Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!mcsun!ukc!mucs!liv-cs!phil
From: phil@mva.cs.liv.ac.uk
Newsgroups: comp.sys.mac.programmer
Subject: The old "dragging a pict" problem...
Message-ID: <5168.25f674b1@mva.cs.liv.ac.uk>
Date: 8 Mar 90 15:05:21 GMT
Organization: Computer Science CSMVAX, Liverpool University
Lines: 22

Has anyone used Superpaint, and noticed the efect you get when you drag a
picture that has a patterned filling around the screen?  The object moves - but
the pattern stays relative to a fixed point.  I'm writing
a program, which lets the user drag a picture around the screen.  Some of the
pictures are bitmaps, some are filled polygons or quite complicated quickdraw
pictures.  The system I'm using at the moment is to draw the picture once into
an offscreen bitmap, and then to blat it on at the correct location as themouse
moves around, while simultaneously redrawing the stuff that was underneath, and
copying new stuff out of the way.  My problem is that using this method, the
pattern gets out of sync.  Any sugggestion from anyone as to how to emulate
that SuperPaint system (for very complicated pictures, just redrawing the
picture over and over takes too long!)

If I get any useful replies I'll summarise them here.

Phil Jimmieson,           ***************************************************
Computer Science Dept.,   * JANET : PHIL@UK.AC.LIV.CS.MVA                   *
Liverpool University,     * ARPA  : PHIL%mva.cs.liv.ac.uk@cunyvm.cuny.edu   *
PO Box 147                ***************************************************
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