Re: potential bug in graphics:draw-image

["William M. York" <York%chuck-jones.ila-west.dialnet.symbolics.com@RELAY.CS.NET>]

    Date: Fri, 03 Nov 89 18:03:16 EST
    From: bouma@cs.purdue.edu


	   image at the same offsets. This leaves some ugly residue. Is there
	   something that I don't understand or is this a bug. I was under the
	   impression that graphics:draw-image simply did a bitblt. Am I wrong?
		   Jeff

	   (defun BUG ()
	    (let ((c (graphics:with-output-to-bitmap (t)
		       (graphics:draw-circle 100 100 100))))
	      (dw:with-own-coordinates (t :erase-window t :enable-output-recording 
	  nil)
		(graphics:draw-image c 0 0 :alu :flip)
		(graphics:draw-image c 10 10 :alu :flip)
		(graphics:draw-image c 10 10 :alu :flip)
		(graphics:draw-image c 0 0 :alu :flip)))
	    (read-char)
	    t)

      Well, it is doing something other than just a bitblt, because if you
      replace the calls to draw-image with ones to bitblt, it works fine!
      Draw-image appears to be doing an AND before it does the XOR. I would
      consider this a bug.

Use :OPAQUE NIL in the calls to DRAW-IMAGE.