/*  Part of XPCE --- The SWI-Prolog GUI toolkit

    Author:        Jan Wielemaker and Anjo Anjewierden
    E-mail:        jan@swi.psy.uva.nl
    WWW:           http://www.swi.psy.uva.nl/projects/xpce/
    Copyright (c)  1995-2011, University of Amsterdam
    All rights reserved.

    Redistribution and use in source and binary forms, with or without
    modification, are permitted provided that the following conditions
    are met:

    1. Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.

    2. Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in
       the documentation and/or other materials provided with the
       distribution.

    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
    POSSIBILITY OF SUCH DAMAGE.
*/

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
The XPCE PNM interface. Converts between   X11 images and p[bgp]m images
for loading and saving XPCE  bitmaps  in   a  form  accessible for other
applications.

PNM (Portable aNy  Map)  is  a   public  simple  format  for  exchanging
bitmap/pixmap  information.  It  has  6  flavours,  three  of  them  are
`rawbits' (binary) versions of the  three   main  formats: PBM (Portable
BitMap), PGM (Portable GrayMap) and PPM (Portable PixMap).

The PNM package is public domain  and available as pbmplus10dec91.tar.gz
on many anonymous ftp servers. Search for   pbmplus is you want to check
for more recent releases.

The magnificient tool xv by John Bradley (bradley@cis.upenn.edu) version
3 can also generate ppm files.

This module implements two additional formats:   PGM  and PPM PNM_RUNLEN
encoded files. These are similar to the   RAWBIT files, but encode their
info as tuples <colour-info> <times-repeated>.  These files are normally
more compact and read/write faster. As   yet  this format is exclusively
used in saved object (object ->save_in_file).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#include <h/kernel.h>
#include "include.h"
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif

#define BRIGHT ((1L<<16)-1)
#define NOPIXEL (~0UL)

#undef roundup
#define valdigit(d)		((d) - '0')
#define roundup(v, n)		((((v)+(n)-1)/(n))*(n))
#define rescale(v, o, n)	((v) * (n) / (o))

#ifndef TRUE
#define TRUE 1
#define FALSE 0
#endif

#define Symbol PixSymbol		/* name-clash with kernel */
#define symbol pix_symbol

static int ncolours;			/* colours in image */
static int nmapped;			/* remapped colours */
static int nfailed;			/* failed conversions */

		 /*******************************
		 * HASH-TABLE FOR PIXEL LOOKUP	*
		 *******************************/

typedef struct symbol *Symbol;
typedef struct table  *Table;

struct symbol
{ unsigned long name;
  unsigned long value;
  Symbol	next;
};

struct table
{ int		size;
  Symbol	symbols[1];
};


#define hashvalue(size, v) ((v) % size)

static Table
newTable(int size)
{ Table t = (Table)pceMalloc(sizeof(struct table) + (size-1) * sizeof(Symbol));
  int i;
  Symbol *s;

  t->size = size;
  for(i=size, s=t->symbols; --i >= 0; s++)
    *s = NULL;

  return t;
}


static void
freeTable(Table t)
{ Symbol *s;
  int i;

  for(i=t->size, s=t->symbols; --i >= 0; s++)
  { Symbol n, m = *s;

    for( ; m; m = n)
    { n = m->next;
      pceFree(m);
    }
  }

  pceFree(t);
}


static void
addTable(Table t, unsigned long name, unsigned long value)
{ Symbol *l = &t->symbols[hashvalue(t->size, name)];
  Symbol s = (Symbol)pceMalloc(sizeof(struct symbol));

  s->name = name;
  s->value = value;
  s->next = *l;
  *l = s;
}


static unsigned long
memberTable(Table t, unsigned long name)
{ Symbol s = t->symbols[hashvalue(t->size, name)];

  for(; s; s = s->next)
  { if ( s->name == name )
      return s->value;
  }

  return NOPIXEL;
}


		 /*******************************
		 *	   COLOUR PIXELS	*
		 *******************************/

static unsigned long
colourPixel(Display *disp, int depth, Colormap cmap,
	    Table t, int r, int g, int b)
{ unsigned long pixel;
  unsigned long direct = (r << 16) + (g << 8) + b;
  XColor c;

  if ( (pixel = memberTable(t, direct)) != NOPIXEL )
    return pixel;

  ncolours++;

  c.red   = r * 257;
  c.green = g * 257;
  c.blue  = b * 257;
  if ( !XAllocColor(disp, cmap, &c) )
  { if ( !allocNearestColour(disp, cmap, depth, DEFAULT, &c) )
    { Cprintf("PNM: failed to alloc pixel %d/%d/%d\n", r, g, b);
      c.pixel = 0;
      nfailed++;
    }
  }

  addTable(t, direct, c.pixel);

  DEBUG(NAME_ppm, Cprintf("PNM: Colour %d %d %d on pixel %d\n",
			  r, g, b, c.pixel));
  return c.pixel;
}

		 /*******************************
		 *     ASCII FORMAT PARSING	*
		 *******************************/

static int
getNum(IOSTREAM *fd)
{ int c;
  int v;

  for(;;)
  { do
    { c = Sgetc(fd);
    } while(isspace(c));

    if ( isdigit(c) )
    { v = valdigit(c);
      for(;;)
      { c = Sgetc(fd);
	if ( isdigit(c) )
	  v = v*10 + valdigit(c);
	else
	  break;
      }
      if ( !isspace(c) )
	Sungetc(c, fd);

      return v;
    }
    if ( c == '#' )
    { do
      { c = Sgetc(fd);
      } while( c != '\n' && c != EOF );
    } else
      return -1;
  }
}


XImage *
read_ppm_file(Display *disp, Colormap cmap, int depth, IOSTREAM *fd)
{ XImage *img;
  long here = Stell(fd);
  int c;
  int fmt, encoding;
  int width, height, bytes_per_line, scale=0;
  char *data;
  int allocdepth;
  int pad = XBitmapPad(disp);
  Visual *v = DefaultVisual(disp, DefaultScreen(disp));

  ncolours = nmapped = nfailed = 0;	/* statistics */
  assert(pad%8 == 0);

  if ( (c=Sgetc(fd)) != 'P' )
  { Sungetc(c, fd);
    return NULL;
  }

  if ( !cmap )
    cmap = DefaultColormap(disp, DefaultScreen(disp));

  c = Sgetc(fd);
  if ( c < '1' || c > '9' )
    goto errout;
  c -= '0';
  fmt      = ((c - 1) % 3) + 1;
  encoding = c - fmt;

  width = getNum(fd);
  height = getNum(fd);

  if ( fmt == PNM_PBM )
  { depth = 1;
  } else
  { scale = getNum(fd);
    if ( !depth )
      depth = DefaultDepth(disp, DefaultScreen(disp));
  }

  if ( width < 0 || height < 0 || scale < 0 )
    goto errout;

  allocdepth = (depth >= 24 ? 32 : depth);
  bytes_per_line = roundup((width*allocdepth+7)/8, pad/8);
  data = (char *)pceMalloc(height * bytes_per_line);

  img = XCreateImage(disp,
		     v,
		     depth,
		     fmt == PNM_PBM ? XYBitmap : ZPixmap,
		     0,
		     data,
		     width, height,
		     pad, bytes_per_line);
  if ( !img )
  { perror("XCreateImage");
    pceFree(data);
    goto errout;
  }
  img->bits_per_pixel = depth;

  switch(encoding)
  { int x, y;

    case PNM_ASCII:
    { switch(fmt)
      { case PNM_PBM:
	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { int value = getNum(fd);

	      if ( value < 0 || value > 1 )
		goto errout;

	      XPutPixel(img, x, y, value);
	    }
	  }
	  break;
	case PNM_PGM:
	{ Table t = newTable(64);

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { int g = getNum(fd);
	      unsigned long pixel;

	      if ( g < 0 || g > scale )
		goto errout;
	      if ( scale != 255 )
		g = rescale(g, scale, 255);

	      pixel = colourPixel(disp, depth, cmap, t, g, g, g);
	      XPutPixel(img, x, y, pixel);
	    }
	  }
	  freeTable(t);

	  break;
	}
	case PNM_PPM:
	{ Table t = newTable(64);

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { int r = getNum(fd);
	      int g = getNum(fd);
	      int b = getNum(fd);
	      unsigned long pixel;

	      if ( r < 0 || r > scale ||
		   g < 0 || g > scale ||
		   b < 0 || b > scale )
		goto errout;

	      if ( scale != 255 )
	      { r = rescale(r, scale, 255);
		g = rescale(g, scale, 255);
		b = rescale(b, scale, 255);
	      }

	      pixel = colourPixel(disp, depth, cmap, t, r, g, b);

	      XPutPixel(img, x, y, pixel);
	    }
	  }
	  freeTable(t);

	  break;
	}
	break;
      }
      break;
    }
    case PNM_RAWBITS:
    { switch(fmt)
      { case PNM_PBM:
	{ int byte = 0;
	  int bit = 0;

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { if ( !bit )
	      { byte = Sgetc(fd);
		bit = 8;
	      }

	      bit--;
	      XPutPixel(img, x, y, (byte & (1<<bit)) ? 1 : 0);
	    }
	    bit = 0;			/* scanlines are byte-aligned */
	  }
	  break;
	}
	case PNM_PGM:
	{ Table t = newTable(64);

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { int g;
	      unsigned long pixel;

	      if ( Sfeof(fd) || (g=Sgetc(fd)) > scale )
		goto errout;
	      if ( scale != 255 )
		g = rescale(g, scale, 255);

	      pixel = colourPixel(disp, depth, cmap, t, g, g, g);
	      XPutPixel(img, x, y, pixel);
	    }
	  }
	  freeTable(t);

	  break;
	}
	case PNM_PPM:
	{ Table t = newTable(64);

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { int r, g, b;
	      unsigned long pixel;

	      if ( Sfeof(fd) ||
		   (r=Sgetc(fd)) > scale ||
		   (g=Sgetc(fd)) > scale ||
		   (b=Sgetc(fd)) > scale )
		goto errout;

	      if ( scale != 255 )
	      { r = rescale(r, scale, 255);
		g = rescale(g, scale, 255);
		b = rescale(b, scale, 255);
	      }

	      pixel = colourPixel(disp, depth, cmap, t, r, g, b);

	      XPutPixel(img, x, y, pixel);
	    }
	  }
	  freeTable(t);

	  break;
	}
	break;
      }
      break;
    }
    case PNM_RUNLEN:
    { int rlen = 0;
      unsigned long cpixel = NOPIXEL;

      switch(fmt)
      { case PNM_PGM:
	{ Table t = newTable(64);

	  DEBUG(NAME_pnm, Cprintf("Reading runlength encoded graymap\n"));

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { if ( rlen-- > 0 )
	      { XPutPixel(img, x, y, cpixel);
	      } else
	      { int g;

		if ( (g=Sgetc(fd)) > scale ||
		     (rlen = Sgetc(fd)) == EOF )
		  goto errout;
		rlen &= 0xff;
		if ( scale != 255 )
		  g = rescale(g, scale, 255);

		cpixel = colourPixel(disp, depth, cmap, t, g, g, g);
		XPutPixel(img, x, y, cpixel);
		rlen--;
	      }
	    }
	  }
	  freeTable(t);

	  break;
	}
	case PNM_PPM:
	{ Table t = newTable(64);

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { if ( rlen-- > 0 )
	      { XPutPixel(img, x, y, cpixel);
	      } else
	      { int r, g, b;

		if ( (r=Sgetc(fd)) > scale ||
		     (g=Sgetc(fd)) > scale ||
		     (b=Sgetc(fd)) > scale ||
		     (rlen = Sgetc(fd)) == EOF )
		  goto errout;

		rlen &= 0xff;
		if ( scale != 255 )
		{ r = rescale(r, scale, 255);
		  g = rescale(g, scale, 255);
		  b = rescale(b, scale, 255);
		}

		cpixel = colourPixel(disp, depth, cmap, t, r, g, b);

		XPutPixel(img, x, y, cpixel);
		rlen--;
	      }
	    }
	  }
	  freeTable(t);

	  break;
	}
      }
    }
  }

  DEBUG(NAME_ppm,
	Cprintf("PNM: Converted %dx%dx%d image, %d colours (%d mapped, %d failed)\n",
		width, height, depth, ncolours, nmapped, nfailed));

  return img;

errout:
  DEBUG(NAME_ppm,
	Cprintf("PNM: Format error, index = %d\n", Stell(fd)));
  Sseek(fd, here, SEEK_SET);
  return NULL;
}

		 /*******************************
		 *	     WRITING		*
		 *******************************/


static int file_col;

static int
putNum(int n, IOSTREAM *fd)
{ if ( file_col != 0 && Sputc(' ', fd) == EOF )
    return -1;

  do
  { if ( Sputc(n % 10 + '0', fd) == EOF )
      return -1;
    file_col++;
    n /= 10;
  } while( n > 0 );

  if ( file_col >= 70 )
  { if ( Sputc('\n', fd) == EOF )
      return -1;
    file_col = 0;
  }

  return 0;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Low-level XImage hacking.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

typedef struct
{ XColor       *cinfo;			/* a colour-info vector */
  int		r_shift;		/* red-shift */
  int		g_shift;		/* green-shift */
  int		b_shift;		/* blue-shift */
  int		r_fill;			/* shift to make 16-bit */
  int		g_fill;			/* shift to make 16-bit */
  int		b_fill;			/* shift to make 16-bit */
  XColor	xc;			/* static one */
} XPixelInfo;


static int
mask_width(unsigned long mask)
{ unsigned long m = 0x1;
  int width = 0;

  while((mask&m) == 0)
    m <<= 1;
  while((mask&m))
  { m <<= 1;
    width++;
  }

  return width;
}


static XColor *
pixelToColor(XImage *im, unsigned long pixel, XPixelInfo *info)
{ if ( info->cinfo )
  { return &info->cinfo[pixel];
  } else
  { info->xc.red   = (pixel >> info->r_shift) << info->r_fill;
    info->xc.green = (pixel >> info->g_shift) << info->g_fill;
    info->xc.blue  = (pixel >> info->b_shift) << info->b_fill;

    return &info->xc;
  }
}


static void
makeXPixelInfo(XPixelInfo *info, XImage *img, Display *disp, Colormap cmap)
{ if ( img->depth <= 8 )
  { XColor *cdata = info->cinfo;
    int entries	= 1<<img->depth;
    int i;

    for(i=0; i<entries; i++)
      cdata[i].pixel = i;

    if ( !cmap )
      cmap = DefaultColormap(disp, DefaultScreen(disp));
    XQueryColors(disp, cmap, cdata, entries);
  } else
  { info->cinfo = 0;

    info->r_shift = shift_for_mask(img->red_mask);
    info->g_shift = shift_for_mask(img->green_mask);
    info->b_shift = shift_for_mask(img->blue_mask);

    info->r_fill  = 16 - mask_width(img->red_mask);
    info->g_fill  = 16 - mask_width(img->green_mask);
    info->b_fill  = 16 - mask_width(img->blue_mask);
  }
}


int
write_pnm_file(IOSTREAM *fd, XImage *img,
	       Display *disp, Colormap cmap, int scale, int fmt, int encode)
{ int width  = img->width;
  int height = img->height;
  XColor cdata[256];
  XPixelInfo info;
  int x, y;


  if ( !scale )
    scale = 255;

  if ( !fmt )
  { if ( img->format == XYBitmap )
      fmt = PNM_PBM;
    else
      fmt = PNM_PPM;
  }

  if ( fmt == PNM_PBM && encode == PNM_RUNLEN )
    encode = PNM_RAWBITS;		/* no use to runlen encode a bitmap */

  if ( img->format != XYBitmap )
  { info.cinfo = cdata;
    makeXPixelInfo(&info, img, disp, cmap);
  }

  Sfprintf(fd, "P%c\n", fmt + encode + '0');
  Sfprintf(fd, "# Creator: XPCE version %s\n",
	   strName(get(PCE,NAME_version,EAV)));
  Sfprintf(fd, "%d %d\n", width, height);

  if ( fmt != PNM_PBM )
    Sfprintf(fd, "%d\n", scale);

  file_col = 0;

  switch(encode)
  { case PNM_ASCII:
    { switch(fmt)
      { case PNM_PBM:
	{ for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { unsigned long pixel = XGetPixel(img, x, y);

	      if ( img->format != XYBitmap )
	      { XColor *c;
		int r;

		c = pixelToColor(img, pixel, &info);
		r = intensityXColor(c);
		pixel = r < 32768 ? 1 : 0;
	      }

	      if ( putNum(pixel, fd) < 0 )
		return -1;
	    }
	  }
	  break;
	}
	case PNM_PGM:
	{ for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { XColor *c;
	      unsigned int r;

	      c = pixelToColor(img, XGetPixel(img, x, y), &info);
	      r = intensityXColor(c);
	      r = rescale(r, BRIGHT, scale);

	      if ( putNum(r, fd) < 0 )
		return -1;
	    }
	  }
	  break;
	}
	case PNM_PPM:
	{ for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { XColor *c;
	      unsigned int r, g, b;

	      c = pixelToColor(img, XGetPixel(img, x, y), &info);
	      r = rescale(c->red,   BRIGHT, scale);
	      g = rescale(c->green, BRIGHT, scale);
	      b = rescale(c->blue,  BRIGHT, scale);

	      if ( putNum(r, fd) < 0 ||
		   putNum(g, fd) < 0 ||
		   putNum(b, fd) < 0 )
		return -1;
	    }
	  }
	  break;
	}
      }
      if ( file_col && Sputc('\n', fd) == EOF )
	return -1;
      file_col = 0;
    }
    case PNM_RAWBITS:
    { switch(fmt)
      { case PNM_PBM:
	{ int byte = 0;
	  int bit = 7;

	  for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { unsigned long pixel = XGetPixel(img, x, y);

	      if ( img->format != XYBitmap )
	      { XColor *c;
		int r;

		c = pixelToColor(img, pixel, &info);
		r = intensityXColor(c);
		pixel = r < 32768 ? 1 : 0;
	      }

	      if ( pixel )
		byte |= 1<<bit;
	      if ( bit-- == 0 )
	      { if ( Sputc(byte, fd) == EOF )
		  return -1;
		bit = 7;
		byte = 0;
	      }
	    }
	    if ( bit != 7 )		/* flush after finishing scanline */
	    { if ( Sputc(byte, fd) == EOF )
		return -1;
	      bit = 7;
	      byte = 0;
	    }
	  }

	  if ( bit != 7 )
	  { if ( Sputc(byte, fd) == EOF )
	      return -1;
	  }
	  break;
	}
	case PNM_PGM:
	{ for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { XColor *c;
	      unsigned int r;

	      c = pixelToColor(img, XGetPixel(img, x, y), &info);
	      r = intensityXColor(c);
	      r = rescale(r, BRIGHT, scale);

	      if ( Sputc(r, fd) == EOF )
		return -1;
	    }
	  }
	  break;
	}
	case PNM_PPM:
	{ for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { XColor *c;
	      unsigned int r, g, b;

	      c = pixelToColor(img, XGetPixel(img, x, y), &info);
	      r = rescale(c->red,   BRIGHT, scale);
	      g = rescale(c->green, BRIGHT, scale);
	      b = rescale(c->blue,  BRIGHT, scale);

	      if ( Sputc(r, fd) == EOF ||
		   Sputc(g, fd) == EOF ||
		   Sputc(b, fd) == EOF )
		return -1;
	    }
	  }

	  break;
	}
      }
    }
    case PNM_RUNLEN:
    { int rlen=-1;
      unsigned long cpixel = NOPIXEL;

      switch(fmt)
      { case PNM_PGM:
	{ for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { unsigned long pixel = XGetPixel(img, x, y);

	      if ( pixel == cpixel && rlen < 255 )
		rlen++;
	      else
	      { XColor *c;
		int r;

		if ( rlen > 0 && Sputc(rlen, fd) == EOF )
		  return -1;
		cpixel = pixel;
		rlen = 1;
		c = pixelToColor(img, pixel, &info);
		r = intensityXColor(c);
		r = rescale(r, BRIGHT, scale);
		if ( Sputc(r, fd) == EOF )
		  return -1;
	      }
	    }
	  }
	  if ( Sputc(rlen, fd) == EOF )
	    return -1;

	  break;
	}
	case PNM_PPM:
	{ for(y=0; y<height; y++)
	  { for(x=0; x<width; x++)
	    { unsigned long pixel = XGetPixel(img, x, y);

	      if ( pixel == cpixel && rlen < 255 )
		rlen++;
	      else
	      { XColor *c;
		unsigned int r, g, b;

		if ( rlen > 0 && Sputc(rlen, fd) == EOF )
		  return -1;
		cpixel = pixel;
		rlen = 1;
		c = pixelToColor(img, pixel, &info);
		r = rescale(c->red,   BRIGHT, scale);
		g = rescale(c->green, BRIGHT, scale);
		b = rescale(c->blue,  BRIGHT, scale);

		if ( Sputc(r, fd) == EOF ||
		     Sputc(g, fd) == EOF ||
		     Sputc(b, fd) == EOF )
		  return -1;
	      }
	    }
	  }
	  if ( Sputc(rlen, fd) == EOF )
	    return -1;

	  break;
	}
      }
    }
  }

  return 0;
}


/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Translate an XImage and an optional mask into  an RBGA image in a format
that is suitable for _NET_WM_ICON.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

unsigned long *
XImageToRGBA(XImage *img, XImage *msk,
	     Display *disp, Colormap cmap, size_t *lenp)
{ int width  = img->width;
  int height = img->height;
  XPixelInfo img_info;
  XPixelInfo msk_info;
  XColor img_cdata[256];
  XColor msk_cdata[256];
  int msk_is_bitmap = TRUE;
  int x, y;
  unsigned long *data, *p;
  const int scale = 255;
  size_t len;

  if ( msk && (msk->height != height || msk->width != width) )
    msk = NULL;

  if ( img->format != XYBitmap )
  { img_info.cinfo = img_cdata;
    makeXPixelInfo(&img_info, img, disp, cmap);
  }
  if ( msk )
  { if ( msk->format == XYBitmap ||
	 (msk->format == ZPixmap && msk->bits_per_pixel == 1) )
    { msk_is_bitmap = TRUE;
    } else
    { msk_is_bitmap = FALSE;
      msk_info.cinfo = msk_cdata;
      makeXPixelInfo(&msk_info, msk, disp, cmap);
    }
  }

  len = 2+width*height;
  if ( lenp )
    *lenp = len;
  if ( !(data = malloc(len*sizeof(*data))) )
    return data;
  p = data;
  *p++ = width;
  *p++ = height;

  for(y=0; y<height; y++)
  { for(x=0; x<width; x++)
    { XColor *c;
      unsigned int r, g, b, a;
      union
      { unsigned int i32;
	char c32[4];
      } upix;

      c = pixelToColor(img, XGetPixel(img, x, y), &img_info);
      r = rescale(c->red,   BRIGHT, scale);
      g = rescale(c->green, BRIGHT, scale);
      b = rescale(c->blue,  BRIGHT, scale);

      if ( msk )
      { unsigned long pixel = XGetPixel(msk, x, y);
	if ( msk_is_bitmap )
	{ a = pixel ? scale : 0;
	} else
	{ XColor *c;
	  int r;

	  c = pixelToColor(img, pixel, &msk_info);
	  r = intensityXColor(c);
	  a = rescale(r, BRIGHT, scale);
	}
      } else
      { a = 255;
      }

      upix.c32[0] = b;			/* blue */
      upix.c32[1] = g;			/* green */
      upix.c32[2] = r;			/* red */
      upix.c32[3] = a;
      *p++ = upix.i32;
    }
  }

  return data;
}