#include <stdlib.h>
#include "gd.h"

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;

        for (i=0; (i < gdMaxColors); i++) {
           im->open[i] = 1;
	   im->red[i] = 0;
           im->green[i] = 0;
           im->blue[i] = 0;
	};

	return im;
}

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

void gdImageSetPixel(gdImagePtr im, int x, int y, int color)
{
	int p;
	switch(color) {
		default:
		if (gdImageBoundsSafe(im, x, y)) {
			/* NOW ROW-MAJOR IN GD 1.3 */
			im->pixels[y][x] = color;
		}
		break;
	}
}

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);
			}
		}
	}
}

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

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);
		}
	}
}