/* $XConsortium: imagelib.c,v 1.0 93/11/22 12:08:52 rws Exp $ */

/*
        NOTICE TO USER: The source code in this file is copyrighted under
        U.S. and international laws.  SunSoft, Inc., a Sun Microsystems,
        Inc. business of Mountain View, California owns the copyright. 
        Users and possessors of this source code are hereby granted a
        nonexclusive, royalty-free copyright and design patent license
        to use this code in individual and commercial software. 

        Any use of this source code must include, in the user documentation 
        and internal comments to the code, notices to the end user as follows:

(c) Copyright 1989, 1990, 1991, 1992, 1993 SunSoft, Inc., a Sun Microsystems, Inc. business.

        SUNSOFT, INC. AND SUN MICROSYSTEMS, INC. MAKE NO REPRESENTATIONS
        ABOUT THE SUITABILITY OF THIS SOURCE CODE FOR ANY PURPOSE. IT IS
        PROVIDED "AS IS" WITHOUT EXPRESS OR IMPLIED WARRANTY OF ANY KIND. 
        SUNSOFT, INC., AND SUN MICROSYSTEMS, INC., SEVERALLY AND
        INDIVIDUALLY, DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOURCE
        CODE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
        FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SUNSOFT, INC.
        OR SUN MICROSYSTEMS, INC., BE LIABLE FOR ANY SPECIAL, INDIRECT,
        INCIDENTAL, OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER
        RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
        OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
        OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOURCE CODE.
*/


/*
 * imagelib.c - image library.
 * image utilities library for comparison tool
 */

/* 
 * header files
 */
#include "stdio.h"
#include "fcntl.h"
#include "X11/Xlib.h"
#include "X11/Xutil.h"
#include "imagelib.h"
#include "varargs.h"

/*
 * constants
 */
#define MASK24 0xffffff
#define SIZECMAPENTRY 4
#define MAXCMAPDATASIZE  (MAXCOLOR * SIZECMAPENTRY + 2)
                /* extra 2 bytes to store number of bytes of cmap data */

#define PSEUDOCOLOR 1
#define TRUECOLOR 2


/* 
 * global variables 
 */
static Unsign8 cmapdata[MAXCMAPDATASIZE]; /* image data to be saved */

/*
 * extern funcitons
 */
char *malloc();

/*
 * table of contents
 */

/* exported routines */
void i_diff_image();
void i_diff_image24();
void i_load_image();
void i_load_image2();
void i_load_image24();
void i_display_image();
void i_free_image();
void i_free_cmap();

/* local routines */
static void i_retrieve_image();
static void i_retrieve_image24();
static void i_retrieve_cmap();
static void i_convert_image();
static void i_load_image_info();
static void i_read();
static void i_8_to_16();
static void i_8_to_32();
static unsigned short i_scale_uchar_to_ushort();
static int i_get_bits_per_rgb();
static void fatal();
static char *emalloc();

/*
 Image file format:
<1 byte : flag indicating monochrome or pseudocolor type>
<2 bytes: number of bytes of ascii text to follow>
<n bytes: ascii text>
<2 bytes: width of image>
<2 bytes: height of image>
<2 bytes: number of colormap data entries>
<n bytes: colormap data of the form
        (pixel[1 byte],red[1 byte],green[1 byte],blue[1 byte]) quadriples >
<4 bytes: number of bytes of image data>
<n bytes: image data of the form (number[1 byte],pixel[1 byte]) pairs >
*/

/*
 * i_load_image(filename,display,visual,imagestr,cmapstr,text,err) 
 * load an image from a file 
 */
void
i_load_image(filename,display,visual,imagestr,cmapstr,text,err)
	char *filename;		/* image file name */
	Display *display;	/* X display */
	Visual *visual;		/* visual type */
	I_image *imagestr;	/* OUT image structure */
        I_cmap *cmapstr;       	/* OUT colormap structure */
        char *text;             /* OUT image description */
	int *err;		/* OUT error flag */
{
	/*
	To load an image from file to X's image structure.
	Create and store necessary colors in the color map.
	*/
        int fd;
	Unsign32 nbyte;
	static Unsign8 cmaptbl[MAXCOLOR];
	Unsign16 ncol;
	Unsign8 buf[4];
        Window rootwindow;
	int type;

	*err = 0;
        rootwindow = DefaultRootWindow(display);
        if ((fd = open(filename,O_RDONLY)) == -1) {
                printf("ERROR: i_loadimage: can't open file %s\n",filename);
		*err = 1;
		return;
	}
        i_load_image_info(fd,imagestr,text,&type);
	if (type != PSEUDOCOLOR)
		fatal("ABORT: i_loadimage: image file type != PSEUDOCOLOR\n");
	i_read(fd,2,(char*)buf);
	i_8_to_16(&buf[0],&ncol); 	
	if (ncol > MAXCOLOR) {
		printf("ERROR: i_loadimage: invalid data: number of colors > %d\n",MAXCOLOR);
		*err = 1;
		return;
	}
	i_read(fd,(int)(ncol*SIZECMAPENTRY),(char*)cmapdata);
	i_retrieve_cmap(display,rootwindow,visual,1,ncol,cmapdata,cmapstr,cmaptbl);
	i_read(fd,4,(char*)buf);
	i_8_to_32(&buf[0],&nbyte);
	imagestr->imagedata = (unsigned char*) emalloc(nbyte);
	i_read(fd,(int)nbyte,(char*)imagestr->imagedata);
	i_retrieve_image(display,visual,cmaptbl,nbyte,imagestr,err);
        if (close(fd) == -1)
                fatal("ERROR: i_load_image: in closing \"%s\", exiting...\n",filename);
}

/*
 * i_load_image2(filename1,filename2,display,visual,imagestr1,imagestr2,cmapstr1,
 *	cmapstr2,text1,text2,singlecmap,err) load 2 images from 2 files
 *      This has the advantage of sharing a single colormap if the total
 *      number of color used is less than MAXCOLOR-1 (1 less for background)
 */
void
i_load_image2(filename1,filename2,display,visual,imagestr1,imagestr2,cmapstr1,
	cmapstr2,text1,text2,istwocmap,err) 
	char *filename1;	/* image file name */
	char *filename2;	/* image file name */
	Display *display;	/* X display */
	Visual *visual;		/* visual type */
	I_image *imagestr1;	/* OUT image structure */
	I_image *imagestr2;	/* OUT image structure */
        I_cmap *cmapstr1;      	/* OUT colormap structure */
        I_cmap *cmapstr2;      	/* OUT colormap structure */
        char *text1;            /* OUT image description */
        char *text2;            /* OUT image description */
	int *istwocmap;		/* OUT 1 if 2 cmap is used, 0 otherwise */
	int *err;		/* OUT error flag */
{
        int fd1,fd2;
	Unsign32 nbyte;
	static Unsign8 cmaptbl1[MAXCOLOR],cmaptbl2[MAXCOLOR];
	Unsign16 ntext,ncol1,ncol2;
	Unsign8 buf1[4],buf2[4];
        Window rootwindow;
	int type;


	*err = 0;
        rootwindow = DefaultRootWindow(display);

        if ((fd1 = open(filename1,O_RDONLY)) == -1) {
                printf("ERROR: i_readimage: can't open file %s\n",filename1);
		*err = 1;
		return;
	}
        if ((fd2 = open(filename2,O_RDONLY)) == -1) {
                printf("ERROR: i_readimage: can't open file %s\n",filename2);
		*err = 1;
		return;
	}
        i_load_image_info(fd1,imagestr1,text1,&type);
	if (type != PSEUDOCOLOR)
		fatal("ABORT: i_loadimage: image file type != PSEUDOCOLOR\n");
        i_load_image_info(fd2,imagestr2,text2,&type);
	if (type != PSEUDOCOLOR)
		fatal("ABORT: i_loadimage: image file type != PSEUDOCOLOR\n");

	i_read(fd1,2,(char*)buf1);
	i_8_to_16(&buf1[0],&ncol1); 	
	i_read(fd2,2,(char*)buf2);
	i_8_to_16(&buf2[0],&ncol2); 	

	if (ncol1 > MAXCOLOR || ncol2 > MAXCOLOR) {
		printf("ERROR: i_loadimage2: invalid data\n");
		*err = 1;
		return;
	}
	/* 1 less than MAXCOLOR because of background color */
	*istwocmap = ((int) (ncol1 + ncol2) < MAXCOLOR -1)? 0 : 1; 

	i_read(fd1,(int)(ncol1*SIZECMAPENTRY),(char*)cmapdata);
	i_retrieve_cmap(display,rootwindow,visual,1,ncol1,cmapdata,cmapstr1, cmaptbl1);
	i_read(fd2,(int)(ncol2*SIZECMAPENTRY),(char*)cmapdata);
	if (*istwocmap) { /* can not share colormap */
		i_retrieve_cmap(display,rootwindow,visual,1,ncol2,cmapdata,
			cmapstr2,cmaptbl2);
	} else { /* can share colormap */
		i_retrieve_cmap(display,rootwindow,visual,0,ncol2,cmapdata,
			cmapstr1,cmaptbl2);
	}

	i_read(fd1,4,(char*)buf1);
	i_8_to_32(&buf1[0],&nbyte);
	imagestr1->imagedata = (unsigned char*) emalloc(nbyte);
	i_read(fd1,(int)nbyte,(char*)imagestr1->imagedata);
	i_retrieve_image(display,visual,cmaptbl1,nbyte,imagestr1,err);
	if (*err) return;
	i_read(fd2,4,(char*)buf2);
	i_8_to_32(&buf2[0],&nbyte);
	imagestr2->imagedata = (unsigned char*) emalloc(nbyte);
	i_read(fd2,(int)nbyte,(char*)imagestr2->imagedata);
	i_retrieve_image(display,visual,cmaptbl2,nbyte,imagestr2,err);
        if (close(fd1) == -1)
                fatal("ERROR: i_load_image2: in closing \"%s\", exiting...\n",filename1);
        if (close(fd2) == -1)
                fatal("ERROR: i_load_image2: in closing \"%s\", exiting...\n",filename2);
}


/*
 * i_load_image_info(fd,imagestr,text,type)
 * load general image information from file
 */
static void
i_load_image_info(fd,imagestr,text,type)
        int fd;                 /* file fd */
        I_image *imagestr;      /* OUT image structure */
        char *text;             /* OUT image description */
        int *type;              /* OUT file type */
{
        Unsign16 ntext;
        Unsign8 buf[4];

        i_read(fd,3,(char*)buf);
        *type = buf[0];
        i_8_to_16(&buf[1],&ntext); /* get number of bytes of text */
        i_read(fd,(int)ntext,text);
        text[ntext] = '\0';
        i_read(fd,4,(char*)buf);
        i_8_to_16(&buf[0],&imagestr->width);
        i_8_to_16(&buf[2],&imagestr->height);
}


/*
 * i_retrieve_cmap(display,window,visual,iscreatecmap,ncol,cmapdata,cmapstr,cmaptbl)
 *  read cmap data from "cmapdata" buffer and create and store cmap
 *  if "iscreatecmap" is 0, do not create cmap but add color to the cmap
 *  from "cmapstr".
 */
static void
i_retrieve_cmap(display,window,visual,iscreatecmap,ncol,cmapdata,cmapstr,cmaptbl)
	Display *display;	/* X display */
	Window window;		/* X window */
	Visual *visual;		/* visual type */
	int iscreatecmap;	/* 1 if a new cmap is needed */
        Unsign16 ncol;    	/* number of colors */
        Unsign8 *cmapdata;	/* cmap data */
        I_cmap *cmapstr;        /* OUT colormap str */
        Unsign8 *cmaptbl; 	/* OUT color mapping table */
{
	int i;
	int extrapix=0;
	Unsign8 *cp;
	static unsigned long pixels[MAXCOLOR];
	static XColor cols[MAXCOLOR];
	static char rgb = DoRed | DoGreen | DoBlue;
	int bits_per_rgb;  	/* bits_per_rgb for display */

	/* given PSEUDOCOLOR visual */
	bits_per_rgb = i_get_bits_per_rgb(display);
	if (iscreatecmap) {
        	cmapstr->cmap = XCreateColormap(display,window,visual,
			AllocNone);
		if (ncol < MAXCOLOR) {
			extrapix = 1;		
			ncol++;  /* extra entry for background color */
		}
	}
	if (XAllocColorCells(display,cmapstr->cmap,False,(unsigned long*)NULL,
		0,pixels,(unsigned int)ncol)==0)
		fatal("ABORT: i_retrieve_cmap: XAllocColorCells failed\n");
	if (iscreatecmap) { /* initialize zero'th entry for background pixel */
		cmapstr->blackpixel = cols[0].pixel = pixels[0]; 
		if (extrapix) { 
			/* if there is space for extra background color */
			/* initialize it as black */
			cols[0].red=cols[0].green=cols[0].blue=0;
			cols[0].flags = rgb;
		}
	}
        for (cp=cmapdata,i=extrapix?1:0;i<(int)ncol;++i,cp+=4) {
                cmaptbl[cp[0]] = pixels[i];
                cmapstr->ctbl[pixels[i]][0] = cp[1];
                cmapstr->ctbl[pixels[i]][1] = cp[2];
                cmapstr->ctbl[pixels[i]][2] = cp[3];
                cols[i].pixel = pixels[i];
                cols[i].flags = rgb;
                cols[i].red = i_scale_uchar_to_ushort(bits_per_rgb,cp[1]);
                cols[i].green = i_scale_uchar_to_ushort(bits_per_rgb,cp[2]);
                cols[i].blue = i_scale_uchar_to_ushort(bits_per_rgb,cp[3]);
	} 
	XStoreColors(display,cmapstr->cmap,cols,(int)ncol);
}

/*
 *  i_scale_uchar_to_ushort(bits_per_rgb,value)
 */
static unsigned short
i_scale_uchar_to_ushort(bits_per_rgb,value)
        int bits_per_rgb;
        Unsign8 value;
{
	switch (sizeof(unsigned short)) {
	case 1:
                return( (unsigned short) value );
	case 2:
		switch (bits_per_rgb) {
                case 8:
                case 16:
                	return( (unsigned short) (value << 8));
                default:
                        fatal("ABORT: i_scale_uchar_to_ushort: unknown bits_per_rgb %d\n",bits_per_rgb);
		}
        default:
                fatal("ABORT: i_scale_uchar_to_ushort: unknown size of unsigned short %d\n",sizeof(unsigned short));
        }
}
	

/*
 * i_retrieve_image(display,visual,cmaptbl,nbyte,imagestr,err)  read image data 
 * 	from file and create image
 */
static void
i_retrieve_image(display,visual,cmaptbl,nbyte,imagestr,err)
	Display *display;	/* X display */
	Visual *visual;		/* visual type */
	Unsign8 *cmaptbl;	/* color mapping table */
	Unsign32 nbyte;		/* length of image data */
	I_image *imagestr;	/* OUT image structure */
	int *err;		/* OUT error flag */
{
	int i,j;
	Unsign8 *ip,pixelcount;
	unsigned long pixel,bytecount;
	int pad;
	int defdepth;

	/* given PSEUDOCOLOR visual */
	defdepth = DefaultDepth(display,DefaultScreen(display));
	*err = 0;
	pad = 8;
	imagestr->image = XCreateImage(display,visual,defdepth,ZPixmap,0,
		(char*)NULL, (unsigned int)imagestr->width,
		(unsigned int)imagestr->height,pad,0);
	(imagestr->image)->data = emalloc((imagestr->image)->bytes_per_line * imagestr->height);
	i_convert_image(cmaptbl,nbyte,imagestr->imagedata);
	for (ip=imagestr->imagedata, pixelcount = 0, bytecount = 0, 
		j=0;j<(int)imagestr->height;++j) {
		for (i=0;i<(int)imagestr->width;++i) {
			if (pixelcount == 0) {
				if (++bytecount > nbyte) {
					printf("ERROR: i_retrieve_image: image data corrupted\n");
					*err = 1;
					return;
				}
				pixelcount = *ip++;
				pixel = (Unsign32) *ip++;
			}
			if (XPutPixel(imagestr->image,i,j,pixel) > 0)
				pixelcount--;
			else
				fatal("ABORT: i_retrieve_image: XPutPixel failed\n");
		}
	}
}

/*
 * i_convert_image(tbl,nbyte,imagedata) correct imagedata
 * image data read from image file uses pixel values which are not
 * the same as the pixel values allocated from i_retrieve_cmap. This
 * procedure maps the imagedata to the correct values.
 */
static void
i_convert_image(tbl,nbyte,imagedata)
        Unsign32 nbyte;    	/* number of bytes */
        Unsign8 *tbl;     	/* color mapping table */
        Unsign8 *imagedata;	/* image data */
{
        int i;
        Unsign8 *ip;

        for (ip = &imagedata[1],i=0;i<nbyte/2;i++,ip+=2) {
                *ip = tbl[(int)*ip];
        }
}


/*
 * i_diff_image(display,cstr1,cstr2;istr1,istr2,istr3,istr4,err)
 * generate output 2 images that captures the difference of 2 input images
 */
void
i_diff_image(display,cstr1,cstr2,istr1,istr2,istr3,istr4,err)
	Display *display;	/* X display */
	I_cmap *cstr1;		/* colormap structure */
	I_cmap *cstr2;		/* colormap structure */
	I_image *istr1;		/* image strucuture */
	I_image *istr2;		/* image strucuture */
	I_image *istr3;		/* OUT image strucuture */
	I_image *istr4;		/* OUT image strucuture */
	int *err;		/* OUT error flag */
{
	/*
	Show the difference of two images in the given windows
	*/
	int eqtbl[MAXCOLOR];
	int i,j;
	Unsign8 p1,p2,n1,n2;
	Unsign8 *ip1,*ip2;
	Unsign32 npixel;
	Unsign16 w,h;
	static GC gc = NULL;
	XGCValues gcvals;

	Pixmap pixmap1,pixmap2;
	Window rootwindow;
	unsigned int defdepth;

	/* given PSEUDOCOLOR visual */
	*err = 0;
	if (istr1->width != istr2->width ||
	    istr1->height != istr2->height ) {
		printf("ERROR: i_diff_image: image1's dim (%d,%d) != image2's (%d,%d)\n",
			istr1->width,istr1->height,istr2->width,istr2->height);
		*err = 1;
		return;
	} 
	w = istr1->width;
	h = istr1->height;
	for (i=0;i<MAXCOLOR;++i)
		eqtbl[i] = -1;
	istr3->width = istr4->width = w;
	istr3->height = istr4->height = h;
        rootwindow = DefaultRootWindow(display);
	defdepth = DefaultDepth(display,DefaultScreen(display));
	pixmap1 = XCreatePixmap(display,rootwindow,(unsigned int)w,
			(unsigned int)h,defdepth);
	pixmap2 = XCreatePixmap(display,rootwindow,(unsigned int)w,
			(unsigned int)h,defdepth);
	if (gc == NULL) {  /* hasn't been created yet */
	    gcvals.foreground = cstr1->blackpixel;
	    gc = XCreateGC(display,pixmap1, GCForeground, &gcvals);
	} else {
	    XSetForeground(display,gc,cstr1->blackpixel);
	}
	XFillRectangle(display,pixmap1,gc,0,0,(unsigned int)w,(unsigned int)h);
	XSetForeground(display,gc,cstr2->blackpixel);
	XFillRectangle(display,pixmap2,gc,0,0,(unsigned int)w,(unsigned int)h);
	istr3->image = XGetImage(display,pixmap1,0,0,(int)w,(int)h,-1,ZPixmap);
	istr4->image = XGetImage(display,pixmap2,0,0,(int)w,(int)h,-1,ZPixmap);
	if (! istr3->image || ! istr4->image)
                fatal("ABORT: i_diff_image: XGetImage failed\n");
	for (npixel=0,n1=0,n2=0,i=0,j=0,ip1=istr1->imagedata,
		ip2=istr2-> imagedata;
		npixel<w*h;npixel++,n1--,n2--) {
		if (n1==0) {
			n1 = *ip1++;
			p1 = *ip1++;
		}
		if (n2==0) {
			n2 = *ip2++;
			p2 = *ip2++;
		}
		if (eqtbl[p1] != (int)p2) { 
			if (cstr1->ctbl[p1][0] == cstr2->ctbl[p2][0] &&
			    cstr1->ctbl[p1][1] == cstr2->ctbl[p2][1] &&
			    cstr1->ctbl[p1][2] == cstr2->ctbl[p2][2]) {
				eqtbl[p1] = (int)p2;
			} else {
				if (XPutPixel(istr3->image,i,j,
					(unsigned long)p1) == 0)
			    		fatal("ABORT: i_diff_image: XPutPixel failed\n");
				if (XPutPixel(istr4->image,i,j,
					(unsigned long)p2) == 0)
			    		fatal("ABORT: i_diff_image: XPutPixel failed\n");
		    	}
		}
		if (++i == w) {
			i = 0;
			j++;
		}
	}
	XFreePixmap(display,pixmap1);
	XFreePixmap(display,pixmap2);
}

/*
 * i_display_image(display,window,imagestr) display an image on a window 
 */
void
i_display_image(display,window,imagestr)
	Display *display;	/* X display */
	Window window;		/* X window */
	I_image *imagestr;	/* image structure */
{
        static GC gc = NULL;
	/*
	 * To display an image on window
	 * given: window is created for pseudo color visual
	*/
        if (gc == NULL)
                gc = XCreateGC(display,window,0,0);
	XPutImage(display,(Drawable)window, gc,
		imagestr->image, 0,0,0,0,(unsigned int) imagestr->width,
		(unsigned int) imagestr->height);
}

/*
 * i_free_image(imagestr) free image resources
 */
void
i_free_image(imagestr)
	I_image *imagestr;	/* image structure */
{
	/*
	To free up image resources 
	*/
	XDestroyImage(imagestr->image);
	if (imagestr->imagedata) free(imagestr->imagedata);
}

/*
 * i_free_cmap(display,cmapstr) free cmap resources
 */
void
i_free_cmap(display,cmapstr)
	Display *display;	/* X display */
	I_cmap *cmapstr;	/* colormap structure */
{
	/*
	To free up colormap resources 
	*/
	XFreeColormap(display,cmapstr->cmap);
}

/*
 * i_get_bits_per_rgb(display)
 */
static int
i_get_bits_per_rgb(display)
        Display *display;       /* X display */
{
        int defdepth,defscreen;
        Visual *visual;
        int bits_per_rgb;

        defscreen = DefaultScreen(display);
        defdepth = DefaultDepth(display,defscreen);
        visual = DefaultVisual(display,defscreen);
        bits_per_rgb = visual->bits_per_rgb;
        if (bits_per_rgb != 8 && bits_per_rgb != 16)
                fatal("ABORT: i_get_bits_per_rgb: bits_per_rgb = %d, currently only support 8 or 16\n",bits_per_rgb);
        return(bits_per_rgb);
}


/*
 Image file format:
<1 byte : flag image type, currently only support pseudocolor and truecolor>
<2 bytes: number of bytes of ascii text to follow>
<n bytes: ascii text>
<2 bytes: width of image>
<2 bytes: height of image>
<4 bytes: number of bytes of image data>
<n bytes: image data of the form
        (number[1 byte],red[1 byte],green[1 byte],blue[1 byte]) quadruples>
*/

/*
 * i_load_image24(filename,display,visual,pinfo,imagestr,text,err) 
 * load an 24-bit image from a file 
 */
void
i_load_image24(filename,display,visual,pinfo,imagestr,text,err)
	char *filename;		/* image file name */
	Display *display;	/* X display */
	Visual *visual;		/* visual type */
	Pixel_info *pinfo;	/* pixel conversion info */
	I_image *imagestr;	/* OUT image structure */
        char *text;             /* OUT image description */
	int *err;		/* OUT error flag */
{
	/*
	To load an image from file to X's image structure.
	Create and store necessary colors in the color map.
	*/
        int fd;
	Unsign32 nbyte;
	Unsign8 buf[4];
	int type;

	*err = 0;
        if ((fd = open(filename,O_RDONLY)) == -1) {
                printf("ERROR: i_loadimage24: can't open file %s\n",filename);
		*err = 1;
		return;
	}
	i_load_image_info(fd,imagestr,text,&type);
	if (type != TRUECOLOR)
		fatal("ABORT: i_loadimage24: image file type != TRUECOLOR\n");
	i_read(fd,4,(char*)buf);
	i_8_to_32(&buf[0],&nbyte);
	imagestr->imagedata = (unsigned char*) emalloc(nbyte);
	i_read(fd,(int)nbyte,(char*)imagestr->imagedata);
	i_retrieve_image24(display,visual,pinfo,nbyte,imagestr,err);
	if (close(fd) == -1)
                fatal("ERROR: i_load_image24: in closing \"%s\", exiting...\n",filename);
}


/*
 * i_retrieve_image24(display,visual,pinfo,nbyte,imagestr,err)  
 * retrieve 24 image data and create image
 */
static void
i_retrieve_image24(display,visual,pinfo,nbyte,imagestr,err)
	Display *display;	/* X display */
	Visual *visual;		/* visual type */
	Pixel_info *pinfo;	/* pixel conversion info */
	Unsign32 nbyte;		/* length of image data */
	I_image *imagestr;	/* OUT image structure */
	int *err;		/* OUT error flag */
{
	int i,j;
	Unsign8 *ip,pixelcount,pixel_r,pixel_g,pixel_b;
	unsigned long pixel,bytecount;
	int pad;
	int depth;

	*err = 0;
	depth = 24;
	pad = 32;
	imagestr->image = XCreateImage(display,visual,depth,ZPixmap,0,
		(char*)NULL, (unsigned int)imagestr->width,
		(unsigned int)imagestr->height,pad,0);
	(imagestr->image)->data = emalloc((imagestr->image)->bytes_per_line * imagestr->height);
	for (ip=imagestr->imagedata, pixelcount = 0, bytecount = 0, 
		j=0;j<(int)imagestr->height;++j) {
		for (i=0;i<(int)imagestr->width;++i) {
			if (pixelcount == 0) {
				if (++bytecount > nbyte) {
					printf("ERROR: i_retrieve_image24: image data corrupted\n");
					*err = 1;
					return;
				}
				pixelcount = *ip++;
				pixel_r = *ip++;
				pixel_g = *ip++;
				pixel_b = *ip++;
				pixel = MASK24 & 
					((Unsign32)pixel_r << pinfo->rshift | 
					(Unsign32)pixel_g << pinfo->gshift | 
					(Unsign32)pixel_b << pinfo->bshift);
			}
			if (XPutPixel(imagestr->image,i,j,pixel) > 0)
				pixelcount--;
			else
				fatal("ABORT: i_retrieve_image24: XPutPixel failed\n");
		}
	}
}

/*
 * i_diff_image24(display,pinfo,istr1,istr2,istr3,istr4,err)
 * generate output 2 24-bit images that captures the difference of 
 * 2 input 24-bit images
 */
void
i_diff_image24(display,pinfo,istr1,istr2,istr3,istr4,err)
	Display *display;	/* X display */
	Pixel_info *pinfo;	/* pixel conversion info */
	I_image *istr1;		/* image strucuture */
	I_image *istr2;		/* image strucuture */
	I_image *istr3;		/* OUT image strucuture */
	I_image *istr4;		/* OUT image strucuture */
	int *err;		/* OUT error flag */
{
	/*
	Show the difference of two images in the given windows
	*/
	int i,j;
	Unsign8 n1,n2,r,g,b;
	Unsign8 *ip1,*ip2;
	Unsign32 npixel,p1,p2;
	Unsign16 w,h;
	static GC gc = NULL;
	XGCValues gcvals;

	Pixmap pixmap1,pixmap2;
	Window rootwindow;
	unsigned int defdepth;

	/* given TRUECOLOR visual */
	*err = 0;
	if (istr1->width != istr2->width ||
	    istr1->height != istr2->height ) {
		printf("ERROR: i_diff_image24: image1's dim (%d,%d) != image2's (%d,%d)\n",
			istr1->width,istr1->height,istr2->width,istr2->height);
		*err = 1;
		return;
	} 
	w = istr1->width;
	h = istr1->height;
	istr3->width = istr4->width = w;
	istr3->height = istr4->height = h;
        rootwindow = DefaultRootWindow(display);
	defdepth = 24;
	pixmap1 = XCreatePixmap(display,rootwindow,(unsigned int)w,
			(unsigned int)h,defdepth);
	pixmap2 = XCreatePixmap(display,rootwindow,(unsigned int)w,
			(unsigned int)h,defdepth);
	if (gc == NULL) {
	    gcvals.foreground = 0x0;
	    gc = XCreateGC(display,pixmap1, GCForeground, &gcvals);
	}
	XFillRectangle(display,pixmap1,gc,0,0,(unsigned int)w,(unsigned int)h);
	XFillRectangle(display,pixmap2,gc,0,0,(unsigned int)w,(unsigned int)h);
	istr3->image = XGetImage(display,pixmap1,0,0,(int)w,(int)h,-1,ZPixmap);
	istr4->image = XGetImage(display,pixmap2,0,0,(int)w,(int)h,-1,ZPixmap);
	if (! istr3->image || ! istr4->image)
                fatal("ABORT: i_diff_image24: XGetImage failed\n");
	for (npixel=0,n1=0,n2=0,i=0,j=0,ip1=istr1->imagedata,
		ip2=istr2-> imagedata;
		npixel<w*h;npixel++,n1--,n2--) {
		if (n1==0) {
			n1 = *ip1++;
			r = *ip1++;
			g = *ip1++;
			b = *ip1++;
			p1 = MASK24 & 
				((Unsign32)r << pinfo->rshift | 
				(Unsign32)g << pinfo->gshift | 
				(Unsign32)b << pinfo->bshift);
		}
		if (n2==0) {
			n2 = *ip2++;
			r = *ip2++;
			g = *ip2++;
			b = *ip2++;
			p2 = MASK24 & ((Unsign32)r | (Unsign32)g << 8 | (Unsign32)b << 16);
		}
		if (p1 != p2) { 
			if (XPutPixel(istr3->image,i,j,
				(unsigned long)p1) == 0)
			    	fatal("ABORT: i_diff_image24: XPutPixel failed\n");
			if (XPutPixel(istr4->image,i,j,
				(unsigned long)p2) == 0)
			    	fatal("ABORT: i_diff_image24: XPutPixel failed\n");
		}
		if (++i == w) {
			i = 0;
			j++;
		}
	}
	XFreePixmap(display,pixmap1);
	XFreePixmap(display,pixmap2);
}

/*
 * fatal(fmt,va_alist)
 * prints out error message and abort program
 */
static void
fatal(fmt,va_alist)
        char *fmt;              /* message fmt */
        va_dcl                  /* variable data */
{
        va_list ap;

        va_start(ap);
        vprintf(fmt,ap);
        va_end(ap);
        exit(1);
}


/*
 * i_8_to_16(buf,n) convert 2 8-bit to 1 16-bit data
 */
static void
i_8_to_16(buf,n)
        Unsign8 *buf;     /* buffer */
        Unsign16 *n;
{
	/* add up low & high byte */
	*n = (Unsign16) buf[0] + (((Unsign16) buf[1]) << 8); 
}

/*
 * i_8_to_32(buf,n) convert 4 8-bit to 1 32-bit data
 */
static void
i_8_to_32(buf,n)
        Unsign8 *buf;     /* buffer */
        Unsign32 *n;
{
	/* add up all bytes */
	*n = (Unsign32) buf[0] + (((Unsign32) buf[1]) << 8) +
	     (((Unsign32) buf[2]) << 16) + (((Unsign32) buf[3]) << 24)
; 
}


/*
 * i_read(fd,n,buf)  read n bytes of data to buffer
 */
static void
i_read(fd,n,buf) 
	int fd;		/* file descritor */
	int n;		/* number of bytes */
	char *buf; 	/* OUT value */
{
	if (read(fd,buf,n)!= n)
               	fatal("ABORT: i_read: read failed\n");
}


/*
 * emalloc(size) allocate memory.
 */
static char *
emalloc(size)
        int size;
{
        char *p; 
 
        if (! (p=malloc(size)))
                fatal("ABORT: emalloc: malloc failed\n");
        return(p);
}