807941 - Outer edge of shadow having weird color on Github, when using hw-accelerated layers on Linux.

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Paul Adenot (:padenot)]

Attachment: Screenshot of the problem

STR:
- Go to about:config, turn |layers.acceleration.force-enabled| and |layers.acceleration.draw-fps| to true.
- Open a Github page, e.g. https://github.com/mozilla/
- Look at the repository list, especially titles and descriptions

Expected:
- The shadow on the text is clean

Actual result:
- There is something weird about the shadow. The CSS specifies: 

  text-shadow: 0px 1px 0px rgb(255, 255, 255), 
               1px 0px 0px rgb(255, 255, 255),
               0px -1px 0px rgb(255, 255, 255),
               -1px 0px 0px rgb(255, 255, 255),
               0px 2px 0px rgb(255, 255, 255),
               2px 0px 0px rgb(255, 255, 255),
               0px -2px 0px rgb(255, 255, 255),
               -2px 0px 0px rgb(255, 255, 255);

And I see something else than a black shadow, here, see attached screenshot.

Comment 1

[Karl Tomlinson (:karlt)]

I see only a white shadow (as expected, same as basic layers rendering) with Mesa 8.0.4 r600g.

Can you describe the graphics driver involved, please?
(glxinfo | grep OpenGL)

Comment 2

[Paul Adenot (:padenot)]

~  » glxinfo | grep OpenGL         
OpenGL vendor string: Tungsten Graphics, Inc
OpenGL renderer string: Mesa DRI Intel(R) Sandybridge Mobile 
OpenGL version string: 3.0 Mesa 8.0.4
OpenGL shading language version string: 1.30
OpenGL extensions:

Comment 3

[Jan Alexander Steffens [:heftig]]

Seeing the same issue here, but Github has removed the shadow by now. Readding the above text-shadow rule brings the color back.

Aurora 24

OpenGL vendor string: Intel Open Source Technology Center
OpenGL renderer string: Mesa DRI Intel(R) Sandybridge Mobile 
OpenGL core profile version string: 3.1 (Core Profile) Mesa 9.1.6
OpenGL core profile shading language version string: 1.40
OpenGL core profile context flags: (none)
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 9.1.6
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:

Comment 4

[Jan Alexander Steffens [:heftig]]

Switching from RGB subpixel antialiasing to grayscale antialiasing makes the shadow's color fringes disappear. Component alpha issue?

Comment 5

[Jan Alexander Steffens [:heftig]]

I can't reproduce this anymore.