Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!haven!umd5!zben
From: zben@umd5.umd.edu (Ben Cranston)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Offscreen BitMaps
Summary: Alternate code for computing rowBytes
Keywords: bitmap, offscreen
Message-ID: <5115@umd5.umd.edu>
Date: 20 Jul 89 01:43:09 GMT
References: <3023@helios.ee.lbl.gov>
Reply-To: zben@umd5.umd.edu (Ben Cranston)
Organization: University of Maryland, College Park
Lines: 18

What's wrong with this?

  deep = (**MyGrafPort.portPixMap).pixelSize;
  rowsize = 2 * ( (15+width*deep) / 16 );
  (**MyGrafPort.portPixMap).rowbytes = 0x8000 | rowsize;

or

  deep = MyGrafPort.portPixMap^^.pixelSize;
  rowsize = ( (width*deep)+15 ) DIV 16 * 2;
  MyGrafPort.portPixMap^^.rowBytes = BitOr(RowSize,$8000);

Admittedly these are Color Quickdraw examples, but how is storage being
wasted if you just do a rounded divide by 16 then halve the result?
-- 
Sig     DS.L    ('ZBen')       ; Ben Cranston <zben@umd2.UMD.EDU>
* Computer Science Center Network Infrastructures Group
* University of Maryland at College Park