728393 - MAPLE: Scrolling invalidation happens when not panned all the way to the left

Status: RESOLVED WORKSFORME

(Firefox for Android Graveyard :: General, defect, P1)

Description

[Patrick Walton (:pcwalton)]

STR:

1. Go to cnn.com. Zoom in a bit.
2. Pan all the way to the left. Wait for the viewport to snap back.
3. Scroll down. You will notice that there isn't much checkerboarding.
4. Pan to the right a little bit.
5. Scroll down. You will notice a lot more checkerboarding; the entire layer is getting invalidated at every scroll.

Comment 1

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: HTML non-testcase

Here's my HTML approximation of this situation. We don't invalidate the transformed layer in desktop FF.

I can't set up a native Fennec build and debug environment to test this myself, at least not tonight or tomorrow.

Comment 2

[Patrick Walton (:pcwalton)]

We don't use CSS transforms for pan/zoom anymore in Maple. Instead we use displayports, ScrollTo(), and SetResolution() for zooming.

Comment 3

[Joe Drew (not getting mail)]

Mats, this is another layers bug that we could use some layout help with.

Comment 4

[Mats Palmgren (inactive)]

cnn.com works reasonably well for me on my Samsung Nexus with a maple branch build.
I can't reproduce the STR in comment 0 -- I see the same amount of checker-boarding
when zoomed in and horizontally scrolled to the left edge as when scrolled to the
right edge.  I suspect the initially reported problem is specific to the use
of CSS transforms.  It sounds like the same problem as in bug 725983.
(ie. having overflow on the left side disables some optimization we have)

Comment 5

[Patrick Walton (:pcwalton)]

I still see this on timecube.com. If zoomed in a bit such that some of the page is not visible to the left, then scrolling down shows significantly more checkerboards.

Comment 6

[Joe Drew (not getting mail)]

The zooming in is checkerboardy bug is bug 733041.

Comment 7

[Joe Drew (not getting mail)]

The original bug report doesn't happen any more.