DrawableSurface only exposes DrawableFrameRef to its users. This is
sufficient for the drawing related code in general, but FrameAnimator
really needs RawAccessFrameRef to the underlying pixel data (which may
be paletted). While one can get a RawAccessFrameRef from a
DrawableFrameRef, it requires yet another lock of the imgFrame's mutex.
We can avoid this extra lock if we just allow the callers to get the
right data type in the first place.
We can discard frames from an animated image if the memory footprint
exceeds the threshold. This will cause us to redecode frames on demand
instead. However decoders can fail to produce the same results on
subsequent runs due to differences in memory pressure, etc. If this
happens our state can get inconsistent. In particular, if we keep
failing on the first frame, we end up in an infinite loop on the decoder
thread.
Since we don't have the owning image to signal, as we had to release our
reference to it after the first pass, we can do little but stop decoding.
From the user's perspective, the animation will come to a stop.
We can discard frames from an animated image if the memory footprint
exceeds the threshold. This will cause us to redecode frames on demand
instead. However decoders can fail to produce the same results on
subsequent runs due to differences in memory pressure, etc. If this
happens our state can get inconsistent. In particular, if we keep
failing on the first frame, we end up in an infinite loop on the decoder
thread.
Since we don't have the owning image to signal, as we had to release our
reference to it after the first pass, we can do little but stop decoding.
From the user's perspective, the animation will come to a stop.
Andrew Osmond
Cosmin Sabou