Embedding Gecko

Mark Finkle

Mozilla Corporation

Why Embed Gecko?

• Quick, robust, and highly standards compliant Web renderer
• Cross platform
• Open-source and royalty-free

How do You Embed Gecko?

• Gecko is part of XULRunner
• Initialization & teardown
• Use the Gecko-provided interfaces
• Implement the required embedder interfaces

Embedding APIs

Problems with Embedding

• Complicated
• Fragile
• Not maintained
• Sparse documentation
• Missing functionality
• Low-level
• Competition

Refactoring Embedding

• Use simple C++ whenever possible
• Create a Gecko isolation layer
• Create framework specific wrappers
• Add functionality
• Minimize the number of "interfaces"

Design Thoughts - Host/Gecko Interaction

• Event callbacks from Gecko to C++
• Inject C++ objects into Gecko JavaScript contexts

Design Thoughts - Event Callbacks

void SomeFunc(nsIDOMEvent* aEvent) {...}

pHost->AddEventListener("element-id", "click", SomeFunc);
		

Design Thoughts - Inject C++ Objects

class MyObject : MagicBase {
public:
  void addData(string) {...}
};

MyObject* pObj = new MyObject;
pHost->AddObject("special", pObj);

//---------------------------------------

<input type="text" onblur="blurHandler(event);"/>

function blurHandler(aEvent) {
  window.special.addData(aEvent.target.value);
}
		

Frameworks Built on the New API

• Win32
• Win32/Qt
• Linux/GTK
• Linux/Qt
• Win32/GTK (contributor)
• OS X (?)

Roadmap

• Win32/ActiveX/.NET component
• Render content to image
• Code snippets section on the MDC
• Simplified access to DOM from embedder
• Access to C++ objects from JS
• Include in nightly SDK builds
• Additional platforms support (OS X and Mobile)

Resources

• NewAPI - Details on using the new embedding API
• Gecko embedding basics - Good background document on the core embedding system
• Embedding FAQ - Good answers to common embedding tasks
• #embedding on Mozilla IRC

Questions?