EndPos, 4);        {Reads next chunk size}

+        fStream.Read(IDATHeader[0], 4); {Next chunk header}

+        {It must be a IDAT chunk since image data is required and PNG}

+        {specification says that multiple IDAT chunks must be consecutive}

+        if IDATHeader <> 'IDAT' then

+        begin

+          Owner.RaiseError(EPNGMissingMultipleIDAT, EPNGMissingMultipleIDATText);

+          result := -1;

+          exit;

+        end;

+

+        {Calculate chunk name part of the crc}

+        {$IFDEF CheckCRC}

+          crcfile := update_crc($ffffffff, @IDATHeader[0], 4);

+        {$ENDIF}

+        EndPos := fStream.Position + ByteSwap(EndPos);

+      end;

+

+

+      {In case it needs compressed data to read from}

+      if avail_in = 0 then

+      begin

+        {In case it's trying to read more than it is avaliable}

+        if fStream.Position + ZLIBAllocate > EndPos then

+          avail_in := fStream.Read(Data^, EndPos - fStream.Position)

+         else

+          avail_in := fStream.Read(Data^, ZLIBAllocate);

+        {Update crc}

+        {$IFDEF CheckCRC}

+          crcfile := update_crc(crcfile, Data, avail_in);

+        {$ENDIF}

+

+        {In case there is no more compressed data to read from}

+        if avail_in = 0 then

+        begin

+          Result := Count - avail_out;

+          Exit;

+        end;

+

+        {Set next buffer to read and record current position}

+        next_in := Data;

+

+      end {if avail_in = 0};

+

+      ProcResult := inflate(zlib, 0);

+

+      {In case the result was not sucessfull}

+      if (ProcResult < 0) then

+      begin

+        Result := -1;

+        Owner.RaiseError(EPNGZLIBError,

+          EPNGZLIBErrorText + zliberrors[procresult]);

+        exit;

+      end;

+

+    end {while avail_out > 0};

+

+  end {with};

+

+  {If everything gone ok, it returns the count bytes}

+  Result := Count;

+end;

+

+{TChunkIDAT implementation}

+

+const

+  {Adam 7 interlacing values}

+  RowStart: array[0..6] of Integer = (0, 0, 4, 0, 2, 0, 1);

+  ColumnStart: array[0..6] of Integer = (0, 4, 0, 2, 0, 1, 0);

+  RowIncrement: array[0..6] of Integer = (8, 8, 8, 4, 4, 2, 2);

+  ColumnIncrement: array[0..6] of Integer = (8, 8, 4, 4, 2, 2, 1);

+

+{Copy interlaced images with 1 byte for R, G, B}

+procedure TChunkIDAT.CopyInterlacedRGB8(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Dest := pChar(Longint(Dest) + Col * 3);

+  repeat

+    {Copy this row}

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+

+    {Move to next column}

+    inc(Src, 3);

+    inc(Dest, ColumnIncrement[Pass] * 3 - 3);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy interlaced images with 2 bytes for R, G, B}

+procedure TChunkIDAT.CopyInterlacedRGB16(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Dest := pChar(Longint(Dest) + Col * 3);

+  repeat

+    {Copy this row}

+    Byte(Dest^) := Owner.GammaTable[pByte(Longint(Src) + 4)^]; inc(Dest);

+    Byte(Dest^) := Owner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := Owner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+    {$IFDEF Store16bits}

+    {Copy extra pixel values}

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 5)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 3)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Extra);

+    {$ENDIF}

+

+    {Move to next column}

+    inc(Src, 6);

+    inc(Dest, ColumnIncrement[Pass] * 3 - 3);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy ímages with palette using bit depths 1, 4 or 8}

+procedure TChunkIDAT.CopyInterlacedPalette148(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+const

+  BitTable: Array[1..8] of Integer = ($1, $3, 0, $F, 0, 0, 0, $FF);

+  StartBit: Array[1..8] of Integer = (7 , 0 , 0, 4,  0, 0, 0, 0);

+var

+  CurBit, Col: Integer;

+  Dest2: PChar;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  repeat

+    {Copy data}

+    CurBit := StartBit[Header.BitDepth];

+    repeat

+      {Adjust pointer to pixel byte bounds}

+      Dest2 := pChar(Longint(Dest) + (Header.BitDepth * Col) div 8);

+      {Copy data}

+      Byte(Dest2^) := Byte(Dest2^) or

+        ( ((Byte(Src^) shr CurBit) and BitTable[Header.BitDepth])

+          shl (StartBit[Header.BitDepth] - (Col * Header.BitDepth mod 8)));

+

+      {Move to next column}

+      inc(Col, ColumnIncrement[Pass]);

+      {Will read next bits}

+      dec(CurBit, Header.BitDepth);

+    until CurBit < 0;

+

+    {Move to next byte in source}

+    inc(Src);

+  until Col >= ImageWidth;

+end;

+

+{Copy ímages with palette using bit depth 2}

+procedure TChunkIDAT.CopyInterlacedPalette2(const Pass: Byte; Src, Dest,

+  Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  CurBit, Col: Integer;

+  Dest2: PChar;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  repeat

+    {Copy data}

+    CurBit := 6;

+    repeat

+      {Adjust pointer to pixel byte bounds}

+      Dest2 := pChar(Longint(Dest) + Col div 2);

+      {Copy data}

+      Byte(Dest2^) := Byte(Dest2^) or (((Byte(Src^) shr CurBit) and $3)

+         shl (4 - (4 * Col) mod 8));

+      {Move to next column}

+      inc(Col, ColumnIncrement[Pass]);

+      {Will read next bits}

+      dec(CurBit, 2);

+    until CurBit < 0;

+

+    {Move to next byte in source}

+    inc(Src);

+  until Col >= ImageWidth;

+end;

+

+{Copy ímages with grayscale using bit depth 2}

+procedure TChunkIDAT.CopyInterlacedGray2(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  CurBit, Col: Integer;

+  Dest2: PChar;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  repeat

+    {Copy data}

+    CurBit := 6;

+    repeat

+      {Adjust pointer to pixel byte bounds}

+      Dest2 := pChar(Longint(Dest) + Col div 2);

+      {Copy data}

+      Byte(Dest2^) := Byte(Dest2^) or ((((Byte(Src^) shr CurBit) shl 2) and $F)

+         shl (4 - (Col*4) mod 8));

+      {Move to next column}

+      inc(Col, ColumnIncrement[Pass]);

+      {Will read next bits}

+      dec(CurBit, 2);

+    until CurBit < 0;

+

+    {Move to next byte in source}

+    inc(Src);

+  until Col >= ImageWidth;

+end;

+

+{Copy ímages with palette using 2 bytes for each pixel}

+procedure TChunkIDAT.CopyInterlacedGrayscale16(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Dest := pChar(Longint(Dest) + Col);

+  repeat

+    {Copy this row}

+    Dest^ := Src^; inc(Dest);

+    {$IFDEF Store16bits}

+    Extra^ := pChar(Longint(Src) + 1)^; inc(Extra);

+    {$ENDIF}

+

+    {Move to next column}

+    inc(Src, 2);

+    inc(Dest, ColumnIncrement[Pass] - 1);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Decodes interlaced RGB alpha with 1 byte for each sample}

+procedure TChunkIDAT.CopyInterlacedRGBAlpha8(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Dest := pChar(Longint(Dest) + Col * 3);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {Copy this row and alpha value}

+    Trans^ := pChar(Longint(Src) + 3)^;

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+

+    {Move to next column}

+    inc(Src, 4);

+    inc(Dest, ColumnIncrement[Pass] * 3 - 3);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Decodes interlaced RGB alpha with 2 bytes for each sample}

+procedure TChunkIDAT.CopyInterlacedRGBAlpha16(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Dest := pChar(Longint(Dest) + Col * 3);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {Copy this row and alpha value}

+    Trans^ := pChar(Longint(Src) + 6)^;

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 4)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+    {$IFDEF Store16bits}

+    {Copy extra pixel values}

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 5)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 3)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Extra);

+    {$ENDIF}

+

+    {Move to next column}

+    inc(Src, 8);

+    inc(Dest, ColumnIncrement[Pass] * 3 - 3);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Decodes 8 bit grayscale image followed by an alpha sample}

+procedure TChunkIDAT.CopyInterlacedGrayscaleAlpha8(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column, pointers to the data and enter in loop}

+  Col := ColumnStart[Pass];

+  Dest := pChar(Longint(Dest) + Col);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {Copy this grayscale value and alpha}

+    Dest^ := Src^;  inc(Src);

+    Trans^ := Src^; inc(Src);

+

+    {Move to next column}

+    inc(Dest, ColumnIncrement[Pass]);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Decodes 16 bit grayscale image followed by an alpha sample}

+procedure TChunkIDAT.CopyInterlacedGrayscaleAlpha16(const Pass: Byte;

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column, pointers to the data and enter in loop}

+  Col := ColumnStart[Pass];

+  Dest := pChar(Longint(Dest) + Col);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {$IFDEF Store16bits}

+    Extra^ := pChar(Longint(Src) + 1)^; inc(Extra);

+    {$ENDIF}

+    {Copy this grayscale value and alpha, transforming 16 bits into 8}

+    Dest^ := Src^;  inc(Src, 2);

+    Trans^ := Src^; inc(Src, 2);

+

+    {Move to next column}

+    inc(Dest, ColumnIncrement[Pass]);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Decodes an interlaced image}

+procedure TChunkIDAT.DecodeInterlacedAdam7(Stream: TStream;

+  var ZLIBStream: TZStreamRec2; const Size: Integer; var crcfile: Cardinal);

+var

+  CurrentPass: Byte;

+  PixelsThisRow: Integer;

+  CurrentRow: Integer;

+  Trans, Data{$IFDEF Store16bits}, Extra{$ENDIF}: pChar;

+  CopyProc: procedure(const Pass: Byte; Src, Dest,

+    Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar) of object;

+begin

+

+  CopyProc := nil; {Initialize}

+  {Determine method to copy the image data}

+  case Header.ColorType of

+    {R, G, B values for each pixel}

+    COLOR_RGB:

+      case Header.BitDepth of

+        8:  CopyProc := CopyInterlacedRGB8;

+       16:  CopyProc := CopyInterlacedRGB16;

+      end {case Header.BitDepth};

+    {Palette}

+    COLOR_PALETTE, COLOR_GRAYSCALE:

+      case Header.BitDepth of

+        1, 4, 8: CopyProc := CopyInterlacedPalette148;

+        2      : if Header.ColorType = COLOR_PALETTE then

+                   CopyProc := CopyInterlacedPalette2

+                 else

+                   CopyProc := CopyInterlacedGray2;

+        16     : CopyProc := CopyInterlacedGrayscale16;

+      end;

+    {RGB followed by alpha}

+    COLOR_RGBALPHA:

+      case Header.BitDepth of

+        8:  CopyProc := CopyInterlacedRGBAlpha8;

+       16:  CopyProc := CopyInterlacedRGBAlpha16;

+      end;

+    {Grayscale followed by alpha}

+    COLOR_GRAYSCALEALPHA:

+      case Header.BitDepth of

+        8:  CopyProc := CopyInterlacedGrayscaleAlpha8;

+       16:  CopyProc := CopyInterlacedGrayscaleAlpha16;

+      end;

+  end {case Header.ColorType};

+

+  {Adam7 method has 7 passes to make the final image}

+  FOR CurrentPass := 0 TO 6 DO

+  begin

+    {Calculates the number of pixels and bytes for this pass row}

+    PixelsThisRow := (ImageWidth - ColumnStart[CurrentPass] +

+      ColumnIncrement[CurrentPass] - 1) div ColumnIncrement[CurrentPass];

+    Row_Bytes := BytesForPixels(PixelsThisRow, Header.ColorType,

+      Header.BitDepth);

+    {Clear buffer for this pass}

+    ZeroMemory(Row_Buffer[not RowUsed], Row_Bytes);

+

+    {Get current row index}

+    CurrentRow := RowStart[CurrentPass];

+    {Get a pointer to the current row image data}

+    Data := Ptr(Longint(Header.ImageData) + Header.BytesPerRow *

+      (ImageHeight - 1 - CurrentRow));

+    Trans := Ptr(Longint(Header.ImageAlpha) + ImageWidth * CurrentRow);

+    {$IFDEF Store16bits}

+    Extra := Ptr(Longint(Header.ExtraImageData) + Header.BytesPerRow *

+      (ImageHeight - 1 - CurrentRow));

+    {$ENDIF}

+

+    if Row_Bytes > 0 then {There must have bytes for this interlaced pass}

+      while CurrentRow < ImageHeight do

+      begin

+        {Reads this line and filter}

+        if IDATZlibRead(ZLIBStream, @Row_Buffer[RowUsed][0], Row_Bytes + 1,

+          EndPos, CRCFile) = 0 then break;

+

+        FilterRow;

+        {Copy image data}

+

+        CopyProc(CurrentPass, @Row_Buffer[RowUsed][1], Data, Trans

+          {$IFDEF Store16bits}, Extra{$ENDIF});

+

+        {Use the other RowBuffer item}

+        RowUsed := not RowUsed;

+

+        {Move to the next row}

+        inc(CurrentRow, RowIncrement[CurrentPass]);

+        {Move pointer to the next line}

+        dec(Data, RowIncrement[CurrentPass] * Header.BytesPerRow);

+        inc(Trans, RowIncrement[CurrentPass] * ImageWidth);

+        {$IFDEF Store16bits}

+        dec(Extra, RowIncrement[CurrentPass] * Header.BytesPerRow);

+        {$ENDIF}

+      end {while CurrentRow < ImageHeight};

+

+  end {FOR CurrentPass};

+

+end;

+

+{Copy 8 bits RGB image}

+procedure TChunkIDAT.CopyNonInterlacedRGB8(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    {Copy pixel values}

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+    {Move to next pixel}

+    inc(Src, 3);

+  end {for I}

+end;

+

+{Copy 16 bits RGB image}

+procedure TChunkIDAT.CopyNonInterlacedRGB16(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    //Since windows does not supports 2 bytes for

+    //each R, G, B value, the method will read only 1 byte from it

+    {Copy pixel values}

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src) + 4)^]; inc(Dest);

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := fOwner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+    {$IFDEF Store16bits}

+    {Copy extra pixel values}

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 5)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 3)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Extra);

+    {$ENDIF}

+

+    {Move to next pixel}

+    inc(Src, 6);

+  end {for I}

+end;

+

+{Copy types using palettes (1, 4 or 8 bits per pixel)}

+procedure TChunkIDAT.CopyNonInterlacedPalette148(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+begin

+  {It's simple as copying the data}

+  CopyMemory(Dest, Src, Row_Bytes);

+end;

+

+{Copy grayscale types using 2 bits for each pixel}

+procedure TChunkIDAT.CopyNonInterlacedGray2(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  i: Integer;

+begin

+  {2 bits is not supported, this routine will converted into 4 bits}

+  FOR i := 1 TO Row_Bytes do

+  begin

+    Byte(Dest^) := ((Byte(Src^) shr 2) and $F) or ((Byte(Src^)) and $F0); inc(Dest);

+    Byte(Dest^) := ((Byte(Src^) shl 2) and $F) or ((Byte(Src^) shl 4) and $F0); inc(Dest);

+    inc(Src);

+  end {FOR i}

+end;

+

+{Copy types using palette with 2 bits for each pixel}

+procedure TChunkIDAT.CopyNonInterlacedPalette2(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  i: Integer;

+begin

+  {2 bits is not supported, this routine will converted into 4 bits}

+  FOR i := 1 TO Row_Bytes do

+  begin

+    Byte(Dest^) := ((Byte(Src^) shr 4) and $3) or ((Byte(Src^) shr 2) and $30); inc(Dest);

+    Byte(Dest^) := (Byte(Src^) and $3) or ((Byte(Src^) shl 2) and $30); inc(Dest);

+    inc(Src);

+  end {FOR i}

+end;

+

+{Copy grayscale images with 16 bits}

+procedure TChunkIDAT.CopyNonInterlacedGrayscale16(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    {Windows does not supports 16 bits for each pixel in grayscale}

+    {mode, so reduce to 8}

+    Dest^ := Src^; inc(Dest);

+    {$IFDEF Store16bits}

+    Extra^ := pChar(Longint(Src) + 1)^; inc(Extra);

+    {$ENDIF}

+

+    {Move to next pixel}

+    inc(Src, 2);

+  end {for I}

+end;

+

+{Copy 8 bits per sample RGB images followed by an alpha byte}

+procedure TChunkIDAT.CopyNonInterlacedRGBAlpha8(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  i: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    {Copy pixel values and transparency}

+    Trans^ := pChar(Longint(Src) + 3)^;

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+    {Move to next pixel}

+    inc(Src, 4); inc(Trans);

+  end {for I}

+end;

+

+{Copy 16 bits RGB image with alpha using 2 bytes for each sample}

+procedure TChunkIDAT.CopyNonInterlacedRGBAlpha16(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    //Copy rgb and alpha values (transforming from 16 bits to 8 bits)

+    {Copy pixel values}

+    Trans^ := pChar(Longint(Src) + 6)^;

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 4)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^)  := fOwner.GammaTable[pByte(Longint(Src)    )^]; inc(Dest);

+    {$IFDEF Store16bits}

+    {Copy extra pixel values}

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 5)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 3)^]; inc(Extra);

+    Byte(Extra^) := fOwner.GammaTable[pByte(Longint(Src) + 1)^]; inc(Extra);

+    {$ENDIF}

+    {Move to next pixel}

+    inc(Src, 8); inc(Trans);

+  end {for I}

+end;

+

+{Copy 8 bits per sample grayscale followed by alpha}

+procedure TChunkIDAT.CopyNonInterlacedGrayscaleAlpha8(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    {Copy alpha value and then gray value}

+    Dest^  := Src^;  inc(Src);

+    Trans^ := Src^;  inc(Src);

+    inc(Dest); inc(Trans);

+  end;

+end;

+

+{Copy 16 bits per sample grayscale followed by alpha}

+procedure TChunkIDAT.CopyNonInterlacedGrayscaleAlpha16(

+  Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    {Copy alpha value and then gray value}

+    {$IFDEF Store16bits}

+    Extra^ := pChar(Longint(Src) + 1)^; inc(Extra);

+    {$ENDIF}

+    Dest^  := Src^;  inc(Src, 2);

+    Trans^ := Src^;  inc(Src, 2);

+    inc(Dest); inc(Trans);

+  end;

+end;

+

+{Decode non interlaced image}

+procedure TChunkIDAT.DecodeNonInterlaced(Stream: TStream;

+  var ZLIBStream: TZStreamRec2; const Size: Integer; var crcfile: Cardinal);

+var

+  j: Cardinal;

+  Trans, Data{$IFDEF Store16bits}, Extra{$ENDIF}: pChar;

+  CopyProc: procedure(

+    Src, Dest, Trans{$IFDEF Store16bits}, Extra{$ENDIF}: pChar) of object;

+begin

+  CopyProc := nil; {Initialize}

+  {Determines the method to copy the image data}

+  case Header.ColorType of

+    {R, G, B values}

+    COLOR_RGB:

+      case Header.BitDepth of

+        8: CopyProc := CopyNonInterlacedRGB8;

+       16: CopyProc := CopyNonInterlacedRGB16;

+      end;

+    {Types using palettes}

+    COLOR_PALETTE, COLOR_GRAYSCALE:

+      case Header.BitDepth of

+        1, 4, 8: CopyProc := CopyNonInterlacedPalette148;

+        2      : if Header.ColorType = COLOR_PALETTE then

+                   CopyProc := CopyNonInterlacedPalette2

+                 else

+                   CopyProc := CopyNonInterlacedGray2;

+        16     : CopyProc := CopyNonInterlacedGrayscale16;

+      end;

+    {R, G, B followed by alpha}

+    COLOR_RGBALPHA:

+      case Header.BitDepth of

+        8  : CopyProc := CopyNonInterlacedRGBAlpha8;

+       16  : CopyProc := CopyNonInterlacedRGBAlpha16;

+      end;

+    {Grayscale followed by alpha}

+    COLOR_GRAYSCALEALPHA:

+      case Header.BitDepth of

+        8  : CopyProc := CopyNonInterlacedGrayscaleAlpha8;

+       16  : CopyProc := CopyNonInterlacedGrayscaleAlpha16;

+      end;

+  end;

+

+  {Get the image data pointer}

+  Longint(Data) := Longint(Header.ImageData) +

+    Header.BytesPerRow * (ImageHeight - 1);

+  Trans := Header.ImageAlpha;

+  {$IFDEF Store16bits}

+  Longint(Extra) := Longint(Header.ExtraImageData) +

+    Header.BytesPerRow * (ImageHeight - 1);

+  {$ENDIF}

+  {Reads each line}

+  FOR j := 0 to ImageHeight - 1 do

+  begin

+    {Read this line Row_Buffer[RowUsed][0] if the filter type for this line}

+    if IDATZlibRead(ZLIBStream, @Row_Buffer[RowUsed][0], Row_Bytes + 1, EndPos,

+      CRCFile) = 0 then break;

+

+    {Filter the current row}

+    FilterRow;

+    {Copies non interlaced row to image}

+    CopyProc(@Row_Buffer[RowUsed][1], Data, Trans{$IFDEF Store16bits}, Extra

+      {$ENDIF});

+

+    {Invert line used}

+    RowUsed := not RowUsed;

+    dec(Data, Header.BytesPerRow);

+    {$IFDEF Store16bits}dec(Extra, Header.BytesPerRow);{$ENDIF}

+    inc(Trans, ImageWidth);

+  end {for I};

+

+

+end;

+

+{Filter the current line}

+procedure TChunkIDAT.FilterRow;

+var

+  pp: Byte;

+  vv, left, above, aboveleft: Integer;

+  Col: Cardinal;

+begin

+  {Test the filter}

+  case Row_Buffer[RowUsed]^[0] of

+    {No filtering for this line}

+    FILTER_NONE: begin end;

+    {AND 255 serves only to never let the result be larger than one byte}

+    {Sub filter}

+    FILTER_SUB:

+      FOR Col := Offset + 1 to Row_Bytes DO

+        Row_Buffer[RowUsed][Col] := (Row_Buffer[RowUsed][Col] +

+          Row_Buffer[RowUsed][Col - Offset]) and 255;

+    {Up filter}

+    FILTER_UP:

+      FOR Col := 1 to Row_Bytes DO

+        Row_Buffer[RowUsed][Col] := (Row_Buffer[RowUsed][Col] +

+          Row_Buffer[not RowUsed][Col]) and 255;

+    {Average filter}

+    FILTER_AVERAGE:

+      FOR Col := 1 to Row_Bytes DO

+      begin

+        {Obtains up and left pixels}

+        above := Row_Buffer[not RowUsed][Col];

+        if col - 1 < Offset then

+          left := 0

+        else

+          Left := Row_Buffer[RowUsed][Col - Offset];

+

+        {Calculates}

+        Row_Buffer[RowUsed][Col] := (Row_Buffer[RowUsed][Col] +

+          (left + above) div 2) and 255;

+      end;

+    {Paeth filter}

+    FILTER_PAETH:

+    begin

+      {Initialize}

+      left := 0;

+      aboveleft := 0;

+      {Test each byte}

+      FOR Col := 1 to Row_Bytes DO

+      begin

+        {Obtains above pixel}

+        above := Row_Buffer[not RowUsed][Col];

+        {Obtains left and top-left pixels}

+        if (col - 1 >= offset) Then

+        begin

+          left := row_buffer[RowUsed][col - offset];

+          aboveleft := row_buffer[not RowUsed][col - offset];

+        end;

+

+        {Obtains current pixel and paeth predictor}

+        vv := row_buffer[RowUsed][Col];

+        pp := PaethPredictor(left, above, aboveleft);

+

+        {Calculates}

+        Row_Buffer[RowUsed][Col] := (pp + vv) and $FF;

+      end {for};

+    end;

+      

+  end {case};

+end;

+

+{Reads the image data from the stream}

+function TChunkIDAT.LoadFromStream(Stream: TStream; const ChunkName: TChunkName;

+  Size: Integer): Boolean;

+var

+  ZLIBStream: TZStreamRec2;

+  CRCCheck,

+  CRCFile  : Cardinal;

+begin

+  {Get pointer to the header chunk}

+  Header := Owner.Chunks.Item[0] as TChunkIHDR;

+  {Build palette if necessary}

+  if Header.HasPalette then PreparePalette();

+

+  {Copy image width and height}

+  ImageWidth := Header.Width;

+  ImageHeight := Header.Height;

+

+  {Initialize to calculate CRC}

+  {$IFDEF CheckCRC}

+    CRCFile := update_crc($ffffffff, @ChunkName[0], 4);

+  {$ENDIF}

+

+  Owner.GetPixelInfo(Row_Bytes, Offset); {Obtain line information}

+  ZLIBStream := ZLIBInitInflate(Stream);  {Initializes decompression}

+

+  {Calculate ending position for the current IDAT chunk}

+  EndPos := Stream.Position + Size;

+

+  {Allocate memory}

+  GetMem(Row_Buffer[false], Row_Bytes + 1);

+  GetMem(Row_Buffer[true], Row_Bytes + 1);

+  ZeroMemory(Row_Buffer[false], Row_bytes + 1);

+  {Set the variable to alternate the Row_Buffer item to use}

+  RowUsed := TRUE;

+

+  {Call special methods for the different interlace methods}

+  case Owner.InterlaceMethod of

+    imNone:  DecodeNonInterlaced(stream, ZLIBStream, Size, crcfile);

+    imAdam7: DecodeInterlacedAdam7(stream, ZLIBStream, size, crcfile);

+  end;

+

+  {Free memory}

+  ZLIBTerminateInflate(ZLIBStream); {Terminates decompression}

+  FreeMem(Row_Buffer[False], Row_Bytes + 1);

+  FreeMem(Row_Buffer[True], Row_Bytes + 1);

+

+  {Now checks CRC}

+  Stream.Read(CRCCheck, 4);

+  {$IFDEF CheckCRC}

+    CRCFile := CRCFile xor $ffffffff;

+    CRCCheck := ByteSwap(CRCCheck);

+    Result := CRCCheck = CRCFile;

+

+    {Handle CRC error}

+    if not Result then

+    begin

+      {In case it coult not load chunk}

+      Owner.RaiseError(EPngInvalidCRC, EPngInvalidCRCText);

+      exit;

+    end;

+  {$ELSE}Result := TRUE; {$ENDIF}

+end;

+

+const

+  IDATHeader: Array[0..3] of char = ('I', 'D', 'A', 'T');

+  BUFFER = 5;

+

+{Saves the IDAT chunk to a stream}

+function TChunkIDAT.SaveToStream(Stream: TStream): Boolean;

+var

+  ZLIBStream : TZStreamRec2;

+begin

+  {Get pointer to the header chunk}

+  Header := Owner.Chunks.Item[0] as TChunkIHDR;

+  {Copy image width and height}

+  ImageWidth := Header.Width;

+  ImageHeight := Header.Height;

+  Owner.GetPixelInfo(Row_Bytes, Offset); {Obtain line information}

+

+  {Allocate memory}

+  GetMem(Encode_Buffer[BUFFER], Row_Bytes);

+  ZeroMemory(Encode_Buffer[BUFFER], Row_Bytes);

+  {Allocate buffers for the filters selected}

+  {Filter none will always be calculated to the other filters to work}

+  GetMem(Encode_Buffer[FILTER_NONE], Row_Bytes);

+  ZeroMemory(Encode_Buffer[FILTER_NONE], Row_Bytes);

+  if pfSub in Owner.Filters then

+    GetMem(Encode_Buffer[FILTER_SUB], Row_Bytes);

+  if pfUp in Owner.Filters then

+    GetMem(Encode_Buffer[FILTER_UP], Row_Bytes);

+  if pfAverage in Owner.Filters then

+    GetMem(Encode_Buffer[FILTER_AVERAGE], Row_Bytes);

+  if pfPaeth in Owner.Filters then

+    GetMem(Encode_Buffer[FILTER_PAETH], Row_Bytes);

+

+  {Initialize ZLIB}

+  ZLIBStream := ZLIBInitDeflate(Stream, Owner.fCompressionLevel,

+    Owner.MaxIdatSize);

+  {Write data depending on the interlace method}

+  case Owner.InterlaceMethod of

+    imNone: EncodeNonInterlaced(stream, ZLIBStream);

+    imAdam7: EncodeInterlacedAdam7(stream, ZLIBStream);

+  end;

+  {Terminates ZLIB}

+  ZLIBTerminateDeflate(ZLIBStream);

+

+  {Release allocated memory}

+  FreeMem(Encode_Buffer[BUFFER], Row_Bytes);

+  FreeMem(Encode_Buffer[FILTER_NONE], Row_Bytes);

+  if pfSub in Owner.Filters then

+    FreeMem(Encode_Buffer[FILTER_SUB], Row_Bytes);

+  if pfUp in Owner.Filters then

+    FreeMem(Encode_Buffer[FILTER_UP], Row_Bytes);

+  if pfAverage in Owner.Filters then

+    FreeMem(Encode_Buffer[FILTER_AVERAGE], Row_Bytes);

+  if pfPaeth in Owner.Filters then

+    FreeMem(Encode_Buffer[FILTER_PAETH], Row_Bytes);

+

+  {Everything went ok}

+  Result := True;

+end;

+

+{Writes the IDAT using the settings}

+procedure WriteIDAT(Stream: TStream; Data: Pointer; const Length: Cardinal);

+var

+  ChunkLen, CRC: Cardinal;

+begin

+  {Writes IDAT header}

+  ChunkLen := ByteSwap(Length);

+  Stream.Write(ChunkLen, 4);                      {Chunk length}

+  Stream.Write(IDATHeader[0], 4);                 {Idat header}

+  CRC := update_crc($ffffffff, @IDATHeader[0], 4); {Crc part for header}

+

+  {Writes IDAT data and calculates CRC for data}

+  Stream.Write(Data^, Length);

+  CRC := Byteswap(update_crc(CRC, Data, Length) xor $ffffffff);

+  {Writes final CRC}

+  Stream.Write(CRC, 4);

+end;

+

+{Compress and writes IDAT chunk data}

+procedure TChunkIDAT.IDATZlibWrite(var ZLIBStream: TZStreamRec2;

+  Buffer: Pointer; const Length: Cardinal);

+begin

+  with ZLIBStream, ZLIBStream.ZLIB do

+  begin

+    {Set data to be compressed}

+    next_in := Buffer;

+    avail_in := Length;

+

+    {Compress all the data avaliable to compress}

+    while avail_in > 0 do

+    begin

+      deflate(ZLIB, Z_NO_FLUSH);

+

+      {The whole buffer was used, save data to stream and restore buffer}

+      if avail_out = 0 then

+      begin

+        {Writes this IDAT chunk}

+        WriteIDAT(fStream, Data, ZLIBAllocate);

+

+        {Restore buffer}

+        next_out := Data;

+        avail_out := ZLIBAllocate;

+      end {if avail_out = 0};

+

+    end {while avail_in};

+

+  end {with ZLIBStream, ZLIBStream.ZLIB}

+end;

+

+{Finishes compressing data to write IDAT chunk}

+procedure TChunkIDAT.FinishIDATZlib(var ZLIBStream: TZStreamRec2);

+begin

+  with ZLIBStream, ZLIBStream.ZLIB do

+  begin

+    {Set data to be compressed}

+    next_in := nil;

+    avail_in := 0;

+

+    while deflate(ZLIB,Z_FINISH) <> Z_STREAM_END do

+    begin

+      {Writes this IDAT chunk}

+      WriteIDAT(fStream, Data, ZLIBAllocate - avail_out);

+      {Re-update buffer}

+      next_out := Data;

+      avail_out := ZLIBAllocate;

+    end;

+

+    if avail_out < ZLIBAllocate then

+      {Writes final IDAT}

+      WriteIDAT(fStream, Data, ZLIBAllocate - avail_out);

+

+  end {with ZLIBStream, ZLIBStream.ZLIB};

+end;

+

+{Copy memory to encode RGB image with 1 byte for each color sample}

+procedure TChunkIDAT.EncodeNonInterlacedRGB8(Src, Dest, Trans: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    {Copy pixel values}

+    Byte(Dest^) := fOwner.InverseGamma[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := fOwner.InverseGamma[pByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^) := fOwner.InverseGamma[pByte(Longint(Src)    )^]; inc(Dest);

+    {Move to next pixel}

+    inc(Src, 3);

+  end {for I}

+end;

+

+{Copy memory to encode RGB images with 16 bits for each color sample}

+procedure TChunkIDAT.EncodeNonInterlacedRGB16(Src, Dest, Trans: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    //Now we copy from 1 byte for each sample stored to a 2 bytes (or 1 word)

+    //for sample

+    {Copy pixel values}

+    pWORD(Dest)^ := fOwner.InverseGamma[pByte(Longint(Src) + 2)^]; inc(Dest, 2);

+    pWORD(Dest)^ := fOwner.InverseGamma[pByte(Longint(Src) + 1)^]; inc(Dest, 2);

+    pWORD(Dest)^ := fOwner.InverseGamma[pByte(Longint(Src)    )^]; inc(Dest, 2);

+    {Move to next pixel}

+    inc(Src, 3);

+  end {for I}

+

+end;

+

+{Copy memory to encode types using palettes (1, 4 or 8 bits per pixel)}

+procedure TChunkIDAT.EncodeNonInterlacedPalette148(Src, Dest, Trans: pChar);

+begin

+  {It's simple as copying the data}

+  CopyMemory(Dest, Src, Row_Bytes);

+end;

+

+{Copy memory to encode grayscale images with 2 bytes for each sample}

+procedure TChunkIDAT.EncodeNonInterlacedGrayscale16(Src, Dest, Trans: pChar);

+var

+  I: Integer;

+begin

+  FOR I := 1 TO ImageWidth DO

+  begin

+    //Now we copy from 1 byte for each sample stored to a 2 bytes (or 1 word)

+    //for sample

+    pWORD(Dest)^ := pByte(Longint(Src))^; inc(Dest, 2);

+    {Move to next pixel}

+    inc(Src);

+  end {for I}

+end;

+

+{Encode images using RGB followed by an alpha value using 1 byte for each}

+procedure TChunkIDAT.EncodeNonInterlacedRGBAlpha8(Src, Dest, Trans: pChar);

+var

+  i: Integer;

+begin

+  {Copy the data to the destination, including data from Trans pointer}

+  FOR i := 1 TO ImageWidth do

+  begin

+    Byte(Dest^) := Owner.InverseGamma[PByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := Owner.InverseGamma[PByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^) := Owner.InverseGamma[PByte(Longint(Src)    )^]; inc(Dest);

+    Dest^ := Trans^; inc(Dest);

+    inc(Src, 3); inc(Trans);

+  end {for i};

+end;

+

+{Encode images using RGB followed by an alpha value using 2 byte for each}

+procedure TChunkIDAT.EncodeNonInterlacedRGBAlpha16(Src, Dest, Trans: pChar);

+var

+  i: Integer;

+begin

+  {Copy the data to the destination, including data from Trans pointer}

+  FOR i := 1 TO ImageWidth do

+  begin

+    pWord(Dest)^ := Owner.InverseGamma[PByte(Longint(Src) + 2)^]; inc(Dest, 2);

+    pWord(Dest)^ := Owner.InverseGamma[PByte(Longint(Src) + 1)^]; inc(Dest, 2);

+    pWord(Dest)^ := Owner.InverseGamma[PByte(Longint(Src)    )^]; inc(Dest, 2);

+    pWord(Dest)^ := PByte(Longint(Trans)  )^; inc(Dest, 2);

+    inc(Src, 3); inc(Trans);

+  end {for i};

+end;

+

+{Encode grayscale images followed by an alpha value using 1 byte for each}

+procedure TChunkIDAT.EncodeNonInterlacedGrayscaleAlpha8(

+  Src, Dest, Trans: pChar);

+var

+  i: Integer;

+begin

+  {Copy the data to the destination, including data from Trans pointer}

+  FOR i := 1 TO ImageWidth do

+  begin

+    Dest^ := Src^; inc(Dest);

+    Dest^ := Trans^; inc(Dest);

+    inc(Src); inc(Trans);

+  end {for i};

+end;

+

+{Encode grayscale images followed by an alpha value using 2 byte for each}

+procedure TChunkIDAT.EncodeNonInterlacedGrayscaleAlpha16(

+  Src, Dest, Trans: pChar);

+var

+  i: Integer;

+begin

+  {Copy the data to the destination, including data from Trans pointer}

+  FOR i := 1 TO ImageWidth do

+  begin

+    pWord(Dest)^ := pByte(Src)^;    inc(Dest, 2);

+    pWord(Dest)^ := pByte(Trans)^;  inc(Dest, 2);

+    inc(Src); inc(Trans);

+  end {for i};

+end;

+

+{Encode non interlaced images}

+procedure TChunkIDAT.EncodeNonInterlaced(Stream: TStream;

+  var ZLIBStream: TZStreamRec2);

+var

+  {Current line}

+  j: Cardinal;

+  {Pointers to image data}

+  Data, Trans: PChar;

+  {Filter used for this line}

+  Filter: Byte;

+  {Method which will copy the data into the buffer}

+  CopyProc: procedure(Src, Dest, Trans: pChar) of object;

+begin

+  CopyProc := nil;  {Initialize to avoid warnings}

+  {Defines the method to copy the data to the buffer depending on}

+  {the image parameters}

+  case Header.ColorType of

+    {R, G, B values}

+    COLOR_RGB:

+      case Header.BitDepth of

+        8: CopyProc := EncodeNonInterlacedRGB8;

+       16: CopyProc := EncodeNonInterlacedRGB16;

+      end;

+    {Palette and grayscale values}

+    COLOR_GRAYSCALE, COLOR_PALETTE:

+      case Header.BitDepth of

+        1, 4, 8: CopyProc := EncodeNonInterlacedPalette148;

+             16: CopyProc := EncodeNonInterlacedGrayscale16;

+      end;

+    {RGB with a following alpha value}

+    COLOR_RGBALPHA:

+      case Header.BitDepth of

+          8: CopyProc := EncodeNonInterlacedRGBAlpha8;

+         16: CopyProc := EncodeNonInterlacedRGBAlpha16;

+      end;

+    {Grayscale images followed by an alpha}

+    COLOR_GRAYSCALEALPHA:

+      case Header.BitDepth of

+        8:  CopyProc := EncodeNonInterlacedGrayscaleAlpha8;

+       16:  CopyProc := EncodeNonInterlacedGrayscaleAlpha16;

+      end;

+  end {case Header.ColorType};

+

+  {Get the image data pointer}

+  Longint(Data) := Longint(Header.ImageData) +

+    Header.BytesPerRow * (ImageHeight - 1);

+  Trans := Header.ImageAlpha;

+

+  {Writes each line}

+  FOR j := 0 to ImageHeight - 1 do

+  begin

+    {Copy data into buffer}

+    CopyProc(Data, @Encode_Buffer[BUFFER][0], Trans);

+    {Filter data}

+    Filter := FilterToEncode;

+

+    {Compress data}

+    IDATZlibWrite(ZLIBStream, @Filter, 1);

+    IDATZlibWrite(ZLIBStream, @Encode_Buffer[Filter][0], Row_Bytes);

+

+    {Adjust pointers to the actual image data}

+    dec(Data, Header.BytesPerRow);

+    inc(Trans, ImageWidth);

+  end;

+

+  {Compress and finishes copying the remaining data}

+  FinishIDATZlib(ZLIBStream);

+end;

+

+{Copy memory to encode interlaced images using RGB value with 1 byte for}

+{each color sample}

+procedure TChunkIDAT.EncodeInterlacedRGB8(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Src := pChar(Longint(Src) + Col * 3);

+  repeat

+    {Copy this row}

+    Byte(Dest^) := fOwner.InverseGamma[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := fOwner.InverseGamma[pByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^) := fOwner.InverseGamma[pByte(Longint(Src)    )^]; inc(Dest);

+

+    {Move to next column}

+    inc(Src, ColumnIncrement[Pass] * 3);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy memory to encode interlaced RGB images with 2 bytes each color sample}

+procedure TChunkIDAT.EncodeInterlacedRGB16(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Src := pChar(Longint(Src) + Col * 3);

+  repeat

+    {Copy this row}

+    pWord(Dest)^ := Owner.InverseGamma[pByte(Longint(Src) + 2)^]; inc(Dest, 2);

+    pWord(Dest)^ := Owner.InverseGamma[pByte(Longint(Src) + 1)^]; inc(Dest, 2);

+    pWord(Dest)^ := Owner.InverseGamma[pByte(Longint(Src)    )^]; inc(Dest, 2);

+

+    {Move to next column}

+    inc(Src, ColumnIncrement[Pass] * 3);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy memory to encode interlaced images using palettes using bit depths}

+{1, 4, 8 (each pixel in the image)}

+procedure TChunkIDAT.EncodeInterlacedPalette148(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+const

+  BitTable: Array[1..8] of Integer = ($1, $3, 0, $F, 0, 0, 0, $FF);

+  StartBit: Array[1..8] of Integer = (7 , 0 , 0, 4,  0, 0, 0, 0);

+var

+  CurBit, Col: Integer;

+  Src2: PChar;

+begin

+  {Clean the line}

+  fillchar(Dest^, Row_Bytes, #0);

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  with Header.BitmapInfo.bmiHeader do

+    repeat

+      {Copy data}

+      CurBit := StartBit[biBitCount];

+      repeat

+        {Adjust pointer to pixel byte bounds}

+        Src2 := pChar(Longint(Src) + (biBitCount * Col) div 8);

+        {Copy data}

+        Byte(Dest^) := Byte(Dest^) or

+          (((Byte(Src2^) shr (StartBit[Header.BitDepth] - (biBitCount * Col)

+            mod 8))) and (BitTable[biBitCount])) shl CurBit;

+

+        {Move to next column}

+        inc(Col, ColumnIncrement[Pass]);

+        {Will read next bits}

+        dec(CurBit, biBitCount);

+      until CurBit < 0;

+

+      {Move to next byte in source}

+      inc(Dest);

+    until Col >= ImageWidth;

+end;

+

+{Copy to encode interlaced grayscale images using 16 bits for each sample}

+procedure TChunkIDAT.EncodeInterlacedGrayscale16(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Src := pChar(Longint(Src) + Col);

+  repeat

+    {Copy this row}

+    pWord(Dest)^ := Byte(Src^); inc(Dest, 2);

+

+    {Move to next column}

+    inc(Src, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy to encode interlaced rgb images followed by an alpha value, all using}

+{one byte for each sample}

+procedure TChunkIDAT.EncodeInterlacedRGBAlpha8(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Src := pChar(Longint(Src) + Col * 3);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {Copy this row}

+    Byte(Dest^) := Owner.InverseGamma[pByte(Longint(Src) + 2)^]; inc(Dest);

+    Byte(Dest^) := Owner.InverseGamma[pByte(Longint(Src) + 1)^]; inc(Dest);

+    Byte(Dest^) := Owner.InverseGamma[pByte(Longint(Src)    )^]; inc(Dest);

+    Dest^ := Trans^; inc(Dest);

+

+    {Move to next column}

+    inc(Src, ColumnIncrement[Pass] * 3);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy to encode interlaced rgb images followed by an alpha value, all using}

+{two byte for each sample}

+procedure TChunkIDAT.EncodeInterlacedRGBAlpha16(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Src := pChar(Longint(Src) + Col * 3);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {Copy this row}

+    pWord(Dest)^ := pByte(Longint(Src) + 2)^; inc(Dest, 2);

+    pWord(Dest)^ := pByte(Longint(Src) + 1)^; inc(Dest, 2);

+    pWord(Dest)^ := pByte(Longint(Src)    )^; inc(Dest, 2);

+    pWord(Dest)^ := pByte(Trans)^; inc(Dest, 2);

+

+    {Move to next column}

+    inc(Src, ColumnIncrement[Pass] * 3);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy to encode grayscale interlaced images followed by an alpha value, all}

+{using 1 byte for each sample}

+procedure TChunkIDAT.EncodeInterlacedGrayscaleAlpha8(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Src := pChar(Longint(Src) + Col);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {Copy this row}

+    Dest^ := Src^;   inc(Dest);

+    Dest^ := Trans^; inc(Dest);

+

+    {Move to next column}

+    inc(Src, ColumnIncrement[Pass]);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Copy to encode grayscale interlaced images followed by an alpha value, all}

+{using 2 bytes for each sample}

+procedure TChunkIDAT.EncodeInterlacedGrayscaleAlpha16(const Pass: Byte;

+  Src, Dest, Trans: pChar);

+var

+  Col: Integer;

+begin

+  {Get first column and enter in loop}

+  Col := ColumnStart[Pass];

+  Src := pChar(Longint(Src) + Col);

+  Trans := pChar(Longint(Trans) + Col);

+  repeat

+    {Copy this row}

+    pWord(Dest)^ := pByte(Src)^; inc(Dest, 2);

+    pWord(Dest)^ := pByte(Trans)^; inc(Dest, 2);

+

+    {Move to next column}

+    inc(Src, ColumnIncrement[Pass]);

+    inc(Trans, ColumnIncrement[Pass]);

+    inc(Col, ColumnIncrement[Pass]);

+  until Col >= ImageWidth;

+end;

+

+{Encode interlaced images}

+procedure TChunkIDAT.EncodeInterlacedAdam7(Stream: TStream;

+  var ZLIBStream: TZStreamRec2);

+var

+  CurrentPass, Filter: Byte;

+  PixelsThisRow: Integer;

+  CurrentRow : Integer;

+  Trans, Data: pChar;

+  CopyProc: procedure(const Pass: Byte;

+    Src, Dest, Trans: pChar) of object;

+begin

+  CopyProc := nil;  {Initialize to avoid warnings}

+  {Defines the method to copy the data to the buffer depending on}

+  {the image parameters}

+  case Header.ColorType of

+    {R, G, B values}

+    COLOR_RGB:

+      case Header.BitDepth of

+        8: CopyProc := EncodeInterlacedRGB8;

+       16: CopyProc := EncodeInterlacedRGB16;

+      end;

+    {Grayscale and palette}

+    COLOR_PALETTE, COLOR_GRAYSCALE:

+      case Header.BitDepth of

+        1, 4, 8: CopyProc := EncodeInterlacedPalette148;

+             16: CopyProc := EncodeInterlacedGrayscale16;

+      end;

+    {RGB followed by alpha}

+    COLOR_RGBALPHA:

+      case Header.BitDepth of

+          8: CopyProc := EncodeInterlacedRGBAlpha8;

+         16: CopyProc := EncodeInterlacedRGBAlpha16;

+      end;

+    COLOR_GRAYSCALEALPHA:

+    {Grayscale followed by alpha}

+      case Header.BitDepth of

+          8: CopyProc := EncodeInterlacedGrayscaleAlpha8;

+         16: CopyProc := EncodeInterlacedGrayscaleAlpha16;

+      end;

+  end {case Header.ColorType};

+

+  {Compress the image using the seven passes for ADAM 7}

+  FOR CurrentPass := 0 TO 6 DO

+  begin

+    {Calculates the number of pixels and bytes for this pass row}

+    PixelsThisRow := (ImageWidth - ColumnStart[CurrentPass] +

+      ColumnIncrement[CurrentPass] - 1) div ColumnIncrement[CurrentPass];

+    Row_Bytes := BytesForPixels(PixelsThisRow, Header.ColorType,

+      Header.BitDepth);

+    ZeroMemory(Encode_Buffer[FILTER_NONE], Row_Bytes);

+

+    {Get current row index}

+    CurrentRow := RowStart[CurrentPass];

+    {Get a pointer to the current row image data}

+    Data := Ptr(Longint(Header.ImageData) + Header.BytesPerRow *

+      (ImageHeight - 1 - CurrentRow));

+    Trans := Ptr(Longint(Header.ImageAlpha) + ImageWidth * CurrentRow);

+

+    {Process all the image rows}

+    if Row_Bytes > 0 then

+      while CurrentRow < ImageHeight do

+      begin

+        {Copy data into buffer}

+        CopyProc(CurrentPass, Data, @Encode_Buffer[BUFFER][0], Trans);

+        {Filter data}

+        Filter := FilterToEncode;

+

+        {Compress data}

+        IDATZlibWrite(ZLIBStream, @Filter, 1);

+        IDATZlibWrite(ZLIBStream, @Encode_Buffer[Filter][0], Row_Bytes);

+

+        {Move to the next row}

+        inc(CurrentRow, RowIncrement[CurrentPass]);

+        {Move pointer to the next line}

+        dec(Data, RowIncrement[CurrentPass] * Header.BytesPerRow);

+        inc(Trans, RowIncrement[CurrentPass] * ImageWidth);

+      end {while CurrentRow < ImageHeight}

+

+  end {CurrentPass};

+

+  {Compress and finishes copying the remaining data}

+  FinishIDATZlib(ZLIBStream);

+end;

+

+{Filters the row to be encoded and returns the best filter}

+function TChunkIDAT.FilterToEncode: Byte;

+var

+  Run, LongestRun, ii, jj: Cardinal;

+  Last, Above, LastAbove: Byte;

+begin

+  {Selecting more filters using the Filters property from TPngObject}

+  {increases the chances to the file be much smaller, but decreases}

+  {the performace}

+

+  {This method will creates the same line data using the different}

+  {filter methods and select the best}

+

+  {Sub-filter}

+  if pfSub in Owner.Filters then

+    for ii := 0 to Row_Bytes - 1 do

+    begin

+      {There is no previous pixel when it's on the first pixel, so}

+      {set last as zero when in the first}

+      if (ii >= Offset) then

+        last := Encode_Buffer[BUFFER]^[ii - Offset]

+      else

+        last := 0;

+      Encode_Buffer[FILTER_SUB]^[ii] := Encode_Buffer[BUFFER]^[ii] - last;

+    end;

+

+  {Up filter}

+  if pfUp in Owner.Filters then

+    for ii := 0 to Row_Bytes - 1 do

+      Encode_Buffer[FILTER_UP]^[ii] := Encode_Buffer[BUFFER]^[ii] -

+        Encode_Buffer[FILTER_NONE]^[ii];

+

+  {Average filter}

+  if pfAverage in Owner.Filters then

+    for ii := 0 to Row_Bytes - 1 do

+    begin

+      {Get the previous pixel, if the current pixel is the first, the}

+      {previous is considered to be 0}

+      if (ii >= Offset) then

+        last := Encode_Buffer[BUFFER]^[ii - Offset]

+      else

+        last := 0;

+      {Get the pixel above}

+      above := Encode_Buffer[FILTER_NONE]^[ii];

+

+      {Calculates formula to the average pixel}

+      Encode_Buffer[FILTER_AVERAGE]^[ii] := Encode_Buffer[BUFFER]^[ii] -

+        (above + last) div 2 ;

+    end;

+

+  {Paeth filter (the slower)}

+  if pfPaeth in Owner.Filters then

+  begin

+    {Initialize}

+    last := 0;

+    lastabove := 0;

+    for ii := 0 to Row_Bytes - 1 do

+    begin

+      {In case this pixel is not the first in the line obtains the}

+      {previous one and the one above the previous}

+      if (ii >= Offset) then

+      begin

+        last := Encode_Buffer[BUFFER]^[ii - Offset];

+        lastabove := Encode_Buffer[FILTER_NONE]^[ii - Offset];

+      end;

+      {Obtains the pixel above}

+      above := Encode_Buffer[FILTER_NONE]^[ii];

+      {Calculate paeth filter for this byte}

+      Encode_Buffer[FILTER_PAETH]^[ii] := Encode_Buffer[BUFFER]^[ii] -

+        PaethPredictor(last, above, lastabove);

+    end;

+  end;

+

+  {Now calculates the same line using no filter, which is necessary}

+  {in order to have data to the filters when the next line comes}

+  CopyMemory(@Encode_Buffer[FILTER_NONE]^[0],

+    @Encode_Buffer[BUFFER]^[0], Row_Bytes);

+

+  {If only filter none is selected in the filter list, we don't need}

+  {to proceed and further}

+  if (Owner.Filters = [pfNone]) or (Owner.Filters = []) then

+  begin

+    Result := FILTER_NONE;

+    exit;

+  end {if (Owner.Filters = [pfNone...};

+

+  {Check which filter is the best by checking which has the larger}

+  {sequence of the same byte, since they are best compressed}

+  LongestRun := 0; Result := FILTER_NONE;

+  for ii := FILTER_NONE TO FILTER_PAETH do

+    {Check if this filter was selected}

+    if TFilter(ii) in Owner.Filters then

+    begin

+      Run := 0;

+      {Check if it's the only filter}

+      if Owner.Filters = [TFilter(ii)] then

+      begin

+        Result := ii;

+        exit;

+      end;

+

+      {Check using a sequence of four bytes}

+      for jj := 2 to Row_Bytes - 1 do

+        if (Encode_Buffer[ii]^[jj] = Encode_Buffer [ii]^[jj-1]) or

+            (Encode_Buffer[ii]^[jj] = Encode_Buffer [ii]^[jj-2]) then

+          inc(Run);  {Count the number of sequences}

+

+      {Check if this one is the best so far}

+      if (Run > LongestRun) then

+      begin

+        Result := ii;

+        LongestRun := Run;

+      end {if (Run > LongestRun)};

+

+    end {if TFilter(ii) in Owner.Filters};

+end;

+

+{TChunkPLTE implementation}

+

+{Returns an item in the palette}

+function TChunkPLTE.GetPaletteItem(Index: Byte): TRGBQuad;

+begin

+  {Test if item is valid, if not raise error}

+  if Index > Count - 1 then

+    Owner.RaiseError(EPNGError, EPNGUnknownPalEntryText)

+  else

+    {Returns the item}

+    Result := Header.BitmapInfo.bmiColors[Index];

+end;

+

+{Loads the palette chunk from a stream}

+function TChunkPLTE.LoadFromStream(Stream: TStream;

+  const ChunkName: TChunkName; Size: Integer): Boolean;

+type

+  pPalEntry = ^PalEntry;

+  PalEntry = record r, g, b: Byte end;

+var

+  j        : Integer;          {For the FOR}

+  PalColor : pPalEntry;

+begin

+  {Let ancestor load data and check CRC}

+  Result := inherited LoadFromStream(Stream, ChunkName, Size);

+  if not Result then exit;

+

+  {This chunk must be divisible by 3 in order to be valid}

+  if (Size mod 3 <> 0) or (Size div 3 > 256) then

+  begin

+    {Raise error}

+    Result := FALSE;

+    Owner.RaiseError(EPNGInvalidPalette, EPNGInvalidPaletteText);

+    exit;

+  end {if Size mod 3 <> 0};

+

+  {Fill array with the palette entries}

+  fCount := Size div 3;

+  PalColor := Data;

+  FOR j := 0 TO fCount - 1 DO

+    with Header.BitmapInfo.bmiColors[j] do

+    begin

+      rgbRed  :=  Owner.GammaTable[PalColor.r];

+      rgbGreen := Owner.GammaTable[PalColor.g];

+      rgbBlue :=  Owner.GammaTable[PalColor.b];

+      rgbReserved := 0;

+      inc(PalColor); {Move to next palette entry}

+    end;

+end;

+

+{Saves the PLTE chunk to a stream}

+function TChunkPLTE.SaveToStream(Stream: TStream): Boolean;

+var

+  J: Integer;

+  DataPtr: pByte;

+begin

+  {Adjust size to hold all the palette items}

+  ResizeData(fCount * 3);

+  {Copy pointer to data}

+  DataPtr := fData;

+

+  {Copy palette items}

+  with Header do

+    FOR j := 0 TO fCount - 1 DO

+      with BitmapInfo.bmiColors[j] do

+      begin

+        DataPtr^ := Owner.InverseGamma[rgbRed]; inc(DataPtr);

+        DataPtr^ := Owner.InverseGamma[rgbGreen]; inc(DataPtr);

+        DataPtr^ := Owner.InverseGamma[rgbBlue]; inc(DataPtr);

+      end {with BitmapInfo};

+

+  {Let ancestor do the rest of the work}

+  Result := inherited SaveToStream(Stream);

+end;

+

+{Assigns from another PLTE chunk}

+procedure TChunkPLTE.Assign(Source: TChunk);

+begin

+  {Copy the number of palette items}

+  if Source is TChunkPLTE then

+    fCount := TChunkPLTE(Source).fCount

+  else

+    Owner.RaiseError(EPNGError, EPNGCannotAssignChunkText);

+end;

+

+{TChunkgAMA implementation}

+

+{Assigns from another chunk}

+procedure TChunkgAMA.Assign(Source: TChunk);

+begin

+  {Copy the gamma value}

+  if Source is TChunkgAMA then

+    Gamma := TChunkgAMA(Source).Gamma

+  else

+    Owner.RaiseError(EPNGError, EPNGCannotAssignChunkText);

+end;

+

+{Gamma chunk being created}

+constructor TChunkgAMA.Create(Owner: TPngObject);

+begin

+  {Call ancestor}

+  inherited Create(Owner);

+  Gamma := 1;  {Initial value}

+end;

+

+{Returns gamma value}

+function TChunkgAMA.GetValue: Cardinal;

+begin

+  {Make sure that the size is four bytes}

+  if DataSize <> 4 then

+  begin

+    {Adjust size and returns 1}

+    ResizeData(4);

+    Result := 1;

+  end

+  {If it's right, read the value}

+  else Result := Cardinal(ByteSwap(pCardinal(Data)^))

+end;

+

+function Power(Base, Exponent: Extended): Extended;

+begin

+  if Exponent = 0.0 then

+    Result := 1.0               {Math rule}

+  else if (Base = 0) or (Exponent = 0) then Result := 0

+  else

+    Result := Exp(Exponent * Ln(Base));

+end;

+

+

+{Loading the chunk from a stream}

+function TChunkgAMA.LoadFromStream(Stream: TStream;

+  const ChunkName: TChunkName; Size: Integer): Boolean;

+var

+  i: Integer;

+  Value: Cardinal;

+begin

+  {Call ancestor and test if it went ok}

+  Result := inherited LoadFromStream(Stream, ChunkName, Size);

+  if not Result then exit;

+  Value := Gamma;

+  {Build gamma table and inverse table for saving}

+  if Value <> 0 then

+    with Owner do

+      FOR i := 0 TO 255 DO

+      begin

+        GammaTable[I] := Round(Power((I / 255), 1 /

+          (Value / 100000 * 2.2)) * 255);

+        InverseGamma[Round(Power((I / 255), 1 /

+          (Value / 100000 * 2.2)) * 255)] := I;

+      end

+end;

+

+{Sets the gamma value}

+procedure TChunkgAMA.SetValue(const Value: Cardinal);

+begin

+  {Make sure that the size is four bytes}

+  if DataSize <> 4 then ResizeData(4);

+  {If it's right, set the value}

+  pCardinal(Data)^ := ByteSwap(Value);

+end;

+

+{TPngObject implementation}

+

+{Assigns from another object}

+procedure TPngObject.Assign(Source: TPersistent);

+begin

+  {Assigns contents from another TPNGObject}

+  if Source is TPNGObject then

+    AssignPNG(Source as TPNGObject)

+  {Copy contents from a TBitmap}

+  {$IFDEF UseDelphi}else if Source is TBitmap then

+    with Source as TBitmap do

+      AssignHandle(Handle, Transparent,

+        ColorToRGB(TransparentColor)){$ENDIF}

+  {Unknown source, let ancestor deal with it}

+  else

+    inherited;

+end;

+

+{Clear all the chunks in the list}

+procedure TPngObject.ClearChunks;

+var

+  i: Integer;

+begin

+  {Initialize gamma}

+  InitializeGamma();

+  {Free all the objects and memory (0 chunks Bug fixed by Noel Sharpe)}

+  for i := 0 TO Integer(Chunks.Count) - 1 do

+    TChunk(Chunks.Item[i]).Free;

+  Chunks.Count := 0;

+end;

+

+{Portable Network Graphics object being created}

+constructor TPngObject.Create;

+begin

+  {Let it be created}

+  inherited Create;

+

+  {Initial properties}

+  TempPalette := 0;

+  fFilters := [pfSub];

+  fCompressionLevel := 7;

+  fInterlaceMethod := imNone;

+  fMaxIdatSize := High(Word);

+  {Create chunklist object}

+  fChunkList := TPngList.Create(Self);

+end;

+

+{Portable Network Graphics object being destroyed}

+destructor TPngObject.Destroy;

+begin

+  {Free object list}

+  ClearChunks;

+  fChunkList.Free;

+  {Free the temporary palette}

+  if TempPalette <> 0 then DeleteObject(TempPalette);

+

+  {Call ancestor destroy}

+  inherited Destroy;

+end;

+

+{Returns linesize and byte offset for pixels}

+procedure TPngObject.GetPixelInfo(var LineSize, Offset: Cardinal);

+begin

+  {There must be an Header chunk to calculate size}

+  if HeaderPresent then

+  begin

+    {Calculate number of bytes for each line}

+    LineSize := BytesForPixels(Header.Width, Header.ColorType, Header.BitDepth);

+

+    {Calculates byte offset}

+    Case Header.ColorType of

+      {Grayscale}

+      COLOR_GRAYSCALE:

+        If Header.BitDepth = 16 Then

+          Offset := 2

+        Else

+          Offset := 1 ;

+      {It always smaller or equal one byte, so it occupes one byte}

+      COLOR_PALETTE:

+        offset := 1;

+      {It might be 3 or 6 bytes}

+      COLOR_RGB:

+        offset := 3 * Header.BitDepth Div 8;

+      {It might be 2 or 4 bytes}

+      COLOR_GRAYSCALEALPHA:

+        offset := 2 * Header.BitDepth Div 8;

+      {4 or 8 bytes}

+      COLOR_RGBALPHA:

+        offset := 4 * Header.BitDepth Div 8;

+      else

+        Offset := 0;

+      End ;

+

+  end

+  else

+  begin

+    {In case if there isn't any Header chunk}

+    Offset := 0;

+    LineSize := 0;

+  end;

+

+end;

+

+{Returns image height}

+function TPngObject.GetHeight: Integer;

+begin

+  {There must be a Header chunk to get the size, otherwise returns 0}

+  if HeaderPresent then

+    Result := TChunkIHDR(Chunks.Item[0]).Height

+  else Result := 0;

+end;

+

+{Returns image width}

+function TPngObject.GetWidth: Integer;

+begin

+  {There must be a Header chunk to get the size, otherwise returns 0}

+  if HeaderPresent then

+    Result := Header.Width

+  else Result := 0;

+end;

+

+{Returns if the image is empty}

+function TPngObject.GetEmpty: Boolean;

+begin

+  Result := (Chunks.Count = 0);

+end;

+

+{Raises an error}

+procedure TPngObject.RaiseError(ExceptionClass: ExceptClass; Text: String);

+begin

+  raise ExceptionClass.Create(Text);

+end;

+

+{Set the maximum size for IDAT chunk}

+procedure TPngObject.SetMaxIdatSize(const Value: Cardinal);

+begin

+  {Make sure the size is at least 65535}

+  if Value < High(Word) then

+    fMaxIdatSize := High(Word) else fMaxIdatSize := Value;

+end;

+

+{$IFNDEF UseDelphi}

+  {Creates a file stream reading from the filename in the parameter and load}

+  procedure TPngObject.LoadFromFile(const Filename: String);

+  var

+    FileStream: TFileStream;

+  begin

+    {Test if the file exists}

+    if not FileExists(Filename) then

+    begin

+      {In case it does not exists, raise error}

+      RaiseError(EPNGNotExists, EPNGNotExistsText);

+      exit;

+    end;

+

+    {Creates the file stream to read}

+    FileStream := TFileStream.Create(Filename, [fsmRead]);

+    LoadFromStream(FileStream);  {Loads the data}

+    FileStream.Free;             {Free file stream}

+  end;

+

+  {Saves the current png image to a file}

+  procedure TPngObject.SaveToFile(const Filename: String);

+  var

+    FileStream: TFileStream;

+  begin

+    {Creates the file stream to write}

+    FileStream := TFileStream.Create(Filename, [fsmWrite]);

+    SaveToStream(FileStream);    {Saves the data}

+    FileStream.Free;             {Free file stream}

+  end;

+

+{$ENDIF}

+

+{Returns pointer to the chunk TChunkIHDR which should be the first}

+function TPngObject.GetHeader: TChunkIHDR;

+begin

+  {If there is a TChunkIHDR returns it, otherwise returns nil}

+  if (Chunks.Count <> 0) and (Chunks.Item[0] is TChunkIHDR) then

+    Result := Chunks.Item[0] as TChunkIHDR

+  else

+  begin

+    {No header, throw error message}

+    RaiseError(EPNGHeaderNotPresent, EPNGHeaderNotPresentText);

+    Result := nil

+  end

+end;

+

+{Draws using partial transparency}

+procedure TPngObject.DrawPartialTrans(DC: HDC; Rect: TRect);

+type

+  {Access to pixels}

+  TPixelLine = Array[Word] of TRGBQuad;

+  pPixelLine = ^TPixelLine;

+const

+  {Structure used to create the bitmap}

+  BitmapInfoHeader: TBitmapInfoHeader =

+    (biSize: sizeof(TBitmapInfoHeader);

+     biWidth: 100;

+     biHeight: 100;

+     biPlanes: 1;

+     biBitCount: 32;

+     biCompression: BI_RGB;

+     biSizeImage: 0;

+     biXPelsPerMeter: 0;

+     biYPelsPerMeter: 0;

+     biClrUsed: 0;

+     biClrImportant: 0);

+var

+  {Buffer bitmap creation}

+  BitmapInfo  : TBitmapInfo;

+  BufferDC    : HDC;

+  BufferBits  : Pointer;

+  OldBitmap,

+  BufferBitmap: HBitmap;

+

+  {Transparency/palette chunks}

+  TransparencyChunk: TChunktRNS;

+  PaletteChunk: TChunkPLTE;

+  TransValue, PaletteIndex: Byte;

+  CurBit: Integer;

+  Data: PByte;

+

+  {Buffer bitmap modification}

+  BytesPerRowDest,

+  BytesPerRowSrc,

+  BytesPerRowAlpha: Integer;

+  ImageSource,

+  AlphaSource     : pByteArray;

+  ImageData       : pPixelLine;

+  i, j            : Integer;

+begin

+  {Prepare to create the bitmap}

+  Fillchar(BitmapInfo, sizeof(BitmapInfo), #0);

+  BitmapInfoHeader.biWidth := Header.Width;

+  BitmapInfoHeader.biHeight := -1 * Header.Height;

+  BitmapInfo.bmiHeader := BitmapInfoHeader;

+

+  {Create the bitmap which will receive the background, the applied}

+  {alpha blending and then will be painted on the background}

+  BufferDC := CreateCompatibleDC(0);

+  {In case BufferDC could not be created}

+  if (BufferDC = 0) then RaiseError(EPNGOutMemory, EPNGOutMemoryText);

+  BufferBitmap := CreateDIBSection(BufferDC, BitmapInfo, DIB_RGB_COLORS,

+    BufferBits, 0, 0);

+  {In case buffer bitmap could not be created}

+  if (BufferBitmap = 0) or (BufferBits = Nil) then

+  begin

+    if BufferBitmap <> 0 then DeleteObject(BufferBitmap);

+    DeleteDC(BufferDC);

+    RaiseError(EPNGOutMemory, EPNGOutMemoryText);

+  end;

+

+  {Selects new bitmap and release old bitmap}

+  OldBitmap := SelectObject(BufferDC, BufferBitmap);

+

+  {Draws the background on the buffer image}

+  StretchBlt(BufferDC, 0, 0, Header.Width, Header.height, DC, Rect.Left,

+    Rect.Top, Header.Width, Header.Height, SRCCOPY);

+

+  {Obtain number of bytes for each row}

+  BytesPerRowAlpha := Header.Width;

+  BytesPerRowDest := (((BitmapInfo.bmiHeader.biBitCount * Width) + 31)

+    and not 31) div 8; {Number of bytes for each image row in destination}

+  BytesPerRowSrc := (((Header.BitmapInfo.bmiHeader.biBitCount * Header.Width) +

+    31) and not 31) div 8; {Number of bytes for each image row in source}

+

+  {Obtains image pointers}

+  ImageData := BufferBits;

+  AlphaSource := Header.ImageAlpha;

+  Longint(ImageSource) := Longint(Header.ImageData) +

+    Header.BytesPerRow * Longint(Header.Height - 1);

+

+  case Header.BitmapInfo.bmiHeader.biBitCount of

+    {R, G, B images}

+    24:

+      FOR j := 1 TO Header.Height DO

+      begin

+        {Process all the pixels in this line}

+        FOR i := 0 TO Header.Width - 1 DO

+          with ImageData[i] do

+          begin

+            rgbRed := (255+ImageSource[2+i*3] * AlphaSource[i] + rgbRed * (255 -

+              AlphaSource[i])) shr 8;

+            rgbGreen := (255+ImageSource[1+i*3] * AlphaSource[i] + rgbGreen *

+              (255 - AlphaSource[i])) shr 8;

+            rgbBlue := (255+ImageSource[i*3] * AlphaSource[i] + rgbBlue *

+             (255 - AlphaSource[i])) shr 8;

+          end;

+

+        {Move pointers}

+        Longint(ImageData) := Longint(ImageData) + BytesPerRowDest;

+        Longint(ImageSource) := Longint(ImageSource) - BytesPerRowSrc;

+        Longint(AlphaSource) := Longint(AlphaSource) + BytesPerRowAlpha;

+      end;

+    {Palette images with 1 byte for each pixel}

+    1,4,8: if Header.ColorType = COLOR_GRAYSCALEALPHA then

+      FOR j := 1 TO Header.Height DO

+      begin

+        {Process all the pixels in this line}

+        FOR i := 0 TO Header.Width - 1 DO

+          with ImageData[i], Header.BitmapInfo do begin

+            rgbRed := (255 + ImageSource[i] * AlphaSource[i] +

+              rgbRed * (255 - AlphaSource[i])) shr 8;

+            rgbGreen := (255 + ImageSource[i] * AlphaSource[i] +

+              rgbGreen * (255 - AlphaSource[i])) shr 8;

+            rgbBlue := (255 + ImageSource[i] * AlphaSource[i] +

+              rgbBlue * (255 - AlphaSource[i])) shr 8;

+          end;

+

+        {Move pointers}

+        Longint(ImageData) := Longint(ImageData) + BytesPerRowDest;

+        Longint(ImageSource) := Longint(ImageSource) - BytesPerRowSrc;

+        Longint(AlphaSource) := Longint(AlphaSource) + BytesPerRowAlpha;

+      end

+    else {Palette images}

+    begin

+      {Obtain pointer to the transparency chunk}

+      TransparencyChunk := TChunktRNS(Chunks.ItemFromClass(TChunktRNS));

+      PaletteChunk := TChunkPLTE(Chunks.ItemFromClass(TChunkPLTE));

+

+      FOR j := 1 TO Header.Height DO

+      begin

+        {Process all the pixels in this line}

+        i := 0; Data := @ImageSource[0];

+        repeat

+          CurBit := 0;

+

+          repeat

+            {Obtains the palette index}

+            case Header.BitDepth of

+              1: PaletteIndex := (Data^ shr (7-(I Mod 8))) and 1;

+            2,4: PaletteIndex := (Data^ shr ((1-(I Mod 2))*4)) and $0F;

+             else PaletteIndex := Data^;

+            end;

+

+            {Updates the image with the new pixel}

+            with ImageData[i] do

+            begin

+              TransValue := TransparencyChunk.PaletteValues[PaletteIndex];

+              rgbRed := (255 + PaletteChunk.Item[PaletteIndex].rgbRed *

+                 TransValue + rgbRed * (255 - TransValue)) shr 8;

+              rgbGreen := (255 + PaletteChunk.Item[PaletteIndex].rgbGreen *

+                 TransValue + rgbGreen * (255 - TransValue)) shr 8;

+              rgbBlue := (255 + PaletteChunk.Item[PaletteIndex].rgbBlue *

+                 TransValue + rgbBlue * (255 - TransValue)) shr 8;

+            end;

+

+            {Move to next data}

+            inc(i); inc(CurBit, Header.BitmapInfo.bmiHeader.biBitCount);

+          until CurBit >= 8;

+          {Move to next source data}

+          inc(Data);

+        until i >= Integer(Header.Width);

+

+        {Move pointers}

+        Longint(ImageData) := Longint(ImageData) + BytesPerRowDest;

+        Longint(ImageSource) := Longint(ImageSource) - BytesPerRowSrc;

+      end

+    end {Palette images}

+  end {case Header.BitmapInfo.bmiHeader.biBitCount};

+

+  {Draws the new bitmap on the foreground}

+  StretchBlt(DC, Rect.Left, Rect.Top, Header.Width, Header.Height, BufferDC,

+    0, 0, Header.Width, Header.Height, SRCCOPY);

+

+  {Free bitmap}

+  SelectObject(BufferDC, OldBitmap);

+  DeleteObject(BufferBitmap);

+  DeleteDC(BufferDC);

+end;

+

+{Draws the image into a canvas}

+procedure TPngObject.Draw(ACanvas: TCanvas; const Rect: TRect);

+var

+  Header: TChunkIHDR;

+begin

+  {Quit in case there is no header, otherwise obtain it}

+  if (Chunks.Count = 0) or not (Chunks.GetItem(0) is TChunkIHDR) then Exit;

+  Header := Chunks.GetItem(0) as TChunkIHDR;

+

+  {Copy the data to the canvas}

+  case Self.TransparencyMode of

+  {$IFDEF PartialTransparentDraw}

+    ptmPartial:

+      DrawPartialTrans(ACanvas{$IFDEF UseDelphi}.Handle{$ENDIF}, Rect);

+  {$ENDIF}

+    ptmBit: DrawTransparentBitmap(ACanvas{$IFDEF UseDelphi}.Handle{$ENDIF},

+      Header.ImageData, Header.BitmapInfo.bmiHeader,

+      pBitmapInfo(@Header.BitmapInfo), Rect,

+      {$IFDEF UseDelphi}ColorToRGB({$ENDIF}TransparentColor)

+      {$IFDEF UseDelphi}){$ENDIF}

+    else

+      StretchDiBits(ACanvas{$IFDEF UseDelphi}.Handle{$ENDIF}, Rect.Left,

+        Rect.Top, Rect.Right - Rect.Left, Rect.Bottom - Rect.Top, 0, 0,

+        Header.Width, Header.Height, Header.ImageData,

+        pBitmapInfo(@Header.BitmapInfo)^, DIB_RGB_COLORS, SRCCOPY)

+  end {case}

+end;

+

+{Characters for the header}

+const

+  PngHeader: Array[0..7] of Char = (#137, #80, #78, #71, #13, #10, #26, #10);

+

+{Loads the image from a stream of data}

+procedure TPngObject.LoadFromStream(Stream: TStream);

+var

+  Header    : Array[0..7] of Char;

+  HasIDAT   : Boolean;

+

+  {Chunks reading}

+  ChunkCount : Cardinal;

+  ChunkLength: Cardinal;

+  ChunkName  : TChunkName;

+begin

+  {Initialize before start loading chunks}

+  ChunkCount := 0;

+  ClearChunks();

+  {Reads the header}

+  Stream.Read(Header[0], 8);

+

+  {Test if the header matches}

+  if Header <> PngHeader then

+  begin

+    RaiseError(EPNGInvalidFileHeader, EPNGInvalidFileHeaderText);

+    Exit;

+  end;

+

+

+  HasIDAT := FALSE;

+  Chunks.Count := 10;

+

+  {Load chunks}

+  repeat

+    inc(ChunkCount);  {Increment number of chunks}

+    if Chunks.Count < ChunkCount then  {Resize the chunks list if needed}

+      Chunks.Count := Chunks.Count + 10;

+

+    {Reads chunk length and invert since it is in network order}

+    {also checks the Read method return, if it returns 0, it}

+    {means that no bytes was readed, probably because it reached}

+    {the end of the file}

+    if Stream.Read(ChunkLength, 4) = 0 then

+    begin

+      {In case it found the end of the file here}

+      Chunks.Count := ChunkCount - 1;

+      RaiseError(EPNGUnexpectedEnd, EPNGUnexpectedEndText);

+    end;

+

+    ChunkLength := ByteSwap(ChunkLength);

+    {Reads chunk name}

+    Stream.Read(Chunkname, 4);

+

+    {Here we check if the first chunk is the Header which is necessary}

+    {to the file in order to be a valid Portable Network Graphics image}

+    if (ChunkCount = 1) and (ChunkName <> 'IHDR') then

+    begin

+      Chunks.Count := ChunkCount - 1;

+      RaiseError(EPNGIHDRNotFirst, EPNGIHDRNotFirstText);

+      exit;

+    end;

+

+    {Has a previous IDAT}

+    if (HasIDAT and (ChunkName = 'IDAT')) or (ChunkName = 'cHRM') then

+    begin

+      dec(ChunkCount);

+      Stream.Seek(ChunkLength + 4, soFromCurrent);

+      Continue;

+    end;

+    {Tell it has an IDAT chunk}

+    if ChunkName = 'IDAT' then HasIDAT := TRUE;

+

+    {Creates object for this chunk}

+    Chunks.SetItem(ChunkCount - 1, CreateClassChunk(Self, ChunkName));

+

+    {Check if the chunk is critical and unknown}

+    {$IFDEF ErrorOnUnknownCritical}

+      if (TChunk(Chunks.Item[ChunkCount - 1]).ClassType = TChunk) and

+        ((Byte(ChunkName[0]) AND $20) = 0) and (ChunkName <> '') then

+      begin

+        Chunks.Count := ChunkCount;

+        RaiseError(EPNGUnknownCriticalChunk, EPNGUnknownCriticalChunkText);

+      end;

+    {$ENDIF}

+

+    {Loads it}

+    try if not TChunk(Chunks.Item[ChunkCount - 1]).LoadFromStream(Stream,

+       ChunkName, ChunkLength) then break;

+    except

+      Chunks.Count := ChunkCount;

+      raise;

+    end;

+

+  {Terminates when it reaches the IEND chunk}

+  until (ChunkName = 'IEND');

+

+  {Resize the list to the appropriate size}

+  Chunks.Count := ChunkCount;

+

+  {Check if there is data}

+  if not HasIDAT then

+    RaiseError(EPNGNoImageData, EPNGNoImageDataText);

+end;

+

+{Changing height is not supported}

+procedure TPngObject.SetHeight(Value: Integer);

+begin

+  RaiseError(EPNGError, EPNGCannotChangeSizeText);

+end;

+

+{Changing width is not supported}

+procedure TPngObject.SetWidth(Value: Integer);

+begin

+  RaiseError(EPNGError, EPNGCannotChangeSizeText);

+end;

+

+{$IFDEF UseDelphi}

+{Saves to clipboard format (thanks to Antoine Pottern)}

+procedure TPNGObject.SaveToClipboardFormat(var AFormat: Word;

+  var AData: THandle; var APalette: HPalette);

+begin

+  with TBitmap.Create do

+    try

+      Width := Self.Width;

+      Height := Self.Height;

+      Self.Draw(Canvas, Rect(0, 0, Width, Height));

+      SaveToClipboardFormat(AFormat, AData, APalette);

+    finally

+      Free;

+    end {try}

+end;

+

+{Loads data from clipboard}

+procedure TPngObject.LoadFromClipboardFormat(AFormat: Word;

+  AData: THandle; APalette: HPalette);

+begin

+  with TBitmap.Create do

+    try

+      LoadFromClipboardFormat(AFormat, AData, APalette);

+      Self.AssignHandle(Handle, False, 0);

+    finally

+      Free;

+    end {try}

+end;

+

+{Returns if the image is transparent}

+function TPngObject.GetTransparent: Boolean;

+begin

+  Result := (TransparencyMode <> ptmNone);

+end;

+

+{$ENDIF}

+

+{Saving the PNG image to a stream of data}

+procedure TPngObject.SaveToStream(Stream: TStream);

+var

+  j: Integer;

+begin

+  {Reads the header}

+  Stream.Write(PNGHeader[0], 8);

+  {Write each chunk}

+  FOR j := 0 TO Chunks.Count - 1 DO

+    Chunks.Item[j].SaveToStream(Stream)

+end;

+

+{Prepares the Header chunk}

+procedure BuildHeader(Header: TChunkIHDR; Handle: HBitmap; Info: pBitmap;

+  HasPalette: Boolean);

+var

+  DC: HDC;

+begin

+  {Set width and height}

+  Header.Width := Info.bmWidth;

+  Header.Height := abs(Info.bmHeight);

+  {Set bit depth}

+  if Info.bmBitsPixel >= 16 then

+    Header.BitDepth := 8 else Header.BitDepth := Info.bmBitsPixel;

+  {Set color type}

+  if Info.bmBitsPixel >= 16 then

+    Header.ColorType := COLOR_RGB else Header.ColorType := COLOR_PALETTE;

+  {Set other info}

+  Header.CompressionMethod := 0;  {deflate/inflate}

+  Header.InterlaceMethod := 0;    {no interlace}

+

+  {Prepares bitmap headers to hold data}

+  Header.PrepareImageData();

+  {Copy image data}

+  DC := CreateCompatibleDC(0);

+  GetDIBits(DC, Handle, 0, Header.Height, Header.ImageData,

+    pBitmapInfo(@Header.BitmapInfo)^, DIB_RGB_COLORS);

+  DeleteDC(DC);

+end;

+

+{Loads the image from a resource}

+procedure TPngObject.LoadFromResourceName(Instance: HInst;

+  const Name: String);

+var

+  ResStream: TResourceStream;

+begin

+  {Creates an especial stream to load from the resource}

+  try ResStream := TResourceStream.Create(Instance, Name, RT_RCDATA);

+  except RaiseError(EPNGCouldNotLoadResource, EPNGCouldNotLoadResourceText);

+  exit; end;

+

+  {Loads the png image from the resource}

+  try

+    LoadFromStream(ResStream);

+  finally

+    ResStream.Free;

+  end;

+end;

+

+{Loads the png from a resource ID}

+procedure TPngObject.LoadFromResourceID(Instance: HInst; ResID: Integer);

+begin

+  LoadFromResourceName(Instance, String(ResID));

+end;

+

+{Assigns this tpngobject to another object}

+procedure TPngObject.AssignTo(Dest: TPersistent);

+{$IFDEF UseDelphi}

+var

+  DeskDC: HDC;

+  TRNS: TChunkTRNS;

+{$ENDIF}

+begin

+  {If the destination is also a TPNGObject make it assign}

+  {this one}

+  if Dest is TPNGObject then

+    TPNGObject(Dest).AssignPNG(Self)

+  {$IFDEF UseDelphi}

+  {In case the destination is a bitmap}

+  else if (Dest is TBitmap) and HeaderPresent then

+  begin

+    {Device context}

+    DeskDC := GetDC(0);

+    {Copy the data}

+    TBitmap(Dest).Handle := CreateDIBitmap(DeskDC,

+      Header.BitmapInfo.bmiHeader, CBM_INIT, Header.ImageData,

+      pBitmapInfo(@Header.BitmapInfo)^, DIB_RGB_COLORS);

+    ReleaseDC(0, DeskDC);

+    {Tests for the best pixelformat}

+    case Header.BitmapInfo.bmiHeader.biBitCount of

+      1: TBitmap(Dest).PixelFormat := pf1Bit;

+      4: TBitmap(Dest).PixelFormat := pf4Bit;

+      8: TBitmap(Dest).PixelFormat := pf8Bit;

+     24: TBitmap(Dest).PixelFormat := pf24Bit;

+     32: TBitmap(Dest).PixelFormat := pf32Bit;

+    end {case Header.BitmapInfo.bmiHeader.biBitCount};

+

+    {Copy transparency mode}

+    if (TransparencyMode = ptmBit) then

+    begin

+      TRNS := Chunks.ItemFromClass(TChunkTRNS) as TChunkTRNS;

+      TBitmap(Dest).TransparentColor := TRNS.TransparentColor;

+      TBitmap(Dest).Transparent := True

+    end {if (TransparencyMode = ptmBit)}

+

+  end

+  else

+    {Unknown destination kind, }

+    inherited AssignTo(Dest);

+  {$ENDIF}

+end;

+

+{Assigns from a bitmap object}

+procedure TPngObject.AssignHandle(Handle: HBitmap; Transparent: Boolean;

+  TransparentColor: ColorRef);

+var

+  BitmapInfo: Windows.TBitmap;

+  HasPalette: Boolean;

+

+  {Chunks}

+  Header: TChunkIHDR;

+  PLTE: TChunkPLTE;

+  IDAT: TChunkIDAT;

+  IEND: TChunkIEND;

+  TRNS: TChunkTRNS;

+begin

+  {Obtain bitmap info}

+  GetObject(Handle, SizeOf(BitmapInfo), @BitmapInfo);

+

+  {Only bit depths 1, 4 and 8 needs a palette}

+  HasPalette := (BitmapInfo.bmBitsPixel < 16);

+

+  {Clear old chunks and prepare}

+  ClearChunks();

+

+  {Create the chunks}

+  Header := TChunkIHDR.Create(Self);

+  if HasPalette then PLTE := TChunkPLTE.Create(Self) else PLTE := nil;

+  if Transparent then TRNS := TChunkTRNS.Create(Self) else TRNS := nil;

+  IDAT := TChunkIDAT.Create(Self);

+  IEND := TChunkIEND.Create(Self);

+

+  {Add chunks}

+  TPNGPointerList(Chunks).Add(Header);

+  if HasPalette then TPNGPointerList(Chunks).Add(PLTE);

+  if Transparent then TPNGPointerList(Chunks).Add(TRNS);

+  TPNGPointerList(Chunks).Add(IDAT);

+  TPNGPointerList(Chunks).Add(IEND);

+

+  {This method will fill the Header chunk with bitmap information}

+  {and copy the image data}

+  BuildHeader(Header, Handle, @BitmapInfo, HasPalette);

+  {In case there is a image data, set the PLTE chunk fCount variable}

+  {to the actual number of palette colors which is 2^(Bits for each pixel)}

+  if HasPalette then PLTE.fCount := 1 shl BitmapInfo.bmBitsPixel;

+

+  {In case it is a transparent bitmap, prepares it}

+  if Transparent then TRNS.TransparentColor := TransparentColor;

+

+end;

+

+{Assigns from another PNG}

+procedure TPngObject.AssignPNG(Source: TPNGObject);

+var

+  J: Integer;

+begin

+  {Copy properties}

+  InterlaceMethod := Source.InterlaceMethod;

+  MaxIdatSize := Source.MaxIdatSize;

+  CompressionLevel := Source.CompressionLevel;

+  Filters := Source.Filters;

+

+  {Clear old chunks and prepare}

+  ClearChunks();

+  Chunks.Count := Source.Chunks.Count;

+  {Create chunks and makes a copy from the source}

+  FOR J := 0 TO Chunks.Count - 1 DO

+    with Source.Chunks do

+    begin

+      Chunks.SetItem(J, TChunkClass(TChunk(Item[J]).ClassType).Create(Self));

+      TChunk(Chunks.Item[J]).Assign(TChunk(Item[J]));

+    end {with};

+end;

+

+{Returns a alpha data scanline}

+function TPngObject.GetAlphaScanline(const LineIndex: Integer): pByteArray;

+begin

+  with Header do

+    if (ColorType = COLOR_RGBALPHA) or (ColorType = COLOR_GRAYSCALEALPHA) then

+      Longint(Result) := Longint(ImageAlpha) + (LineIndex * Longint(Width))

+    else Result := nil;  {In case the image does not use alpha information}

+end;

+

+{$IFDEF Store16bits}

+{Returns a png data extra scanline}

+function TPngObject.GetExtraScanline(const LineIndex: Integer): Pointer;

+begin

+  with Header do

+    Longint(Result) := (Longint(ExtraImageData) + ((Longint(Height) - 1) *

+      BytesPerRow)) - (LineIndex * BytesPerRow);

+end;

+{$ENDIF}

+

+{Returns a png data scanline}

+function TPngObject.GetScanline(const LineIndex: Integer): Pointer;

+begin

+  with Header do

+    Longint(Result) := (Longint(ImageData) + ((Longint(Height) - 1) *

+      BytesPerRow)) - (LineIndex * BytesPerRow);

+end;

+

+{Initialize gamma table}

+procedure TPngObject.InitializeGamma;

+var

+  i: Integer;

+begin

+  {Build gamma table as if there was no gamma}

+  FOR i := 0 to 255 do

+  begin

+    GammaTable[i] := i;

+    InverseGamma[i] := i;

+  end {for i}

+end;

+

+{Returns the transparency mode used by this png}

+function TPngObject.GetTransparencyMode: TPNGTransparencyMode;

+var

+  TRNS: TChunkTRNS;

+begin

+  with Header do

+  begin

+    Result := ptmNone; {Default result}

+    {Gets the TRNS chunk pointer}

+    TRNS := Chunks.ItemFromClass(TChunkTRNS) as TChunkTRNS;

+

+    {Test depending on the color type}

+    case ColorType of

+      {This modes are always partial}

+      COLOR_RGBALPHA, COLOR_GRAYSCALEALPHA: Result := ptmPartial;

+      {This modes support bit transparency}

+      COLOR_RGB, COLOR_GRAYSCALE: if TRNS <> nil then Result := ptmBit;

+      {Supports booth translucid and bit}

+      COLOR_PALETTE:

+        {A TRNS chunk must be present, otherwise it won't support transparency}

+        if TRNS <> nil then

+          if TRNS.BitTransparency then

+            Result := ptmBit else Result := ptmPartial

+    end {case}

+

+  end {with Header}

+end;

+

+{Add a text chunk}

+procedure TPngObject.AddtEXt(const Keyword, Text: String);

+var

+  TextChunk: TChunkTEXT;

+begin

+  TextChunk := Chunks.Add(TChunkText) as TChunkTEXT;

+  TextChunk.Keyword := Keyword;

+  TextChunk.Text := Text;

+end;

+

+{Add a text chunk}

+procedure TPngObject.AddzTXt(const Keyword, Text: String);

+var

+  TextChunk: TChunkzTXt;

+begin

+  TextChunk := Chunks.Add(TChunkText) as TChunkzTXt;

+  TextChunk.Keyword := Keyword;

+  TextChunk.Text := Text;

+end;

+

+{Removes the image transparency}

+procedure TPngObject.RemoveTransparency;

+var

+  TRNS: TChunkTRNS;

+begin

+  TRNS := Chunks.ItemFromClass(TChunkTRNS) as TChunkTRNS;

+  if TRNS <> nil then Chunks.RemoveChunk(TRNS)

+end;

+

+{Generates alpha information}

+procedure TPngObject.CreateAlpha;

+var

+  TRNS: TChunkTRNS;

+begin

+  {Generates depending on the color type}

+  with Header do

+    case ColorType of

+      {Png allocates different memory space to hold alpha information}

+      {for these types}

+      COLOR_GRAYSCALE, COLOR_RGB:

+      begin

+        {Transform into the appropriate color type}

+        if ColorType = COLOR_GRAYSCALE then

+          ColorType := COLOR_GRAYSCALEALPHA

+        else ColorType := COLOR_RGBALPHA;

+        {Allocates memory to hold alpha information}

+        GetMem(ImageAlpha, Integer(Width) * Integer(Height));

+        FillChar(ImageAlpha^, Integer(Width) * Integer(Height), #255);

+      end;

+      {Palette uses the TChunktRNS to store alpha}

+      COLOR_PALETTE:

+      begin

+        {Gets/creates TRNS chunk}

+        if Chunks.ItemFromClass(TChunkTRNS) = nil then

+          TRNS := Chunks.Add(TChunkTRNS) as TChunkTRNS

+        else

+          TRNS := Chunks.ItemFromClass(TChunkTRNS) as TChunkTRNS;

+

+          {Prepares the TRNS chunk}

+          with TRNS do

+          begin

+            Fillchar(PaletteValues[0], 256, 255);

+            fDataSize := 1 shl Header.BitDepth;

+            fBitTransparency := False

+          end {with Chunks.Add};

+        end;

+    end {case Header.ColorType}

+

+end;

+

+{Returns transparent color}

+function TPngObject.GetTransparentColor: TColor;

+var

+  TRNS: TChunkTRNS;

+begin

+  TRNS := Chunks.ItemFromClass(TChunkTRNS) as TChunkTRNS;

+  {Reads the transparency chunk to get this info}

+  if Assigned(TRNS) then Result := TRNS.TransparentColor

+    else Result := 0

+end;

+

+{$OPTIMIZATION OFF}

+procedure TPngObject.SetTransparentColor(const Value: TColor);

+var

+  TRNS: TChunkTRNS;

+begin

+  if HeaderPresent then

+    {Tests the ColorType}

+    case Header.ColorType of

+    {Not allowed for this modes}

+    COLOR_RGBALPHA, COLOR_GRAYSCALEALPHA: Self.RaiseError(

+      EPNGCannotChangeTransparent, EPNGCannotChangeTransparentText);

+    {Allowed}

+    COLOR_PALETTE, COLOR_RGB, COLOR_GRAYSCALE:

+      begin

+        TRNS := Chunks.ItemFromClass(TChunkTRNS) as TChunkTRNS;

+        if not Assigned(TRNS) then TRNS := Chunks.Add(TChunkTRNS) as TChunkTRNS;

+

+        {Sets the transparency value from TRNS chunk}

+        TRNS.TransparentColor := {$IFDEF UseDelphi}ColorToRGB({$ENDIF}Value{$IFDEF UseDelphi}){$ENDIF}

+      end {COLOR_PALETTE, COLOR_RGB, COLOR_GRAYSCALE)}

+    end {case}

+end;

+

+{Returns if header is present}

+function TPngObject.HeaderPresent: Boolean;

+begin

+  Result := ((Chunks.Count <> 0) and (Chunks.Item[0] is TChunkIHDR))

+end;

+

+{Returns pixel for png using palette and grayscale}

+function GetByteArrayPixel(const png: TPngObject; const X, Y: Integer): TColor;

+var

+  ByteData: Byte;

+  DataDepth: Byte;

+begin

+  with png, Header do

+  begin

+    {Make sure the bitdepth is not greater than 8}

+    DataDepth := BitDepth;

+    if DataDepth > 8 then DataDepth := 8;

+    {Obtains the byte containing this pixel}

+    ByteData := pByteArray(png.Scanline[Y])^[X div (8 div DataDepth)];

+    {Moves the bits we need to the right}

+    ByteData := (ByteData shr ((8 - DataDepth) -

+      (X mod (8 div DataDepth)) * DataDepth));

+    {Discard the unwanted pixels}

+    ByteData:= ByteData and ($FF shr (8 - DataDepth));

+

+    {For palette mode map the palette entry and for grayscale convert and

+    returns the intensity}

+    case ColorType of

+      COLOR_PALETTE:

+        with TChunkPLTE(png.Chunks.ItemFromClass(TChunkPLTE)).Item[ByteData] do

+          Result := rgb(GammaTable[rgbRed], GammaTable[rgbGreen],

+            GammaTable[rgbBlue]);

+      COLOR_GRAYSCALE:

+      begin

+        ByteData := GammaTable[ByteData * ((1 shl DataDepth) + 1)];

+        Result := rgb(ByteData, ByteData, ByteData);

+      end;

+      else Result := 0;

+    end {case};

+  end {with}

+end;

+

+{In case vcl units are not being used}

+{$IFNDEF UseDelphi}

+function ColorToRGB(const Color: TColor): COLORREF;

+begin

+  Result := Color

+end;

+{$ENDIF}

+

+{Sets a pixel for grayscale and palette pngs}

+procedure SetByteArrayPixel(const png: TPngObject; const X, Y: Integer;

+  const Value: TColor);

+const

+  ClearFlag: Array[1..8] of Integer = (1, 3, 0, 15, 0, 0, 0, $FF);

+var

+  ByteData: pByte;

+  DataDepth: Byte;

+  ValEntry: Byte;

+begin

+  with png.Header do

+  begin

+    {Map into a palette entry}

+    ValEntry := GetNearestPaletteIndex(Png.Palette, ColorToRGB(Value));

+

+    {16 bits grayscale extra bits are discarted}

+    DataDepth := BitDepth;

+    if DataDepth > 8 then DataDepth := 8;

+    {Gets a pointer to the byte we intend to change}

+    ByteData := @pByteArray(png.Scanline[Y])^[X div (8 div DataDepth)];

+    {Clears the old pixel data}

+    ByteData^ := ByteData^ and not (ClearFlag[DataDepth] shl ((8 - DataDepth) -

+      (X mod (8 div DataDepth)) * DataDepth));

+

+    {Setting the new pixel}

+    ByteData^ := ByteData^ or (ValEntry shl ((8 - DataDepth) -

+      (X mod (8 div DataDepth)) * DataDepth));

+  end {with png.Header}

+end;

+

+{Returns pixel when png uses RGB}

+function GetRGBLinePixel(const png: TPngObject;

+  const X, Y: Integer): TColor;

+begin

+  with pRGBLine(png.Scanline[Y])^[X] do

+    Result := RGB(rgbtRed, rgbtGreen, rgbtBlue)

+end;

+

+{Sets pixel when png uses RGB}

+procedure SetRGBLinePixel(const png: TPngObject;

+ const X, Y: Integer; Value: TColor);

+begin

+  with pRGBLine(png.Scanline[Y])^[X] do

+  begin

+    rgbtRed := GetRValue(Value);

+    rgbtGreen := GetGValue(Value);

+    rgbtBlue := GetBValue(Value)

+  end

+end;

+

+{Sets a pixel}

+procedure TPngObject.SetPixels(const X, Y: Integer; const Value: TColor);

+begin

+  if (X in [0..Width - 1]) and (Y in [0..Height - 1]) then

+    with Header do

+    begin

+      if ColorType in [COLOR_GRAYSCALE, COLOR_PALETTE] then

+        SetByteArrayPixel(Self, X, Y, Value)

+      else

+        SetRGBLinePixel(Self, X, Y, Value)

+    end {with}

+end;

+

+{Returns a pixel}

+function TPngObject.GetPixels(const X, Y: Integer): TColor;

+begin

+  if (X in [0..Width - 1]) and (Y in [0..Height - 1]) then

+    with Header do

+    begin

+      if ColorType in [COLOR_GRAYSCALE, COLOR_PALETTE] then

+        Result := GetByteArrayPixel(Self, X, Y)

+      else

+        Result := GetRGBLinePixel(Self, X, Y)

+    end {with}

+  else Result := 0

+end;

+

+{Returns the image palette}

+function TPngObject.GetPalette: HPALETTE;

+var

+  LogPalette: TMaxLogPalette;

+  i: Integer;

+begin

+  {Palette is avaliable for COLOR_PALETTE and COLOR_GRAYSCALE modes}

+  if (Header.ColorType in [COLOR_PALETTE, COLOR_GRAYSCALE])  then

+  begin

+    {In case the pal}

+    if TempPalette = 0 then

+      with LogPalette do

+      begin

+        {Prepares the new palette}

+        palVersion := $300;

+        palNumEntries := 256;

+        {Copy entries}

+        for i := 0 to LogPalette.palNumEntries - 1 do

+        begin

+          palPalEntry[i].peRed := Header.BitmapInfo.bmiColors[i].rgbRed;

+          palPalEntry[i].peGreen := Header.BitmapInfo.bmiColors[i].rgbGreen;

+          palPalEntry[i].peBlue := Header.BitmapInfo.bmiColors[i].rgbBlue;

+          palPalEntry[i].peFlags := 0;

+        end {for i};

+        {Creates the palette}

+        TempPalette := CreatePalette(pLogPalette(@LogPalette)^);

+      end {with LogPalette, if Temppalette = 0}

+  end {if Header.ColorType in ...};

+  Result := TempPalette;

+end;

+

+initialization

+  {Initialize}

+  ChunkClasses := nil;

+  {crc table has not being computed yet}

+  crc_table_computed := FALSE;

+  {Register the necessary chunks for png}

+  RegisterCommonChunks;

+  {Registers TPNGObject to use with TPicture}

+  {$IFDEF UseDelphi}{$IFDEF RegisterGraphic}

+    TPicture.RegisterFileFormat('PNG', 'Portable Network Graphics', TPNGObject);

+  {$ENDIF}{$ENDIF}

+finalization

+  {$IFDEF UseDelphi}{$IFDEF RegisterGraphic}

+    TPicture.UnregisterGraphicClass(TPNGObject);

+  {$ENDIF}{$ENDIF}

+  {Free chunk classes}

+  FreeChunkClassList;

+end.

+

+