Re: Graphics clipping question

[Scott McKay <SWM%sapsucker.scrc.symbolics.com@RELAY.CS.NET>]

    Date: Fri, 03 Mar 89 11:27:34 -0500
    From: kanderso@DINO.BBN.COM

      Date: Thu, 2 Mar 89 16:46 PST
      From: William M. York <York@Chuck-Jones.ILA-West.Dialnet.Symbolics.COM>
      Subject: Graphics clipping question
      To: kanderso@DINO.BBN.COM, slug@Warbucks.AI.SRI.COM
      In-Reply-To: The message of 2 Mar 89 11:24 PST from kanderso@DINO.BBN.COM
      Message-ID: <19890303004631.2.YORK@Chuck-Jones.ILA-West.Dialnet.Symbolics.COM>
  
	  Date: Thu, 02 Mar 89 14:24:35 -0500
	  From: kanderso@DINO.BBN.COM
  
	  I am trying to convert some graph drawing software to use GRAPHICS:
	  functions rather than window operations, and one thing i'm having
	  trouble with is clipping.  I need to be able to clip drawing
	  operations to the rectangular outline of the graph.  My old software
	  modified the TV:CLIPPING-REGION instance variable of the stream being
	  drawn on, and that worked fine.  This doesn't work with GRAPHICS:
	  functions because the stream you think you are drawing on often has
	  nothing to do with the steam you are actually drawing on because you
	  are in a maze of twistly little continuations all alike.
  
      Try:
  
      (graphics:with-room-for-graphics ()
	(graphics:with-clipping-path (t #'(lambda (s)
					  (graphics:draw-rectangle 100 100 200 200 :stream s :filled nil)))
	  (graphics:draw-circle 100 100 50)))
  
      You can construct an arbitrary clipping region by drawing a path that
      surrounds it.

    I tried this too, but it has the same problem.  It seems like i'll
    have to do most of the clipping myself.

Please send a real bug report if it does not work.  All clipping
examples I have tried work properly.