Any ideas on how to implement it for png? It doesn't seem trivial using just cairo: https://lists.cairographics.org/archives/cairo/2017-February/027882.html
Ideas
- Edit file metadata after first writing it to disk using cairo (janky?)
- Stream output to a variable and then edit that before writing to disk (possible using cairo_surface_write_to_png_stream??)
- Basically recreate all the cairo png functions here just to add a call to
png_set_pHYs
Basically recreate all the cairo png functions here just to add a call to png_set_pHYs
We already do that for other formats, so why not.
Fair enough. I might give it a go then.