Bug 43622 – SVG masking performance very slow

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Stephen White]

The above page (once initialized) renders quite fast in Firefox.  In WebKit, it hangs for many seconds each frame.  It seems to be computing a luminance mask for a 5Kx5K image every frame.  Although mask creation could be optimized, I doubt that the other browsers are doing this computation, due to its size.  I suspect that either we're doing it at the wrong resolution, or there is an invalidation issue and the mask is being computed more often than necessary.

[Nikolas Zimmermann]

This also affects clipPaths that may use ImageBuffers, filters and patterns.
We're not allocating image buffers based on the final rendered size, but in the intermediate coordinate system where the object is renderer. This leads to scaling artefacts as well (see similar pattern bugs).

We should try to fix this ASAP.

[Nikolas Zimmermann]

I forgot to ask: Stephen, do you want to work on this?
There's already some code handling the task to figure out the final renderered size in the CG code path in RenderSVGResourceGradient (used for gradient on text).

[Stephen White]

(In reply to comment #2)
> I forgot to ask: Stephen, do you want to work on this?

I'm afraid I'm heavily loaded with other tasks right now, so I was hoping that someone else could take it on.

[Dirk Schulze]

Niko and me began at the same time to fix this issue. Delegating this work to Niko.

[Nikolas Zimmermann]

Created attachment 64195 [details]
Patch

[Early Warning System Bot]

Attachment 64195 [details] did not build on qt:
Build output: http://queues.webkit.org/results/3763096

[Dirk Schulze]

Comment on attachment 64195 [details]
Patch

The qt-build system update is missing. Otherwise looks great r=me.

[Nikolas Zimmermann]

Qt build system updated. Landed in r65229.