Ensure raster cache doesn't bleed over to adjacent physical pixels #35602
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flow/raster_cache.cc
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| canvas.save(); | ||
| // Make sure raster cache doesn't bleed to physical pixels outside of original | ||
| // bounds. https://github.com/flutter/flutter/issues/110002 | ||
| canvas.clipRect(SkRect::Make(bounds.roundOut())); |
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Adding a clip here is going to be expensive in aggregate, especially if it is only needed for low DPR devices. Is there another way to do this?
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The clip is hard edge on pixel boundaries. Is it that expensive? Not sure what you mean by low DPR. The example shows artifacts on 2x iPhone, but I'd assume it will happen on 3x device as well.
I think we might be able to determine situation where the bleeding can't happen i.e. (bounds.fLeft + imageWidth) <= ceil(bounds.fRight)
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I changed the code to only clip if raster image actually exceeds original pixel boundaries. This should remove the clip in vast majority of cases. Still working on tests for this.
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Another possible approach would be to shrink the src and destination rect for the drawImage by replacing it with drawImageRect. lets consider that if we land this and performance degrades, but otherwise a simple check should be good.
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Fixes flutter/flutter#110002
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writing and running engine tests.
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