Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-pcd!hpcvlx!billf
From: billf@hpcvlx.cv.hp.com (Bill F. Faus)
Newsgroups: comp.sys.mac.programmer
Subject: Need help with bitmaps
Message-ID: <101780003@hpcvlx.cv.hp.com>
Date: 9 Mar 90 19:42:07 GMT
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 44

I need help on understanding how bit maps are put onto the screen.

Can someone give me a mimimal program that illustrates how a bit map 
(say a simple rectangle 2 bytes wide and 100 bytes tall) is put onto 
screen.  I've read the QuickDraw chapter of "Inside MacIntosh",
but canot find a complete example that shows how to open a port,
build a bit map, and then display the bitmap onto the screen.

Which command actually writes to the screen?  Is it SetPortBits,
or is it CopyBits?  Can bitmaps be displayed without the use
of windows?

So far I've been fooling with the following Think C program,
which refuses to put anything on the screen:

main()
{
    BitMap     myBlob;
    GrafPort   myPort;
    char       Blob[200];

    InitGraf(&thePort);
    OpenPort(&myPort);
    SetPort(&myPort);  

    myBlob.baseAddr = Blob;
    myBlob.rowBytes = 2;
    SetRect(&myBlob.bounds, 100, 100, 200, 102);

    for (i = 0; i < 200; i++)
        Blob[i] = 0x0F;

    CopyBits(&myBlob, &myPort.portBits, &myBlob.bounds, &myPort.portRect, 
             srcCopy, 0L);
}
 
Any help would be appreciated.  Or pointers to reference material.

-------------------------------

Bill Faus
HP Calculator Learning Products

billf@cv.hp.com