+(defun image-display-size (spec &optional pixels frame)
+ "Wrapper around `image-size', to handle slice display properties.
+If SPEC is an image display property, call `image-size' with the
+given arguments.
+If SPEC is a list of properties containing `image' and `slice'
+properties, calculate the display size from the slice property.
+If SPEC contains `image' but not `slice', call `image-size' with
+the specified image."
+ (if (eq (car spec) 'image)
+ (image-size spec pixels frame)
+ (let ((image (assoc 'image spec))
+ (slice (assoc 'slice spec)))
+ (cond ((and image slice)
+ (if pixels
+ (cons (nth 3 slice) (nth 4 slice))
+ (cons (/ (float (nth 3 slice)) (frame-char-width frame))
+ (/ (float (nth 4 slice)) (frame-char-height frame)))))
+ (image
+ (image-size image pixels frame))
+ (t
+ (error "Invalid image specification: %s" spec))))))
+