Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!psuvax1!xavier!jackiw
From: jackiw@cs.swarthmore.edu (Nick Jackiw)
Newsgroups: comp.sys.mac.programmer
Subject: ARGH!! Trivial Question; Please Help
Message-ID: <KKZF972@xavier.swarthmore.edu>
Date: 7 Mar 90 20:53:44 GMT
Sender: news@xavier.swarthmore.edu (USENET News System)
Organization: Visual Geometry Project, Swarthmore College, PA
Lines: 47


I've been knocking myself out over a simple (stupid) question:

I want to copyBits from one pixmap to another without using any cGrafPorts.
How?

IM V says "CopyBits now accepts either bitMaps or pixMaps as parameters."

Obviously, CopyBits(pixMapHandle^^,pixMapHandle^^,...) isn't going to work;
pixMapHandle^^ is not the same type as BitMap, and even if I coerce it
into so believing, with CopyBits(BitMapHandle(PixMapHandle)^^,) I'm
hacking off many of the fields of the pixMap (including important ones
like pixelDepth) and I get stack overflows, bus errors, and other symptoms
of the Wrong Approach.

In that thePort^.portBits can still be passed, and that its format is now

	thePort^.portBits	equivalent bytes in cGrafPort

	baseAddr			PortPixMapHandle;
	rowBytes			portVersion
	bounds				grafVars

I assume copyBits checks the rowBytes of a passed bitmap to see if
(two high bits set) the baseAddr contains a pixMapHandle or if
(two high bits clear) the baseAddr contains a regular bit-map bit-image.

Thus I'd assume that aBitMap:=thePort^.portBits (where thePort is pointing
to a cGrafPtr, not a grafPtr), would fill in the appropriate values for
copyBits to know it was getting a pixMap, and then aBitMap.baseAddr:=
ptr(myPixMapHand) before CopyBits would tell it which bitMap. Also not
so--while the system errors stop, the results aren't right either (the
offscreen pixmap, when copied, copies as ultra-slow all black regardless
of the contents of its baseAddr field).

NEITHER OF THESE METHODS ARE RIGHT.  WHAT'S THE RIGHT WAY? (Or must I use
a pixMap embedded in a port?  What a shameful waste.)

Thanks!



--
------------------------
Nick Jackiw		jackiw@cs.swarthmore.edu  "Just break out the
Visual Geometry Project	jackiw@swarthmr.bitnet     rum so we seem natural!"
Swarthmore College, PA 19081-1397				-F. Franklin