This is an uninitialized thing, you're responsible for filling in all data yourself. You probably don't want to use this except for use in the factory function you pass to readApng.
If palette is null, it is a true color image. If it has data, it is indexed.
Adds a frame with the given size and returns the object. You can change other values in the frameControlChunk on it and get the data bytes out of there.
Hook for subclasses to add custom chunks to the png file as it is written by writeApngToData and writeApngToFile.
Hook for subclasses to handle custom chunks in the png file as it is loaded by readApng.
Class that represents an apng file.