Bug 127337 – Fix SVG animations which set rx or ry attributes

• Component: SVG
• Status: RESOLVED FIXED

[Peter Molnar]

Fix SVG animations which set rx or ry attributes

Merged from Blink: https://src.chromium.org/viewvc/blink?revision=152376&view=revision

[Peter Molnar]

Created attachment 221730 [details]
patch

[WebKit Commit Bot]

Comment on attachment 221730 [details]
patch

Clearing flags on attachment: 221730

Committed r162438: <http://trac.webkit.org/changeset/162438>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Darin Adler]

Comment on attachment 221730 [details]
patch

View in context: https://bugs.webkit.org/attachment.cgi?id=221730&action=review

> Source/WebCore/rendering/svg/SVGPathData.cpp:119
> +    bool hasRx = rect->rx().value(lengthContext) > 0;
> +    bool hasRy = rect->ry().value(lengthContext) > 0;

Wasteful to repeat these expressions once to evaluate the has booleans and a second time if either is true. Should refactor so we don’t do it twice.

Also, is > 0 really the correct test? Is that from the spec, or just copying what the Blink folks did? Did the Blink folks give a rationale for that particular test?

[Philip Rogers]

(In reply to comment #4)
> (From update of attachment 221730 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=221730&action=review
> 
> > Source/WebCore/rendering/svg/SVGPathData.cpp:119
> > +    bool hasRx = rect->rx().value(lengthContext) > 0;
> > +    bool hasRy = rect->ry().value(lengthContext) > 0;
> 
> Wasteful to repeat these expressions once to evaluate the has booleans and a second time if either is true. Should refactor so we don’t do it twice.

Excellent catch Darin. We should definitely refactor that into a helper function.

> 
> Also, is > 0 really the correct test? Is that from the spec, or just copying what the Blink folks did? Did the Blink folks give a rationale for that particular test?

The Blink folks did a terrible job of describing this change and I apologize for that :(
The spec is clear about negative rx/ry values in https://svgwg.org/svg2-draft/single-page.html#shapes-RectElement, and the new behavior matches Firefox (IE does not support SMIL). This change is really about making the negative rx/ry logic work for animations as well. The hasAttribute check is not appropriate for attributes that can be set by an animation element.

[Peter Molnar]

(In reply to comment #5)
> (In reply to comment #4)
> > (From update of attachment 221730 [details] [details])
> > View in context: https://bugs.webkit.org/attachment.cgi?id=221730&action=review
> > 
> > > Source/WebCore/rendering/svg/SVGPathData.cpp:119
> > > +    bool hasRx = rect->rx().value(lengthContext) > 0;
> > > +    bool hasRy = rect->ry().value(lengthContext) > 0;
> > 
> > Wasteful to repeat these expressions once to evaluate the has booleans and a second time if either is true. Should refactor so we don’t do it twice.
> 
> Excellent catch Darin. We should definitely refactor that into a helper function.
> 
> > 
> > Also, is > 0 really the correct test? Is that from the spec, or just copying what the Blink folks did? Did the Blink folks give a rationale for that particular test?
> 
> The Blink folks did a terrible job of describing this change and I apologize for that :(
> The spec is clear about negative rx/ry values in https://svgwg.org/svg2-draft/single-page.html#shapes-RectElement, and the new behavior matches Firefox (IE does not support SMIL). This change is really about making the negative rx/ry logic work for animations as well. The hasAttribute check is not appropriate for attributes that can be set by an animation element.

I created a new bug for the follow-up: https://bugs.webkit.org/show_bug.cgi?id=127423

The double calculation issue is resolved there.