Neale Pickett
·
2008-12-14
magic.c
1/* magic -- "Magic" (qix) screen saver hack
2 * Copyright (C) 2008 Neale Pickett <neale@woozle.org>
3 *
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, either version 3 of the License, or (at
7 * your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
16 */
17
18#include <stdlib.h>
19#include <unistd.h>
20#include <stdio.h>
21#include <time.h>
22#include <X11/Xlib.h>
23#include "obj.h"
24
25#define FPS 17 /* Frames Per Second */
26#define TRAILPCT 50 /* Percentage of width to cover */
27#define MAXDELTAPML 14 /* Maximum velocity per-mil width */
28#define MINDELTAPML 2 /* Minimum verocity per-mil width */
29#define MINCOLORDELTA 40 /* Minimum color steps per line */
30#define MAXCOLORDELTA 150 /* Maximum color steps per line */
31
32#define nsec (1000000000 / FPS)
33#define max(a,b) (((a) > (b)) ? (a) : (b))
34
35
36#define randint(x) (random() % (x))
37#define rand(l, h) (randint(h-l) + l)
38
39#define sum(a, b, v, m) \
40 if (b < -v) { \
41 v *= -1; \
42 a = v - b; \
43 } else if (m - b <= v) { \
44 v *= -1; \
45 a = v + b; \
46 } else { \
47 a = v + b; \
48 }
49
50int
51main(int argc, char * const argv[])
52{
53 Display *display;
54 Window w = (Window)0;
55 GC egc = (GC)0;
56 XSegment *lines = NULL;
57 char *winstr = NULL;
58 int i;
59
60 for (i = 1; i < argc; i += 1) {
61 if (0 == strcmp(argv[i], "-window-id")) {
62 /* For compatibility with xscreensaver. We just ignore it. */
63 } else if (winstr) {
64 w = (Window)-1;
65 break;
66 } else {
67 winstr = argv[i];
68 }
69 }
70 if (! winstr) winstr = getenv("XSS_WINDOW");
71 if (winstr) {
72 char *end;
73
74 if (winstr[0] == '0' && winstr[1] == 'x') {
75 w = (Window)strtol(winstr + 2, &end, 16);
76 } else {
77 w = (Window)strtol(winstr, &end, 10);
78 }
79 if ('\0' != *end) {
80 w = (Window)-1;
81 }
82 }
83 if ((Window)-1 == w) {
84 (void)fprintf(stderr, "Usage: %s [WINDOW_ID]\n", argv[0]);
85 return 64; /* EX_USAGE */
86 }
87
88 if (! (display = XOpenDisplay(NULL))) {
89 (void)fprintf(stderr, "cannot open display");
90 return 69; /* EX_UNAVAILABLE */
91 }
92
93 try {
94 int screen = DefaultScreen(display);
95 Window root = RootWindow(display, screen);
96 Colormap cmap = DefaultColormap(display, screen);
97 XSegment velocity;
98 int width, height, nlines;
99 unsigned short red, green, blue; /* because color.red is reset to the color you got */
100 int dred, dgreen, dblue;
101 GC gc;
102 XColor color;
103
104 if (w) {
105 XWindowAttributes wa;
106
107 XGetWindowAttributes(display, w, &wa);
108 width = wa.width;
109 height = wa.height;
110 } else {
111 XSetWindowAttributes wa;
112
113 zero(wa);
114
115 wa.override_redirect = 1;
116 wa.background_pixel = BlackPixel(display, screen);
117 width = DisplayWidth(display, screen) / 3;
118 height = DisplayHeight(display, screen) / 3;
119 w = XCreateWindow(display, root,
120 0, 0,
121 width, height, 0,
122 CopyFromParent, CopyFromParent, CopyFromParent,
123 CWBackPixel,
124 &wa);
125 XMapWindow(display, w);
126 }
127
128 srandom((unsigned int)time(NULL));
129
130 {
131 int u, l;
132
133 u = width * MAXDELTAPML / 1000;
134 l = max(width * MINDELTAPML / 1000, 1);
135 velocity.x1 = (short)rand(l, u);
136 velocity.y1 = (short)rand(l, u);
137 velocity.x2 = (short)rand(l, u);
138 velocity.y2 = (short)rand(l, u);
139 }
140
141 nlines = (width * TRAILPCT) / (max(velocity.y1, velocity.y2) * 100);
142 lines = (XSegment *)calloc(nlines, sizeof(XSegment));
143
144 lines[0].x1 = (short)randint(width);
145 lines[0].y1 = (short)randint(height);
146 lines[0].x2 = (short)randint(width);
147 lines[0].y2 = (short)randint(height);
148
149
150 /* Allocate graphics contexts */
151 {
152 XGCValues values;
153
154 values.background = values.foreground = BlackPixel(display, screen);
155 egc = XCreateGC(display, w, GCBackground | GCForeground, &values);
156
157 red = color.red = (unsigned short)randint(65536);
158 green = color.green = (unsigned short)randint(65536);
159 blue = color.blue = (unsigned short)randint(65536);
160 dred = rand(MINCOLORDELTA, MAXCOLORDELTA);
161 dgreen = rand(MINCOLORDELTA, MAXCOLORDELTA);
162 dblue = rand(MINCOLORDELTA, MAXCOLORDELTA);
163
164 if (! XAllocColor(display, cmap, &color)) break;
165 values.foreground = color.pixel;
166 gc = XCreateGC(display, w, GCBackground | GCForeground, &values);
167 }
168
169 for (i = 0; ;) {
170 XSegment segments[2];
171 struct timespec req = {0, nsec};
172 int j = (i + 1) % nlines;
173
174 /* Erase old line */
175 (void)memcpy(segments + 0, lines + j, sizeof(XSegment));
176 (void)memcpy(segments + 1, lines + j, sizeof(XSegment));
177 segments[1].x1 = width - segments[0].x1;
178 segments[1].x2 = width - segments[0].x2;
179 (void)XDrawSegments(display, (Drawable)w, egc, segments, 2);
180
181 /* Calculate new line */
182 sum(lines[j].x1, lines[i].x1, velocity.x1, width);
183 sum(lines[j].y1, lines[i].y1, velocity.y1, height);
184 sum(lines[j].x2, lines[i].x2, velocity.x2, width);
185 sum(lines[j].y2, lines[i].y2, velocity.y2, height);
186
187 /* Draw new line */
188 (void)memcpy(segments + 0, lines + j, sizeof(XSegment));
189 (void)memcpy(segments + 1, lines + j, sizeof(XSegment));
190 segments[1].x1 = width - segments[0].x1;
191 segments[1].x2 = width - segments[0].x2;
192 (void)XDrawSegments(display, (Drawable)w, gc, segments, 2);
193
194 /* Change color */
195 {
196 unsigned long pixel = color.pixel;
197
198 sum(color.red = red, red, dred, 65536);
199 sum(color.green = green, green, dgreen, 65536);
200 sum(color.blue = blue, blue, dblue, 65536);
201
202 if (! XAllocColor(display, cmap, &color)) break;
203 if (! XSetForeground(display, gc, color.pixel)) break;
204 if (! XFreeColors(display, cmap, &pixel, 1, 0)) break;
205 }
206 XSync(display, True);
207
208 (void)nanosleep(&req, NULL);
209
210 i = j;
211 }
212
213 (void)XFreeGC(display, gc);
214 }
215
216 if (lines) {
217 free(lines);
218 }
219
220 if (display) {
221 if (egc) {
222 (void)XFreeGC(display, egc);
223 }
224 (void)XCloseDisplay(display);
225 }
226
227 except {
228 (void)fprintf(stderr, "Error: %s\n", exception);
229 return 69; /* EX_UNAVAILABLE */
230 }
231 return 0;
232}