Defines the type of the function that gets called once the size of the loaded image is known.
The function is expected to set width and height to the desired size to which the image should be scaled. If a module has no efficient way to achieve the desired scaling during the loading of the image, it may either ignore the size request, or only approximate it - gdk-pixbuf will then perform the required scaling on the completely loaded image.
If the function sets width or height to zero, the module should interpret this as a hint that it will be closed soon and shouldn't allocate further resources. This convention is used to implement gdk_pixbuf_get_file_info() efficiently.
Pointer(Int32), Pointer(Int32) -> Nil