1362914 - stylo: Serialization of font for canvas is different from gecko

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, defect, P2)

Description

[Hiroyuki Ikezoe (:hiro)]

Gecko returns "10px sans-serif", whereas stylo returns "normal normal normal normal 10px sans-serif".

Below test cases fail because of this bug:

 dom/canvas/test/test_canvas_font_setter.html
 dom/canvas/test/test_canvas.html

Comment 1

[Hiroyuki Ikezoe (:hiro)]

This is caused by the difference of serialization of font shorthand property.

Comment 2

[Hiroyuki Ikezoe (:hiro)]

From the canvas spec [1]

 For example, after the following statement:

 context.font = 'italic 400 12px/2 Unknown Font, sans-serif';

 ...the expression context.font would evaluate to the string "italic 12px "Unknown Font", sans-serif". The "400" font-weight doesn't appear because that is the default value. The line-height doesn't appear because it is forced to "normal", the default value.

As per this spec, we need another serialization function to drop default values for canvas.

[1] https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-font

Comment 3

[Hiroyuki Ikezoe (:hiro)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=9f7068a2abae1e6596f46c660f02f55ac8915568

Comment 4

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 1362914 - Factor out PropertyDeclaration only iterator.

Review commit: https://reviewboard.mozilla.org/r/140996/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/140996/

Comment 5

[Hiroyuki Ikezoe (:hiro)]

Attachment: Bug 1362914 - Drop initial values of properties other than font-size and font-family in serialization of canvas font attribute.

According to the canvas spec [1], we must drop initial values other than
font-size and font-family when we serialize canvas font attribute.
As for font-size and font-family, the default values, '10px sans-serif' [2]
are not dropped at all.

[1] https://html.spec.whatwg.org/multipage/scripting.html#dom-context-2d-font
[2] https://html.spec.whatwg.org/multipage/scripting.html#canvastextdrawingstyles

Review commit: https://reviewboard.mozilla.org/r/140998/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/140998/

Comment 6

[Manish Goregaokar [:manishearth]]

Comment on attachment 8869353 [details]
Bug 1362914 - Factor out PropertyDeclaration only iterator.

https://reviewboard.mozilla.org/r/140996/#review144664

Comment 7

[Manish Goregaokar [:manishearth]]

Comment on attachment 8869354 [details]
Bug 1362914 - Drop initial values of properties other than font-size and font-family in serialization of canvas font attribute.

https://reviewboard.mozilla.org/r/140998/#review144668

Comment 8

[Hiroyuki Ikezoe (:hiro)]

Thank you!

https://github.com/servo/servo/pull/16959

Comment 9

[Hiroyuki Ikezoe (:hiro)]

Comment on attachment 8869354 [details]
Bug 1362914 - Drop initial values of properties other than font-size and font-family in serialization of canvas font attribute.

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/140998/diff/1-2/

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0db843910232
Drop initial values of properties other than font-size and font-family in serialization of canvas font attribute. r=manishearth

Comment 11

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/0db843910232