XLOADIMAGE - X11 Image Loading Utility

WHAT IS IT?

This utility will view several types of images under X11, or load
images onto the root window.  The current version supports X11 Bitmap,
Portable Bitmap, Faces Project, and Sun Rasterfile images.  More are
planned.

A variety of options are available to modify images prior to viewing.
These options include clipping, dithering, depth reduction, zoom
(either X or Y axis independently or both at once),
brightening/darkening, and image merging.  When applicable, these
options are done automatically (eg a color image to be displayed on a
monochrome screen will be dithered automatically).

IMPLEMENTATION

Most functions are not particularly fast, and some functions use
simple-minded algorithms deliberately over more advanced ones.  I
stressed portability over all and simplicity over performance.  I
believe the result is a usable, portable tool which should serve the
needs of most users.

The source code is basically in two parts: image manipulation routines
and everything else.  The image manipulation routines should be
completely independent of X, thus allowing people to use them under
other graphical systems.  No guarantees here, but I tried.

Performance-oriented people will notice that when loading a color
image, the colormap of the image is minimized (and all pixel values in
the image changed), then the colormap is redone (and all pixel values
in the image changed again) before sending to X.  This could be
reduced to only one remapping of the image but I wanted to keep the
image from X's grubby (greedy?) hands as long as possible, and the
image merging function really wants the image to have a minimized
colormap.

COMPILING

There are three ways to compile xloadimage, depending on what
environment you have.

If you are compiling under the X11R4 distribution, the apropriate
Imakefile is included and you should compile as with any other client.
I haven't personally tested this, but if it's broken it'll be easy to
fix.

If you have gcc on your system, compile via "make -f Makefile.gcc".
Gcc should be used if it works because the strength-reduction and
inline-functions directives dramatically improve performance of some
operations.

Normal compilations can be done via "make -f Makefile.std".  This
invokes the standard cc using the -O flag.

INSTALLATION

After compiling and installing xloadimage, I recommend linking or
symlinking to the executable with the names "xview" and "xsetbg".  The
default behavior is slightly different when invoked with these
commands (they're also easier to type).

OWNERSHIP

I used the MIT X Consortium copyright with all of these functions,
thereby allowing full freedom with the code so long as the copyright
notices remain intact.  Free code can be good code.

SUGGESTIONS AND BUG REPORTS

Suggestions and bug reports should go to:

	Jim Frost
	madd@std.com
	..uunet!world!madd

Please include the version number and sample image data if you are
reporting a bug.

Functions implementing new image types are welcomed; mail them to the
same address and I'll do my best to distribute them.

THANKS

Special thanks to the crew at the Boston University Graphics Lab for
their assistance and sample images, and to bzs@std.com for his simple
dithering algorithm (or what's left of it).

HISTORY

Patch 01 contained a new Makefile.std, Makefile.gcc, and Imakefile.
It contained a bug-fix to sendImageToX() which allowed bitmaps to be
sent from little-endian machines (eg VAX, 80386) correctly, and a fix
to xbitmapLoad() to allow correct loading of X10 bitmap images.  An
enhancement to imageInWindow() which allowed exiting from image
windows by typing 'q' was submitted by Chris Tengi
(tengi@idunno.princeton.edu) and was included.  The previously missing
file 'patchlevel' was included.