saveToPng
Store the given @texture to the @filename as a PNG file.
This is a utility function intended for debugging and testing. If you want more control over formats, proper error handling or want to store to a iface@Gio.File or other location, you might want to use method@Gdk.Texture.save_to_png_bytes or look into the gdk-pixbuf library.
Return
true if saving succeeded, false on failure.
Parameters
filename
the filename to store to