Bug 99524 – zooming with text-rendering: geometricPrecision is very janky

• Status: NEW
• Component: Layout and Rendering

[Eric Seidel (no email)]

zooming with text-rendering: geometricPrecision is very janky

It appears that you get sent down the complex-text path with geometricPrecision (not too surprising), and thus we end up in malloc-city!

https://bug-99383-attachments.webkit.org/attachment.cgi?id=168805 is the SVG in question, I'll attach a version of it with text-rendering: geometricPrecision enabled.

[Eric Seidel (no email)]

Created attachment 169052 [details]
attachment 168805 [details] with text-rendering: geometricPrecision set on the root element (note how laggy zooming is!)

[Eric Seidel (no email)]

Created attachment 169053 [details]
sample of attachment 168805 [details] zooming (fast-text path)

[Eric Seidel (no email)]

Created attachment 169055 [details]
sample of attachment 169052 [details] zooming (complex text path), notice all the mallocs in under ComplexTextController

[Eric Seidel (no email)]

I see.  geometricPrecision enables ligatures/kerning typesetting features:

TypesettingFeatures typesettingFeatures() const
{
...
        case GeometricPrecision:
        case OptimizeLegibility:
            features |= Kerning | Ligatures;
            break;

Which then causes us to go down the complex text path:

Font::CodePath Font::codePath(const TextRun& run) const
{
...
    if (run.length() > 1 && !WidthIterator::supportsTypesettingFeatures(*this))
        return Complex;

I suspect that this is "expected" behavior.  Although perhaps it's possible to optimize this case, or the complex text path in general.  Mitz would know much better than I.


I should note that I was turning on geometric-precision to get around the font-stair-stepping, which is covered by bug 60317.