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Issue 626305 link

Starred by 2 users

Issue metadata

Status: Duplicate
Merged: issue 485650
Owner:
Closed: Aug 2016
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Linux , Windows , Chrome , Mac
Pri: 1
Type: Bug-Regression



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Regression: Downloaded files appear blurred on downloads page on zooming out to 90%

Reported by lpa...@etouch.net, Jul 7 2016

Issue description

Chrome Version: 53.0.2785.8 (Official Build) c6d43518027ef223fe101efd8baa5a9b1bc979b4-refs/branch-heads/2785@{#37} 32/64 bit
OS: Windows(7,8,10), Mac(10.10.5)(10.11.4), Linux(Ubuntu 14.04 LTS)

Steps:
1. Launch chrome and press Ctrl+J.
2. Have at least two downloaded files in the downloads list.
3. Zoom out to 90% and observe the files below the first file.

Actual:   The files appear blurred on zooming out.
Expected: The files should appear clearly on zooming out.

This is a regression issue broken in 'M-48' and below is the manual regression range.
Good  Build: 48.0.2536.0
Bad Build  : 48.0.2537.0

Narrow Bisect:
https://chromium.googlesource.com/chromium/src/+log/e4471ed4dce8f2fc53e3e7f54aa8c4e18b93ea8c..e143ef44edfa1ea8cda564edd457f5ca644203e7?pretty=fuller&n=1000

Suspecting: r354221?

Kindly help to re-assign if your change is not the cause of this issue.
 
Blur_Actual.mp4
509 KB View Download
Blur_Expected.mp4
196 KB View Download

Comment 1 by dbeam@chromium.org, Jul 15 2016

Cc: esprehn@chromium.org dbeam@chromium.org
Components: Blink>Fonts Blink>Compositing
Owner: ----
don't know if these are the right tags, but definitely not something that's changed in downloads lately
Owner: danakj@chromium.org
The download items have will-change: transform; because iron-list will fly them around, I wonder if this is because we now don't re-raster when you set will-change: transform and the scale changes. We totally should re-raster when zooming though.

Comment 3 by danakj@chromium.org, Jul 15 2016

Cc: chrishtr@chromium.org vmp...@chromium.org

Comment 4 by danakj@chromium.org, Jul 15 2016

Labels: Needs-Bisect
I think that bisect is wrong?

Comment 5 by danakj@chromium.org, Jul 15 2016

Zoom isn't implemented by transform, so I'd be surprised if that is the reason, but need to take a trace to see.

Comment 6 by e...@chromium.org, Jul 15 2016

Components: -Blink>Fonts

Comment 7 by lpa...@etouch.net, Jul 18 2016

Labels: -Needs-Bisect
With response to comment #4 re-bisected again and getting the same range as mentioned.

Kindly help to re-assign if your change is not the cause of this issue.

Comment 8 by danakj@chromium.org, Jul 18 2016

Cc: danakj@chromium.org
Owner: esprehn@chromium.org
If the bisect it right, can this be the patch from levi then?
No the iron-list patch is the "cause". It made all of the download items composited because that's how iron-list does infinite scroll. Sounds like a compositor bug that the page just triggers now.

Sorry I wasn't clear in my original reply, the bisect was correct.
Owner: danakj@chromium.org
ok thanks. fwiw reloading the page at 90% zoom stays blurry. investigating.
Cc: osh...@chromium.org
Owner: chrishtr@chromium.org
Confirmed in a trace that the recording is not blurry.

Both the first and second items in the list are in layers, however only the second one is blurry.

The transform on the first one is 0,0,0 in the inspector. No partial pixel offset there. The transform on the actual layer is identity.

The transform on the second one is 0,176,0 in the inspector. The transform on the actual layer in a trace is:

[1, 0, 0, 0,
 0, 1, 0, 158.39999389648438,
 0, 0, 1, 0,
 0, 0, 0, 1],

Which is 176 * 0.9.  So the page zoom is scaling the transforms but not snapping them to pixels. And non-integer-aligned layers produce blurry results.

https://bugs.chromium.org/p/chromium/issues/detail?id=521364 is the bug for blurry under non-integer offset.

I'm not sure if it is a bug that page zoom is not snapping to integer pixels on top of that.

chrishtr@ can you comment, and dupe into 521364 if the latter is not a separate bug? (+oshima who's working on using page zoom for DSF fyi)
Labels: OS-Chrome
Thanks, I confirmed that this happens on chromeos too.
Mergedinto: 485650
Status: Duplicate (was: Assigned)

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