[Webkit-unassigned] [Bug 50527] [Qt] Background image rendering is slow

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=50527





--- Comment #13 from Noam Rosenthal <noam.rosenthal at nokia.com>  2010-12-06 08:38:40 PST ---
(In reply to comment #12)
> (In reply to comment #11)
> > > I don't understand the coordinates here. Why you start at 0, 0? Why the width is destinationRect.right() - offset.x()? The offset could be bigger than destinationRect.right(), and the result should still be correct.
> > 
> > Since we translate(offset) a line earlier, this would draw the tile pixmap between the points 
> > (offset -> destinationRect.bottomRight()). Maybe I need to write it in a more verbose way :)
> 
> The offset should be the offset of the pixmap being rendered. The pattern does not necessary starts at (0, 0).
> 
> That is not what you are doing, or I am missing completely what you are doing and yet a more verbose way would be nice :)

Looking it a second time, yes - something is funky with my geometry. I'll revise and submit.
Btw I'm thinking the performance gain is not necessarily from fillRect vs. drawTiledPixmap, it might be because of the optimization to pre-transform the image, while I'm not sure fillRect does it (it's really a raster-specific optimization, in OpenGL it's probably better to transform on each draw).

If anybody is up to figuring it out inside the raster engine, go for it... I'll continue trying to fix it inside GraphicsContext and friends for now.

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