/* $XConsortium: XImUtil.c,v 11.51 91/07/23 12:02:13 rws Exp $ */
/* Copyright    Massachusetts Institute of Technology    1986	*/

/*
Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation, and that the name of M.I.T. not be used in advertising or
publicity pertaining to distribution of the software without specific,
written prior permission.  M.I.T. makes no representations about the
suitability of this software for any purpose.  It is provided "as is"
without express or implied warranty.
*/

#include <X11/Xlibint.h>
#include <X11/Xutil.h>
#include <stdio.h>

#if __STDC__
#define Const const
#else
#define Const /**/
#endif

static unsigned char Const _lomask[0x09] = { 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff };
static unsigned char Const _himask[0x09] = { 0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00 };

/* These two convenience routines return the scanline_pad and bits_per_pixel 
	associated with a specific depth of ZPixmap format image for a 
	display. */

 _XGetScanlinePad(dpy, depth)
 Display *dpy;
 int depth;
 {
 	register ScreenFormat *fmt = dpy->pixmap_format;
 	register int i;
 
 	for (i = dpy->nformats + 1; --i; ++fmt)
 		if (fmt->depth == depth)
 			return(fmt->scanline_pad);
 
 	return(dpy->bitmap_pad);
 }
 
 _XGetBitsPerPixel(dpy, depth)
 Display *dpy;
 int depth;
 {
 	register ScreenFormat *fmt = dpy->pixmap_format;
 	register int i;
 
 	for (i = dpy->nformats + 1; --i; ++fmt)
 		if (fmt->depth == depth)
 			return(fmt->bits_per_pixel);
 
 	return(depth);
 }
 

/*
 * This module provides rudimentary manipulation routines for image data
 * structures.  The functions provided are:
 *
 *	XCreateImage	Creates a default XImage data structure
 *	_XDestroyImage	Deletes an XImage data structure
 *	_XGetPixel	Reads a pixel from an image data structure
 *	_XGetPixel32	Reads a pixel from a 32-bit Z image data structure
 *	_XGetPixel16	Reads a pixel from a 16-bit Z image data structure
 *	_XGetPixel8	Reads a pixel from an 8-bit Z image data structure
 *	_XGetPixel1	Reads a pixel from an 1-bit image data structure
 *	_XPutPixel	Writes a pixel into an image data structure
 *	_XPutPixel32	Writes a pixel into a 32-bit Z image data structure
 *	_XPutPixel16	Writes a pixel into a 16-bit Z image data structure
 *	_XPutPixel8	Writes a pixel into an 8-bit Z image data structure
 *	_XPutPixel1	Writes a pixel into an 1-bit image data structure
 *	_XSubImage	Clones a new (sub)image from an existing one
 *	_XSetImage	Writes an image data pattern into another image
 *	_XAddPixel	Adds a constant value to every pixel in an image
 *
 * The logic contained in these routines makes several assumptions about
 * the image data structures, and at least for current implementations
 * these assumptions are believed to be true.  They are: 
 *
 *	For all formats, bits_per_pixel is less than or equal to 32.
 *	For XY formats, bitmap_unit is always less than or equal to bitmap_pad.
 *	For XY formats, bitmap_unit is 8, 16, or 32 bits.
 *	For Z format, bits_per_pixel is 1, 4, 8, 16, 24, or 32 bits.
 */
static _xynormalizeimagebits (bp, img)
    register unsigned char *bp;
    register XImage *img;
{
	register unsigned char c;

	if (img->byte_order != img->bitmap_bit_order) {
	    switch (img->bitmap_unit) {

		case 16:
		    c = *bp;
		    *bp = *(bp + 1);
		    *(bp + 1) = c;
		    break;

		case 32:
		    c = *(bp + 3);
		    *(bp + 3) = *bp;
		    *bp = c;
		    c = *(bp + 2);
		    *(bp + 2) = *(bp + 1);
		    *(bp + 1) = c;
		    break;
	    }
	}
	if (img->bitmap_bit_order == MSBFirst)
	    _XReverse_Bytes (bp, img->bitmap_unit >> 3);
}

static _znormalizeimagebits (bp, img)
    register unsigned char *bp;
    register XImage *img;
{
	register unsigned char c;
	switch (img->bits_per_pixel) {

	    case 4:
		*bp = ((*bp >> 4) & 0xF) | ((*bp << 4) & ~0xF);
		break;

	    case 16:
		c = *bp;
		*bp = *(bp + 1);
		*(bp + 1) = c;
		break;

	    case 24:
		c = *(bp + 2);
		*(bp + 2) = *bp;
		*bp = c;
		break;

	    case 32:
		c = *(bp + 3);
		*(bp + 3) = *bp;
		*bp = c;
		c = *(bp + 2);
		*(bp + 2) = *(bp + 1);
		*(bp + 1) = c;
		break;
	}
}

static _putbits (src, dstoffset, numbits, dst)
    register char *src;	/* address of source bit string */
    int dstoffset;	/* bit offset into destination; range is 0-31 */
    register int numbits;/* number of bits to copy to destination */
    register char *dst;	/* address of destination bit string */
{
	register unsigned char chlo, chhi;
	int hibits;
	dst = dst + (dstoffset >> 3);
	dstoffset = dstoffset & 7;
	hibits = 8 - dstoffset;
	chlo = *dst & _lomask[dstoffset];
	for (;;) {
	    chhi = (*src << dstoffset) & _himask[dstoffset];
	    if (numbits <= hibits) {
		chhi = chhi & _lomask[dstoffset + numbits];
		*dst = (*dst & _himask[dstoffset + numbits]) | chlo | chhi;
		break;
	    }
	    *dst = chhi | chlo;
	    dst++;
	    numbits = numbits - hibits;
	    chlo = (unsigned char) (*src & _himask[hibits]) >> hibits;
	    src++;
	    if (numbits <= dstoffset) {
		chlo = chlo & _lomask[numbits];
		*dst = (*dst & _himask[numbits]) | chlo;
		break;
	    }
	    numbits = numbits - dstoffset;
	}	
}


/*
 * Macros
 * 
 * The ROUNDUP macro rounds up a quantity to the specified boundary,
 * then truncates to bytes.
 *
 * The XYNORMALIZE macro determines whether XY format data requires 
 * normalization and calls a routine to do so if needed. The logic in
 * this module is designed for LSBFirst byte and bit order, so 
 * normalization is done as required to present the data in this order.
 *
 * The ZNORMALIZE macro performs byte and nibble order normalization if 
 * required for Z format data.
 *
 * The XYINDEX macro computes the index to the starting byte (char) boundary
 * for a bitmap_unit containing a pixel with coordinates x and y for image
 * data in XY format.
 * 
 * The ZINDEX macro computes the index to the starting byte (char) boundary 
 * for a pixel with coordinates x and y for image data in ZPixmap format.
 * 
 */

#define ROUNDUP(nbytes, pad) ((((nbytes) + ((pad)-1)) / (pad)) * ((pad)>>3))

#define XYNORMALIZE(bp, img) \
    if ((img->byte_order == MSBFirst) || (img->bitmap_bit_order == MSBFirst)) \
	_xynormalizeimagebits((unsigned char *)(bp), img)

#define ZNORMALIZE(bp, img) \
    if (img->byte_order == MSBFirst) \
	_znormalizeimagebits((unsigned char *)(bp), img)

#define XYINDEX(x, y, img) \
    ((y) * img->bytes_per_line) + \
    (((x) + img->xoffset) / img->bitmap_unit) * (img->bitmap_unit >> 3)

#define ZINDEX(x, y, img) ((y) * img->bytes_per_line) + \
    (((x) * img->bits_per_pixel) >> 3)


/*
 * CreateImage
 * 
 * Allocates the memory necessary for an XImage data structure. 
 * Initializes the structure with "default" values and returns XImage. 
 * 
 */

XImage *XCreateImage (dpy, visual, depth, format, offset, data, width, height,
    xpad, image_bytes_per_line)
    register Display *dpy;
    register Visual *visual;
    unsigned int depth;
    int format;
    int offset; /*How many pixels from the start of the data does the
		picture to be transmitted start?*/

    char *data;
    unsigned int width;
    unsigned int height;
    int xpad;	
    int image_bytes_per_line; 
		/*How many bytes between a pixel on one line and the pixel with
		  the same X coordinate on the next line? 0 means
		  XCreateImage can calculate it.*/
{
	register XImage *image;
	int bits_per_pixel = 1;

	if ((image = (XImage *) Xcalloc(1, (unsigned) sizeof(XImage))) == NULL)
	    return (XImage *) NULL;

	image->width = width;
	image->height = height;
	image->format = format;
	image->byte_order = dpy->byte_order;
	image->bitmap_unit = dpy->bitmap_unit;
	image->bitmap_bit_order = dpy->bitmap_bit_order;
	if (visual != NULL) {
		image->red_mask = visual->red_mask;
		image->green_mask = visual->green_mask;
		image->blue_mask = visual->blue_mask;
	}
	else {
		image->red_mask = image->green_mask = image->blue_mask = 0;
	}
	if (format == ZPixmap) 
	{
	    bits_per_pixel = _XGetBitsPerPixel(dpy, (int) depth);
	}

	image->xoffset = offset;
	image->bitmap_pad = xpad;
	image->depth = depth;
 	image->data = data;
	/*
	 * compute per line accelerator.
	 */
	if (image_bytes_per_line == 0)
	{
	if (format == ZPixmap)
	    image->bytes_per_line = 
	       ROUNDUP((bits_per_pixel * width), image->bitmap_pad);
	else
	    image->bytes_per_line =
	        ROUNDUP((width + offset), image->bitmap_pad);
	}
	else image->bytes_per_line = image_bytes_per_line;

	image->bits_per_pixel = bits_per_pixel;
	image->obdata = NULL;
	_XInitImageFuncPtrs (image);

	return image;
}

/*
 * _DestroyImage
 * 	
 * Deallocates the memory associated with the ximage data structure. 
 * this version handles the case of the image data being malloc'd
 * entirely by the library.
 */

static int _XDestroyImage (ximage)
    XImage *ximage;

{
	if (ximage->data != NULL) Xfree((char *)ximage->data);
	if (ximage->obdata != NULL) Xfree((char *)ximage->obdata);
	Xfree((char *)ximage);
	return 1;
}


/*
 * GetPixel
 * 
 * Returns the specified pixel.  The X and Y coordinates are relative to 
 * the origin (upper left [0,0]) of the image.  The pixel value is returned
 * in normalized format, i.e. the LSB of the long is the LSB of the pixel.
 * The algorithm used is:
 *
 *	copy the source bitmap_unit or Zpixel into temp
 *	normalize temp if needed
 *	extract the pixel bits into return value
 *
 */

static unsigned long Const low_bits_table[] = {
    0x00000000, 0x00000001, 0x00000003, 0x00000007,
    0x0000000f, 0x0000001f, 0x0000003f, 0x0000007f,
    0x000000ff, 0x000001ff, 0x000003ff, 0x000007ff,
    0x00000fff, 0x00001fff, 0x00003fff, 0x00007fff,
    0x0000ffff, 0x0001ffff, 0x0003ffff, 0x0007ffff,
    0x000fffff, 0x001fffff, 0x003fffff, 0x007fffff,
    0x00ffffff, 0x01ffffff, 0x03ffffff, 0x07ffffff,
    0x0fffffff, 0x1fffffff, 0x3fffffff, 0x7fffffff,
    0xffffffff
};

static unsigned long _XGetPixel (ximage, x, y)
    register XImage *ximage;
    int x;
    int y;

{
	unsigned long pixel, px;
	register char *src;
	register char *dst;
	register int i, j;
	int bits, nbytes;
	long plane;
     
	if (ximage->depth == 1) {
		src = &ximage->data[XYINDEX(x, y, ximage)];
		dst = (char *)&pixel;
		pixel = 0;
		for (i = ximage->bitmap_unit >> 3; --i >= 0; ) *dst++ = *src++;
		XYNORMALIZE(&pixel, ximage);
          	bits = (x + ximage->xoffset) % ximage->bitmap_unit;
		pixel = ((((char *)&pixel)[bits>>3])>>(bits&7)) & 1;
	} else if (ximage->format == XYPixmap) {
		pixel = 0;
		plane = 0;
		nbytes = ximage->bitmap_unit >> 3;
		for (i = ximage->depth; --i >= 0; ) {
		    src = &ximage->data[XYINDEX(x, y, ximage)+ plane];
		    dst = (char *)&px;
		    px = 0;
		    for (j = nbytes; --j >= 0; ) *dst++ = *src++;
		    XYNORMALIZE(&px, ximage);
		    bits = (x + ximage->xoffset) % ximage->bitmap_unit;
		    pixel = (pixel << 1) |
			    (((((char *)&px)[bits>>3])>>(bits&7)) & 1);
		    plane = plane + (ximage->bytes_per_line * ximage->height);
		}
	} else if (ximage->format == ZPixmap) {
		src = &ximage->data[ZINDEX(x, y, ximage)];
		dst = (char *)&px;
		px = 0;
		for (i = (ximage->bits_per_pixel + 7) >> 3; --i >= 0; )
		    *dst++ = *src++;		
		ZNORMALIZE(&px, ximage);
		pixel = 0;
		for (i=sizeof(unsigned long); --i >= 0; )
		    pixel = (pixel << 8) | ((unsigned char *)&px)[i];
		if (ximage->bits_per_pixel == 4) {
		    if (x & 1)
			pixel >>= 4;
		    else
			pixel &= 0xf;
		}
	} else {
		return 0; /* bad image */
	}
	if (ximage->bits_per_pixel == ximage->depth)
	  return pixel;
	else
	  return (pixel & low_bits_table[ximage->depth]);
}

#ifndef WORD64
static unsigned long byteorderpixel = MSBFirst << 24;
#endif

static unsigned long _XGetPixel32 (ximage, x, y)
    register XImage *ximage;
    int x;
    int y;
{
	register unsigned char *addr;
	unsigned long pixel;

	if ((ximage->format == ZPixmap) && (ximage->bits_per_pixel == 32)) {
	    addr = &((unsigned char *)ximage->data)
			[y * ximage->bytes_per_line + (x << 2)];
#ifndef WORD64
	    if (*((char *)&byteorderpixel) == ximage->byte_order)
		pixel = *((unsigned long *)addr);
	    else
#endif
	    if (ximage->byte_order == MSBFirst)
		pixel = ((unsigned long)addr[0] << 24 |
			 (unsigned long)addr[1] << 16 |
			 (unsigned long)addr[2] << 8 |
			 addr[3]);
	    else
		pixel = ((unsigned long)addr[3] << 24 |
			 (unsigned long)addr[2] << 16 |
			 (unsigned long)addr[1] << 8 |
			 addr[0]);
	    if (ximage->depth != 32)
		pixel &= low_bits_table[ximage->depth];
	    return pixel;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XGetPixel(ximage, x, y);
	}
}

static unsigned long _XGetPixel16 (ximage, x, y)
    register XImage *ximage;
    int x;
    int y;
{
	register unsigned char *addr;
	unsigned long pixel;

	if ((ximage->format == ZPixmap) && (ximage->bits_per_pixel == 16)) {
	    addr = &((unsigned char *)ximage->data)
			[y * ximage->bytes_per_line + (x << 1)];
	    if (ximage->byte_order == MSBFirst)
		pixel = addr[0] << 8 | addr[1];
	    else
		pixel = addr[1] << 8 | addr[0];
	    if (ximage->depth != 16)
		pixel &= low_bits_table[ximage->depth];
	    return pixel;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XGetPixel(ximage, x, y);
	}
}

static unsigned long _XGetPixel8 (ximage, x, y)
    register XImage *ximage;
    int x;
    int y;
{
	unsigned char pixel;

	if ((ximage->format == ZPixmap) && (ximage->bits_per_pixel == 8)) {
	    pixel = ((unsigned char *)ximage->data)
			[y * ximage->bytes_per_line + x];
	    if (ximage->depth != 8)
		pixel &= low_bits_table[ximage->depth];
	    return pixel;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XGetPixel(ximage, x, y);
	}
}

static unsigned long _XGetPixel1 (ximage, x, y)
    register XImage *ximage;
    int x;
    int y;
{
	unsigned char bit;
	int xoff, yoff;

	if ((ximage->depth == 1) &&
	    (ximage->byte_order == ximage->bitmap_bit_order)) {
	    xoff = x + ximage->xoffset;
	    yoff = y * ximage->bytes_per_line + (xoff >> 3);
	    xoff &= 7;
	    if (ximage->bitmap_bit_order == MSBFirst)
	        bit = 0x80 >> xoff;
	    else
		bit = 1 << xoff;
	    return (ximage->data[yoff] & bit) ? 1 : 0;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XGetPixel(ximage, x, y);
	}
}
	
/*
 * PutPixel
 * 
 * Overwrites the specified pixel.  The X and Y coordinates are relative to 
 * the origin (upper left [0,0]) of the image.  The input pixel value must be
 * in normalized format, i.e. the LSB of the long is the LSB of the pixel.
 * The algorithm used is:
 *
 *	copy the destination bitmap_unit or Zpixel to temp
 *	normalize temp if needed
 *	copy the pixel bits into the temp
 *	renormalize temp if needed
 *	copy the temp back into the destination image data
 *
 */

static int _XPutPixel (ximage, x, y, pixel)
    register XImage *ximage;
    int x;
    int y;
    unsigned long pixel;

{
	unsigned long px, npixel;
	register char *src;
	register char *dst;
	register int i;
	int j, nbytes;
	long plane;

	if (ximage->depth == 4)
	    pixel &= 0xf;
        npixel = pixel;
	for (i=0, px=pixel; i<sizeof(unsigned long); i++, px>>=8)
	    ((unsigned char *)&pixel)[i] = px;
	if (ximage->depth == 1) {
		src = &ximage->data[XYINDEX(x, y, ximage)];
		dst = (char *)&px;
		px = 0;
		nbytes = ximage->bitmap_unit >> 3;
		for (i = nbytes; --i >= 0; ) *dst++ = *src++;
		XYNORMALIZE(&px, ximage);
		i = ((x + ximage->xoffset) % ximage->bitmap_unit);
		_putbits ((char *)&pixel, i, 1, (char *)&px);
		XYNORMALIZE(&px, ximage);
		src = (char *) &px;
		dst = &ximage->data[XYINDEX(x, y, ximage)];
		for (i = nbytes; --i >= 0; ) *dst++ = *src++;
	} else if (ximage->format == XYPixmap) {
		plane = (ximage->bytes_per_line * ximage->height) *
		    (ximage->depth - 1); /* do least signif plane 1st */
		nbytes = ximage->bitmap_unit >> 3;
		for (j = ximage->depth; --j >= 0; ) {
		    src = &ximage->data[XYINDEX(x, y, ximage) + plane];
		    dst = (char *) &px;
		    px = 0;
		    for (i = nbytes; --i >= 0; ) *dst++ = *src++;
		    XYNORMALIZE(&px, ximage);
		    i = ((x + ximage->xoffset) % ximage->bitmap_unit);
		    _putbits ((char *)&pixel, i, 1, (char *)&px);
		    XYNORMALIZE(&px, ximage);
		    src = (char *)&px;
		    dst = &ximage->data[XYINDEX(x, y, ximage) + plane];
		    for (i = nbytes; --i >= 0; ) *dst++ = *src++;
		    npixel = npixel >> 1;
		    for (i=0, px=npixel; i<sizeof(unsigned long); i++, px>>=8)
			((unsigned char *)&pixel)[i] = px;
		    plane = plane - (ximage->bytes_per_line * ximage->height);
		}
	} else if (ximage->format == ZPixmap) {
		src = &ximage->data[ZINDEX(x, y, ximage)];
		dst = (char *)&px;
		px = 0;
		nbytes = (ximage->bits_per_pixel + 7) >> 3;
		for (i = nbytes; --i >= 0; ) *dst++ = *src++;
		ZNORMALIZE(&px, ximage);
		_putbits ((char *)&pixel, 
			  (x * ximage->bits_per_pixel) & 7, 
			  ximage->bits_per_pixel, (char *)&px);
		ZNORMALIZE(&px, ximage);
		src = (char *)&px;
		dst = &ximage->data[ZINDEX(x, y, ximage)];
		for (i = nbytes; --i >= 0; ) *dst++ = *src++;
	} else {
		return 0; /* bad image */
	}
	return 1;
}

static int _XPutPixel32 (ximage, x, y, pixel)
    register XImage *ximage;
    int x;
    int y;
    unsigned long pixel;
{
	unsigned char *addr;

	if ((ximage->format == ZPixmap) && (ximage->bits_per_pixel == 32)) {
	    addr = &((unsigned char *)ximage->data)
			[y * ximage->bytes_per_line + (x << 2)];
#ifndef WORD64
	    if (*((char *)&byteorderpixel) == ximage->byte_order)
		*((unsigned long *)addr) = pixel;
	    else
#endif
	    if (ximage->byte_order == MSBFirst) {
		addr[0] = pixel >> 24;
		addr[1] = pixel >> 16;
		addr[2] = pixel >> 8;
		addr[3] = pixel;
	    } else {
		addr[3] = pixel >> 24;
		addr[2] = pixel >> 16;
		addr[1] = pixel >> 8;
		addr[0] = pixel;
	    }
	    return 1;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XPutPixel(ximage, x, y, pixel);
	}
}

static int _XPutPixel16 (ximage, x, y, pixel)
    register XImage *ximage;
    int x;
    int y;
    unsigned long pixel;
{
	unsigned char *addr;

	if ((ximage->format == ZPixmap) && (ximage->bits_per_pixel == 16)) {
	    addr = &((unsigned char *)ximage->data)
			[y * ximage->bytes_per_line + (x << 1)];
	    if (ximage->byte_order == MSBFirst) {
		addr[0] = pixel >> 8;
		addr[1] = pixel;
	    } else {
		addr[1] = pixel >> 8;
		addr[0] = pixel;
	    }
	    return 1;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XPutPixel(ximage, x, y, pixel);
	}
}

static int _XPutPixel8 (ximage, x, y, pixel)
    register XImage *ximage;
    int x;
    int y;
    unsigned long pixel;
{
	if ((ximage->format == ZPixmap) && (ximage->bits_per_pixel == 8)) {
	    ximage->data[y * ximage->bytes_per_line + x] = pixel;
	    return 1;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XPutPixel(ximage, x, y, pixel);
	}
}

static int _XPutPixel1 (ximage, x, y, pixel)
    register XImage *ximage;
    int x;
    int y;
    unsigned long pixel;
{
	unsigned char bit;
	int xoff, yoff;

	if ((ximage->depth == 1) &&
	    (ximage->byte_order == ximage->bitmap_bit_order)) {
	    xoff = x + ximage->xoffset;
	    yoff = y * ximage->bytes_per_line + (xoff >> 3);
	    xoff &= 7;
	    if (ximage->bitmap_bit_order == MSBFirst)
		bit = 0x80 >> xoff;
	    else
		bit = 1 << xoff;
	    if (pixel & 1)
		ximage->data[yoff] |= bit;
	    else
		ximage->data[yoff] &= ~bit;
	    return 1;
	} else {
	    _XInitImageFuncPtrs(ximage);
	    return XPutPixel(ximage, x, y, pixel);
	}
}

/*
 * SubImage
 * 
 * Creates a new image that is a subsection of an existing one.
 * Allocates the memory necessary for the new XImage data structure. 
 * Pointer to new image is returned.  The algorithm used is repetitive
 * calls to get and put pixel.
 *
 */

static XImage *_XSubImage (ximage, x, y, width, height)
    XImage *ximage;
    register int x;	/* starting x coordinate in existing image */
    register int y;	/* starting y coordinate in existing image */
    unsigned int width;	/* width in pixels of new subimage */
    unsigned int height;/* height in pixels of new subimage */

{
	register XImage *subimage;
	int dsize;
	register int row, col;
	register unsigned long pixel;
	char *data;

	if ((subimage = (XImage *) Xcalloc (1, sizeof (XImage))) == NULL)
	    return (XImage *) NULL;
	subimage->width = width;
	subimage->height = height;
	subimage->xoffset = 0;
	subimage->format = ximage->format;
	subimage->byte_order = ximage->byte_order;
	subimage->bitmap_unit = ximage->bitmap_unit;
	subimage->bitmap_bit_order = ximage->bitmap_bit_order;
	subimage->bitmap_pad = ximage->bitmap_pad;
	subimage->bits_per_pixel = ximage->bits_per_pixel;
	subimage->depth = ximage->depth;
	/*
	 * compute per line accelerator.
	 */
	if (subimage->format == ZPixmap) 	
	    subimage->bytes_per_line = 
		ROUNDUP(subimage->bits_per_pixel * width,
			subimage->bitmap_pad);
	else
	    subimage->bytes_per_line =
		ROUNDUP(width, subimage->bitmap_pad);
	subimage->obdata = NULL;
	_XInitImageFuncPtrs (subimage);
	dsize = subimage->bytes_per_line * height;
	if (subimage->format == XYPixmap) dsize = dsize * subimage->depth;
	if (((data = Xcalloc (1, (unsigned) dsize)) == NULL) && (dsize > 0)) {
	    Xfree((char *) subimage);
	    return (XImage *) NULL;
	}
	subimage->data = data;

	/*
	 * Test for cases where the new subimage is larger than the region
	 * that we are copying from the existing data.  In those cases,
	 * copy the area of the existing image, and allow the "uncovered"
	 * area of new subimage to remain with zero filled pixels.
	 */
	if (height > ximage->height - y ) height = ximage->height - y;
	if (width > ximage->width - x ) width = ximage->width - x;

	for (row = y; row < (y + height); row++) {
	    for (col = x; col < (x + width); col++) {
		pixel = XGetPixel(ximage, col, row);
		XPutPixel(subimage, (col - x), (row - y), pixel);
	    }
	}
	return subimage;
}


/*
 * SetImage
 * 
 * Overwrites a section of one image with all of the data from another.
 * If the two images are not of the same format (i.e. XYPixmap and ZPixmap),
 * the image data is converted to the destination format.  The following
 * restrictions apply:
 *
 *	1. The depths of the source and destination images must be equal.
 *
 *	2. If the height of the source image is too large to fit between
 *	   the specified y starting point and the bottom of the image,
 *	   then scanlines are truncated on the bottom.
 *
 *	3. If the width of the source image is too large to fit between
 *	   the specified x starting point and the end of the scanline,
 *	   then pixels are truncated on the right.
 * 
 * The images need not have the same bitmap_bit_order, byte_order,
 * bitmap_unit, bits_per_pixel, bitmap_pad, or xoffset.
 *
 */

int _XSetImage (srcimg, dstimg, x, y)
    XImage *srcimg;
    register XImage *dstimg;
    register int x;
    register int y;

{
	register unsigned long pixel;
	register int row, col;
	int width, height, startrow, startcol;
	if (x < 0) {
	    startcol = -x;
	    x = 0;
	} else
	    startcol = 0;
	if (y < 0) {
	    startrow = -y;
	    y = 0;
	} else
	    startrow = 0;
	width = dstimg->width - x;
	if (srcimg->width < width)
	    width = srcimg->width;
	height = dstimg->height - y;
	if (srcimg->height < height)
	    height = srcimg->height;

	/* this is slow, will do better later */
	for (row = startrow; row < height; row++) {
	    for (col = startcol; col < width; col++) {
		pixel = XGetPixel(srcimg, col, row);
		XPutPixel(dstimg, x + col, y + row, pixel);
	    }
	}
	return 1;
}

/*
 * AddPixel
 * 
 * Adds a constant value to every pixel in a pixmap.
 *
 */

static _XAddPixel (ximage, value)
    register XImage *ximage;
    register long value;
{
	register int x;
	register int y;

	if (!value)
	    return;
	if (ximage->depth == 1) {
	    /* The only value that we can add here to an XYBitmap
	     * is one.  Since 1 + value = ~value for one bit wide
	     * data, we do this quickly by taking the ones complement
	     * of the entire bitmap data (offset and pad included!).
	     * Note that we don't need to be concerned with bit or
	     * byte order at all.
	     */
	    register unsigned char *dp = (unsigned char *) ximage->data;
	    x = ximage->bytes_per_line * ximage->height;
	    while (--x >= 0) {
		*dp = ~*dp;
		dp++;
	    }
	} else if ((ximage->format == ZPixmap) &&
		   (ximage->bits_per_pixel == 8)) {
	    register unsigned char *dp = (unsigned char *) ximage->data;
	    x = ximage->bytes_per_line * ximage->height;
	    while (--x >= 0)
		*dp++ += value;
#ifndef WORD64
	} else if ((ximage->format == ZPixmap) &&
		   (ximage->bits_per_pixel == 16) &&
		   (*((char *)&byteorderpixel) == ximage->byte_order)) {
	    register unsigned short *dp = (unsigned short *) ximage->data;
	    x = (ximage->bytes_per_line >> 1) * ximage->height;
	    while (--x >= 0)
		*dp++ += value;
	} else if ((ximage->format == ZPixmap) &&
		   (ximage->bits_per_pixel == 32) &&
		   (*((char *)&byteorderpixel) == ximage->byte_order)) {
	    register unsigned long *dp = (unsigned long *) ximage->data;
	    x = (ximage->bytes_per_line >> 2) * ximage->height;
	    while (--x >= 0)
		*dp++ += value;
#endif
	} else {
	    for (y = ximage->height; --y >= 0; ) {
		for (x = ximage->width; --x >= 0; ) {
		    register unsigned long pixel = XGetPixel(ximage, x, y);
		    pixel = pixel + value;
		    XPutPixel(ximage, x, y, pixel);
		}
	    }
	}
}

/*
 * This routine initializes the image object function pointers.  The
 * intent is to provide native (i.e. fast) routines for native format images
 * only using the generic (i.e. slow) routines when fast ones don't exist.
 * However, with the current rather botched external interface, clients may
 * have to mung image attributes after the image gets created, so the fast
 * routines always have to check to make sure the optimization is still
 * valid, and reinit the functions if not.
 */
_XInitImageFuncPtrs (image)
    register XImage *image;
{
	image->f.create_image = XCreateImage;
	image->f.destroy_image = _XDestroyImage;
	if ((image->format == ZPixmap) && (image->bits_per_pixel == 8)) {
	    image->f.get_pixel = _XGetPixel8;
	    image->f.put_pixel = _XPutPixel8;
	} else if ((image->depth == 1) &&
		   (image->byte_order == image->bitmap_bit_order)) {
	    image->f.get_pixel = _XGetPixel1;
	    image->f.put_pixel = _XPutPixel1;
	} else if ((image->format == ZPixmap) &&
		   (image->bits_per_pixel == 32)) {
	    image->f.get_pixel = _XGetPixel32;
	    image->f.put_pixel = _XPutPixel32;
	} else if ((image->format == ZPixmap) &&
		   (image->bits_per_pixel == 16)) {
	    image->f.get_pixel = _XGetPixel16;
	    image->f.put_pixel = _XPutPixel16;
	} else {
	    image->f.get_pixel = _XGetPixel;
	    image->f.put_pixel = _XPutPixel;
	}
	image->f.sub_image = _XSubImage;
/*	image->f.set_image = _XSetImage;*/
	image->f.add_pixel = _XAddPixel;
}
