Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!uunet!mcsun!ukc!acorn!john
From: john@acorn.co.uk (John Bowler)
Newsgroups: comp.windows.x
Subject: Re: A wish for R5
Summary: XDrawBitmap -> XCopyPlane
Keywords: XCopyPlane
Message-ID: <6922@acorn.co.uk>
Date: 9 May 91 15:13:07 GMT
References: <1991May8.234851.576@agate.berkeley.edu>
Organization: Acorn Computers Ltd, Cambridge, UK
Lines: 41

In article <1991May8.234851.576@agate.berkeley.edu> vojta@powdermilk.berkeley.edu (Paul Vojta) writes:
>I hope it's not too late to suggest something, but it would be very helpful
>(at least for xdvi and the like) to have another X call for putting bitmaps.
>Quoting from the man page for XDrawString,
>
>	"the drawable is only modified where the font character
>	 has a bit set to 1."
>
>What I am suggesting would be an XDrawBitmap() call to provide the same
>functionality for drawing bitmaps.

Use XCopyPlane twice with the bitmap as the source.  The first time use the
raster op GXandInverted (sp?) with a foreground pixel value of ~0 (all bits
set) and a background of 0 to clear destination pixels (effectively using
the bitmap as an inverted mask).  The second time use GXor and set the
foreground to the desired pixel value, leave the background as 1.

If the foreground value is 0 (no bits set) omit the second step.  If the
foreground value is ~0 (all bits set) omit the first step.  If using a plane
mask just consider the set bits in the plane mask when working out this
optimisation.

>Or, allowing clients to download fonts would also suffice for this purpose.

And be more efficient when the operation really does correspond to a set of
glyphs... as in xdvi.  IMHO it would also be better than using font servers;
part of the problem for an application installing a font is dealing with
the services which do the installation (currently a font compiler and a font
path set operation, but possibly in the future a font server).  A protocol
extension is probably no more complex than the extensions to handle the font
server (in both the X server and for a new font server ``protocol''), and
could be very easy to use:-

	fontid = CreateFont(name,type)
	for-all-characters
		DefineCharacter(fontid,index,size_etc,bits)
	CompleteFont(fontid)
	<use the font>
	DestroyFont(fontid)

John Bowler (jbowler@acorn.co.uk)