1361662 - Fix rounding tests after enabling background color layer

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, enhancement)

Description

[Ethan Lin[:ethlin]]

After enabling background color layer, the test '1ayout/reftests/pixel-rounding/rounded-background-color-top-4.html' will fail[1]. It looks like we'll have some difference on the edge of the elements. I guess it's because originally we paint everything in a painted layer and the coordinate is in float[2]. After we have a color layer for it, the layer's coordinate is in integer[3]. Not sure if we should fuzz these tests or fix them.


[1] https://hg.mozilla.org/mozilla-central/raw-file/tip/layout/tools/reftest/reftest-analyzer.xhtml#logurl=https://queue.taskcluster.net/v1/task/DkZtEIYsRSmLYrTDb-fd_Q/runs/0/artifacts/public/logs/live_backing.log&only_show_unexpected=1
[2] https://dxr.mozilla.org/mozilla-central/source/layout/painting/nsDisplayList.cpp?q=path%3AnsDisplayList.cpp&redirect_type=single#4071
[3] https://dxr.mozilla.org/mozilla-central/source/layout/painting/nsDisplayList.cpp?q=path%3AnsDisplayList.cpp&redirect_type=single#4036

Comment 1

[Ethan Lin[:ethlin]]

Matt, would you mind providing some suggestions on this?

Comment 2

[Matt Woodrow (:mattwoodrow)]

Do we need the ColorLayer bounds to be an IntRect?

Comment 3

[Ethan Lin[:ethlin]]

I think I found the problem. Gecko does rounding for the coordinate of layers except mask layer. In this case, we have a color layer and there is a mask layer on it. The position mismatch between the color layer and mask layer causes this problem.

Comment 4

[Ethan Lin[:ethlin]]

Attachment: fix rounding problem

I use the same way "ToNearestPixels" to round the bound of mask layer. Then the round reftests passed[1] with background color layer on. I also checked m-c try result[2] and it looks like the change doesn't effect the original tests.

[1] https://treeherder.mozilla.org/#/jobs?repo=try&revision=d25b69de022a955fc179d0adbe40f8355ae0ef42&selectedJob=98236784

[2] https://treeherder.mozilla.org/#/jobs?repo=try&revision=11a9f57acce04d1942937d56746c390534635d43&selectedJob=98239148

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/8336687998c5
Round mask layer boundary to match other layers. r=mattwoodrow

Comment 6

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/8336687998c5