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Starred by 3 users

Issue metadata

Status: WontFix
Owner:
Closed: Jan 4
Components:
EstimatedDays: ----
NextAction: ----
OS: Fuchsia
Pri: 3
Type: Bug



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Scrollbar is not rendered correctly in layout tests on Fuchsia.

Project Member Reported by sergeyu@chromium.org, Feb 13 2018

Issue description

Some layout tests draw scroll bars. On Fuchsia these tests produce pixel results where RGB values for some pixel are off by one. See examples in the attached screenshots.
In these screenshots incorrect black pixels are set to (1,1,1) instead of (0,0,0). Similarly incorrect values in blue pixels are shifted by one in all three channels. 
I verified that the scroll bars are rasterized correctly: SkARGB32_Blitter::blitH() writes correct values for these pixels. So it appears that the problem in the compositing step. We currently use OSMesa GL implementation in layout tests on Fuchsia.

The following 4 tests are affected:
 fast/css3-text/css3-text-decoration/text-decoration-style-inherit.html
 tables/mozilla/bugs/ bug1188 .html
 tables/mozilla/bugs/ bug2479 -3.html
 tables/mozilla/core/bloomberg.html
 
scrollbar-1.png
113 KB View Download
scrollbar-2.png
114 KB View Download
Components: -Blink>Compositing Internals>Compositing

Comment 2 by piman@chromium.org, Feb 20 2018

Owner: sergeyu@chromium.org
Status: Assigned (was: Untriaged)
OSMesa isn't what we use for production, so pixel differences (or outright bugs) may exist.
I'd suggest SwiftShader, but I don't know that it's ready for Fuchsia
I have swiftshader compiling on Fuchsia. Headless ozone currently supports only osmesa. It will need to be migrated to SwiftShader in order to use SwiftShader in layout tests on Fuchsia. Longer term I think we will want to use Vulkan, but it will require running the tests on Vulkan-capable HW.

Status: WontFix (was: Assigned)
Can't repro the problem anymore because these tests no longer render the scroll bar.

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