1250773 - negative width/height in viewBox should not disable rendering

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[Robert O'Callahan (:roc) (email my personal email if necessary)]

https://www.khronos.org/registry/vulkan/specs/1.0/xhtml/images/tstripadj.svg doesn't render in Firefox because it has a negative viewBox width. It does render (tiny) in Chrome. We should treat this viewBox attribute as invalid and ignore it.

Comment 1

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: MozReview Request: Bug 1250773. Ignore viewBoxes with negative width/height. r=heycam

Review commit: https://reviewboard.mozilla.org/r/36257/diff/#index_header
See other reviews: https://reviewboard.mozilla.org/r/36257/

Comment 2

[Cameron McCormack (:heycam)]

Comment on attachment 8722825 [details]
MozReview Request: Bug 1250773. Ignore viewBoxes with negative width/height. r=heycam

https://reviewboard.mozilla.org/r/36257/#review32817

::: dom/svg/nsSVGViewBox.h:54
(Diff revision 1)
>     * This method does not check whether the width or height values are
>     * positive, so callers must check whether the viewBox rect is valid where
>     * necessary!

Update the comment to say it takes negative width/height into account.

::: dom/svg/nsSVGViewBox.h:68
(Diff revision 1)
>    bool IsExplicitlySet() const
>      { return mAnimVal || mHasBaseVal; }

Looking at the callers of IsExplicitlySet, I think we want to update it so that it returns false if we have a value with a negative width/height, too.

Comment 3

[Robert Longson [:longsonr]]

The SVG 1.1 and SVG 2 specification say explicitly that negative values for width/height are an error. https://www.w3.org/TR/SVG2/coords.html#ViewBoxAttribute

They both then go on to say that the element or the part that is in error is not rendered. https://www.w3.org/TR/SVG2/implnote.html#ErrorProcessing

The specification really should be clearer as to what should occur here as ignore the viewBox and carry on rendering that element is not an obvious interpretation of that sentence.

Comment 4

[Cameron McCormack (:heycam)]

I agree; I filed an issue: https://github.com/w3c/svgwg/issues/52

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Comment on attachment 8722825 [details]
MozReview Request: Bug 1250773. Ignore viewBoxes with negative width/height. r=heycam

Review request updated; see interdiff: https://reviewboard.mozilla.org/r/36257/diff/1-2/

Comment 6

[Cameron McCormack (:heycam)]

Comment on attachment 8722825 [details]
MozReview Request: Bug 1250773. Ignore viewBoxes with negative width/height. r=heycam

https://reviewboard.mozilla.org/r/36257/#review32835

Comment 7

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/4894d75bf376

Comment 8

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/4894d75bf376