commit bfa0a699311cee58d76311925aa6abb947cfc251
author Gaston Rodriguez Lopez <gastonr@microsoft.com> Tue Jan 30 00:07:33 2024
committer Chromium LUCI CQ <chromium-scoped@luci-project-accounts.iam.gserviceaccount.com> Tue Jan 30 00:07:33 2024
tree 8a06a707573e0d3002fc18a438f4c6934dd61946
parent 99e1c863159244eabfc5d0e6aa9407ddeeab49e6

Fix difference in Fluent scrollbar grays caused by their alpha

Fluent scrollbars grays are currently achieved by applying a certain
transparency to a pure white (255, 255, 255) or black (0,0,0) color.
This CL changes the way to achieve the desired color from applying an
alpha to a white or black, to directly setting the color of the gray
that we want with an alpha of 1.
The reason for this change is that the transparencies cause light mode
scrollbar gray parts (non-hovered) to be painted with different shades
of gray. Main threaded thumbs are being drawn at a shade of gray darker
than composited scrollbars' thumbs, and win10 arrows are also being
drawn with a darker gray.
This doesn't happen in dark mode, nor with the hovered/pressed colors,
but these colors are receiving the same treatment in order to avoid
potential future problems.
The new colors were chosen by picking the final rendered color of
the scrollbar parts. For example, light themed non-hovered gray is a
gray with the RGB values (139,139,139).

The root cause of this issue is suspected to be caused by a different
rounding mechanism used to apply the alpha in the different call ops.
For example, for win10 vs win11 arrows, the color is the same but the
skia paint function called is different (see
NativeThemeFluent::PaintArrow).

Most rebaselines are due to a few anti aliasing pixels containing
different values, except for win10 arrows and main threaded thumbs
which are completely replaced by the new selected color.

Bug: 1517769
Change-Id: Ic258a0e3a26a8bee96c005df6c721a4f6ab1f582
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5191003
Reviewed-by: Yaroslav Shalivskyy <yshalivskyy@microsoft.com>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Olga Gerchikov <gerchiko@microsoft.com>
Commit-Queue: Gaston Rodriguez <gastonr@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#1253636}