1367488 - Scrollbar thumb inside iframe can still be cut off after being offscreen

Status: VERIFIED FIXED

(Core :: Panning and Zooming, defect, P3)

Description

[Botond Ballo [:botond]]

STR:
  1. Load https://people-mozilla.org/~bballo/bug1359868.html
  2. Unmaximize the Firefox window if necessary, and position it
     so that there's space below it.
  3. Grab the subframe's scroll thumb near the top.
  4. Drag it down until mouse leaves the Firefox window, and then back up.

Expected results:

  The scrollbar thumb is fully painted when you drag it back up.

Actual results:

  The scrollbar thumb is only partially painted.

Comment 1

[Botond Ballo [:botond]]

Attachment: Bug 1367488 - Pre-render offscreen portions of scrollbar thumbs inside an iframe.

Review commit: https://reviewboard.mozilla.org/r/143508/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/143508/

Comment 2

[Botond Ballo [:botond]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=73c52aa6e198e04e07dc4f27d22b0a61b8dce5e9

Comment 3

[Botond Ballo [:botond]]

Getting this to work ended up requiring several changes:

  - Capturing the current clip state on the scroll thumb's container layer,
    so it doesn't clip the thumb's contents.

  - Getting nsDisplayOwnLayer to override ShouldBuildLayerEvenIfInvisible()
    to return true for thumb container layers, so it's rendered even if its
    clipped bounds are empty.

  - Overriding the animated geometry root for nsDisplayOwnLayer items
    representing thumb layers to be the AGR created for the thumb.

With these changes things seem to be working well. I'll flag this for review if the Try push looks good.

Comment 4

[Botond Ballo [:botond]]

Looks like the patch is breaking:

  layout/reftests/layers/pull-background-{1-6}.html
  layout/reftests/layers/pull-background-displayport-{1-6}.html
  layout/reftests/invalidation/layer-splitting-{5,6}.html

Comment 5

[Botond Ballo [:botond]]

(In reply to Botond Ballo [:botond] from comment #4)
> Looks like the patch is breaking:

Indeed, the patch was stomping all over attempts to merge content before and after a scrollframe with a layerized thumb into the same layer (and other optimizations like lifting background colors), because the thumb layer wasn't clipped to the slider track, so FrameLayerBuilder thought it could potentially move around arbitrarily. This is fixed in the updated patch.

Comment 6

[Botond Ballo [:botond]]

Comment on attachment 8871975 [details]
Bug 1367488 - Pre-render offscreen portions of scrollbar thumbs inside an iframe.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/143508/diff/1-2/

Comment 7

[Botond Ballo [:botond]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=f8a06b2919cb26c0706a78d11ef5d0063f804370

Comment 8

[Botond Ballo [:botond]]

Comment on attachment 8871975 [details]
Bug 1367488 - Pre-render offscreen portions of scrollbar thumbs inside an iframe.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/143508/diff/2-3/

Comment 9

[Markus Stange [:mstange]]

Comment on attachment 8871975 [details]
Bug 1367488 - Pre-render offscreen portions of scrollbar thumbs inside an iframe.

https://reviewboard.mozilla.org/r/143508/#review148962

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0d50eaa8bfa0
Pre-render offscreen portions of scrollbar thumbs inside an iframe. r=mstange

Comment 11

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/0d50eaa8bfa0

Comment 12

[ovidiu boca[:Ovidiu]]

Hi Botond,

I retested this issue and on Windows, there are some problems. I followed the steps from comment 0 but clicked on "Append". I see some flickers on the scrollbar when you move it up and down. The issue is reproducible only on Windows (tested on Win 7,10,8.1) with the latest Nightly 55.0a1 (2017-06-05).
On Mac and Ubuntu, the issue can't be reproduced.

Comment 13

[Kartikaya Gupta (email:[e-mail])]

Let's file a new bug for the remaining issue.

Comment 14

[ovidiu boca[:Ovidiu]]

I filed bug https://bugzilla.mozilla.org/show_bug.cgi?id=1371299 for comment 12.

Comment 15

[ovidiu boca[:Ovidiu]]

I verified this issue on Mac OS X 10.12, Ubuntu 16.04 x64 and Windows 10 x64 with FF Nightly 56.0a1(2017-07-03) and I can confirm the fix.