Tells the delegate that enough data has been read to determine the size of the image.
- macOS 10.2+
The image object whose contents are being loaded.
The image representation object that is receiving and processing the image data.
By the time this method is called, the
NSBitmap object specified in the
rep parameter is valid and has allocated the memory needed to store the bitmap. The bitmap itself is filled with the image's background color. This method is optional; incremental loading will continue if the delegate does not implement it.