1666905 - [wpt-sync] Sync PR 25727 - Revert "Enable transformed rasterization for most layers"

Status: RESOLVED INVALID

(Core :: DOM: Animation, task, P4)

Description

[Web Platform Test Sync Bot [:wpt-sync] (Matrix: #interop:mozilla.org)]

Sync web-platform-tests PR 25727 into mozilla-central (this bug is closed when the sync is complete).

PR: https://github.com/web-platform-tests/wpt/pull/25727
Details from upstream follow.

b'Xianzhu Wang <[e-mail]>' wrote:

Revert "Enable transformed rasterization for most layers"

This reverts commit b179b125df4cd0a3a81ba7b45d1d2e9309359a38.

Reason for revert: for debugging crbug.com/1121730

Original change's description:

Enable transformed rasterization for most layers

Background: transformed rasterization is used to render sharp text in a
composited layer with fractional transform. It snaps the composited
transform of the layer to whole pixels, then applies the fraction
during rasterization.

Previously we disallowed transformed rasterization in blink for directly
composited layers (excluding backface-visibility:hidden and trivial 3d
transforms such as translateZ(0)), especially for will-change:transform
because change of fractional transform would cause re-rasterization
which would defeat the purpose of will-change:transform.

Now for a layer that was not eligible for transformed rasterization,
calculate the initial raster translation which achieves sharp text
rendering with the initial transform. When the transform of the layer
changes, keep its original raster translation to avoid invalidation
of tilings, to ensure animation performance. The rendered result will
be blurry during animation but the initial rendering result is sharp.

Remove blink-side transformed rasterization conditions and let cc
decide it based on screen and draw transforms of the layers.

Bug: 1111195
Change-Id: If0455be2f29e69cd7152c951626e6e8cc143b5bd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351164
Reviewed-by: Philip Rogers \<[e-mail]>
Reviewed-by: vmpstr \<[e-mail]>
Commit-Queue: Xianzhu Wang \<[e-mail]>
Cr-Commit-Position: refs/heads/master@{#798268}

TBR=[e-mail],[e-mail],[e-mail]

Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 1111195, 1121630
Change-Id: Ibab42e963cab263cab062377ffa2aad38291c5a9
Reviewed-on: https://chromium-review.googlesource.com/2427125
WPT-Export-Revision: ba0bd9eba23f40b3d49f5713015d7ecadb195a34