ark@cs.rit.edu (11/09/88)
I was reading about the picture-related calls (OpenPicture, ClosePicture, etc.) in Inside Macintosh Volume I the other day. The description of OpenPicture said that if the grafPort's clipRect is set to the default arbitrarily-large clipping rectangle when a picture is opened, there may be problems later when the picture is drawn; it may happen that nothing appears. I found all this very obscure. Can someone (a) tell me why one can't use the default clipRect, and (b) post or send a code fragment (C or Pascal) that shows me everything I am supposed to do when I create a picture and when I draw the picture? Thank you for your support. Alan Kaminsky P. O. Box 9887 School of Computer Science Rochester, NY 14623 Rochester Institute of Technology 716-475-5255 ark@cs.rit.edu
lsr@Apple.COM (Larry Rosenstein) (11/10/88)
In article <749@cs.rit.edu> ark@cs.rit.edu (Alan Kaminsky) writes: > >I found all this very obscure. Can someone (a) tell me why one can't use the >default clipRect, and (b) post or send a code fragment (C or Pascal) that shows >me everything I am supposed to do when I create a picture and when I draw the >picture? The problem is that if you then draw the picture at some place other than its original position, that default clipRect gets offset as well. Unfortunately, the coordinates will overflow if the offset is more than 1 pixel (or so). The solution is to call ClipRect before or after calling OpenPicture. In general, you would pass the same rectangle to ClipRect and OpenPicture. Larry Rosenstein, Object Specialist Apple Computer, Inc. 20525 Mariani Ave, MS 46-B Cupertino, CA 95014 AppleLink:Rosenstein1 domain:lsr@Apple.COM UUCP:{sun,voder,nsc,decwrl}!apple!lsr