Improve CrOS WM shadow drawing for small windows.

Improve CrOS WM shadow drawing for small windows.

We can't fully imitate what CSS would do for a box shadow
on a small box without redrawing the shadow for every height
below a certain threshold. Instead, simply reduce the "elevation"
of the shadows (which controls blur and offset) to something
we can handle.

This only has any effect on active windows that are shorter or
narrower than 100dip, and it maintains a distinction between active
and inactive all the way down to 36dip. It gets rid of the unsightly
seam that our current strategy causes. Sebastien has agreed to this
mitigation (although he might have additional feedback when he plays
with it live, once it's on canary).

BUG=608852
Committed: https://crrev.com/ec9aafe08581e34321ab003bb7c6b74b086d7f96
Cr-Commit-Position: refs/heads/master@{#439588}

[Evan Stade, 2016-12-17 02:15:48]

The CQ bit was checked by estade@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-17 02:16:33]

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, 2016-12-17 03:34:18]

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

[commit-bot: I haz the power, 2016-12-17 03:34:19]

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

[Evan Stade, 2016-12-19 18:08:16]

Description was changed from

==========
Improve CrOS WM shadow drawing for small windows.

BUG=608852
==========

to

==========
Improve CrOS WM shadow drawing for small windows.

We can't fully imitate what CSS would do for a box shadow
on a small box without redrawing the shadow for every height
below a certain threshold. Instead, simply reduce the "elevation"
of the shadows (which controls blur and offset) to something
we can handle.

This only has any effect on active windows that are shorter or
narrower than 100dip, and it maintains a distinction between active
and inactive all the way down to 36dip. It gets rid of the unsightly
seam that our current strategy causes. Sebastien has agreed to this
mitigation (although he might have additional feedback when he plays
with it live, once it's on canary).

BUG=608852
==========

[Evan Stade, 2016-12-19 18:08:16]

estade@chromium.org changed reviewers:
+ jamescook@chromium.org

[Evan Stade, 2016-12-19 18:08:25]

The CQ bit was checked by estade@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-19 18:08:44]

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

[Evan Stade, 2016-12-19 18:12:13]

This is the result of a couple of days of trying different strategies and is the
only one that actually looks good and doesn't require either recreating shadows
for the cross product of elevation and window dimensions or using additional
layers.

[commit-bot: I haz the power, 2016-12-19 19:10:38]

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

[commit-bot: I haz the power, 2016-12-19 19:10:38]

Dry run: This issue passed the CQ dry run.

[James Cook, 2016-12-19 19:51:49]

LGTM. Thanks for adding a test.

https://codereview.chromium.org/2586653002/diff/20001/ui/wm/core/shadow.cc
File ui/wm/core/shadow.cc (right):

https://codereview.chromium.org/2586653002/diff/20001/ui/wm/core/shadow.cc#ne...
ui/wm/core/shadow.cc:146: 2 * kRoundedCornerRadius) /
nit: wrapping is really ugly here. Maybe try pulling something out into a
constant or other local, or doing the math in multiple lines? Like maybe
max_elevation_for_size or some such?

[Evan Stade, 2016-12-19 21:09:41]

https://codereview.chromium.org/2586653002/diff/20001/ui/wm/core/shadow.cc
File ui/wm/core/shadow.cc (right):

https://codereview.chromium.org/2586653002/diff/20001/ui/wm/core/shadow.cc#ne...
ui/wm/core/shadow.cc:146: 2 * kRoundedCornerRadius) /
On 2016/12/19 19:51:49, James Cook wrote:
> nit: wrapping is really ugly here. Maybe try pulling something out into a
> constant or other local, or doing the math in multiple lines? Like maybe
> max_elevation_for_size or some such?

Done.

[Evan Stade, 2016-12-19 21:09:45]

The CQ bit was checked by estade@chromium.org

[Evan Stade, 2016-12-19 21:09:45]

The patchset sent to the CQ was uploaded after l-g-t-m from
jamescook@chromium.org
Link to the patchset: https://codereview.chromium.org/2586653002/#ps40001
(title: "wrapping")

[commit-bot: I haz the power, 2016-12-19 21:10:38]

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, 2016-12-19 22:20:28]

CQ is committing da patch.

Bot data: {"patchset_id": 40001, "attempt_start_ts": 1482181785471330,
"parent_rev": "85a448873794ba9f13fd0b1d9b241e58373824ed", "commit_rev":
"36fe7e84e2485ef5e862b33939841375abd65065"}

[commit-bot: I haz the power, 2016-12-19 22:20:57]

Description was changed from

==========
Improve CrOS WM shadow drawing for small windows.

We can't fully imitate what CSS would do for a box shadow
on a small box without redrawing the shadow for every height
below a certain threshold. Instead, simply reduce the "elevation"
of the shadows (which controls blur and offset) to something
we can handle.

This only has any effect on active windows that are shorter or
narrower than 100dip, and it maintains a distinction between active
and inactive all the way down to 36dip. It gets rid of the unsightly
seam that our current strategy causes. Sebastien has agreed to this
mitigation (although he might have additional feedback when he plays
with it live, once it's on canary).

BUG=608852
==========

to

==========
Improve CrOS WM shadow drawing for small windows.

We can't fully imitate what CSS would do for a box shadow
on a small box without redrawing the shadow for every height
below a certain threshold. Instead, simply reduce the "elevation"
of the shadows (which controls blur and offset) to something
we can handle.

This only has any effect on active windows that are shorter or
narrower than 100dip, and it maintains a distinction between active
and inactive all the way down to 36dip. It gets rid of the unsightly
seam that our current strategy causes. Sebastien has agreed to this
mitigation (although he might have additional feedback when he plays
with it live, once it's on canary).

BUG=608852

Review-Url: https://codereview.chromium.org/2586653002
==========

[commit-bot: I haz the power, 2016-12-19 22:20:58]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-12-19 22:23:34]

Description was changed from

==========
Improve CrOS WM shadow drawing for small windows.

We can't fully imitate what CSS would do for a box shadow
on a small box without redrawing the shadow for every height
below a certain threshold. Instead, simply reduce the "elevation"
of the shadows (which controls blur and offset) to something
we can handle.

This only has any effect on active windows that are shorter or
narrower than 100dip, and it maintains a distinction between active
and inactive all the way down to 36dip. It gets rid of the unsightly
seam that our current strategy causes. Sebastien has agreed to this
mitigation (although he might have additional feedback when he plays
with it live, once it's on canary).

BUG=608852

Review-Url: https://codereview.chromium.org/2586653002
==========

to

==========
Improve CrOS WM shadow drawing for small windows.

We can't fully imitate what CSS would do for a box shadow
on a small box without redrawing the shadow for every height
below a certain threshold. Instead, simply reduce the "elevation"
of the shadows (which controls blur and offset) to something
we can handle.

This only has any effect on active windows that are shorter or
narrower than 100dip, and it maintains a distinction between active
and inactive all the way down to 36dip. It gets rid of the unsightly
seam that our current strategy causes. Sebastien has agreed to this
mitigation (although he might have additional feedback when he plays
with it live, once it's on canary).

BUG=608852

Committed: https://crrev.com/ec9aafe08581e34321ab003bb7c6b74b086d7f96
Cr-Commit-Position: refs/heads/master@{#439588}
==========

[commit-bot: I haz the power, 2016-12-19 22:23:35]

Patchset 3 (id:??) landed as
https://crrev.com/ec9aafe08581e34321ab003bb7c6b74b086d7f96
Cr-Commit-Position: refs/heads/master@{#439588}