Further filter/clear <SkPaint>.setDither(true), this time in DlSkPaintDispatchHelper

[matanlurey]

Closes flutter/flutter#132860.

• If setDither(true) is called, and an existing setColorSource is a gradient, it is ignored.
• If setColorSource(...) is called, and it is a gradient, and dithering was previously set, it is cleared.

I'm not sure this is fool proof.

[jonahwilliams]

RSLGTM

[matanlurey]

This doesn't actually work as written :(

It's possible for code to run the following (otherwise valid) branch:

paint.setDither(true);
...
paint.setColorSource(aGradient);

With this PR, setDither is discarded (the last known colorSource was not a gradient).

Let me try to understand the lifecycle of this class better, maybe there is a better place to do this kind of check?

[jonahwilliams]

Ahh that makes sense. You'd probably need to intercept the dithering call when it is being converted into an SkPaint.

[matanlurey]

I think <DlSkPaintDispatchHelper>.paint is the whole integration point that makes sense:

const SkPaint& paint() { return paint_; }

... and could be used to clear dithering if a color source of a gradient was not provided.

[matanlurey]

Appears to be all good now! Yay!

[flar]

LGTM