In Firefox (but not in Chrome or Safari) the transform perspective is dependent on devicePixelRatio. Steps to reproduce: 1) load attached test case on non-retina screen 2) compare rendering to reference included in test case 3) move tab/window to retina screen 4) repeat 2) Result: In Firefox on a retina screen, elements to not line up. They do on non-retina screen. Expected result: Rendering should be the same on both screens. Note: for elements to line up on retina in Firefox (but only Firefox), the perspective needs to be doubled (in this case to 500px) which matches the devicePixelRatio of 2 on a retina screen.
Timothy, is this something you'd know about, or someone else?
This was caused by bug 1181240 exposing a bug in Matrix4x4. Specifically Matrix4x4::PreScale should be scaling all values in the first three rows, not just the first three columns. That code came from bug 825928 (the layers refactoring). Patch coming up.
Assignee: nobody → tnikkel
Attachment #8661957 - Flags: review?(bas)
Attachment #8661957 - Flags: review?(bas) → review+
[Tracking Requested - why for this release]: A regression in 42, effecting matrix computation on devices with different than 1 pixel ratio. This is across the board on CSS computations and would have far reaching effects.
Comment on attachment 8661957 [details] [diff] [review] Patch Approval Request Comment [Feature/regressing bug #]: 1181240 [User impact if declined]: Wrong CSS transformations. [Describe test coverage new/current, TreeHerder]: none [Risks and why]: low, there was a bug in the matrix computation. [String/UUID change made/needed]: The Aurora request is assuming 42 is still in Aurora
Attachment #8661957 - Flags: approval-mozilla-aurora?
4 years ago
Duplicate of this bug: 1204657
No longer blocks: 1197972
Duplicate of this bug: 1197972
Comment on attachment 8661957 [details] [diff] [review] Patch This missed aurora 42. Moving the flag for beta approval instead.
Attachment #8661957 - Flags: approval-mozilla-aurora? → approval-mozilla-beta?
Comment on attachment 8661957 [details] [diff] [review] Patch Regression, taking it. Should be in 42 beta 2.
Attachment #8661957 - Flags: approval-mozilla-beta? → approval-mozilla-beta+
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