1	#include <stdlib.h>
2	#include <stdio.h>
3	#include <string.h>
4	#include <stdint.h>
5	#include <time.h>
6	#include <math.h>
7	#include "wgif.h"
8
9	#define WIDTH80 80
10	#define HEIGHT40 40
11
12
13	int fwr(uint8_t *ptr, size_t bytes, void *wp) {
14	return fwrite(ptr, 1, bytes, wp);
15	}
16
17	int gbham_sgn(int x) {
18	if (x>0) {
19	return 1;
20	}
21	if (x<0) {
22	return -1;
23	}
24	return 0;
25	}
26
27	void gbham(uint8_t *bitmap, uint8_t colorid, int x0, int y0, int x1, int y1) {
28	int i;
29	int x, y;
30	int dx, dy;
31	int incx, incy;
32	int pdx, pdy, ddx, ddy;
33	int dfast, dslow;
34	int err;
35
36	dx=x1-x0;
37	dy=y1-y0;
38	incx=gbham_sgn(dx);
39	incy=gbham_sgn(dy);
40	if (dx<0) {
41	dx=-dx;
42	}
43	if (dy<0) {
44	dy=-dy;
45	}
46	if (dx>dy) {
47	pdx=incx;
48	pdy=0;
49	ddx=incx;
50	ddy=incy;
51	dslow=dy;
52	dfast=dx;
53
54	} else {
55	pdx=0;
56	pdy=incy;
57	ddx=incx;
58	ddy=incy;
59	dslow=dx;
60	dfast=dy;
61	}
62	x=x0;
63	y=y0;
64	err=dfast/2;
65	bitmap[x+y*WIDTH80]=colorid;
66	for (i=0;i<dfast;i++) {
67	err=err-dslow;
68	if (err<0) {
69	err=err+dfast;
70	x=x+ddx;
71	y=y+ddy;
72	} else {
73	x=x+pdx;
74	y=y+pdy;
75	}
76	bitmap[x+y*WIDTH80]=colorid;
77	}
78	}
79
80	void line(struct gif_file *gf, uint8_t *bitmap, int tx, int ty) {
81	uint32_t ct[2];
82
83	ct[0]=(rand()&0xfff)|((rand()&0xfff)<<12);
84	ct[1]=0;
85
86	memset(bitmap, 1, WIDTH80*HEIGHT40);
87	gif_graphicControlExtension(gf, 10, 1);
88	gbham(bitmap, 0, WIDTH80>>1, HEIGHT40>>1, tx, ty);
89	gif_image(gf, 0, 0, WIDTH80, HEIGHT40, ct, 2, bitmap);
90	}
91
92	int main() {
93	struct gif_file gf;
94	uint8_t bitmap[WIDTH80*HEIGHT40];
95	int i;
96
97	gf.wr_fnct=fwr;
98	gf.wparm=fopen("bresenham.gif", "wb");
99	srand(time(NULL((void *)0)));
100
101	gif_init(&gf, WIDTH80, HEIGHT40, NULL((void *)0), 0, 0);
102	gif_ext_loop(&gf, 0);
103	memset(bitmap, 0, WIDTH80*HEIGHT40);
104
105
106	for (i=0;i<WIDTH80;i++) {
107	line(&gf, bitmap, i, 0);
108	}
109
110	for (i=0;i<HEIGHT40;i++) {
111	line(&gf, bitmap, WIDTH80-1, i);
112	}
113
114	for (i=WIDTH80-1;i>=0;i--) {
115	line(&gf, bitmap, i, HEIGHT40-1);
116	}
117
118	for (i=HEIGHT40-1;i>=0;i--) {
119	line(&gf, bitmap, 0, i);
120	}
121	gif_end(&gf);
122	fclose(gf.wparm);
123
124	return 0;
125	}