The incremental PNG loader ignores trailing metadata
There are no comments, so it's not apparent if the omission is intentional:
https://gitlab.gnome.org/GNOME/gdk-pixbuf/-/blob/2.42.6/gdk-pixbuf/io-png.c#L812
libpng-manual.txt specifies that the png_infop
is the same one it passes to png_info_callback()
:
You will usually have the same info chunk as you had in the header, although some data may have been added to the comments and time fields.
Luckily it doesn't matter for thumbnailers, where the spec does not say where metadata should be located, because that path is not used:
- https://gitlab.gnome.org/GNOME/gnome-desktop/-/blob/master/libgnome-desktop/gnome-desktop-thumbnail.c#L830
- https://gitlab.gnome.org/GNOME/gdk-pixbuf/-/blob/master/gdk-pixbuf/gdk-pixbuf-io.c#L1067
There does not seem to be any documented intended behaviour: