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Diffstat (limited to 'src/lib/other/DirWatch.pas')
| -rw-r--r-- | src/lib/other/DirWatch.pas | 345 |
1 files changed, 345 insertions, 0 deletions
diff --git a/src/lib/other/DirWatch.pas b/src/lib/other/DirWatch.pas new file mode 100644 index 00000000..9d395840 --- /dev/null +++ b/src/lib/other/DirWatch.pas @@ -0,0 +1,345 @@ +unit DirWatch; + +// ----------------------------------------------------------------------------- +// Component Name: TDirectoryWatch . +// Module: DirWatch . +// Description: Implements watching for file changes in a designated . +// directory (or directories). . +// Version: 1.4 . +// Date: 10-MAR-2003 . +// Target: Win32, Delphi 3 - Delphi 7 . +// Author: Angus Johnson, angusj-AT-myrealbox-DOT-com . +// A portion of code has been copied from the Drag & Drop . +// Component Suite which I co-authored with Anders Melander. . +// Copyright: © 2003 Angus Johnson . +// . +// Usage: 1. Add a TDirectoryWatch component to your form. . +// 2. Set its Directory property . +// 3. If you wish to watch its subdirectories too then set . +// the WatchSubDir property to true . +// 4. Assign the OnChange event . +// 5. Set Active to true . +// ----------------------------------------------------------------------------- + +interface + +{$IFDEF FPC} + {$MODE Delphi} + {$H+} // use AnsiString +{$ENDIF} + +uses + Windows, + Messages, + Classes, + {$IFDEF FPC} + WinAllocation, + {$ENDIF} + SysUtils; + +type + TNotifyFilters = set of (nfFilename, nfDirname, nfAttrib, + nfSize, nfLastWrite, nfSecurity); + + TWatchThread = class; //forward declaration + + TDirectoryWatch = class(TComponent) + private + fWindowHandle: THandle; + fWatchThread: TWatchThread; + fWatchSubDirs: boolean; + fDirectory: string; + fActive: boolean; + fNotifyFilters: TNotifyFilters; //see FindFirstChangeNotification in winAPI + fOnChangeEvent: TNotifyEvent; + procedure SetActive(aActive: boolean); + procedure SetDirectory(aDir: string); + procedure SetWatchSubDirs(aWatchSubDirs: boolean); + procedure SetNotifyFilters(aNotifyFilters: TNotifyFilters); + procedure WndProc(var aMsg: TMessage); + public + constructor Create(aOwner: TComponent); override; + destructor Destroy; override; + published + property Directory: string read fDirectory write SetDirectory; + property NotifyFilters: TNotifyFilters + read fNotifyFilters write SetNotifyFilters; + property WatchSubDirs: boolean read fWatchSubDirs write SetWatchSubDirs; + property Active: boolean read fActive write SetActive; + property OnChange: TNotifyEvent read fOnChangeEvent write fOnChangeEvent; + end; + + TWatchThread = class(TThread) + private + fOwnerHdl: Thandle; + fChangeNotify : THandle; //Signals whenever Windows detects a change in . + //the watched directory . + fBreakEvent: THandle; //Signals when either the Directory property . + //changes or when the thread terminates . + fDirectory: string; + fWatchSubDirs: longbool; + fNotifyFilters: dword; + fFinished: boolean; + protected + procedure SetDirectory(const Value: string); + procedure ProcessFilenameChanges; + procedure Execute; override; + public + constructor Create( OwnerHdl: THandle; + const InitialDir: string; WatchSubDirs: boolean; NotifyFilters: dword); + destructor Destroy; override; + procedure Terminate; + property Directory: string write SetDirectory; + end; + +procedure Register; + +implementation + +const + NOTIFYCHANGE_MESSAGE = WM_USER + 1; + +resourcestring + sInvalidDir = 'Invalid Directory: '; + +//---------------------------------------------------------------------------- +// Miscellaneous functions ... +//---------------------------------------------------------------------------- + +procedure Register; +begin + RegisterComponents('Samples', [TDirectoryWatch]); +end; +//---------------------------------------------------------------------------- + +function DirectoryExists(const Name: string): Boolean; +var + Code: Integer; +begin + Code := GetFileAttributes(PChar(Name)); + Result := (Code <> -1) and (FILE_ATTRIBUTE_DIRECTORY and Code <> 0); +end; + +//---------------------------------------------------------------------------- +// TDirectoryWatch methods ... +//---------------------------------------------------------------------------- + +constructor TDirectoryWatch.Create(aOwner: TComponent); +begin + inherited Create(aOwner); + //default Notify values - notify if either a file name or a directory name + //changes or if a file is modified ... + fNotifyFilters := [nfFilename, nfDirname, nfLastWrite]; + fDirectory := 'C:\'; + //this non-visual control needs to handle messages, so ... + if not (csDesigning in ComponentState) then + fWindowHandle := AllocateHWnd(WndProc); +end; +//---------------------------------------------------------------------------- + +destructor TDirectoryWatch.Destroy; +begin + Active := false; + if not (csDesigning in ComponentState) then + DeallocateHWnd(fWindowHandle); + inherited Destroy; +end; +//---------------------------------------------------------------------------- + +procedure TDirectoryWatch.WndProc(var aMsg: TMessage); +begin + with aMsg do + if Msg = NOTIFYCHANGE_MESSAGE then + begin + if assigned(OnChange) then OnChange(self); + end else + Result := DefWindowProc(FWindowHandle, Msg, wParam, lParam); +end; +//------------------------------------------------------------------------------ + +procedure TDirectoryWatch.SetNotifyFilters(aNotifyFilters: TNotifyFilters); +begin + if aNotifyFilters = fNotifyFilters then exit; + fNotifyFilters := aNotifyFilters; + if assigned(fWatchThread) then + begin + Active := false; + Active := true; + end; +end; +//------------------------------------------------------------------------------ + +procedure TDirectoryWatch.SetWatchSubDirs(aWatchSubDirs: boolean); +begin + if aWatchSubDirs = fWatchSubDirs then exit; + fWatchSubDirs := aWatchSubDirs; + if assigned(fWatchThread) then + begin + Active := false; + Active := true; + end; +end; +//------------------------------------------------------------------------------ + +procedure TDirectoryWatch.SetDirectory(aDir: string); +begin + if aDir = '' then + begin + Active := false; + fDirectory := ''; + exit; + end; + if (aDir[length(aDir)] <> '\') then aDir := aDir + '\'; + if aDir = fDirectory then exit; + if not (csDesigning in ComponentState) and not DirectoryExists(aDir) then + raise Exception.Create( sInvalidDir + aDir); + fDirectory := aDir; + if assigned(fWatchThread) then + fWatchThread.Directory := fDirectory; +end; +//------------------------------------------------------------------------------ + +procedure TDirectoryWatch.SetActive(aActive: boolean); +var + nf: dword; +begin + if aActive = fActive then exit; + fActive := aActive; + if csDesigning in ComponentState then exit; + if fActive then + begin + if not DirectoryExists(fDirectory) then + begin + fActive := false; + raise Exception.Create(sInvalidDir + fDirectory); + end; + nf := 0; + if nfFilename in fNotifyFilters then + nf := nf or FILE_NOTIFY_CHANGE_FILE_NAME; + if nfDirname in fNotifyFilters then + nf := nf or FILE_NOTIFY_CHANGE_DIR_NAME; + if nfAttrib in fNotifyFilters then + nf := nf or FILE_NOTIFY_CHANGE_ATTRIBUTES; + if nfSize in fNotifyFilters then + nf := nf or FILE_NOTIFY_CHANGE_SIZE; + if nfLastWrite in fNotifyFilters then + nf := nf or FILE_NOTIFY_CHANGE_LAST_WRITE; + if nfSecurity in fNotifyFilters then + nf := nf or FILE_NOTIFY_CHANGE_SECURITY; + fWatchThread := TWatchThread.Create( + fWindowHandle, fDirectory, fWatchSubDirs, nf); + end else + begin + fWatchThread.Terminate; + fWatchThread := nil; + end; +end; + +//---------------------------------------------------------------------------- +// TWatchThread methods ... +//---------------------------------------------------------------------------- + +constructor TWatchThread.Create(OwnerHdl: THandle; + const InitialDir: string; WatchSubDirs: boolean; NotifyFilters: dword); +begin + inherited Create(True); + fOwnerHdl := OwnerHdl; + if WatchSubDirs then + cardinal(fWatchSubDirs) := 1 //workaround a Win9x OS issue + else + fWatchSubDirs := false; + FreeOnTerminate := true; + Priority := tpLowest; + fDirectory := InitialDir; + fNotifyFilters := NotifyFilters; + fBreakEvent := windows.CreateEvent(nil, False, False, nil); + Resume; +end; +//------------------------------------------------------------------------------ + +destructor TWatchThread.Destroy; +begin + CloseHandle(fBreakEvent); + inherited Destroy; +end; +//------------------------------------------------------------------------------ + +procedure TWatchThread.SetDirectory(const Value: string); +begin + if (Value = FDirectory) then exit; + FDirectory := Value; + SetEvent(fBreakEvent); +end; +//------------------------------------------------------------------------------ + +procedure TWatchThread.Terminate; +begin + inherited Terminate; + SetEvent(fBreakEvent); + while not fFinished do sleep(10); //avoids a reported resource leak + //if called while closing the application. +end; +//------------------------------------------------------------------------------ + +procedure TWatchThread.Execute; +begin + //OUTER LOOP - manages Directory property reassignments + while (not Terminated) do + begin + fChangeNotify := FindFirstChangeNotification(pchar(fDirectory), + fWatchSubDirs, fNotifyFilters); + if (fChangeNotify = INVALID_HANDLE_VALUE) then + //Can't monitor the specified directory so we'll just wait for + //a new Directory assignment or the thread terminating ... + WaitForSingleObject(fBreakEvent, INFINITE) + else + try + //Now do the INNER loop... + ProcessFilenameChanges; + finally + FindCloseChangeNotification(fChangeNotify); + end; + end; + fFinished := true; +end; +//------------------------------------------------------------------------------ + +procedure TWatchThread.ProcessFilenameChanges; +var + WaitResult : DWORD; + HandleArray : array[0..1] of THandle; +const + TEN_MSECS = 10; + HUNDRED_MSECS = 100; +begin + HandleArray[0] := fBreakEvent; + HandleArray[1] := fChangeNotify; + //INNER LOOP - exits only when fBreakEvent signaled + while (not Terminated) do + begin + //waits for either fChangeNotify or fBreakEvent ... + WaitResult := WaitForMultipleObjects(2, @HandleArray, False, INFINITE); + if (WaitResult = WAIT_OBJECT_0 + 1) then //fChangeNotify + begin + repeat //ie: if a number of files are changing in a block + //just post the one notification message ... + FindNextChangeNotification(fChangeNotify); + until Terminated or + (WaitForSingleObject(fChangeNotify, TEN_MSECS) <> WAIT_OBJECT_0); + if Terminated then break; + //OK, now notify the main thread (before restarting inner loop)... + PostMessage(fOwnerHdl, NOTIFYCHANGE_MESSAGE, 0, 0); + end else //fBreakEvent ... + begin + //If the Directory property is undergoing multiple rapid reassignments + //wait 'til this stops before restarting monitoring of a new directory ... + while (not Terminated) and + (WaitForSingleObject(fBreakEvent, HUNDRED_MSECS) = WAIT_OBJECT_0) do; + break; //EXIT LOOP HERE + end; + end; +end; +//------------------------------------------------------------------------------ +//------------------------------------------------------------------------------ + +end.
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