gd.cpp

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#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "gd.h"
#include "mtables.cpp"

static void gdImageBrushApply(gdImagePtr im, int x, int y);
static void gdImageTileApply(gdImagePtr im, int x, int y);

gdImagePtr gdImageCreate(int sx, int sy)
{
        int i;
        gdImagePtr im;
        im = (gdImage *) malloc(sizeof(gdImage));
        /* NOW ROW-MAJOR IN GD 1.3 */
        im->pixels = (unsigned char **) malloc(sizeof(unsigned char *) * sy);
        im->polyInts = 0;
        im->polyAllocated = 0;
        im->brush = 0;
        im->tile = 0;
        im->style = 0;
        for (i=0; (i<sy); i++) {
                /* NOW ROW-MAJOR IN GD 1.3 */
                im->pixels[i] = (unsigned char *) calloc(
                        sx, sizeof(unsigned char));
        }       
        im->sx = sx;
        im->sy = sy;
        im->colorsTotal = 0;
        im->transparent = (-1);
        im->interlace = 0;
        return im;
}

void gdImageDestroy(gdImagePtr im)
{
        int i;
        for (i=0; (i<im->sy); i++) {
                free(im->pixels[i]);
        }       
        free(im->pixels);
        if (im->polyInts) {
                        free(im->polyInts);
        }
        if (im->style) {
                free(im->style);
        }
        free(im);
}

int gdImageColorClosest(gdImagePtr im, int r, int g, int b)
{
        int i;
        long rd, gd, bd;
        int ct = (-1);
        long mindist = 0;
        for (i=0; (i<(im->colorsTotal)); i++) {
                long dist;
                if (im->open[i]) {
                        continue;
                }
                rd = (im->red[i] - r);  
                gd = (im->green[i] - g);
                bd = (im->blue[i] - b);
                dist = rd * rd + gd * gd + bd * bd;
                if ((i == 0) || (dist < mindist)) {
                        mindist = dist; 
                        ct = i;
                }
        }
        return ct;
}

int gdImageColorExact(gdImagePtr im, int r, int g, int b)
{
        int i;
        for (i=0; (i<(im->colorsTotal)); i++) {
                if (im->open[i]) {
                        continue;
                }
                if ((im->red[i] == r) && 
                        (im->green[i] == g) &&
                        (im->blue[i] == b)) {
                        return i;
                }
        }
        return -1;
}

int gdImageColorAllocate(gdImagePtr im, int r, int g, int b)
{
        int i;
        int ct = (-1);
        for (i=0; (i<(im->colorsTotal)); i++) {
                if (im->open[i]) {
                        ct = i;
                        break;
                }
        }       
        if (ct == (-1)) {
                ct = im->colorsTotal;
                if (ct == gdMaxColors) {
                        return -1;
                }
                im->colorsTotal++;
        }
        im->red[ct] = r;
        im->green[ct] = g;
        im->blue[ct] = b;
        im->open[ct] = 0;
        return ct;
}

void gdImageColorDeallocate(gdImagePtr im, int color)
{
        /* Mark it open. */
        im->open[color] = 1;
}

void gdImageColorTransparent(gdImagePtr im, int color)
{
        im->transparent = color;
}

void gdImageSetPixel(gdImagePtr im, int x, int y, int color)
{
        int p;
        switch(color) {
                case gdStyled:
                if (!im->style) {
                        /* Refuse to draw if no style is set. */
                        return;
                } else {
                        p = im->style[im->stylePos++];
                }
                if (p != (gdTransparent)) {
                        gdImageSetPixel(im, x, y, p);
                }
                im->stylePos = im->stylePos %  im->styleLength;
                break;
                case gdStyledBrushed:
                if (!im->style) {
                        /* Refuse to draw if no style is set. */
                        return;
                }
                p = im->style[im->stylePos++];
                if ((p != gdTransparent) && (p != 0)) {
                        gdImageSetPixel(im, x, y, gdBrushed);
                }
                im->stylePos = im->stylePos %  im->styleLength;
                break;
                case gdBrushed:
                gdImageBrushApply(im, x, y);
                break;
                case gdTiled:
                gdImageTileApply(im, x, y);
                break;
                default:
                if (gdImageBoundsSafe(im, x, y)) {
                        /* NOW ROW-MAJOR IN GD 1.3 */
                        im->pixels[y][x] = color;
                }
                break;
        }
}

static void gdImageBrushApply(gdImagePtr im, int x, int y)
{
        int lx, ly;
        int hy;
        int hx;
        int x1, y1, x2, y2;
        int srcx, srcy;
        if (!im->brush) {
                return;
        }
        hy = gdImageSY(im->brush)/2;
        y1 = y - hy;
        y2 = y1 + gdImageSY(im->brush); 
        hx = gdImageSX(im->brush)/2;
        x1 = x - hx;
        x2 = x1 + gdImageSX(im->brush);
        srcy = 0;
        for (ly = y1; (ly < y2); ly++) {
                srcx = 0;
                for (lx = x1; (lx < x2); lx++) {
                        int p;
                        p = gdImageGetPixel(im->brush, srcx, srcy);
                        /* Allow for non-square brushes! */
                        if (p != gdImageGetTransparent(im->brush)) {
                                gdImageSetPixel(im, lx, ly,
                                        im->brushColorMap[p]);
                        }
                        srcx++;
                }
                srcy++;
        }       
}               

static void gdImageTileApply(gdImagePtr im, int x, int y)
{
        int srcx, srcy;
        int p;
        if (!im->tile) {
                return;
        }
        srcx = x % gdImageSX(im->tile);
        srcy = y % gdImageSY(im->tile);
        p = gdImageGetPixel(im->tile, srcx, srcy);
        /* Allow for transparency */
        if (p != gdImageGetTransparent(im->tile)) {
                gdImageSetPixel(im, x, y,
                        im->tileColorMap[p]);
        }
}               

int gdImageGetPixel(gdImagePtr im, int x, int y)
{
        if (gdImageBoundsSafe(im, x, y)) {
                /* NOW ROW-MAJOR IN GD 1.3 */
                return im->pixels[y][x];
        } else {
                return 0;
        }
}

/* Bresenham as presented in Foley & Van Dam */

void gdImageLine(gdImagePtr im, int x1, int y1, int x2, int y2, int color)
{
        int dx, dy, incr1, incr2, d, x, y, xend, yend, xdirflag, ydirflag;
        dx = abs(x2-x1);
        dy = abs(y2-y1);
        if (dy <= dx) {
                d = 2*dy - dx;
                incr1 = 2*dy;
                incr2 = 2 * (dy - dx);
                if (x1 > x2) {
                        x = x2;
                        y = y2;
                        ydirflag = (-1);
                        xend = x1;
                } else {
                        x = x1;
                        y = y1;
                        ydirflag = 1;
                        xend = x2;
                }
                gdImageSetPixel(im, x, y, color);
                if (((y2 - y1) * ydirflag) > 0) {
                        while (x < xend) {
                                x++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        y++;
                                        d+=incr2;
                                }
                                gdImageSetPixel(im, x, y, color);
                        }
                } else {
                        while (x < xend) {
                                x++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        y--;
                                        d+=incr2;
                                }
                                gdImageSetPixel(im, x, y, color);
                        }
                }               
        } else {
                d = 2*dx - dy;
                incr1 = 2*dx;
                incr2 = 2 * (dx - dy);
                if (y1 > y2) {
                        y = y2;
                        x = x2;
                        yend = y1;
                        xdirflag = (-1);
                } else {
                        y = y1;
                        x = x1;
                        yend = y2;
                        xdirflag = 1;
                }
                gdImageSetPixel(im, x, y, color);
                if (((x2 - x1) * xdirflag) > 0) {
                        while (y < yend) {
                                y++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        x++;
                                        d+=incr2;
                                }
                                gdImageSetPixel(im, x, y, color);
                        }
                } else {
                        while (y < yend) {
                                y++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        x--;
                                        d+=incr2;
                                }
                                gdImageSetPixel(im, x, y, color);
                        }
                }
        }
}

static void dashedSet(gdImagePtr im, int x, int y, int color,
        int *onP, int *dashStepP);

void gdImageDashedLine(gdImagePtr im, int x1, int y1, int x2, int y2, int color)
{
        int dx, dy, incr1, incr2, d, x, y, xend, yend, xdirflag, ydirflag;
        int dashStep = 0;
        int on = 1;
        dx = abs(x2-x1);
        dy = abs(y2-y1);
        if (dy <= dx) {
                d = 2*dy - dx;
                incr1 = 2*dy;
                incr2 = 2 * (dy - dx);
                if (x1 > x2) {
                        x = x2;
                        y = y2;
                        ydirflag = (-1);
                        xend = x1;
                } else {
                        x = x1;
                        y = y1;
                        ydirflag = 1;
                        xend = x2;
                }
                dashedSet(im, x, y, color, &on, &dashStep);
                if (((y2 - y1) * ydirflag) > 0) {
                        while (x < xend) {
                                x++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        y++;
                                        d+=incr2;
                                }
                                dashedSet(im, x, y, color, &on, &dashStep);
                        }
                } else {
                        while (x < xend) {
                                x++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        y--;
                                        d+=incr2;
                                }
                                dashedSet(im, x, y, color, &on, &dashStep);
                        }
                }               
        } else {
                d = 2*dx - dy;
                incr1 = 2*dx;
                incr2 = 2 * (dx - dy);
                if (y1 > y2) {
                        y = y2;
                        x = x2;
                        yend = y1;
                        xdirflag = (-1);
                } else {
                        y = y1;
                        x = x1;
                        yend = y2;
                        xdirflag = 1;
                }
                dashedSet(im, x, y, color, &on, &dashStep);
                if (((x2 - x1) * xdirflag) > 0) {
                        while (y < yend) {
                                y++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        x++;
                                        d+=incr2;
                                }
                                dashedSet(im, x, y, color, &on, &dashStep);
                        }
                } else {
                        while (y < yend) {
                                y++;
                                if (d <0) {
                                        d+=incr1;
                                } else {
                                        x--;
                                        d+=incr2;
                                }
                                dashedSet(im, x, y, color, &on, &dashStep);
                        }
                }
        }
}

static void dashedSet(gdImagePtr im, int x, int y, int color,
        int *onP, int *dashStepP)
{
        int dashStep = *dashStepP;
        int on = *onP;
        dashStep++;
        if (dashStep == gdDashSize) {
                dashStep = 0;
                on = !on;
        }
        if (on) {
                gdImageSetPixel(im, x, y, color);
        }
        *dashStepP = dashStep;
        *onP = on;
}
        

int gdImageBoundsSafe(gdImagePtr im, int x, int y)
{
        return (!(((y < 0) || (y >= im->sy)) ||
                ((x < 0) || (x >= im->sx))));
}

void gdImageChar(gdImagePtr im, gdFontPtr f, int x, int y, 
        int c, int color)
{
        int cx, cy;
        int px, py;
        int fline;
        cx = 0;
        cy = 0;
        if ((c < f->offset) || (c >= (f->offset + f->nchars))) {
                return;
        }
        fline = (c - f->offset) * f->h * f->w;
        for (py = y; (py < (y + f->h)); py++) {
                for (px = x; (px < (x + f->w)); px++) {
                        if (f->data[fline + cy * f->w + cx]) {
                                gdImageSetPixel(im, px, py, color);     
                        }
                        cx++;
                }
                cx = 0;
                cy++;
        }
}

void gdImageCharUp(gdImagePtr im, gdFontPtr f, 
        int x, int y, int c, int color)
{
        int cx, cy;
        int px, py;
        int fline;
        cx = 0;
        cy = 0;
        if ((c < f->offset) || (c >= (f->offset + f->nchars))) {
                return;
        }
        fline = (c - f->offset) * f->h * f->w;
        for (py = y; (py > (y - f->w)); py--) {
                for (px = x; (px < (x + f->h)); px++) {
                        if (f->data[fline + cy * f->w + cx]) {
                                gdImageSetPixel(im, px, py, color);     
                        }
                        cy++;
                }
                cy = 0;
                cx++;
        }
}

void gdImageString(gdImagePtr im, gdFontPtr f, 
        int x, int y, unsigned char *s, int color)
{
        int i;
        int l;
        l = strlen((char *)s);
        for (i=0; (i<l); i++) {
                gdImageChar(im, f, x, y, s[i], color);
                x += f->w;
        }
}

void gdImageStringUp(gdImagePtr im, gdFontPtr f, 
        int x, int y, unsigned char *s, int color)
{
        int i;
        int l;
        l = strlen((char *)s);
        for (i=0; (i<l); i++) {
                gdImageCharUp(im, f, x, y, s[i], color);
                y -= f->w;
        }
}

static int strlen16(unsigned short *s);

void gdImageString16(gdImagePtr im, gdFontPtr f, 
        int x, int y, unsigned short *s, int color)
{
        int i;
        int l;
        l = strlen16(s);
        for (i=0; (i<l); i++) {
                gdImageChar(im, f, x, y, s[i], color);
                x += f->w;
        }
}

void gdImageStringUp16(gdImagePtr im, gdFontPtr f, 
        int x, int y, unsigned short *s, int color)
{
        int i;
        int l;
        l = strlen16(s);
        for (i=0; (i<l); i++) {
                gdImageCharUp(im, f, x, y, s[i], color);
                y -= f->w;
        }
}

static int strlen16(unsigned short *s)
{
        int len = 0;
        while (*s) {
                s++;
                len++;
        }
        return len;
}

/* s and e are integers modulo 360 (degrees), with 0 degrees
  being the rightmost extreme and degrees changing clockwise.
  cx and cy are the center in pixels; w and h are the horizontal 
  and vertical diameter in pixels. Nice interface, but slow, since
  I don't yet use Bresenham (I'm using an inefficient but
  simple solution with too much work going on in it; generalizing
  Bresenham to ellipses and partial arcs of ellipses is non-trivial,
  at least for me) and there are other inefficiencies (small circles
  do far too much work). */

void gdImageArc(gdImagePtr im, int cx, int cy, int w, int h, int s, int e, int color)
{
        int i;
        int lx = 0, ly = 0;
        int w2, h2;
        w2 = w/2;
        h2 = h/2;
        while (e < s) {
                e += 360;
        }
        for (i=s; (i <= e); i++) {
                int x, y;
                x = ((long)cost[i % 360] * (long)w2 / costScale) + cx; 
                y = ((long)sint[i % 360] * (long)h2 / sintScale) + cy;
                if (i != s) {
                        gdImageLine(im, lx, ly, x, y, color);   
                }
                lx = x;
                ly = y;
        }
}


#if 0
        /* Bresenham octant code, which I should use eventually */
        int x, y, d;
        x = 0;
        y = w;
        d = 3-2*w;
        while (x < y) {
                gdImageSetPixel(im, cx+x, cy+y, color);
                if (d < 0) {
                        d += 4 * x + 6;
                } else {
                        d += 4 * (x - y) + 10;
                        y--;
                }
                x++;
        }
        if (x == y) {
                gdImageSetPixel(im, cx+x, cy+y, color);
        }
#endif

void gdImageFillToBorder(gdImagePtr im, int x, int y, int border, int color)
{
        int lastBorder;
        /* Seek left */
        int leftLimit, rightLimit;
        int i;
        leftLimit = (-1);
        if (border < 0) {
                /* Refuse to fill to a non-solid border */
                return;
        }
        for (i = x; (i >= 0); i--) {
                if (gdImageGetPixel(im, i, y) == border) {
                        break;
                }
                gdImageSetPixel(im, i, y, color);
                leftLimit = i;
        }
        if (leftLimit == (-1)) {
                return;
        }
        /* Seek right */
        rightLimit = x;
        for (i = (x+1); (i < im->sx); i++) {    
                if (gdImageGetPixel(im, i, y) == border) {
                        break;
                }
                gdImageSetPixel(im, i, y, color);
                rightLimit = i;
        }
        /* Look at lines above and below and start paints */
        /* Above */
        if (y > 0) {
                lastBorder = 1;
                for (i = leftLimit; (i <= rightLimit); i++) {
                        int c;
                        c = gdImageGetPixel(im, i, y-1);
                        if (lastBorder) {
                                if ((c != border) && (c != color)) {    
                                        gdImageFillToBorder(im, i, y-1, 
                                                border, color);         
                                        lastBorder = 0;
                                }
                        } else if ((c == border) || (c == color)) {
                                lastBorder = 1;
                        }
                }
        }
        /* Below */
        if (y < ((im->sy) - 1)) {
                lastBorder = 1;
                for (i = leftLimit; (i <= rightLimit); i++) {
                        int c;
                        c = gdImageGetPixel(im, i, y+1);
                        if (lastBorder) {
                                if ((c != border) && (c != color)) {    
                                        gdImageFillToBorder(im, i, y+1, 
                                                border, color);         
                                        lastBorder = 0;
                                }
                        } else if ((c == border) || (c == color)) {
                                lastBorder = 1;
                        }
                }
        }
}

void gdImageFill(gdImagePtr im, int x, int y, int color)
{
        int lastBorder;
        int old;
        int leftLimit, rightLimit;
        int i;
        old = gdImageGetPixel(im, x, y);
        if (color == gdTiled) {
                /* Tile fill -- got to watch out! */
                int p, tileColor;       
                int srcx, srcy;
                if (!im->tile) {
                        return;
                }
                /* Refuse to flood-fill with a transparent pattern --
                        I can't do it without allocating another image */
                if (gdImageGetTransparent(im->tile) != (-1)) {
                        return;
                }       
                srcx = x % gdImageSX(im->tile);
                srcy = y % gdImageSY(im->tile);
                p = gdImageGetPixel(im->tile, srcx, srcy);
                tileColor = im->tileColorMap[p];
                if (old == tileColor) {
                        /* Nothing to be done */
                        return;
                }
        } else {
                if (old == color) {
                        /* Nothing to be done */
                        return;
                }
        }
        /* Seek left */
        leftLimit = (-1);
        for (i = x; (i >= 0); i--) {
                if (gdImageGetPixel(im, i, y) != old) {
                        break;
                }
                gdImageSetPixel(im, i, y, color);
                leftLimit = i;
        }
        if (leftLimit == (-1)) {
                return;
        }
        /* Seek right */
        rightLimit = x;
        for (i = (x+1); (i < im->sx); i++) {    
                if (gdImageGetPixel(im, i, y) != old) {
                        break;
                }
                gdImageSetPixel(im, i, y, color);
                rightLimit = i;
        }
        /* Look at lines above and below and start paints */
        /* Above */
        if (y > 0) {
                lastBorder = 1;
                for (i = leftLimit; (i <= rightLimit); i++) {
                        int c;
                        c = gdImageGetPixel(im, i, y-1);
                        if (lastBorder) {
                                if (c == old) { 
                                        gdImageFill(im, i, y-1, color);         
                                        lastBorder = 0;
                                }
                        } else if (c != old) {
                                lastBorder = 1;
                        }
                }
        }
        /* Below */
        if (y < ((im->sy) - 1)) {
                lastBorder = 1;
                for (i = leftLimit; (i <= rightLimit); i++) {
                        int c;
                        c = gdImageGetPixel(im, i, y+1);
                        if (lastBorder) {
                                if (c == old) {
                                        gdImageFill(im, i, y+1, color);         
                                        lastBorder = 0;
                                }
                        } else if (c != old) {
                                lastBorder = 1;
                        }
                }
        }
}
        
/* Code drawn from ppmtogif.c, from the pbmplus package
**
** Based on GIFENCOD by David Rowley <mgardi@watdscu.waterloo.edu>. A
** Lempel-Zim compression based on "compress".
**
** Modified by Marcel Wijkstra <wijkstra@fwi.uva.nl>
**
** Copyright (C) 1989 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation.  This software is provided "as is" without express or
** implied warranty.
**
** The Graphics Interchange Format(c) is the Copyright property of
** CompuServe Incorporated.  GIF(sm) is a Service Mark property of
** CompuServe Incorporated.
*
*  Heavily modified by Mouse, 1998-02-12.  
*  Remove LZW compression.
*  Added miGIF run length compression.
*
*/

/*
 * a code_int must be able to hold 2**GIFBITS values of type int, and also -1
 */
typedef int code_int;

static int colorstobpp(int colors);
static void BumpPixel (void);
static int GIFNextPixel (gdImagePtr im);
static void GIFEncode (FILE *fp, int GWidth, int GHeight, int GInterlace, int Background, int Transparent, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im);
static void Putword (int w, FILE *fp);
static void compress (int, FILE *, gdImagePtr, int);
static void output (code_int code);
static void char_init (void);
static void char_out (int c);
/* Allows for reuse */
static void init_statics(void);

void gdImageGif(gdImagePtr im, FILE *out)
{
        int interlace, transparent, BitsPerPixel;
        interlace = im->interlace;
        transparent = im->transparent;

        BitsPerPixel = colorstobpp(im->colorsTotal);
        /* Clear any old values in statics strewn through the GIF code */
        init_statics();
        /* All set, let's do it. */
        GIFEncode(
                out, im->sx, im->sy, interlace, 0, transparent, BitsPerPixel,
                im->red, im->green, im->blue, im);
}

static int
colorstobpp(int colors)
{
    int bpp = 0;

    if ( colors <= 2 )
        bpp = 1;
    else if ( colors <= 4 )
        bpp = 2;
    else if ( colors <= 8 )
        bpp = 3;
    else if ( colors <= 16 )
        bpp = 4;
    else if ( colors <= 32 )
        bpp = 5;
    else if ( colors <= 64 )
        bpp = 6;
    else if ( colors <= 128 )
        bpp = 7;
    else if ( colors <= 256 )
        bpp = 8;
    return bpp;
    }

/*****************************************************************************
 *
 * GIFENCODE.C    - GIF Image compression interface
 *
 * GIFEncode( FName, GHeight, GWidth, GInterlace, Background, Transparent,
 *            BitsPerPixel, Red, Green, Blue, gdImagePtr )
 *
 *****************************************************************************/

#define TRUE 1
#define FALSE 0

static int Width, Height;
static int curx, cury;
static long CountDown;
static int Pass = 0;
static int Interlace;

/*
 * Bump the 'curx' and 'cury' to point to the next pixel
 */
static void
BumpPixel(void)
{
        /*
         * Bump the current X position
         */
        ++curx;

        /*
         * If we are at the end of a scan line, set curx back to the beginning
         * If we are interlaced, bump the cury to the appropriate spot,
         * otherwise, just increment it.
         */
        if( curx == Width ) {
                curx = 0;

                if( !Interlace )
                        ++cury;
                else {
                     switch( Pass ) {

                       case 0:
                          cury += 8;
                          if( cury >= Height ) {
                                ++Pass;
                                cury = 4;
                          }
                          break;

                       case 1:
                          cury += 8;
                          if( cury >= Height ) {
                                ++Pass;
                                cury = 2;
                          }
                          break;

                       case 2:
                          cury += 4;
                          if( cury >= Height ) {
                             ++Pass;
                             cury = 1;
                          }
                          break;

                       case 3:
                          cury += 2;
                          break;
                        }
                }
        }
}

/*
 * Return the next pixel from the image
 */
static int
GIFNextPixel(gdImagePtr im)
{
        int r;

        if( CountDown == 0 )
                return EOF;

        --CountDown;

        r = gdImageGetPixel(im, curx, cury);

        BumpPixel();

        return r;
}

/* public */

static void
GIFEncode(FILE *fp, int GWidth, int GHeight, int GInterlace, int Background, int Transparent, int BitsPerPixel, int *Red, int *Green, int *Blue, gdImagePtr im)
{
        int B;
        int RWidth, RHeight;
        int LeftOfs, TopOfs;
        int Resolution;
        int ColorMapSize;
        int InitCodeSize;
        int i;

        Interlace = GInterlace;

        ColorMapSize = 1 << BitsPerPixel;

        RWidth = Width = GWidth;
        RHeight = Height = GHeight;
        LeftOfs = TopOfs = 0;

        Resolution = BitsPerPixel;

        /*
         * Calculate number of bits we are expecting
         */
        CountDown = (long)Width * (long)Height;

        /*
         * Indicate which pass we are on (if interlace)
         */
        Pass = 0;

        /*
         * The initial code size
         */
        if( BitsPerPixel <= 1 )
                InitCodeSize = 2;
        else
                InitCodeSize = BitsPerPixel;

        /*
         * Set up the current x and y position
         */
        curx = cury = 0;

        /*
         * Write the Magic header
         */
        fwrite( Transparent < 0 ? "GIF87a" : "GIF89a", 1, 6, fp );

        /*
         * Write out the screen width and height
         */
        Putword( RWidth, fp );
        Putword( RHeight, fp );

        /*
         * Indicate that there is a global colour map
         */
        B = 0x80;       /* Yes, there is a color map */

        /*
         * OR in the resolution
         */
        B |= (Resolution - 1) << 4;

        /*
         * OR in the Bits per Pixel
         */
        B |= (BitsPerPixel - 1);

        /*
         * Write it out
         */
        fputc( B, fp );

        /*
         * Write out the Background colour
         */
        fputc( Background, fp );

        /*
         * Byte of 0's (future expansion)
         */
        fputc( 0, fp );

        /*
         * Write out the Global Colour Map
         */
        for( i=0; i<ColorMapSize; ++i ) {
                fputc( Red[i], fp );
                fputc( Green[i], fp );
                fputc( Blue[i], fp );
        }

        /*
         * Write out extension for transparent colour index, if necessary.
         */
        if ( Transparent >= 0 ) {
            fputc( '!', fp );
            fputc( 0xf9, fp );
            fputc( 4, fp );
            fputc( 1, fp );
            fputc( 0, fp );
            fputc( 0, fp );
            fputc( (unsigned char) Transparent, fp );
            fputc( 0, fp );
        }

        /*
         * Write an Image separator
         */
        fputc( ',', fp );

        /*
         * Write the Image header
         */

        Putword( LeftOfs, fp );
        Putword( TopOfs, fp );
        Putword( Width, fp );
        Putword( Height, fp );

        /*
         * Write out whether or not the image is interlaced
         */
        if( Interlace )
                fputc( 0x40, fp );
        else
                fputc( 0x00, fp );

        /*
         * Write out the initial code size
         */
        fputc( InitCodeSize, fp );

        /*
         * Go and actually compress the data
         */
        compress( InitCodeSize+1, fp, im, Background );

        /*
         * Write out a Zero-length packet (to end the series)
         */
        fputc( 0, fp );

        /*
         * Write the GIF file terminator
         */
        fputc( ';', fp );
}

/*
 * Write out a word to the GIF file
 */
static void
Putword(int w, FILE *fp)
{
        fputc( w & 0xff, fp );
        fputc( (w / 256) & 0xff, fp );
}

#define GIFBITS 12

/*-----------------------------------------------------------------------
 *
 * miGIF Compression - mouse and ivo's GIF-compatible compression
 *
 *          -run length encoding compression routines-
 *
 * Copyright (C) 1998 Hutchison Avenue Software Corporation
 *               http://www.hasc.com
 *               info@hasc.com
 *
 * Permission to use, copy, modify, and distribute this software and its
 * documentation for any purpose and without fee is hereby granted, provided
 * that the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation.  This software is provided "AS IS." The Hutchison Avenue 
 * Software Corporation disclaims all warranties, either express or implied, 
 * including but not limited to implied warranties of merchantability and 
 * fitness for a particular purpose, with respect to this code and accompanying
 * documentation. 
 * 
 * The miGIF compression routines do not, strictly speaking, generate files 
 * conforming to the GIF spec, since the image data is not LZW-compressed 
 * (this is the point: in order to avoid transgression of the Unisys patent 
 * on the LZW algorithm.)  However, miGIF generates data streams that any 
 * reasonably sane LZW decompresser will decompress to what we want.
 *
 * miGIF compression uses run length encoding. It compresses horizontal runs 
 * of pixels of the same color. This type of compression gives good results
 * on images with many runs, for example images with lines, text and solid 
 * shapes on a solid-colored background. It gives little or no compression 
 * on images with few runs, for example digital or scanned photos.
 *
 *                               der Mouse
 *                      mouse@rodents.montreal.qc.ca
 *            7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B
 *
 *                             ivo@hasc.com
 *
 * The Graphics Interchange Format(c) is the Copyright property of
 * CompuServe Incorporated.  GIF(sm) is a Service Mark property of
 * CompuServe Incorporated.
 *
 */

static int rl_pixel;
static int rl_basecode;
static int rl_count;
static int rl_table_pixel;
static int rl_table_max;
static int just_cleared;
static int out_bits;
static int out_bits_init;
static int out_count;
static int out_bump;
static int out_bump_init;
static int out_clear;
static int out_clear_init;
static int max_ocodes;
static int code_clear;
static int code_eof;
static unsigned int obuf;
static int obits;
static FILE *ofile;
static unsigned char oblock[256];
static int oblen;

/* Used only when debugging GIF compression code */
/* #define DEBUGGING_ENVARS */

#ifdef DEBUGGING_ENVARS

static int verbose_set = 0;
static int verbose;
#define VERBOSE (verbose_set?verbose:set_verbose())

static int set_verbose(void)
{
 verbose = !!getenv("GIF_VERBOSE");
 verbose_set = 1;
 return(verbose);
}

#else

#define VERBOSE 0

#endif


static const char *binformat(unsigned int v, int nbits)
{
 static char bufs[8][64];
 static int bhand = 0;
 unsigned int bit;
 int bno;
 char *bp;

 bhand --;
 if (bhand < 0) bhand = (sizeof(bufs)/sizeof(bufs[0]))-1;
 bp = &bufs[bhand][0];
 for (bno=nbits-1,bit=1U<<bno;bno>=0;bno--,bit>>=1)
  { *bp++ = (v & bit) ? '1' : '0';
    if (((bno&3) == 0) && (bno != 0)) *bp++ = '.';
  }
 *bp = '\0';
 return(&bufs[bhand][0]);
}

static void write_block(void)
{
 int i;

 if (VERBOSE)
  { printf("write_block %d:",oblen);
    for (i=0;i<oblen;i++) printf(" %02x",oblock[i]);
    printf("\n");
  }
 fputc(oblen,ofile);
 fwrite(&oblock[0],1,oblen,ofile);
 oblen = 0;
}

static void block_out(unsigned char c)
{
 if (VERBOSE) printf("block_out %s\n",binformat(c,8));
 oblock[oblen++] = c;
 if (oblen >= 255) write_block();
}

static void block_flush(void)
{
 if (VERBOSE) printf("block_flush\n");
 if (oblen > 0) write_block();
}

static void output(int val)
{
 if (VERBOSE) printf("output %s [%s %d %d]\n",binformat(val,out_bits),binformat(obuf,obits),obits,out_bits);
 obuf |= val << obits;
 obits += out_bits;
 while (obits >= 8)
  { block_out(obuf&0xff);
    obuf >>= 8;
    obits -= 8;
  }
 if (VERBOSE) printf("output leaving [%s %d]\n",binformat(obuf,obits),obits);
}

static void output_flush(void)
{
 if (VERBOSE) printf("output_flush\n");
 if (obits > 0) block_out(obuf);
 block_flush();
}

static void did_clear(void)
{
 if (VERBOSE) printf("did_clear\n");
 out_bits = out_bits_init;
 out_bump = out_bump_init;
 out_clear = out_clear_init;
 out_count = 0;
 rl_table_max = 0;
 just_cleared = 1;
}

static void output_plain(int c)
{
 if (VERBOSE) printf("output_plain %s\n",binformat(c,out_bits));
 just_cleared = 0;
 output(c);
 out_count ++;
 if (out_count >= out_bump)
  { out_bits ++;
    out_bump += 1 << (out_bits - 1);
  }
 if (out_count >= out_clear)
  { output(code_clear);
    did_clear();
  }
}

static unsigned int isqrt(unsigned int) __attribute__((__const__));
static unsigned int isqrt(unsigned int x)
{
 unsigned int r;
 unsigned int v;

 if (x < 2) return(x);
 for (v=x,r=1;v;v>>=2,r<<=1) ;
 while (1)
  { v = ((x / r) + r) / 2;
    if ((v == r) || (v == r+1)) return(r);
    r = v;
  }
}

static unsigned int compute_triangle_count(unsigned int count, unsigned int nrepcodes)
{
 unsigned int perrep;
 unsigned int cost;

 cost = 0;
 perrep = (nrepcodes * (nrepcodes+1)) / 2;
 while (count >= perrep)
  { cost += nrepcodes;
    count -= perrep;
  }
 if (count > 0)
  { unsigned int n;
    n = isqrt(count);
    while ((n*(n+1)) >= 2*count) n --;
    while ((n*(n+1)) < 2*count) n ++;
    cost += n;
  }
 return(cost);
}

static void max_out_clear(void)
{
 out_clear = max_ocodes;
}

static void reset_out_clear(void)
{
 out_clear = out_clear_init;
 if (out_count >= out_clear)
  { output(code_clear);
    did_clear();
  }
}

static void rl_flush_fromclear(int count)
{
 int n;

 if (VERBOSE) printf("rl_flush_fromclear %d\n",count);
 max_out_clear();
 rl_table_pixel = rl_pixel;
 n = 1;
 while (count > 0)
  { if (n == 1)
     { rl_table_max = 1;
       output_plain(rl_pixel);
       count --;
     }
    else if (count >= n)
     { rl_table_max = n;
       output_plain(rl_basecode+n-2);
       count -= n;
     }
    else if (count == 1)
     { rl_table_max ++;
       output_plain(rl_pixel);
       count = 0;
     }
    else
     { rl_table_max ++;
       output_plain(rl_basecode+count-2);
       count = 0;
     }
    if (out_count == 0) n = 1; else n ++;
  }
 reset_out_clear();
 if (VERBOSE) printf("rl_flush_fromclear leaving table_max=%d\n",rl_table_max);
}

static void rl_flush_clearorrep(int count)
{
 int withclr;

 if (VERBOSE) printf("rl_flush_clearorrep %d\n",count);
 withclr = 1 + compute_triangle_count(count,max_ocodes);
 if (withclr < count)
  { output(code_clear);
    did_clear();
    rl_flush_fromclear(count);
  }
 else
  { for (;count>0;count--) output_plain(rl_pixel);
  }
}

static void rl_flush_withtable(int count)
{
 int repmax;
 int repleft;
 int leftover;

 if (VERBOSE) printf("rl_flush_withtable %d\n",count);
 repmax = count / rl_table_max;
 leftover = count % rl_table_max;
 repleft = (leftover ? 1 : 0);
 if (out_count+repmax+repleft > max_ocodes)
  { repmax = max_ocodes - out_count;
    leftover = count - (repmax * rl_table_max);
    repleft = 1 + compute_triangle_count(leftover,max_ocodes);
  }
 if (VERBOSE) printf("rl_flush_withtable repmax=%d leftover=%d repleft=%d\n",repmax,leftover,repleft);
 if (1+compute_triangle_count(count,max_ocodes) < repmax+repleft)
  { output(code_clear);
    did_clear();
    rl_flush_fromclear(count);
    return;
  }
 max_out_clear();
 for (;repmax>0;repmax--) output_plain(rl_basecode+rl_table_max-2);
 if (leftover)
  { if (just_cleared)
     { rl_flush_fromclear(leftover);
     }
    else if (leftover == 1)
     { output_plain(rl_pixel);
     }
    else
     { output_plain(rl_basecode+leftover-2);
     }
  }
 reset_out_clear();
}

static void rl_flush(void)
{
 int table_reps;
 int table_extra;

 if (VERBOSE) printf("rl_flush [ %d %d\n",rl_count,rl_pixel);
 if (rl_count == 1)
  { output_plain(rl_pixel);
    rl_count = 0;
    if (VERBOSE) printf("rl_flush ]\n");
    return;
  }
 if (just_cleared)
  { rl_flush_fromclear(rl_count);
  }
 else if ((rl_table_max < 2) || (rl_table_pixel != rl_pixel))
  { rl_flush_clearorrep(rl_count);
  }
 else
  { rl_flush_withtable(rl_count);
  }
 if (VERBOSE) printf("rl_flush ]\n");
 rl_count = 0;
}

static void compress(int init_bits, FILE *outfile, gdImagePtr im, int background)
{
 int c;

 ofile = outfile;
 obuf = 0;
 obits = 0;
 oblen = 0;
 code_clear = 1 << (init_bits - 1);
 code_eof = code_clear + 1;
 rl_basecode = code_eof + 1;
 out_bump_init = (1 << (init_bits - 1)) - 1;
 /* for images with a lot of runs, making out_clear_init larger will
    give better compression. */ 
 out_clear_init = (init_bits <= 3) ? 9 : (out_bump_init-1);
#ifdef DEBUGGING_ENVARS
  { const char *ocienv;
    ocienv = getenv("GIF_OUT_CLEAR_INIT");
    if (ocienv)
     { out_clear_init = atoi(ocienv);
       if (VERBOSE) printf("[overriding out_clear_init to %d]\n",out_clear_init);
     }
  }
#endif
 out_bits_init = init_bits;
 max_ocodes = (1 << GIFBITS) - ((1 << (out_bits_init - 1)) + 3);
 did_clear();
 output(code_clear);
 rl_count = 0;
 while (1)
  { c = GIFNextPixel(im);
    if ((rl_count > 0) && (c != rl_pixel)) rl_flush();
    if (c == EOF) break;
    if (rl_pixel == c)
     { rl_count ++;
     }
    else
     { rl_pixel = c;
       rl_count = 1;
     }
  }
 output(code_eof);
 output_flush();
}

/*-----------------------------------------------------------------------
 *
 * End of miGIF section  - See copyright notice at start of section.
 *
/*-----------------------------------------------------------------------


/******************************************************************************
 *
 * GIF Specific routines
 *
 ******************************************************************************/

/*
 * Number of characters so far in this 'packet'
 */
static int a_count;

/*
 * Set up the 'byte output' routine
 */
static void
char_init(void)
{
        a_count = 0;
}

/*
 * Define the storage for the packet accumulator
 */
static char accum[ 256 ];

static void init_statics(void) {
        /* Some of these are properly initialized later. What I'm doing
                here is making sure code that depends on C's initialization
                of statics doesn't break when the code gets called more
                than once. */
        Width = 0;
        Height = 0;
        curx = 0;
        cury = 0;
        CountDown = 0;
        Pass = 0;
        Interlace = 0;
        a_count = 0;
}


/* +-------------------------------------------------------------------+ */
/* | Copyright 1990, 1991, 1993, David Koblas.  (koblas@netcom.com)    | */
/* |   Permission to use, copy, modify, and distribute this software   | */
/* |   and its documentation for any purpose and without fee is hereby | */
/* |   granted, provided that the above copyright notice appear in all | */
/* |   copies and that both that copyright notice and this permission  | */
/* |   notice appear in supporting documentation.  This software is    | */
/* |   provided "as is" without express or implied warranty.           | */
/* +-------------------------------------------------------------------+ */


#define        MAXCOLORMAPSIZE         256

#define        TRUE    1
#define        FALSE   0

#define CM_RED         0
#define CM_GREEN       1
#define CM_BLUE                2

#define        MAX_LWZ_BITS            12

#define INTERLACE              0x40
#define LOCALCOLORMAP  0x80
#define BitSet(byte, bit)      (((byte) & (bit)) == (bit))

#define        ReadOK(file,buffer,len) (fread(buffer, len, 1, file) != 0)

#define LM_to_uint(a,b)                        (((b)<<8)|(a))

/* We may eventually want to use this information, but def it out for now */
#if 0
static struct {
       unsigned int    Width;
       unsigned int    Height;
       unsigned char   ColorMap[3][MAXCOLORMAPSIZE];
       unsigned int    BitPixel;
       unsigned int    ColorResolution;
       unsigned int    Background;
       unsigned int    AspectRatio;
} GifScreen;
#endif

static struct {
       int     transparent;
       int     delayTime;
       int     inputFlag;
       int     disposal;
} Gif89 = { -1, -1, -1, 0 };

static int ReadColorMap (FILE *fd, int number, unsigned char (*buffer)[256]);
static int DoExtension (FILE *fd, int label, int *Transparent);
static int GetDataBlock (FILE *fd, unsigned char *buf);
static int GetCode (FILE *fd, int code_size, int flag);
static int LWZReadByte (FILE *fd, int flag, int input_code_size);
static void ReadImage (gdImagePtr im, FILE *fd, int len, int height, unsigned char (*cmap)[256], int interlace, int ignore);

int ZeroDataBlock;

gdImagePtr
gdImageCreateFromGif(FILE *fd)
{
       int imageNumber;
       int BitPixel;
       int ColorResolution;
       int Background;
       int AspectRatio;
       int Transparent = (-1);
       unsigned char   buf[16];
       unsigned char   c;
       unsigned char   ColorMap[3][MAXCOLORMAPSIZE];
       unsigned char   localColorMap[3][MAXCOLORMAPSIZE];
       int             imw, imh;
       int             useGlobalColormap;
       int             bitPixel;
       int             imageCount = 0;
       char            version[4];
       gdImagePtr im = 0;
       ZeroDataBlock = FALSE;

       imageNumber = 1;
       if (! ReadOK(fd,buf,6)) {
                return 0;
        }
       if (strncmp((char *)buf,"GIF",3) != 0) {
                return 0;
        }
       strncpy(version, (char *)buf + 3, 3);
       version[3] = '\0';

       if ((strcmp(version, "87a") != 0) && (strcmp(version, "89a") != 0)) {
                return 0;
        }
       if (! ReadOK(fd,buf,7)) {
                return 0;
        }
       BitPixel        = 2<<(buf[4]&0x07);
       ColorResolution = (int) (((buf[4]&0x70)>>3)+1);
       Background      = buf[5];
       AspectRatio     = buf[6];

       if (BitSet(buf[4], LOCALCOLORMAP)) {    /* Global Colormap */
               if (ReadColorMap(fd, BitPixel, ColorMap)) {
                        return 0;
                }
       }
       for (;;) {
               if (! ReadOK(fd,&c,1)) {
                       return 0;
               }
               if (c == ';') {         /* GIF terminator */
                       int i;
                       if (imageCount < imageNumber) {
                               return 0;
                       }
                       /* Terminator before any image was declared! */
                       if (!im) {
                              return 0;
                       }
                       /* Check for open colors at the end, so
                          we can reduce colorsTotal and ultimately
                          BitsPerPixel */
                       for (i=((im->colorsTotal-1)); (i>=0); i--) {
                               if (im->open[i]) {
                                       im->colorsTotal--;
                               } else {
                                       break;
                               }
                       } 
                       return im;
               }

               if (c == '!') {         /* Extension */
                       if (! ReadOK(fd,&c,1)) {
                               return 0;
                       }
                       DoExtension(fd, c, &Transparent);
                       continue;
               }

               if (c != ',') {         /* Not a valid start character */
                       continue;
               }

               ++imageCount;

               if (! ReadOK(fd,buf,9)) {
                       return 0;
               }

               useGlobalColormap = ! BitSet(buf[8], LOCALCOLORMAP);

               bitPixel = 1<<((buf[8]&0x07)+1);

               imw = LM_to_uint(buf[4],buf[5]);
               imh = LM_to_uint(buf[6],buf[7]);
               if (!(im = gdImageCreate(imw, imh))) {
                         return 0;
               }
               im->interlace = BitSet(buf[8], INTERLACE);
               if (! useGlobalColormap) {
                       if (ReadColorMap(fd, bitPixel, localColorMap)) { 
                                 return 0;
                       }
                       ReadImage(im, fd, imw, imh, localColorMap, 
                                 BitSet(buf[8], INTERLACE), 
                                 imageCount != imageNumber);
               } else {
                       ReadImage(im, fd, imw, imh,
                                 ColorMap, 
                                 BitSet(buf[8], INTERLACE), 
                                 imageCount != imageNumber);
               }
               if (Transparent != (-1)) {
                       gdImageColorTransparent(im, Transparent);
               }           
       }
}

static int
ReadColorMap(FILE *fd, int number, unsigned char (*buffer)[256])
{
       int             i;
       unsigned char   rgb[3];


       for (i = 0; i < number; ++i) {
               if (! ReadOK(fd, rgb, sizeof(rgb))) {
                       return TRUE;
               }
               buffer[CM_RED][i] = rgb[0] ;
               buffer[CM_GREEN][i] = rgb[1] ;
               buffer[CM_BLUE][i] = rgb[2] ;
       }


       return FALSE;
}

static int
DoExtension(FILE *fd, int label, int *Transparent)
{
       static unsigned char     buf[256];

       switch (label) {
       case 0xf9:              /* Graphic Control Extension */
               (void) GetDataBlock(fd, (unsigned char*) buf);
               Gif89.disposal    = (buf[0] >> 2) & 0x7;
               Gif89.inputFlag   = (buf[0] >> 1) & 0x1;
               Gif89.delayTime   = LM_to_uint(buf[1],buf[2]);
               if ((buf[0] & 0x1) != 0)
                       *Transparent = buf[3];

               while (GetDataBlock(fd, (unsigned char*) buf) != 0)
                       ;
               return FALSE;
       default:
               break;
       }
       while (GetDataBlock(fd, (unsigned char*) buf) != 0)
               ;

       return FALSE;
}

static int
GetDataBlock_(FILE *fd, unsigned char *buf)
{
       unsigned char   count;

       if (! ReadOK(fd,&count,1)) {
               return -1;
       }

       ZeroDataBlock = count == 0;

       if ((count != 0) && (! ReadOK(fd, buf, count))) {
               return -1;
       }

       return count;
}

static int
GetDataBlock(FILE *fd, unsigned char *buf)
{
 int rv;
 int i;

 rv = GetDataBlock_(fd,buf);
 if (VERBOSE)
  { printf("[GetDataBlock returning %d",rv);
    if (rv > 0)
     { printf(":");
       for (i=0;i<rv;i++) printf(" %02x",buf[i]);
     }
    printf("]\n");
  }
 return(rv);
}

static int
GetCode_(FILE *fd, int code_size, int flag)
{
       static unsigned char    buf[280];
       static int              curbit, lastbit, done, last_byte;
       int                     i, j, ret;
       unsigned char           count;

       if (flag) {
               curbit = 0;
               lastbit = 0;
               done = FALSE;
               return 0;
       }

       if ( (curbit+code_size) >= lastbit) {
               if (done) {
                       if (curbit >= lastbit) {
                                /* Oh well */
                       }                        
                       return -1;
               }
               buf[0] = buf[last_byte-2];
               buf[1] = buf[last_byte-1];

               if ((count = GetDataBlock(fd, &buf[2])) == 0)
                       done = TRUE;

               last_byte = 2 + count;
               curbit = (curbit - lastbit) + 16;
               lastbit = (2+count)*8 ;
       }

       ret = 0;
       for (i = curbit, j = 0; j < code_size; ++i, ++j)
               ret |= ((buf[ i / 8 ] & (1 << (i % 8))) != 0) << j;

       curbit += code_size;
       return ret;
}

static int
GetCode(FILE *fd, int code_size, int flag)
{
 int rv;

 rv = GetCode_(fd,code_size,flag);
 if (VERBOSE) printf("[GetCode(,%d,%d) returning %d]\n",code_size,flag,rv);
 return(rv);
}

static int
LWZReadByte_(FILE *fd, int flag, int input_code_size)
{
       static int      fresh = FALSE;
       int             code, incode;
       static int      code_size, set_code_size;
       static int      max_code, max_code_size;
       static int      firstcode, oldcode;
       static int      clear_code, end_code;
       static int      table[2][(1<< MAX_LWZ_BITS)];
       static int      stack[(1<<(MAX_LWZ_BITS))*2], *sp;
       register int    i;

       if (flag) {
               set_code_size = input_code_size;
               code_size = set_code_size+1;
               clear_code = 1 << set_code_size ;
               end_code = clear_code + 1;
               max_code_size = 2*clear_code;
               max_code = clear_code+2;

               GetCode(fd, 0, TRUE);
               
               fresh = TRUE;

               for (i = 0; i < clear_code; ++i) {
                       table[0][i] = 0;
                       table[1][i] = i;
               }
               for (; i < (1<<MAX_LWZ_BITS); ++i)
                       table[0][i] = table[1][0] = 0;

               sp = stack;

               return 0;
       } else if (fresh) {
               fresh = FALSE;
               do {
                       firstcode = oldcode =
                               GetCode(fd, code_size, FALSE);
               } while (firstcode == clear_code);
               return firstcode;
       }

       if (sp > stack)
               return *--sp;

       while ((code = GetCode(fd, code_size, FALSE)) >= 0) {
               if (code == clear_code) {
                       for (i = 0; i < clear_code; ++i) {
                               table[0][i] = 0;
                               table[1][i] = i;
                       }
                       for (; i < (1<<MAX_LWZ_BITS); ++i)
                               table[0][i] = table[1][i] = 0;
                       code_size = set_code_size+1;
                       max_code_size = 2*clear_code;
                       max_code = clear_code+2;
                       sp = stack;
                       firstcode = oldcode =
                                       GetCode(fd, code_size, FALSE);
                       return firstcode;
               } else if (code == end_code) {
                       int             count;
                       unsigned char   buf[260];

                       if (ZeroDataBlock)
                               return -2;

                       while ((count = GetDataBlock(fd, buf)) > 0)
                               ;

                       if (count != 0)
                       return -2;
               }

               incode = code;

               if (code >= max_code) {
                       *sp++ = firstcode;
                       code = oldcode;
               }

               while (code >= clear_code) {
                       *sp++ = table[1][code];
                       if (code == table[0][code]) {
                               /* Oh well */
                       }
                       code = table[0][code];
               }

               *sp++ = firstcode = table[1][code];

               if ((code = max_code) <(1<<MAX_LWZ_BITS)) {
                       table[0][code] = oldcode;
                       table[1][code] = firstcode;
                       ++max_code;
                       if ((max_code >= max_code_size) &&
                               (max_code_size < (1<<MAX_LWZ_BITS))) {
                               max_code_size *= 2;
                               ++code_size;
                       }
               }

               oldcode = incode;

               if (sp > stack)
                       return *--sp;
       }
       return code;
}

static int
LWZReadByte(FILE *fd, int flag, int input_code_size)
{
 int rv;

 rv = LWZReadByte_(fd,flag,input_code_size);
 if (VERBOSE) printf("[LWZReadByte(,%d,%d) returning %d]\n",flag,input_code_size,rv);
 return(rv);
}

static void
ReadImage(gdImagePtr im, FILE *fd, int len, int height, unsigned char (*cmap)[256], int interlace, int ignore)
{
       unsigned char   c;      
       int             v;
       int             xpos = 0, ypos = 0, pass = 0;
       int i;
       /* Stash the color map into the image */
       for (i=0; (i<gdMaxColors); i++) {
               im->red[i] = cmap[CM_RED][i];    
               im->green[i] = cmap[CM_GREEN][i];        
               im->blue[i] = cmap[CM_BLUE][i];  
               im->open[i] = 1;
       }
       /* Many (perhaps most) of these colors will remain marked open. */
       im->colorsTotal = gdMaxColors;
       /*
       **  Initialize the Compression routines
       */
       if (! ReadOK(fd,&c,1)) {
               return; 
       }
       if (LWZReadByte(fd, TRUE, c) < 0) {
               return;
       }

       /*
       **  If this is an "uninteresting picture" ignore it.
       */
       if (ignore) {
               while (LWZReadByte(fd, FALSE, c) >= 0)
                       ;
               return;
       }

       while ((v = LWZReadByte(fd,FALSE,c)) >= 0 ) {
               /* This how we recognize which colors are actually used. */
               if (im->open[v]) {
                       im->open[v] = 0;
               }
               gdImageSetPixel(im, xpos, ypos, v);
               ++xpos;
               if (xpos == len) {
                       xpos = 0;
                       if (interlace) {
                               switch (pass) {
                               case 0:
                               case 1:
                                       ypos += 8; break;
                               case 2:
                                       ypos += 4; break;
                               case 3:
                                       ypos += 2; break;
                               }

                               if (ypos >= height) {
                                       ++pass;
                                       switch (pass) {
                                       case 1:
                                               ypos = 4; break;
                                       case 2:
                                               ypos = 2; break;
                                       case 3:
                                               ypos = 1; break;
                                       default:
                                               goto fini;
                                       }
                               }
                       } else {
                               ++ypos;
                       }
               }
               if (ypos >= height)
                       break;
       }

fini:
       if (LWZReadByte(fd,FALSE,c)>=0) {
               /* Ignore extra */
       }
}

void gdImageRectangle(gdImagePtr im, int x1, int y1, int x2, int y2, int color)
{
        gdImageLine(im, x1, y1, x2, y1, color);         
        gdImageLine(im, x1, y2, x2, y2, color);         
        gdImageLine(im, x1, y1, x1, y2, color);
        gdImageLine(im, x2, y1, x2, y2, color);
}

void gdImageFilledRectangle(gdImagePtr im, int x1, int y1, int x2, int y2, int color)
{
        int x, y;
        for (y=y1; (y<=y2); y++) {
                for (x=x1; (x<=x2); x++) {
                        gdImageSetPixel(im, x, y, color);
                }
        }
}

void gdImageCopy(gdImagePtr dst, gdImagePtr src, int dstX, int dstY, int srcX, int srcY, int w, int h)
{
        int c;
        int x, y;
        int tox, toy;
        int i;
        int colorMap[gdMaxColors];
        for (i=0; (i<gdMaxColors); i++) {
                colorMap[i] = (-1);
        }
        toy = dstY;
        for (y=srcY; (y < (srcY + h)); y++) {
                tox = dstX;
                for (x=srcX; (x < (srcX + w)); x++) {
                        int nc;
                        c = gdImageGetPixel(src, x, y);
                        /* Added 7/24/95: support transparent copies */
                        if (gdImageGetTransparent(src) == c) {
                                tox++;
                                continue;
                        }
                        /* Have we established a mapping for this color? */
                        if (colorMap[c] == (-1)) {
                                /* If it's the same image, mapping is trivial */
                                if (dst == src) {
                                        nc = c;
                                } else { 
                                        /* First look for an exact match */
                                        nc = gdImageColorExact(dst,
                                                src->red[c], src->green[c],
                                                src->blue[c]);
                                }       
                                if (nc == (-1)) {
                                        /* No, so try to allocate it */
                                        nc = gdImageColorAllocate(dst,
                                                src->red[c], src->green[c],
                                                src->blue[c]);
                                        /* If we're out of colors, go for the
                                                closest color */
                                        if (nc == (-1)) {
                                                nc = gdImageColorClosest(dst,
                                                        src->red[c], src->green[c],
                                                        src->blue[c]);
                                        }
                                }
                                colorMap[c] = nc;
                        }
                        gdImageSetPixel(dst, tox, toy, colorMap[c]);
                        tox++;
                }
                toy++;
        }
}                       

void gdImageCopyResized(gdImagePtr dst, gdImagePtr src, int dstX, int dstY, int srcX, int srcY, int dstW, int dstH, int srcW, int srcH)
{
        int c;
        int x, y;
        int tox, toy;
        int ydest;
        int i;
        int colorMap[gdMaxColors];
        /* Stretch vectors */
        int *stx;
        int *sty;
        /* We only need to use floating point to determine the correct
                stretch vector for one line's worth. */
        double accum;
        stx = (int *) malloc(sizeof(int) * srcW);
        sty = (int *) malloc(sizeof(int) * srcH);
        accum = 0;
        for (i=0; (i < srcW); i++) {
                int got;
                accum += (double)dstW/(double)srcW;
                got = floor(accum);
                stx[i] = got;
                accum -= got;
        }
        accum = 0;
        for (i=0; (i < srcH); i++) {
                int got;
                accum += (double)dstH/(double)srcH;
                got = floor(accum);
                sty[i] = got;
                accum -= got;
        }
        for (i=0; (i<gdMaxColors); i++) {
                colorMap[i] = (-1);
        }
        toy = dstY;
        for (y=srcY; (y < (srcY + srcH)); y++) {
                for (ydest=0; (ydest < sty[y-srcY]); ydest++) {
                        tox = dstX;
                        for (x=srcX; (x < (srcX + srcW)); x++) {
                                int nc;
                                if (!stx[x - srcX]) {
                                        continue;
                                }
                                c = gdImageGetPixel(src, x, y);
                                /* Added 7/24/95: support transparent copies */
                                if (gdImageGetTransparent(src) == c) {
                                        tox += stx[x-srcX];
                                        continue;
                                }
                                /* Have we established a mapping for this color? */
                                if (colorMap[c] == (-1)) {
                                        /* If it's the same image, mapping is trivial */
                                        if (dst == src) {
                                                nc = c;
                                        } else { 
                                                /* First look for an exact match */
                                                nc = gdImageColorExact(dst,
                                                        src->red[c], src->green[c],
                                                        src->blue[c]);
                                        }       
                                        if (nc == (-1)) {
                                                /* No, so try to allocate it */
                                                nc = gdImageColorAllocate(dst,
                                                        src->red[c], src->green[c],
                                                        src->blue[c]);
                                                /* If we're out of colors, go for the
                                                        closest color */
                                                if (nc == (-1)) {
                                                        nc = gdImageColorClosest(dst,
                                                                src->red[c], src->green[c],
                                                                src->blue[c]);
                                                }
                                        }
                                        colorMap[c] = nc;
                                }
                                for (i=0; (i < stx[x - srcX]); i++) {
                                        gdImageSetPixel(dst, tox, toy, colorMap[c]);
                                        tox++;
                                }
                        }
                        toy++;
                }
        }
        free(stx);
        free(sty);
}

int gdGetWord(int *result, FILE *in)
{
        int r;
        r = getc(in);
        if (r == EOF) {
                return 0;
        }
        *result = r << 8;
        r = getc(in);   
        if (r == EOF) {
                return 0;
        }
        *result += r;
        return 1;
}

void gdPutWord(int w, FILE *out)
{
        putc((unsigned char)(w >> 8), out);
        putc((unsigned char)(w & 0xFF), out);
}

int gdGetByte(int *result, FILE *in)
{
        int r;
        r = getc(in);
        if (r == EOF) {
                return 0;
        }
        *result = r;
        return 1;
}

gdImagePtr gdImageCreateFromGd(FILE *in)
{
        int sx, sy;
        int x, y;
        int i;
        gdImagePtr im;
        if (!gdGetWord(&sx, in)) {
                goto fail1;
        }
        if (!gdGetWord(&sy, in)) {
                goto fail1;
        }
        im = gdImageCreate(sx, sy);
        if (!gdGetByte(&im->colorsTotal, in)) {
                goto fail2;
        }
        if (!gdGetWord(&im->transparent, in)) {
                goto fail2;
        }
        if (im->transparent == 257) {
                im->transparent = (-1);
        }
        for (i=0; (i<gdMaxColors); i++) {
                if (!gdGetByte(&im->red[i], in)) {
                        goto fail2;
                }
                if (!gdGetByte(&im->green[i], in)) {
                        goto fail2;
                }
                if (!gdGetByte(&im->blue[i], in)) {
                        goto fail2;
                }
        }       
        for (y=0; (y<sy); y++) {
                for (x=0; (x<sx); x++) {        
                        int ch;
                        ch = getc(in);
                        if (ch == EOF) {
                                gdImageDestroy(im);
                                return 0;
                        }
                        /* ROW-MAJOR IN GD 1.3 */
                        im->pixels[y][x] = ch;
                }
        }
        return im;
fail2:
        gdImageDestroy(im);
fail1:
        return 0;
}
        
void gdImageGd(gdImagePtr im, FILE *out)
{
        int x, y;
        int i;
        int trans;
        gdPutWord(im->sx, out);
        gdPutWord(im->sy, out);
        putc((unsigned char)im->colorsTotal, out);
        trans = im->transparent;
        if (trans == (-1)) {
                trans = 257;
        }       
        gdPutWord(trans, out);
        for (i=0; (i<gdMaxColors); i++) {
                putc((unsigned char)im->red[i], out);
                putc((unsigned char)im->green[i], out); 
                putc((unsigned char)im->blue[i], out);  
        }
        for (y=0; (y < im->sy); y++) {  
                for (x=0; (x < im->sx); x++) {  
                        /* ROW-MAJOR IN GD 1.3 */
                        putc((unsigned char)im->pixels[y][x], out);
                }
        }
}

gdImagePtr
gdImageCreateFromXbm(FILE *fd)
{
        gdImagePtr im;  
        int bit;
        int w, h;
        int bytes;
        int ch;
        int i, x, y;
        char *sp;
        char s[161];
        if (!fgets(s, 160, fd)) {
                return 0;
        }
        sp = &s[0];
        /* Skip #define */
        sp = strchr(sp, ' ');
        if (!sp) {
                return 0;
        }
        /* Skip width label */
        sp++;
        sp = strchr(sp, ' ');
        if (!sp) {
                return 0;
        }
        /* Get width */
        w = atoi(sp + 1);
        if (!w) {
                return 0;
        }
        if (!fgets(s, 160, fd)) {
                return 0;
        }
        sp = s;
        /* Skip #define */
        sp = strchr(sp, ' ');
        if (!sp) {
                return 0;
        }
        /* Skip height label */
        sp++;
        sp = strchr(sp, ' ');
        if (!sp) {
                return 0;
        }
        /* Get height */
        h = atoi(sp + 1);
        if (!h) {
                return 0;
        }
        /* Skip declaration line */
        if (!fgets(s, 160, fd)) {
                return 0;
        }
        bytes = (w * h / 8) + 1;
        im = gdImageCreate(w, h);
        gdImageColorAllocate(im, 255, 255, 255);
        gdImageColorAllocate(im, 0, 0, 0);
        x = 0;
        y = 0;
        for (i=0; (i < bytes); i++) {
                char h[3];
                int b;
                /* Skip spaces, commas, CRs, 0x */
                while(1) {
                        ch = getc(fd);
                        if (ch == EOF) {
                                goto fail;
                        }
                        if (ch == 'x') {
                                break;
                        }       
                }
                /* Get hex value */
                ch = getc(fd);
                if (ch == EOF) {
                        goto fail;
                }
                h[0] = ch;
                ch = getc(fd);
                if (ch == EOF) {
                        goto fail;
                }
                h[1] = ch;
                h[2] = '\0';
                sscanf(h, "%x", &b);            
                for (bit = 1; (bit <= 128); (bit = bit << 1)) {
                        gdImageSetPixel(im, x++, y, (b & bit) ? 1 : 0); 
                        if (x == im->sx) {
                                x = 0;
                                y++;
                                if (y == im->sy) {
                                        return im;
                                }
                                /* Fix 8/8/95 */
                                break;
                        }
                }
        }
        /* Shouldn't happen */
        fprintf(stderr, "Error: bug in gdImageCreateFromXbm!\n");
        return 0;
fail:
        gdImageDestroy(im);
        return 0;
}

void gdImagePolygon(gdImagePtr im, gdPointPtr p, int n, int c)
{
        int i;
        int lx, ly;
        if (!n) {
                return;
        }
        lx = p->x;
        ly = p->y;
        gdImageLine(im, lx, ly, p[n-1].x, p[n-1].y, c);
        for (i=1; (i < n); i++) {
                p++;
                gdImageLine(im, lx, ly, p->x, p->y, c);
                lx = p->x;
                ly = p->y;
        }
}       
        
int gdCompareInt(const void *a, const void *b);
        
void gdImageFilledPolygon(gdImagePtr im, gdPointPtr p, int n, int c)
{
        int i;
        int y;
        int y1, y2;
        int ints;
        if (!n) {
                return;
        }
        if (!im->polyAllocated) {
                im->polyInts = (int *) malloc(sizeof(int) * n);
                im->polyAllocated = n;
        }               
        if (im->polyAllocated < n) {
                while (im->polyAllocated < n) {
                        im->polyAllocated *= 2;
                }       
                im->polyInts = (int *) realloc(im->polyInts,
                        sizeof(int) * im->polyAllocated);
        }
        y1 = p[0].y;
        y2 = p[0].y;
        for (i=1; (i < n); i++) {
                if (p[i].y < y1) {
                        y1 = p[i].y;
                }
                if (p[i].y > y2) {
                        y2 = p[i].y;
                }
        }
        /* Fix in 1.3: count a vertex only once */
        for (y=y1; (y < y2); y++) {
                int interLast = 0;
                int dirLast = 0;
                int interFirst = 1;
                ints = 0;
                for (i=0; (i <= n); i++) {
                        int x1, x2;
                        int y1, y2;
                        int dir;
                        int ind1, ind2;
                        int lastInd1 = 0;
                        if ((i == n) || (!i)) {
                                ind1 = n-1;
                                ind2 = 0;
                        } else {
                                ind1 = i-1;
                                ind2 = i;
                        }
                        y1 = p[ind1].y;
                        y2 = p[ind2].y;
                        if (y1 < y2) {
                                y1 = p[ind1].y;
                                y2 = p[ind2].y;
                                x1 = p[ind1].x;
                                x2 = p[ind2].x;
                                dir = -1;
                        } else if (y1 > y2) {
                                y2 = p[ind1].y;
                                y1 = p[ind2].y;
                                x2 = p[ind1].x;
                                x1 = p[ind2].x;
                                dir = 1;
                        } else {
                                /* Horizontal; just draw it */
                                gdImageLine(im, 
                                        p[ind1].x, y1, 
                                        p[ind2].x, y1,
                                        c);
                                continue;
                        }
                        if ((y >= y1) && (y <= y2)) {
                                int inter = 
                                        (y-y1) * (x2-x1) / (y2-y1) + x1;
                                /* Only count intersections once
                                        except at maxima and minima. Also, 
                                        if two consecutive intersections are
                                        endpoints of the same horizontal line
                                        that is not at a maxima or minima,      
                                        discard the leftmost of the two. */
                                if (!interFirst) {
                                        if ((p[ind1].y == p[lastInd1].y) &&
                                                (p[ind1].x != p[lastInd1].x)) {
                                                if (dir == dirLast) {
                                                        if (inter > interLast) {
                                                                /* Replace the old one */
                                                                im->polyInts[ints] = inter;
                                                        } else {
                                                                /* Discard this one */
                                                        }       
                                                        continue;
                                                }
                                        }
                                        if (inter == interLast) {
                                                if (dir == dirLast) {
                                                        continue;
                                                }
                                        }
                                } 
                                if (i > 0) {
                                        im->polyInts[ints++] = inter;
                                }
                                lastInd1 = i;
                                dirLast = dir;
                                interLast = inter;
                                interFirst = 0;
                        }
                }
                qsort(im->polyInts, ints, sizeof(int), gdCompareInt);
                for (i=0; (i < (ints-1)); i+=2) {
                        gdImageLine(im, im->polyInts[i], y,
                                im->polyInts[i+1], y, c);
                }
        }
}
        
int gdCompareInt(const void *a, const void *b)
{
        return (*(const int *)a) - (*(const int *)b);
}

void gdImageSetStyle(gdImagePtr im, int *style, int noOfPixels)
{
        if (im->style) {
                free(im->style);
        }
        im->style = (int *) 
                malloc(sizeof(int) * noOfPixels);
        memcpy(im->style, style, sizeof(int) * noOfPixels);
        im->styleLength = noOfPixels;
        im->stylePos = 0;
}

void gdImageSetBrush(gdImagePtr im, gdImagePtr brush)
{
        int i;
        im->brush = brush;
        for (i=0; (i < gdImageColorsTotal(brush)); i++) {
                int index;
                index = gdImageColorExact(im, 
                        gdImageRed(brush, i),
                        gdImageGreen(brush, i),
                        gdImageBlue(brush, i));
                if (index == (-1)) {
                        index = gdImageColorAllocate(im,
                                gdImageRed(brush, i),
                                gdImageGreen(brush, i),
                                gdImageBlue(brush, i));
                        if (index == (-1)) {
                                index = gdImageColorClosest(im,
                                        gdImageRed(brush, i),
                                        gdImageGreen(brush, i),
                                        gdImageBlue(brush, i));
                        }
                }
                im->brushColorMap[i] = index;
        }
}
        
void gdImageSetTile(gdImagePtr im, gdImagePtr tile)
{
        int i;
        im->tile = tile;
        for (i=0; (i < gdImageColorsTotal(tile)); i++) {
                int index;
                index = gdImageColorExact(im, 
                        gdImageRed(tile, i),
                        gdImageGreen(tile, i),
                        gdImageBlue(tile, i));
                if (index == (-1)) {
                        index = gdImageColorAllocate(im,
                                gdImageRed(tile, i),
                                gdImageGreen(tile, i),
                                gdImageBlue(tile, i));
                        if (index == (-1)) {
                                index = gdImageColorClosest(im,
                                        gdImageRed(tile, i),
                                        gdImageGreen(tile, i),
                                        gdImageBlue(tile, i));
                        }
                }
                im->tileColorMap[i] = index;
        }
}

void gdImageInterlace(gdImagePtr im, int interlaceArg)
{
        im->interlace = interlaceArg;
}

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