1695494 - CanvasRenderingContext2D.measureText() does not fill actualBoundingBox properties for emoji

Status: RESOLVED DUPLICATE of bug 1692791

(Core :: Graphics: Canvas2D, defect)

Description

[Dmitry Shachnev]

Attachment: A simple page demonstrating the problem (look at the web console)

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:86.0) Gecko/20100101 Firefox/86.0

Steps to reproduce:

Please see the attached test case. It creates a canvas 2D context and tries to measure dimensions of various characters. For characters that are not emoji, actualBoundingBox{Left,Right,Ascent,Descent} properties are properly set. For emojis, they are all zero.

But the canvas itself can draw these emojis properly, which is also demonstrated.

My environment is: Debian GNU/Linux unstable amd64, with Noto Color Emoji font installed, Firefox 86.0.

Actual results:

Output in console:

A
TextMetrics { width: 34.20000076293945, actualBoundingBoxLeft: 0, actualBoundingBoxRight: 34, actualBoundingBoxAscent: 36, actualBoundingBoxDescent: 0 }
☺
TextMetrics { width: 52.119998931884766, actualBoundingBoxLeft: -4, actualBoundingBoxRight: 48, actualBoundingBoxAscent: 41, actualBoundingBoxDescent: 4 }
😀
TextMetrics { width: 50, actualBoundingBoxLeft: 0, actualBoundingBoxRight: 0, actualBoundingBoxAscent: -0, actualBoundingBoxDescent: 0 }
🦏
TextMetrics { width: 50, actualBoundingBoxLeft: 0, actualBoundingBoxRight: 0, actualBoundingBoxAscent: -0, actualBoundingBoxDescent: 0 }

Expected results:

Output of the same page in Chromium 88:

A
TextMetrics {width: 33.349609375, actualBoundingBoxLeft: 0, actualBoundingBoxRight: 34, fontBoundingBoxAscent: 45, fontBoundingBoxDescent: 11, …}
☺
TextMetrics {width: 51.0498046875, actualBoundingBoxLeft: -10, actualBoundingBoxRight: 41, fontBoundingBoxAscent: 45, fontBoundingBoxDescent: 11, …}
😀
TextMetrics {width: 62.390625, actualBoundingBoxLeft: 0, actualBoundingBoxRight: 63, fontBoundingBoxAscent: 45, fontBoundingBoxDescent: 11, …}
🦏
TextMetrics {width: 62.390625, actualBoundingBoxLeft: 0, actualBoundingBoxRight: 63, fontBoundingBoxAscent: 45, fontBoundingBoxDescent: 11, …}

Comment 1

[Robert Longson [:longsonr]]

Duplicate of bug 1692791 perhaps?

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Canvas: 2D' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 3

[Dmitry Shachnev]

Oh, yes, it looks very similar! Marking as duplicate.