Platform/GFX/Quantum Render: Difference between revisions

Platform/GFX/Quantum Render (view source)

Revision as of 14:07, 5 July 2019

378 bytes removed , 5 July 2019

→‎On Gecko integration: Update to talk about layers-free

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 === On Gecko integration ===
-(Note: the description below applies to the "layers mode" integration with WebRender, which is deprecated now. We are in the process of transitioning to the "layers-free mode", where Gecko display items are directly converted to WebRender commands via their CreateWebRenderCommands functions. Some of the content below still applies though; in particular we still create a WebRenderLayerManager, which manages the conversion from Gecko display items to WebRender display items.)
+If you are familiar with the way Gecko normally works, the Quantum Render changes should be relatively straightforward. Instead of using a ClientLayerManager, we create a [https://hg.mozilla.org/projects/graphics/file/tip/gfx/layers/wr/WebRenderLayerManager.cpp WebRenderLayerManager] instance. However, this "layer manager" doesn't actually manage layers, because WebRender doesn't use layers. Instead, it walks the Gecko display list and calls the <tt>BuildWebRenderCommands</tt> function on each display item to generate WebRender display items. This display list is sent over the [https://hg.mozilla.org/projects/graphics/file/tip/gfx/layers/ipc/PWebRenderBridge.ipdl PWebRenderBridge] IPDL channel, which is conceptually similar to PLayerTransaction in Gecko. The commands are received in [https://hg.mozilla.org/projects/graphics/file/tip/gfx/layers/wr/WebRenderBridgeParent.cpp WebRenderBridgeParent] which interprets the messages, and talks to the core WebRender library using the API in [https://hg.mozilla.org/projects/graphics/file/tip/gfx/webrender_bindings/webrender_ffi.h webrender_ffi.h] (via various wrapper abstractions in <tt>gfx/webrender_bindings/</tt>). The API is implemented in the [https://hg.mozilla.org/projects/graphics/file/tip/gfx/webrender_bindings/src/bindings.rs webrender_bindings] crate, which is written in Rust.
-If you are familiar with the way Gecko normally works, the Quantum Render changes should be relatively straightforward. Instead of using a ClientLayerManager, we create a [https://hg.mozilla.org/projects/graphics/file/tip/gfx/layers/wr/WebRenderLayerManager.cpp WebRenderLayerManager] instance. This layer manager creates its own layer instances, and when those layers have their Render() function called, they generate WebRender-specific commands. These commands are sent over the [https://hg.mozilla.org/projects/graphics/file/tip/gfx/layers/ipc/PWebRenderBridge.ipdl PWebRenderBridge] IPDL channel, which is conceptually similar to PLayerTransaction in Gecko. The commands are received in [https://hg.mozilla.org/projects/graphics/file/tip/gfx/layers/wr/WebRenderBridgeParent.cpp WebRenderBridgeParent] which interprets the messages, and talks to the core WebRender library using the API in [https://hg.mozilla.org/projects/graphics/file/tip/gfx/webrender_bindings/webrender_ffi.h webrender_ffi.h] (via various wrapper abstractions in <tt>gfx/webrender_bindings/</tt>). The API is implemented in the [https://hg.mozilla.org/projects/graphics/file/tip/gfx/webrender_bindings/src/bindings.rs webrender_bindings] crate, which is written in Rust.
 Look through [https://bugzilla.mozilla.org/buglist.cgi?component=Graphics%3A%20WebRender&product=Core&bug_status=__open__&list_id=13349798 open unassigned bugs] (with no open dependencies) in the WebRender bugzilla component to find things to work on.