755187 - External stylesheet in SVG interferes with object sizing

Status: RESOLVED FIXED

(Core :: SVG, defect)

Description

[Brian Birtles (:birtles, Feb 26~ parental leave)]

If an <object> element references an SVG file without specifying a width/height we use the intrinsic size of the SVG file which may be specified by the width/height attributes on the root <svg> element.

However, if the referenced SVG file contains an external stylesheet such as:

  <?xml-stylesheet href="style.css" type="text/css"?>

Then we appear to give up that process. Perhaps we have some limit to how far we read into the file to get the width and height?

Testcase forthcoming.

Comment 1

[Brian Birtles (:birtles, Feb 26~ parental leave)]

Attachment: External stylesheet

Comment 2

[Brian Birtles (:birtles, Feb 26~ parental leave)]

Attachment: SVG file referencing external stylesheet

Comment 3

[Brian Birtles (:birtles, Feb 26~ parental leave)]

Attachment: SVG file without referencing external stylesheet

Comment 4

[Brian Birtles (:birtles, Feb 26~ parental leave)]

Attachment: Test case

Comment 5

[Brian Birtles (:birtles, Feb 26~ parental leave)]

With the attached test case, two SVG files are referenced using <object> elements without width/height specified.

The two SVG files are identical except that the second one includes an <?xml-stylesheet?> PI that causes the circle to be blue.

Expected behaviour: The two circles have the same size

Actual behaviour: The circle with the stylesheet (the blue one) is smaller

Comment 6

[Brian Birtles (:birtles, Feb 26~ parental leave)]

Attachment: Screenshot of failing test

Comment 7

[Boris Zbarsky [:bzbarsky]]

How do we ask for the intrinsic size?  Are we asking the DOM, or layout?  The stylesheet load there may well block layout, but shouldn't block DOM construction, iirc...

Comment 8

[Brian Birtles (:birtles, Feb 26~ parental leave)]

I had a brief look into this but haven't got to the bottom of it yet. The intrinsic size is calculated in layout (nsSVGOuterSVGFrame) but it doesn't seem to get called for the SVG with the stylesheet.

Comment 9

[Brian Birtles (:birtles, Feb 26~ parental leave)]

CC'ing jwatt since he left comments in nsSVGOuterSVGFrame::GetIntrinsicSize :)

I had a quick look and basically, nsSubDocumentFrame::ObtainIntrinsicSizeFrame will return null for the case when we have an external stylesheet since nsIPresShell::GetRootScrollFrameAsScrollable returns null.

Looking at nsSVGOuterSVGFrame::GetIntrinsicSize, it seems like it should be possible to calculate the intrinsic size by just querying the DOM as noted by Boris. The exception being when width/height are specified by style (as noted by jwatt in the comment there).

Comment 12

[Robert Longson [:longsonr]]

Fixed by bug 1063073