When we allow animated images to be discarded we still want to track if the image has been fully decoded before, but it would be confusing to say that it is "done decoding" because that sounds like the image is currently decoded, even though it could be discarded at the time.
Each concrete class of imgIContainer is able to handle opacity already. All we
need to do is pass opacity value to them.
MozReview-Commit-ID: EMkLnG3YXA1
Each concrete class of imgIContainer is able to handle opacity already. All we
need to do is pass opacity value to them.
MozReview-Commit-ID: EMkLnG3YXA1
During painting we do some image decoding, but we want to send the image progress notifications from that decoding async. The CSS image renderer checks if the image is complete before painting it. So if the decoding we did during painting resulted in the images becoming complete there is no way to tell that during the same paint. Thus making that decoding a waste of time.
So we add a limited way of telling if the result of a StartDecoding call has resulting in an image that is ready to paint so we can get that result during the same paint.
I would have prefered to change StartDecoding to just return a bool but that would have made the bool an outparam, which would make every StartDecoding call uglier with extra code. Changing it to a notxpcom function would have fixed that, but I'm not sure if that is safe.
The Decode call may result in synchronously creating the surface, but we only check again if the surface is there for FLAG_SYNC_DECODE, not FLAG_SYNC_DECODE_IF_FAST.
All of the decoding we do during painting is of the type FLAG_SYNC_DECODE_IF_FAST, which means it would be useless to do that decoding synchronously during painting because the paint doesn't benefit from the result of that decoding.
Looking at the history of this code it looks like https://hg.mozilla.org/mozilla-central/rev/435df926eb10 (part 6 of bug 1119774) was where this bug was introduced. Before that changeset we always did another LookupFrameInternal call after the Decode (called WantDecodedFrames back then). But that changeset changed it to only be done for standard sync decodes, not "sync decode if fast".
FrameAnimator::GetCompositedFrame is only ever called with the current animation frame index. This is good because it can return invalid results if it is called for some other frame number.
Layout has been using imgIContainer::IsOpaque to determine if the image will draw opaquely to all pixels it covers, and doing culling based on this.
However imgIContainer::IsOpaque doesn't guarantee anything. It only describes if the image, when in a decoded state, has all opaque pixels. So if the image doesn't have fully decoded frames around (because they got discarded) it may not draw opaquely to all of its pixels.
So we create a new function that first checks if there is a fully decoded frame.
Layout has been using imgIContainer::IsOpaque to determine if the image will draw opaquely to all pixels it covers, and doing culling based on this.
However imgIContainer::IsOpaque doesn't guarantee anything. It only describes if the image, when in a decoded state, has all opaque pixels. So if the image doesn't have fully decoded frames around (because they got discarded) it may not draw opaquely to all of its pixels.
So we create a new function that first checks if there is a fully decoded frame.
