A policy for discarding tile images that contain no data (and so aren't actually images). This policy discards
DiscardEmptyTileImagePolicy.EMPTY_IMAGE, which is expected to be used in place of any empty tile images by the image loading code.
Default value for representing an empty image.
Determines if the discard policy is ready to process images.
True if the discard policy is ready to process images; otherwise, false.
Given a tile image, decide whether to discard that image.
||HTMLImageElement||An image to test.|
True if the image should be discarded; otherwise, false.