1 /* See LICENSE file for copyright and license details.
2  *
3  * X background color daemon is really simple. It just uses interpolation
4  * between steps to get the new background color. If the substep reaches 1.0f,
5  * it resets it, and starts the next step.
6  */
7 #include <X11/Xlib.h>
8 #include <unistd.h>
9 #include <stdint.h>
10 #include <stdlib.h>
11 #include <string.h>
12 #include <stdio.h>
13 
14 struct MyColor {
15 	float r, g, b;
16 };
17 
18 #include "config.h"
19 
20 const size_t num_steps = (sizeof steps) / (sizeof *steps);
21 
22 static Display *dpy;
23 static int screen;
24 static Window root;
25 
26 static unsigned long MyColorToPixel (const struct MyColor *color);
27 static unsigned long NameToPixel (const char *color);
28 static void FillBackground (const struct MyColor *color);
29 static void die (const char *s);
30 
31 int
32 main(int argc, char *argv[])
33 {
34 	if (argc == 2 && !strcmp (argv[1], "-v")) {
35 		die ("xkbcd-" VERSION);
36 	} else if (argc != 1) {
37 		die ("usage: xbcd [-v]");
38 	}
39 
40 	dpy = XOpenDisplay (NULL);
41 	if (!dpy)
42 		die ("xkbcd: unable to open display");
43 
44 #ifdef __OpenBSD__
45 	if (pledge ("stdio", NULL) == -1)
46 		die ("pledge");
47 #endif // __OpenBSD__
48 
49 	screen = DefaultScreen (dpy);
50 	root = RootWindow (dpy, screen);
51  
52 	size_t step = 0;
53 	float sub_step = 0.0f;
54 	struct MyColor prev = initial_color;
55 
56 	while (1) {
57 		const struct MyColor cur = steps[step];
58 		const struct MyColor c = {
59 			.r = prev.r + (cur.r - prev.r) * sub_step,
60 			.g = prev.g + (cur.g - prev.g) * sub_step,
61 			.b = prev.b + (cur.b - prev.b) * sub_step,
62 		};
63 
64 		FillBackground (&c);
65 
66 		sub_step += sub_step_inc;
67 
68 		if (sub_step > 1.0f) {
69 			step = (step + 1) % num_steps;
70 			prev = cur;
71 			sub_step -= 1.0f;
72 		}
73 		usleep (delay * 1000);
74 	}
75 	XCloseDisplay (dpy);
76 	return 0;
77 }
78 
79 static unsigned long
80 MyColorToPixel (const struct MyColor *color)
81 {
82 	char str[8];
83 	const int r = (int)(color->r * 255.0f);
84 	const int g = (int)(color->g * 255.0f);
85 	const int b = (int)(color->b * 255.0f);
86 
87 	snprintf (str, sizeof str, "#%02X%02X%02X", r, g, b);
88 
89 	return NameToPixel (str);
90 }
91 
92 // This function is taken from xsetroot: https://github.com/freedesktop/xorg-xsetroot/blob/master/xsetroot.c
93 static unsigned long
94 NameToPixel (const char *name)
95 {
96 	XColor ecolor;
97 
98 	if (!name || !*name)
99 		return BlackPixel (dpy, screen);
100 
101 	Colormap colormap = DefaultColormap (dpy, screen);
102 
103 	if (!XParseColor (dpy, colormap, name, &ecolor)) {
104 		fprintf (stderr, "xbgcd: unknown color '%s'\n", name);
105 		return BlackPixel (dpy, screen);
106 	}
107 
108 	if (!XAllocColor (dpy, colormap, &ecolor)) {
109 		fprintf (stderr, "xbgcd: unable to allocate color for '%s'\n", name);
110 		return BlackPixel (dpy, screen);
111 	}
112 
113 	return ecolor.pixel;
114 }
115 
116 static void
117 FillBackground (const struct MyColor *color)
118 {
119 	unsigned long pixel = MyColorToPixel (color);
120 	XSetWindowBackground (dpy, root, pixel);
121 	XClearWindow (dpy, root);
122 	XFlush (dpy);
123 }
124 
125 static void
126 die (const char *s)
127 {
128 	fprintf (stderr, "%s\n", s);
129 	exit (1);
130 }