override createOtherChunksWhenSaving(scope void delegate(Chunk c) sink) { sink(*Chunk.create("mine", [payload, bytes, here])); }
See the png spec for guidelines on how to create non-essential, private chunks in a file:
http://www.libpng.org/pub/png/spec/1.2/PNG-Encoders.html#E.Use-of-private-chunks
Added December 26, 2021 (dub v10.5)
Hook for subclasses to add custom chunks to the png file as it is written by writeApngToData and writeApngToFile.