Bug 65793 – Painting of fixed background images is wrong in composited layers

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Abel]

Elements with a fixed background image behave strange when an absolute positioned element has an animated transformation on hover.

For example, the position of the background image in the div elements in the supplied changes position moves away during the animation, and returns to it's original position when the animation is finished.
 
Hover over the black square to reproduce the bug.

[Abel]

Created attachment 103119 [details]
HTML file to recreate the bug

[Simon Fraser (smfr)]

Yeah, fixed backgrounds and animation don't play nicely together. Making them work would be very hard (or at least slow things down horribly).

[Abel]

(In reply to comment #2)
> Yeah, fixed backgrounds and animation don't play nicely together. Making them work would be very hard (or at least slow things down horribly).

I understand that animating elements with a fixed background is hard, but the bug also occurs when elements without a fixed background are animated. No matter where the animated element is on the page, all the containers with fixed background display strange behavior.

[Simon Fraser (smfr)]

*** Bug 102381 has been marked as a duplicate of this bug. ***

[Simon Fraser (smfr)]

*** Bug 110552 has been marked as a duplicate of this bug. ***

[Simon Fraser (smfr)]

*** Bug 117659 has been marked as a duplicate of this bug. ***

[Simon Fraser (smfr)]

Created attachment 204773 [details]
Patch

[Sam Weinig]

Comment on attachment 204773 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=204773&action=review

> Source/WebCore/rendering/RenderBoxModelObject.cpp:1227
> +    // FIXME: transforms spec says that fixed backgrounds behave like scroll inside transforms.

Since we have a bug on this, you should add the link.

> Source/WebCore/rendering/RenderBoxModelObject.h:203
> +        { }

I prefer these on separate lines :(.

[Simon Fraser (smfr)]

http://trac.webkit.org/changeset/151623