Before bug 1298218, in this if branch with APZ enabled, itemClip was always
the display port clip for fixed backgrounds, even for fixed backgrounds on the
canvas frame. But after bug 1298218 we no longer clip canvas fixed backgrounds
to the display port, so itemClip is now the viewport clip. And that clip is
definitely not a scrolled clip, so we must not merge layers around it.
The better solution for this would be to remove this if branch completely and
fix up the scrolled clip layerization detection for the non-APZ case to also
use ASRs. That's tracked by bug 1336516.
MozReview-Commit-ID: 2F7hPrldUlq
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extra : rebase_source : db1e801fc3179fda1a9d3bc8d8f6c6b0789a1e76
Excessive clamping can cause incorrect behaviour in the presence of negative
margins.
MozReview-Commit-ID: AkQEqcQpAxx
--HG--
extra : rebase_source : 33cde31c15608792299a1dbef475e0fe0936270d
The reftest-no-flush avoids some issues on Fennec where the reftest harness
gets into an infinite loop of snapshotting because the pending-paint flag never
gets cleared. The flag seems to be set as a result of the APZ flush and I'm
unclear on why it doesn't get cleared normally, but this bypasses the problem.
MozReview-Commit-ID: 8SGoSkRo5nm
I've decided to fix this in a very explicit way. The only "magic" part that's
left is how we decide that the AGR of the perspective item is outside the
scrolled frame (and I'm not sure myself how that works).
I didn't want to change what scroll clips we set on what items, because the
scroll clip really belongs on the perspective item, because that's the item
that needs to be clipped, and it should also be the item that should be
scrolled if it weren't for the fact that APZ wouldn't know that it should
apply the perspective transform before the APZ transform.
MozReview-Commit-ID: BBw8VPohQI4
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extra : rebase_source : 9e11441af2b5dab93a5908236e153fc6cd2c3d8b
extra : histedit_source : 7b3dd75afa92346856765284be48df5618821326
Always use an ancestor scroll clip of all direct children, or the original
scroll clip if the children don't share the same scroll clip tree.
Unfortunately this requires another pass over the stacking context display list.
Also, fix clips, scroll clips and creation order of blend items:
If a clipped mix-blend-mode item contains absolute / fixed positioned items,
those items should not be clipped, same for blend container items.
When a transform item contains blend modes, create the blend container inside
the transform.
Don't do tree comparisons on scroll clips from different scroll clip trees.
If the inner scroll clip is nullptr, because it was cleared, it will look like
it's the ancestor of the outer non-nullptr scroll clip.
These changes don't look very related, but it was very hard to get tests passing
with only some of the changes and not the others, and after having spent two
weeks on this patch I'm not thrilled about going back and checking exactly which
change was necessary to fix which test failure.
MozReview-Commit-ID: IKGciUBrdNa
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extra : rebase_source : e570f16ecedd80cba16051f0e1ac66764bc95815
extra : histedit_source : fcfbcbc254aaf93594d9d80c117d6ec945805993
This makes sure that for example the bounds of an opacity item are not empty if
the opacity item contains a scroll frame whose contents are currently scrolled
offscreen but still inside that scroll frame's display port.
On its own, this changeset causes test failures due to missed optimizations
because the bounds of many opacity items are now too large. That's because of
the way we're setting scroll clips on opacity items at the moment: Even if the
opacity is inside a scroll frame, we're currently only setting that scroll
frame's scroll clip on the opacity item's contents, not on the opacity item
itself, because the opacity item might also contain other items that are not
scrolled by this scroll frame.
The next patch in this bug will make us only do that when necessary.
MozReview-Commit-ID: 9TtcJ7eQE7U
--HG--
extra : rebase_source : 51cab60bd27e1a7e3c2d6b8d791b79fe3b3baa94
extra : histedit_source : ba421898e442d08f7f711d13f71a693c34d908bb
Boris Zbarsky
Markus Stange
Cameron McCormack
Shing Lyu
Botond Ballo
Sebastian Hengst
Kartikaya Gupta
Wes Kocher
Lee Salzman
Andrew Comminos
Carsten "Tomcat" Book
Phil Ringnalda
James Willcox
Ryan VanderMeulen
Mason Chang