1832955 - Support font-relative CSS lengths as values for letterSpacing/wordSpacing in OffscreenCanvas

Status: RESOLVED FIXED

(Core :: Graphics: Canvas2D, enhancement)

Description

[Jonathan Kew [:jfkthame]]

The patches landed in bug 1778909 only support absolute CSS <length> values (with units such as px, cm, in, etc) when working with offscreen canvas, although for in-document <canvas> elements other length units -- in particular, font-relative units like em and ch -- are supported.

For better consistency between the <canvas> element and OffscreenCanvas, and because font-relative units are useful to authors, we should figure out how to support and resolve them appropriately in the offscreen case.

Comment 1

[Thomas Wisniewski [:twisniewski]]

This is causing us to fail these WPTs for interop2023:

• https://wpt.fyi/results/html/canvas/offscreen/text/2d.text.drawing.style.letterSpacing.change.font.html
• https://wpt.fyi/results/html/canvas/offscreen/text/2d.text.drawing.style.letterSpacing.change.font.worker.html
• https://wpt.fyi/results/html/canvas/offscreen/text/2d.text.drawing.style.wordSpacing.change.font.html
• https://wpt.fyi/results/html/canvas/offscreen/text/2d.text.drawing.style.wordSpacing.change.font.worker.html

Comment 2

[Jonathan Kew [:jfkthame]]

Attachment: Bug 1832955 - Support font-relative units when parsing letterSpacing/wordSpacing for offscreen canvas. r=#style,#gfx-reviewers

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/a7b4be81c1ae
Support font-relative units when parsing letterSpacing/wordSpacing for offscreen canvas. r=gfx-reviewers,lsalzman,emilio

Comment 4

[Cristian Tuns]

https://hg.mozilla.org/mozilla-central/rev/a7b4be81c1ae