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Issue 654959 link

Starred by 1 user
Status: WontFix
Owner: ----
Closed: Aug 23
Cc:
█ jbau...@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: All
Pri: 2
Type: Bug



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Canvas padding incorrectly treated as opaque.

Project Member Reported by jbau...@chromium.org, Oct 12 2016 
The occluded region on some layers seems to be incorrect. I've attached a test that shows the lower layer is occluded out (the black bars on the sides of the green webgl canvas).


I've tried bisecting it, but it looks like we changed how webgl opacity was calculated recently, so it doesn't reproduce early.

You are probably looking for a change made after 414107 (known good), but no later than 414108 (first known bad).
CHANGELOG URL:
The script might not always return single CL as suspectas some perf builds might get missing due to
failure.
  https://chromium.googlesource.com/chromium/src/+log/7a5d260eaadd7efcc073564b94c5c91e1856110d..d5e03be7f3be92a1940c19aab0664ca02ce1011f
badocclusion.png
58.0 KB View Download

Comment 1 by jbau...@chromium.org, Oct 12 2016 

Oops, forgot to attach the test.
webgl-no-alpha.html
1.7 KB View Download

Comment 2 by jbau...@chromium.org, Oct 12 2016

Cc: junov@chromium.org
Summary: Canvas padding incorrectly treated as opaque. (was: Incorrect occlusion calculations)
Modifying the test to use an opaque 2d canvas, it bisects to

https://chromium.googlesource.com/chromium/blink/+log/435acf076b2d5f0243b4a87c5d5ef904ae59bed3..cf5fdf9447d2c84224c74bf676957d6aac0f7f42 so the patch that caused it is probably https://chromium.googlesource.com/chromium/blink/+/5d0bde7c2ad09f64220d99072a1c840e73afd7c5

Comment 3 by junov@chromium.org, Oct 12 2016

Cc: -danakj@chromium.org
Components: -Internals>Compositing Blink>Canvas Blink>Compositing
Owner: junov@chromium.org
Status: Assigned (was: Available)

Comment 4 by xidac...@chromium.org, Nov 18 2016

Cc: jbau...@chromium.org
Status: WontFix (was: Assigned)
jbauman@: I have attached a screenshot that I took with Linux ToT, looks like it has been fixed. Will close the bug for now. Please re-open if you see the bug appears again.
Screenshot from 2016-11-18 09:00:46.png
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Comment 5 by jbau...@chromium.org, Nov 18 2016

Status: Assigned (was: WontFix)
It's still happening on Windows canary 56.0.2924.0.

Comment 6 by xidac...@chromium.org, Nov 24 2016 

I just tried it today on windows canary 57.0.2929.0, apparently it is fixed.
jbauman@: could you confirm?

Comment 7 by junov@chromium.org, Dec 13 2016

Status: WontFix (was: Assigned)
I can confirm no repro in tip of tree -> WontFix

Comment 8 by jbau...@chromium.org, Dec 13 2016

Status: Assigned (was: WontFix)
I'm still seeing this on 57.0.2950.0. Maybe it's flaky? What appears on screen would depend on what happened to be in that black area last. On windows, it may matter whether you're using a theme (don't use one) and whether DWM is enabled (it should be), to make sure that area is cleared.

Comment 9 by junov@chromium.org, Jul 25

Cc: -junov@chromium.org

Comment 10 by junov@chromium.org, Jul 25

Owner: ----
Status: Available (was: Assigned)

Comment 11 by fs...@chromium.org, Aug 23

Status: WontFix (was: Available)
This has been open for a long time with no updates on repro.
Please reopen if it is still happening.
►

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