The changes to ImageBuffer have landed. Here is what port authors need to know:
Image* image() on ImageBuffer is gone.
It has been replaced with:
PassRefPtr<Image> copyImage()
This function should always simply copy the image. It is used in any place
where you want to get a snapshot of the ImageBuffer and not be broken if the
ImageBuffer subsequently changes.
For drawing, callers should now use drawImageBuffer on GraphicsContext instead
of drawImage. drawImageBuffer internally just turns around and calls a draw
function on ImageBuffer. clipToImageBuffer now also turns around and calls
clip on the ImageBuffer.
void clip(GraphicsContext*, const FloatRect&) const;
// The draw method draws the contents of the buffer without copying it.
void draw(GraphicsContext*, ColorSpace styleColorSpace, const
FloatRect& destRect, const FloatRect& srcRect = FloatRect(0, 0, -1, -1),
CompositeOperator = CompositeSourceOver, bool
useLowQualityScale = false);
void drawPattern(GraphicsContext*, const FloatRect& srcRect, const
AffineTransform& patternTransform,
const FloatPoint& phase, ColorSpace styleColorSpace,
CompositeOperator, const FloatRect& destRect);
I've made sure the above functions are implemented in the various ports,
although the Skia and Cairo implementations currently draw by copying the image
and then just calling drawImage. I've left it up to those ports to fix this
issue (the current behavior is the same on those platforms as it was before my
patch).
There is a temporary method implemented by all ports called:
bool drawsUsingCopy() const; // If the image buffer has to
render using a copied image, it will return true.
This method only exists right now because some of the ports are still copying.
Once everyone has switched over to drawing the image buffer without making
copies, then I can remove this method from the interface. HTMLCanvasElement is
using it in order to cache a copy of the image for repeated drawing of a static
canvas, so that the "copying" platforms don't suffer a performance degradation
from my changes.
Feel free to ping me on IRC or in email if you have any questions about this
change.
Thanks,
Dave
([email protected])
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