For https://github.com/flutter/flutter/issues/33807
We still need to make layers' children immutable for full immutability.
That will require us to change the SceneBuilder API to build the layer
bottom up instead of top down (post-order traversal instead of pre-order
traversal).
It ensures that every OpacityLayer can be optimized by retained
rendering.
Tested with `flutter test --local-engine=host_debug_unopt` in
flutter/flutter/packages/flutter.
Related issues: #21756#23535
This PR replaces the unused `PrerollContext::child_paint_bounds` with `PrerollContext::cull_rect` so we can prune unnecessary preroll tasks (especially cache) based on clips. This PR fixes https://github.com/flutter/flutter/issues/24712
Performance test has been added (https://github.com/flutter/flutter/pull/25381) to make sure that we won't regress again in the future.
Note that the cull_rect here is very similar to those removed in https://github.com/flutter/engine/pull/6352 . We can't compute cull rects in SceneBuilder because of retained layers. But we can still compute and use them to optimize performance in Preroll.
When the flag is true, we currently use a single thread configuration,
and disabled the raster cache for opacity layers.
The flag's name is 'io.flutter_embedded_views_preview'.
The overlay surfaces are going to be the same IOSSurface implementation
with the platform views controller set to null (so these are surfaces
that don't support embedding platform views to them).
* Adds a FlutterOverlayView which is a UIView that's showing an
overlay surface.
* Creates an overlay surface for each embedded UIView (done in
FlutterPlatformViewsController).
* Changes CompositeEmbeddedView to return a new canvas.
* Makes the PlatformViewLayer replace the PaintContext's canvas with
the canvas for the overlay view.
* Changed canvas in PaintContext to be a pointer so it can be changed.
TBD in following PRs:
* Copy the current canvas state when replacing a canvas in PaintContext.
* Make FlutterOverlayView work with a GL backend (currently it only
works with software rendering)
* Revert "Revert "Allow raster caching any layer subtree (#6442)" (#6506)"
This reverts commit c6e6da512a54c1bb33a584b117bcf300ce71b166.
* Use raw pointer for RasterCacheKey
So we won't depend on whether it's a std::unique_ptr or std::shared_ptr.
We first test this with OpacityLayer. This test alone (without retained rendering) should have ~30% speedup as we'll have fewer render target switches by snapshoting in the Preroll instead of saveLayer in the Paint.
In my local flutter_gallery transition perf tests, the average frame time drops from ~16ms to ~12ms.
https://github.com/flutter/flutter/issues/21756
We push a bit up the tree during preroll to learn whether there system
composited layers below each layer. During update scene, we squash down
to paint tasks, which we execute after publishing the new scene.
Instead, make Layer::Paint take a new PaintContext that has just exactly
the state that it needs, mirroring PrerollContext. Also, rename
PaintContext to CompositorContext because it holds the context for the
whole compositor.
Previously we were applying opacity in a different way than Skia
expects. Now we use the exact pattern that Skia expects so that we hit
more optimizations inside SkRecordOptimize.
After this patch, we don't actually get the optimization because we
don't yet run SkRecordOptimize over the composited tree. A later patch
will actually cause us to run SkRecordOptimize.
