Path: utzoo!attcan!uunet!husc6!bloom-beacon!EXPO.LCS.MIT.EDU!jim
From: jim@EXPO.LCS.MIT.EDU (Jim Fulton)
Newsgroups: comp.windows.x
Subject: Re: Visual help needed.. Multi-plane as a Monochrome
Message-ID: <8809131605.AA01736@EXPO.LCS.MIT.EDU>
Date: 13 Sep 88 16:05:33 GMT
References: <139@tityus.UUCP>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: X Consortium, MIT Laboratory for Computer Science
Lines: 41


If the display only supports depth 8 visuals, then you probably won't be able
to create any depth 1 windows.

You'll need to ask specific questions.  Some things to watch out for, though:

     o  avoid any GX function other than GXcopy unless you really know what
	you're doing; one exception is inverting between two colors (in simple
	menus, for example):  set the foreground value in the GC to be the
	xor of the two colors and set the function to be GXxor.  Doing a 
	filled rectangle over an area made of up of those two colors will
	appear to toggle them.  But, if any other other colors get in the way
	you'll get trash.

     o  be cautious of thing that requires setting the planemask to any value
	besides AllPlanes; unless you have allocated planes, you're probably
	doing something wrong.

     o  stipples are single plane; tiles (backgrounds, borders, etc.) are
	multi-plane.

     o  when creating a pixmap from single plane (e.g. "bitmap") data, use
	XCreatePixmapFromBitmapData; this will be easier in R3 as there will
	a library of miscellaneous utility routines that will include a call
	for reading bitmap data from files.  Until then:

     o  if you have a bitmap (i.e. single-plane pixmap) that you need to turn 
	into a two color, multi-plane pixmap, create a scratch GC with 
	foreground and background set to the appropriate colors and 
	graphics_exposures set to False; create a pixmap of the appropriate
	size using XCreatePixmap; then, do an XCopyPlane from the bitmap
	to the pixmap and free the scratch GC.

     o  make no assumptions about what value BlackPixel and WhitePixel have.


Obviously, there are exceptions to each of the above.  Caveat hactor.


Jim Fulton
MIT X Consortium