Definitely a bug. Some of these are on file, some are not: http://webkit.org/quality/reporting.html -eric On Tue, Feb 2, 2010 at 8:17 AM, Leif Arne Storset <lstorset@opera.com> wrote:
Hello,
While doing some SVG-related work over here I discovered that WebKit's rendering of SVG in <img> tags differs from Opera's. Since WebKit and Opera to my knowledge are the only engines that currently support SVG in <img> we thought it would be worthwhile to make sure we are compatible.
As far as I can tell from the latest nightly builds (and the latest Chrome release on Linux), WebKit will render an SVG in <img> much like a bitmap: it will resolve the width and height of the image and stretch it to fill the content box. It will respect any viewbox (presumably synthesizing one if it is missing), but preserveAspectRatio [1] seems not to be applied to an SVG in <img>, and the default rendering (whether there is a viewbox or not) is as if preserveAspectRatio="none".
Opera (Presto engine) will also resolve image dimensions and synthesize missing viewboxes, and will synthesize a viewBox if it can, as outlined in SVG WG ISSUE-2258 [2], and applies preserveAspectRatio as specified in SVG 1.1 (note that pAR has a default value 'xMidYMid meet'). The viewBox (whether specified or synthetic) are used together with pAR when rendering the SVG into the viewport established by the <img> element.
The attached images and test case illustrate the two renderings.
A quick Google search of webkit.org revealed little on preserveAspectRatio except a reference to a 2008 bug in SVGImageElement. However, for <svg:image> (that is: <image> elements inside of an <svg>), pAR seems to be applied as per the spec.
We believe that not applying the pAR on svg in <img> means that WebKit has invalid rendering behaviour according to the SVG 1.1 specification.
To enhance cross-browser compatibility it would be good if WebKit also considered synthesizing viewBoxes as outlined in [2], as this makes it easier to reuse existing svg content created by svg editors such as Inkscape (such content most often has a width and height, but lacks a viewBox).
I hope you find these recommendations useful. Please let me know if I can be of further assistance. If desired I can file a bug in your issue tracker.
-- Leif Arne Storset Layout developer, Opera Software
[1] http://www.w3.org/TR/SVG11/coords.html#PreserveAspectRatioAttribute [2] http://www.w3.org/Graphics/SVG/WG/track/issues/2258 _______________________________________________ webkit-dev mailing list webkit-dev@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev