649577 - Before and after the transition of transform, the baseline of the glyphs are uneven.

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect)

Description

[Alan Gresley]

User-Agent:       Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0
Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0

Watch the bottom of the line boxes 'Xx' and 'kK'. The baseline of the glyphs are only level when transitioning is happening. Before and after the transition, there is a 2px or 3px difference.

The baseline of the glyphs are only level when transitioning of transform is happening.

Reproducible: Always

Steps to Reproduce:
1. Hover the examples to cause a transition which causes a transformation.

Actual Results:  
Observed that the baseline of the glyphs is uneven when no transitioning is happening. 

Expected Results:  
The baseline of the glyphs are level when no transitioning is happening

Comment 1

[Alan Gresley]

Attachment: Three examples, one using Ahem font

Comment 2

[Alan Gresley]

Similar to this bug.

https://bugzilla.mozilla.org/show_bug.cgi?id=492214

Comment 3

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

When the transitioning of transform is happening, things are layerized; when it's not, you're probably seeing a similar text layout problem as the bug you point out -- except on Windows.  (Cairo's idea of text layout with interesting transforms generally seems problematic...)

Comment 4

[Gregory Pappas [:gregp]]

Test case looks good now.