1332443 - Support pixel snapping with WebRenderLayer

Status: RESOLVED INVALID

(Core :: Graphics: WebRender, defect)

Description

[Ryan Hunt [:rhunt] (on leave until early May)]

There are a couple reftests failing because we don't support pixel snapping of some kind.

Here is my try run with a first attempt at it. https://treeherder.mozilla.org/#/jobs?repo=try&revision=78605de9a9ab7a4fadb4adeacc0c6a26f5345c55

Comment 1

[Jeff Muizelaar [:jrmuizel]]

Does this snapping happen in the compositor today?

Comment 2

[Ryan Hunt [:rhunt] (on leave until early May)]

If I understand correctly it is happening in the ComputeEffectiveTransform functions and is applied to the transform directly. It may happen in other places.

For now I think we can get by applying it to the bounds post transform. But I'm not sure what the best solution is with transforms (potentially 3D) applied directly.

Comment 3

[Jeff Muizelaar [:jrmuizel]]

I'd like to better understand why we need this snapping if this is the right place to be doing it. What are the reftests that this fixes?

Comment 4

[Ryan Hunt [:rhunt] (on leave until early May)]

Some reftests that are failing are:

layout/reftests/bugs/602200-1.html
layout/reftests/bugs/602200-3.html
layout/reftests/bugs/635373-1.html
layout/reftests/bugs/635373-2.html
layout/reftests/bugs/635373-3.html

The bugs on those reftests are related to scroll snapping.

I don't have a strong opinion on where to fix this. I don't know enough about the feature to say whether it's Gecko specific for Layers or whether it would benefit WebRender.

Comment 5

[Ryan Hunt [:rhunt] (on leave until early May)]

Closing this as is going to be solved on the WebRender side.