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