Embedding/IPCLiteAPI

Lite-weight Embedding API for Mozilla based applications with native UI.

Basic architecture is very close to WebKit2, and MicroB

Story

Mozilla has bunch of technologies integrated recently:

• OMTC - Off Main thread compositing - keeping Gecko/XPCOM and Compositor in separate threads (Android Firefox)
• IPC - Multiprocess rendering - keeping Gecko/XPCOM and Compositor in separate processes (Firefox OS, Desktop Firefox Plugins)

In order to build Simple browser with native UI (Gtk/Qt/UiKit) similar to Android Firefox with Java UI, some internal API need to be exposed. Goal of this project to provide Generic embedding API which could be easily wrapped without bunch of extra code into Toolkit specific Widgets, and embed these widgets into platform UI applications.

Benefits of new architecture comparing to default mozilla embedding:

* No XUL/XPCOM heavy content in UI process/Thread (Best memory footprint (process case), fast startup)
* Process/Thread communication between UI and Content(Gecko/XPCOM) Thread/Process - built on current Mozilla Chromium/IPDL implementation ([https://developer.mozilla.org/en-US/docs/IPDL/Tutorial IPDL Tutorial])
* Rendering based on Shadow/Shadowable layers tree which provide MultiThread/Process responsive rendering (same as content rendering in XUL Mobile FF/OMTC Android Firefox/Firefox OS)
* Multi process model provide ability to load memory greedy content in child process and kill it without increasing memory usage for Main UI application process

New embedding expected initialization sequence

1. Native UI startup (android UI thread view or Gtk/Qt/UIKit event loop)
2. Load EmbedLite library and start point API (can be called in parallel thread)
   LoadEmbedLite(argc, argv);

3. Get EmbedLite application object, which allow to start Gecko in Child-Thread/Process, and create rendering views
   EmbedLiteApp* embedapp = XRE_GetEmbedLite();
4. Setup EmbedLite application listener (Some notifications about main app lifecycle)
   EmbedLiteAppListener[Derived]* listener = new EmbedLiteAppListener[Derived]();
   embedapp->SetListener(listener);
5. Startup Embedding, blocking call, better to start UI first, and call this in some main loop event
   EmbedLite will not freeze application here, and continue native events processing along with Chromium Messages.
   embedapp->Start(EmbedLiteApp::EMBED_THREAD/PROCESS);

 Core Embed Initialization example

6. After EmbedLiteAppListener[Derived] received "Initialized" notification, new EmbedLiteView can be created with:
   EmbedLiteView* view = embedapp->CreateView();
   And setup related EmbedLiteViewListener in order to receive notifications from View actions (title,progress,invalidate et.c.)
   view->SetListener(MyEmbedLiteViewListener);

 View Embed Initialization example

Communication between UI and content process

* Load remote content JS (privileged script with full access) and interact using MessageMessenger (send/receive JSON messages)
* Use embed messaging API (observe broadcast messages)
* Build Custom Gecko C++/JS extensions

Build instructions:

git clone git://github.com/tmeshkova/mozilla-central.git
cd mozilla-central
git checkout embedlite

cp embedding/embedlite/config/mozconfig.gtkdesktop  mozconfig
# or
# for harmattan
# cp embedding/embedlite/config/mozconfig.qtN9-qt mozconfig
MOZCONFIG=$(pwd)/mozconfig make -f client.mk build_all

Try, Test, Report, Contribute:

Fell free to test it, submit issues to github issue tracker, or even better fork it, fix it, contribute changes via Pull Requests.

Pre compiled binaries:

Mer (ARMv7 hardfp)

http://romaxa.info/mer/mozbuild.tar.gz

Harmattan

http://romaxa.info/mer/mozbuildhm.tar.gz

Qt-Desktop and BeagleBoard Ubuntu

http://romaxa.info/fennec/IPCEmbedding/

Run test examples:

cd obj-*/dist/bin

Basic core test
./embedLiteCoreInitTest

EmbedLiteAPI wrapped into qt/qml widget
Qt only, qml based UI with scrolling and zooming (no clicks):
./qmlMozEmbedTest -url linux.org.ru

Basic view of new architecture: