From 98e2821b38a775737e42a2479a6bc65107210859 Mon Sep 17 00:00:00 2001 From: Elliot Kroo Date: Thu, 11 Mar 2010 15:21:30 -0800 Subject: reorganizing the first level of folders (trunk/branch folders are not the git way :) --- infrastructure/ace/README | 69 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 infrastructure/ace/README (limited to 'infrastructure/ace/README') diff --git a/infrastructure/ace/README b/infrastructure/ace/README new file mode 100644 index 0000000..275684f --- /dev/null +++ b/infrastructure/ace/README @@ -0,0 +1,69 @@ +===== +ACE2 (originally AppJet Code Editor) +===== + +(This doc started Dec 2009 by dgreenspan.) + +ACE2 is EtherPad's editor, a content-editable-based rich text editor +that supports IE6+, FF(2?/)3+, Safari(3?/)4+. It supports +collaborative editing using operation transforms (easysync2), +undo/redo, copy/paste. + +The name "ACE2" is because this is a rewrite of aiba's original +content-editable AppJet Code Editor. + +== Building it + +In this directory, run `bin/make normal etherpad` (requires scala), +which generates `build/ace2.js` and copies this and other files into +the etherpad source tree. To have the script keep running and +automatically rebuild when source files change, run `bin/make auto +etherpad`. + +The original reason for the build process was that ACE needs to +construct two nested iframes on the client, and to do this without +incurring round-trips to the server, it programmatically loads code +into the outer iframe that loads code into the inner iframe; so the +bulk of ACE's code is compressed into a string literal (twice). Later +on, refactoring meant that the source is also divided into more than a +dozen files that the build script combines, and some are also +server-side EtherPad modules or client-side libraries (or both). + +The master copy of the operational transform (OT) library, easysync2, +lives here. + +In the early days it was possible to run ACE in a sort of development +mode, without the compression and iframe injection, by running it out +of the 'www' directory, but this is no longer possible. + +== Browser support + +We went out of our way to support IE6+. IE's design-mode is quite +robust, though there are some differences in manipulation of the +selection and insertion point and in the DOM representation we had to +use. + +We don't support Opera. Opera is a problematic case, because +apparently JS running in different iframes is run concurrently, not +linearized into a single event thread. This seems to be a rather +obscure fact and is almost difficult to believe. As if iframes don't +complicate scripting enough! + +== Syntax highlighting + +Though syntax highlighting predated rich text as the original +motivation for the design of ACE, support was eventually dropped in +EtherPad. At first the plan was to generalize it to other programming +languages, but the task was deprioritized (and difficult), and during +subsequent optimization and refactoring of ACE, calls to the +incremental lexer were stripped out because they complicated things. + +One plan for multi-language syntax highlighting, never implemented, +was to calculate syntax highlighting on the server as a sort of "style +overlay" and feed updates to the client along with updates to the +document text. + +== Changeset format + +See easysync-notes.txt for some notes on the changeset format, which +was redesigned with the advent of rich text. -- cgit v1.2.3