1717877 - [css-images] Behaviour of SVG degenerate aspect-ratios

Status: RESOLVED FIXED

(Core :: Layout: Images, Video, and HTML Frames, defect)

Description

[Mozilla Apprentice]

A resolution was made for csswg-drafts/#6286.

[css-images] Behaviour of SVG degenerate aspect-ratios

• RESOLVED: degenerate aspect ratios derived from SVG width/height attributes fall back to viewbox aspect ratio (whether due to negative values or zero values)

Discussion.

Comment 1

[Daniel Holbert [:dholbert]]

This probably requires us to adjust SVGOuterSVGFrame::GetIntrinsicRatio().

https://searchfox.org/mozilla-central/rev/9975889f5c0d5c59bd22121a454beba774cbae71/layout/svg/SVGOuterSVGFrame.cpp#249

(note, iank [from the Chromium team] mentioned there are a few grid WPT tests that depend on our existing behavior, which will need an adjustment [and I think he'll be changing them]. We might continue to pass them, since he'll probably be changing them to remove the viewBox, which is the thing that we weren't falling back to & that the spec now says we should fall back to.)

Comment 2

[Daniel Holbert [:dholbert]]

boris, maybe you'd be interested in taking this, given that it's in the neighborhood of the aspect-ratio work you've been doing?

(This isn't strictly about the aspect-ratio property, but it's a relatively self-contained aspect ratio related change.)

Comment 3

[Boris Chiou [:boris]]

Attachment: test.html

Based on the spec issue, the expected behavior of this test.html should be 3 green squares, and their sizes are:

1. 100x100
2. 50x50
3. 50x50

Comment 4

[Boris Chiou [:boris]]

Attachment: test

Both cases should be 100x100 green squares.

Comment 5

[Boris Chiou [:boris]]

Attachment: Bug 1717877 - Handle degenerate ratio and negative size attributes for intrinsic size calculation of SVG outer frames.

Based on github.com/w3c/csswg-drafts/issues/6286, we fall back to the
viewport rect if

1. width/height is a degenerate ratio, or
2. width or height is a negative number.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/bed7b4b9ff74
Handle degenerate ratio and negative size attributes for intrinsic size calculation of SVG outer frames. r=emilio

Comment 7

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/29487 for changes under testing/web-platform/tests

Comment 8

[Cristian Brindusan [:cbrindusan]]

https://hg.mozilla.org/mozilla-central/rev/bed7b4b9ff74

Comment 9

[Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)]

Upstream PR merged by moz-wptsync-bot