Expose the mutator stack to embedders using the custom compositor interface.

[chinmaygarde]

Internal: b/143612326

Currently, when the Flutter compositor encounters a platform layer, any opacities or clips on the transformation stack cannot be applied to that layer (just the platform layer though, any Flutter rendered contents after the platform layer will be rendered just fine because Flutter controls those renderer backing stores). Flutter should expose this information to the embedder during the layer presentation callback. It would still be embedder responsibility to affect that clip (or opacity) on the layer.

Flutter already calculates this information during the layer tree preroll in the mutator stack. This needs to be exposed via the stable interface.

[chinmaygarde]

xref b/143612326

[chinmaygarde]

@kf6gpe This is tied to the progress on engine AIs of b/143612326.

[chinmaygarde]

Fixed in flutter/engine#13731

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.