Bug 17541 – SVG font support gets wrong metrics by querying 'font' instead of 'font-face' element

• Component: SVG
• Status: RESOLVED FIXED

[Mark Ambachtsheer]

WebKit isn't getting the right metrics for SVG fonts because it is falling back on default metrics when reading correct SVG font definitions with those metrics supplied.

Looking at SVGFontFaceElement::ascent() and SVGFontFaceElement::descent(), the code is attempting to query the 'font' element, when according to the specs here:
http://www.w3.org/TR/SVG/fonts.html#FontElement
http://www.w3.org/TR/SVG/fonts.html#FontFaceElement
the 'ascent' and 'descent' attributes should be defined on the font-face element.

This is using code checked out from SVN 2008/02/25.

[Mark Ambachtsheer]

Created attachment 19450 [details]
test file that reproduces bugs # 17541 and 17608 visually.

[Mark Ambachtsheer]

Created attachment 19451 [details]
Screenshot of 17541_17608.html being rendered by WebKit

[Nikolas Zimmermann]

int SVGFontFaceElement::ascent() const
{
    // Spec: Same syntax and semantics as the 'ascent' descriptor within an @font-face rule. The maximum
    // unaccented height of the font within the font coordinate system. If the attribute is not specified,
    // the effect is as if the attribute were set to the difference between the units-per-em value and the
    // vert-origin-y value for the corresponding font.
    const AtomicString& ascentValue = fastGetAttribute(ascentAttr);
    if (!ascentValue.isEmpty())
        return static_cast<int>(ceilf(ascentValue.toFloat()));

..

This is long resolved in trunk, this bug was forgotten.