Account for borders and padding when calculating background tile size.

Account for borders and padding when calculating background tile size.

This is required when sub-pixel borders and padding are used, otherwise
the tile size may become one pixel too small, causing rendering artifacts.
Test case attached.

BUG=686435
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2689993003
Cr-Commit-Position: refs/heads/master@{#455454}
Committed: https://chromium.googlesource.com/chromium/src/+/0957d8cc17fb3e90d3f0203a0e3cc1b32bfc8528

[Karl Øygard, 2017-02-13 12:37:26]

Description was changed from

==========
Account for borders and padding when calculating background tile size.

This is required when sub-pixel borders and padding are used, otherwise
the tile size may become one pixel too small, causing rendering artifacts.
Test case attached.

BUG=686435
==========

to

==========
Account for borders and padding when calculating background tile size.

This is required when sub-pixel borders and padding are used, otherwise
the tile size may become one pixel too small, causing rendering artifacts.
Test case attached.

BUG=686435
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

[Karl Øygard, 2017-02-13 14:00:18]

The CQ bit was checked by karlo@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2017-02-13 14:00:34]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-13 14:36:20]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-13 14:36:21]

Dry run: Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[Stephen Chennney, 2017-02-13 20:24:00]

schenney@chromium.org changed reviewers:
+ schenney@chromium.org

[Stephen Chennney, 2017-02-13 20:24:00]

I'm also curious why the left circle in the svg/zoom test case now looks better
on the bottom but not the right edge.

https://codereview.chromium.org/2689993003/diff/1/third_party/WebKit/Source/c...
File third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp (right):

https://codereview.chromium.org/2689993003/diff/1/third_party/WebKit/Source/c...
third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp:484:
positioningArea.setSize(rootBox->size());
Do we have a test case that hits this code path? This is the only place I see
where the positioningArea may be very different from the paint rect that we
otherwise would use.

[Karl Øygard, 2017-02-14 13:32:18]

The CQ bit was checked by karlo@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2017-02-14 13:32:37]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-14 14:58:16]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-14 14:58:17]

Dry run: This issue passed the CQ dry run.

[Karl Øygard, 2017-02-28 13:42:20]

On 2017/02/13 20:24:00, Stephen Chennney wrote:
> I'm also curious why the left circle in the svg/zoom test case now looks
better
> on the bottom but not the right edge.

This is a side effect of sub-pixel layout, eg.:

<div style="margin-left: 0.25px">
<img style="border-left: 1.25px solid black" src=image.jpg>

This will render a 1px (rounded down from 1.25px) wide border at 0px (rounded
down from 0.25px), while the image will be painted at 2px (rounded up from
1.5px).  This will leave a one pixel gap at 1px.

The same effect can be seen without sub-pixel borders, although it's a little
less surprising there:

<div style="margin-left: 0.25px">
<img style="border-left: 1px solid black; padding-left: 0.25px" src=image.jpg>
</div>

https://codereview.chromium.org/2689993003/diff/1/third_party/WebKit/Source/c...
> third_party/WebKit/Source/core/paint/BackgroundImageGeometry.cpp:484:
> positioningArea.setSize(rootBox->size());
> Do we have a test case that hits this code path? This is the only place I see
> where the positioningArea may be very different from the paint rect that we
> otherwise would use.

fast/backgrounds/body-generated-image-propagated-to-root.html exercises this
path, but there should be a few more test cases as well, that was just the first
one that I found.

[Stephen Chennney, 2017-02-28 15:51:42]

Thanks for the info. lgtm.

[Karl Øygard, 2017-03-06 13:53:07]

The CQ bit was checked by karlo@opera.com

[commit-bot: I haz the power, 2017-03-06 13:53:21]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-06 14:25:41]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-03-06 14:25:42]

Try jobs failed on following builders:
  linux_layout_tests_slimming_paint_v2 on master.tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_layout_te...)

[Karl Øygard, 2017-03-07 12:55:09]

The CQ bit was checked by karlo@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2017-03-07 12:55:33]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-07 14:34:12]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-03-07 14:34:13]

Dry run: Try jobs failed on following builders:
  win_chromium_x64_rel_ng on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_x64_...)

[Karl Øygard, 2017-03-08 13:54:01]

The CQ bit was checked by karlo@opera.com

[Karl Øygard, 2017-03-08 13:54:01]

The patchset sent to the CQ was uploaded after l-g-t-m from
schenney@chromium.org
Link to the patchset: https://codereview.chromium.org/2689993003/#ps40001
(title: "Rebaselined tests again.")

[commit-bot: I haz the power, 2017-03-08 13:54:13]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-08 15:13:33]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1488981241058390,
"parent_rev": "e78f411844b3986f5a33f0eeba661ab826c8cf2d", "commit_rev":
"0957d8cc17fb3e90d3f0203a0e3cc1b32bfc8528"}

[commit-bot: I haz the power, 2017-03-08 15:14:09]

Description was changed from

==========
Account for borders and padding when calculating background tile size.

This is required when sub-pixel borders and padding are used, otherwise
the tile size may become one pixel too small, causing rendering artifacts.
Test case attached.

BUG=686435
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
==========

to

==========
Account for borders and padding when calculating background tile size.

This is required when sub-pixel borders and padding are used, otherwise
the tile size may become one pixel too small, causing rendering artifacts.
Test case attached.

BUG=686435
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2

Review-Url: https://codereview.chromium.org/2689993003
Cr-Commit-Position: refs/heads/master@{#455454}
Committed:
https://chromium.googlesource.com/chromium/src/+/0957d8cc17fb3e90d3f0203a0e3c...
==========

[commit-bot: I haz the power, 2017-03-08 15:14:10]

Committed patchset #3 (id:40001) as
https://chromium.googlesource.com/chromium/src/+/0957d8cc17fb3e90d3f0203a0e3c...