687547 - Layers bug. Static text shakes as dynamic text passes, is left with a zigzag appearance once the animation completes

Status: RESOLVED WORKSFORME

(Core :: Web Painting, defect)

Description

[nemo]

Tested in latest nightly.
With layers enabled, the grey text shakes as the black text moves above it.  After the black text passes, the grey text is distorted, with portions of each letter shifted out of line relative to the rows of pixels around them, as though someone has used the GIMP Shift filter.

With layers disabled, there is no shaking of the grey text, and no visual artifacts afterwards.

Comment 1

[Timothy Nikkel (:tnikkel)]

Works fine for me with basic layers on Linux and accelerated layers on Mac. Is it still happening on Windows?

Comment 2

[nemo]

I'll recheck when I get back to my windows test machine on Tuesday.  When I filed the bug recently on zoomed SMIL animation, it occurred to me maybe was related, but forgot to recheck once it was fixed.

Comment 3

[nemo]

Behaviour is unchanged.

  Application Basics
        Name
        Firefox

        Version
        13.0a1

        User Agent
        Mozilla/5.0 (Windows NT 5.1; rv:13.0) Gecko/20120301 Firefox/13.0a1

  Graphics

        Adapter Description
        ATI FirePro M5800

        Vendor ID
        0x1002

        Device ID
        0x68c0

        Adapter RAM
        Unknown

        Adapter Drivers
        ati2dvag

        Driver Version
        8.773.1.1000

        Driver Date
        1-15-2011

        WebGL Renderer
        Google Inc. -- ANGLE (ATI FirePro M5800) -- OpenGL ES 2.0 (ANGLE 1.0.0.963)

        GPU Accelerated Windows
        1/1 Direct3D 9

Comment 4

[nemo]

Oh. Deleted profile just in case, and retested.
Still no change.  The grey text was still jiggled and distorted with layers enabled.

If I enable nglayout.debug.paint_flashing I can see the repaint area enclosing the black text moving along the screen.
The grey text inside the paint box "jiggles" and as soon as the paint box has moved on, it stops jiggling and whatever position it was in is where it is painted, all jittered.
I guess this is all kind of obvious to you guys, but, yeah, if the grey text didn't jiggle, I assume the final artifacts would be avoided.

Comment 5

[nemo]

Oh and finally (sorry for spam).
If I set:
layers.acceleration.disabled;true

The paint areas are exactly the same, but there is no text jiggling.  This is probably not news to you guys either, but thought, just in case...

My current "layers" values are.
layers.prefer-opengl;false
layers.prefer-d3d9;false
layers.offmainthreadcomposition.enabled;false
layers.acceleration.force-enabled;false
layers.acceleration.draw-fps;false

layers.acceleration.disabled;true

That last one is the one I set to false to enable the bug.

Comment 6

[nemo]

Possibly related.
This very old test page plays with shadows. (uses javascript)
http://m8y.org/tmp/testcase158.xhtml

If I have layers.acceleration.disabled;false
and stare closely at the letters, I can see the red text shift slightly back and forth.

Interestingly, this only happens with the unicode text (Tengwar) - not the ascii text in the first block.

If I set layers.acceleration.disabled;true  the bug goes away.

Comment 7

[nemo]

Oh, and again I could only reproduce this on the Windows machine listed above, not on my Linux machine.

Comment 8

[David Bancroft]

Attachment: same problem

Thanks from agonliti1981.

Comment 9

[Gregory Pappas [:gregp]]

Reporter, are you still experiencing this issue?

Comment 10

[nemo]

I would be completely unable to reproduce it at this point. I no longer have any Windows machines at all, and certainly not Windows XP.

But, it has been 13 years and I'm pretty sure the graphics layer for windows has been completely changed many times in the interim.

Comment 11

[Gregory Pappas [:gregp]]

Thanks for following up!!

I tested Windows & Linux and could not reproduce; closing.