1566712 - Fix quality issues with picture caching when the transform has a fractional offset.

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P3)

Comment 1

[Glenn Watson [:gw]]

Attachment: Bug 1566712 - Fix quality issues with picture caching when the transform has a fractional offset.

This patch reverts the previous attempted fix for snapping issues
with picture caching, and implements a better solution.

This fixes the main visual issue by ensuring that any fractional
offset in the root transform is accounted for by:

• Offsetting the tile rects by this amount, so that the content
  origin is a whole device pixel.
• Invalidating all tiles if the fractional part of the root
  transform changes. This is required since it can affect the
  snapping logic that WR applies. Fortunately, this occurs
  very rarely - Gecko typically has a constant fractional part
  for each page.

Comment 2

[Glenn Watson [:gw]]

Pending try:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=c37fe6296ec248161e57710c4dffcac65451b5ff

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a2fdbfed0d71
Fix quality issues with picture caching when the transform has a fractional offset. r=kvark

Comment 4

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/a2fdbfed0d71

Comment 5

[Alexandru Michis [:malexandru]]

Backed out changeset a2fdbfed0d71 for causing Bug 1567089.

Backout link: https://hg.mozilla.org/integration/autoland/rev/8442d36972721915a1d00d7c4f06f0a9872b0769

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&resultStatus=pending%2Crunning%2Csuccess%2Ctestfailed%2Cbusted%2Cexception%2Cusercancel%2Crunnable&searchStr=linux%2Cx64%2Cquantumrender%2Cdebug%2Cmochitests%2Ctest-linux64-qr%2Fdebug-mochitest-e10s-12%2Cm%2812%29&fromchange=7cce1e378da8fdcc719da8698b8ff73973c7a918&tochange=8442d36972721915a1d00d7c4f06f0a9872b0769&selectedJob=257119909

https://treeherder.mozilla.org/#/jobs?repo=mozilla-central&resultStatus=testfailed%2Cbusted%2Cexception&searchStr=android%2C8.0%2Cpixel2%2Cquantumrender%2Cdebug%2Creftests%2Ctest-android-hw-p2-8-0-arm7-api-16-qr%2Fdebug-reftest-e10s-4%2Cr%28r4%29&fromchange=4116a7254a4ee7033f38b7126007bd2af678a7b8&tochange=b3f5385fa0b37bca7c46269ff394aca964baec7c&selectedJob=257120387

Failure logs:
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=257120387&repo=mozilla-central&lineNumber=4835
https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=257119909&repo=autoland&lineNumber=25771

Comment 6

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/8442d3697272

Comment 7

[Glenn Watson [:gw]]

I'll investigate this today, and get it re-landed.

Even if I just comment out those debug asserts that are occurring on a couple of tests, this patch should still be a net improvement on what's currently in m-c. But I'll look into those test cases / platforms that hit the assert this morning, and see if I can work out what's going on first.

Comment 8

[Glenn Watson [:gw]]

Rebased and updated patch to account for zoom factors in the root transform, which was causing a test failure on some platforms.

Pending try:
https://treeherder.mozilla.org/#/jobs?repo=try&revision=11dc6dfe8a21404ef2858974e2f01bccfc53fc86

Comment 9

[Glenn Watson [:gw]]

The try run looks good now, as far as I can tell.

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/5c6895ea59af
Fix quality issues with picture caching when the transform has a fractional offset. r=kvark

Comment 11

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/5c6895ea59af

Comment 12

[Glenn Watson [:gw]]

Comment on attachment 9078586 [details]
Bug 1566712 - Fix quality issues with picture caching when the transform has a fractional offset.

Beta/Release Uplift Approval Request

• User impact if declined: Visual artifacts in text rendering on some platforms with WebRender on some pages.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This will fix some or all of these beta bugs for users with WR enabled:

https://bugzilla.mozilla.org/show_bug.cgi?id=1566178
https://bugzilla.mozilla.org/show_bug.cgi?id=1541072
https://bugzilla.mozilla.org/show_bug.cgi?id=1565473
https://bugzilla.mozilla.org/show_bug.cgi?id=1566517

• String changes made/needed:

Comment 13

[Ryan VanderMeulen [:RyanVM]]

Comment on attachment 9078586 [details]
Bug 1566712 - Fix quality issues with picture caching when the transform has a fractional offset.

Fixes a number of text rendering bugs for users with WebRender enabled. Approved for 69.0b7.

Comment 14

[Razvan Maries]

https://hg.mozilla.org/releases/mozilla-beta/rev/94b21fc8b643