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From: crunch@well.sf.ca.us (John Draper)
Newsgroups: comp.sys.mac.programmer
Subject: CopyBits
Message-ID: <21789@well.sf.ca.us>
Date: 22 Nov 90 05:56:56 GMT
Sender: crunch@well.sf.ca.us
Organization: Whole Earth 'Lectronic Link, Sausalito, CA
Lines: 56



Does anyone know if it is possible to CopyBits from one off screen
Pixmap to another one??   So far,  nothing I have done has worked.

I made sure the bounds to both are set the same,  and the allocated
memory for both are identical,  but they have different buffers.

The reason for this is so I can do scaling of the PixMaps.   In this
case,  I want to scale the picture to a SMALLER size.   So I set the
following values.

SetRect(&srcRect,  0, 0, 108, 128);	/* Origional size		*/
SetRect(&destrect, 0, 0,  75, 100);	/* Want scaled down to this size*/

I tried the following:

srcPix is the source PixMap.   destPix is the one I want to scale down 
into.

   destMap = NewPixMap();  		/* To create a new Pixmap 	*/
   CopyPixMap(srcPix, destMap);		/* To clone Ctab and other stuff*/
   
Before I copyBits, I want to allocate a buffer size at least the same size 
as the source buffer.   I get this from RowBytes after masking off the hi bit
of course.

   /*-------------------------------------------------------*/
   /* I calculate the width using the recommended formula   */
   /* width is the scaled down width			    */
   /*-------------------------------------------------------*/
   xwidth = (((width * (**aPix).pixelSize) + 15) >> 4) << 1;
   srcBnds = (**srcPix).bounds;
   size = (long)xwidth * (long)(srcBnds.bottom - srcBnds.top);
   
   buff = NewPtr(size);
   (**destMap).baseAddr = buff;

   HLock(srcPix);
   HLock(destMap);
   CopyBits(	*srcPix,		/* Needs pointer,  not handle 	*/
   		*destMap,		/* Same here		     	*/
		&srcRect,		/* Source is origional size	*/
		&destrect,		/* Dest is to be scaled down    */
		patCopy,		/* Xfer mode			*/
		0L);			/* No region			*/
   		
   HUnlock(srcPix);
   HUnlock(destMap);
   
The "bounds" of both PixMaps are (0, 0, 108, 128).   Is there anything Else
I might have overlooked??

John D.

Please respond to:  crunch@well.sf.ca.us