794465 - Progressive tile painting causes seams to appear in updated content (such as animated gifs)

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: Toolbar, defect)

Description

[Chris Lord [:cwiiis]]

When progressive tile painting is enabled, seams can appear in updated content (commonly in animated gifs).

BenWa and I discussed a few strategies:
- Size-based - If an update is <= the screen size, don't update it progressively
- Number of tiles - Pick a number of tiles to handle per transaction (similar to above)
- Time-based - Spend X ms per transaction updating tiles

Another strategy I just thought of:
- Only do progressive updates when scrolling

Comment 1

[Chris Lord [:cwiiis]]

Attachment: Only do progressive tile drawing when scrolling

This pretty much does what we want.

One caveat, if you scroll around with an animated gif or some such, you'll see seams again. I'm not sure how much this matters, as coupled with the movement, it's not obvious (also, animated gifs seem to pause when moving quite a lot - not sure if this is a feature or a side-effect).

If we forced non-progressive in this case, interactivity would suffer, which I think would be worse. Ideally, animated gifs would be optimised to image layers and the animation could be handled async like video. Will file a bug for this.

Comment 2

[Benoit Girard (:BenWa)]

Comment on attachment 664991 [details] [diff] [review]
Only do progressive tile drawing when scrolling

Review of attachment 664991 [details] [diff] [review]:
-----------------------------------------------------------------

again with the small nit. Nice patch

::: gfx/layers/basic/BasicTiledThebesLayer.cpp
@@ +261,1 @@
>    // Force immediate tile painting when the layer has changed resolution.

// Only draw progressively when we're panning at the same resolution.

Comment 3

[Chris Lord [:cwiiis]]

Comment changed + rebased, pushed to inbound:

https://hg.mozilla.org/integration/mozilla-inbound/rev/2786b171b97f

Comment 4

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/2786b171b97f