Add more descriptive usage information

README.md

@@ -5,7 +5,7 @@ If arguments are given, outputs the title of each arguments, otherwise outputs t
 	xtitle [-h|-v|-s|-e|-i|-f FORMAT|-t NUMBER] [WID ...]
 
 # Options
-- `-h` — Print the synopsis to standard output and exit.
+- `-h` — Print usage information to standard output and exit.
 - `-v` — Print the version to standard output and exit.
 - `-s` — Activate the *snoop* mode.
 - `-e` — Escape the following characters: ', " and \\.

xtitle.c

@@ -37,7 +37,7 @@ int main(int argc, char *argv[])
 	while ((opt = getopt(argc, argv, "hvseif:t:")) != -1) {
 		switch (opt) {
 			case 'h':
-				printf("xtitle [-h|-v|-s|-e|-i|-f FORMAT|-t NUMBER] [WID ...]\n");
+				print_usage();
 				goto end;
 				break;
 			case 'v':
@@ -137,6 +137,26 @@ int main(int argc, char *argv[])
 	return ret;
 }
 
+void print_usage()
+{
+	printf("%s",
+		"Description:\n"
+		" Output title of WID(s) or focused window\n\n"
+		"Synopsis:\n"
+		" xtitle [-h|-v|-s|-e|-i|-f FORMAT|-t NUMBER] [WID ...]\n\n"
+		"Options:\n"
+		" -h         Print usage information to standard output and exit.\n"
+		" -v         Print version to standard output and exit.\n"
+		" -s         Snoop mode.\n"
+		" -e         Escape the following characters: ', \" and \\.\n"
+		" -i         Try to retrieve the title from the _NET_WM_VISIBLE_NAME atom.\n"
+		" -f FORMAT  Use the given printf-style format.\n"
+		"            Supported sequences are %s (for title), %u (for window id) and \\n.\n"
+		" -t NUMBER  Truncate the title after |NUMBER| characters,\n"
+		"            starting at the first (or the last if negative) character.\n"
+	);
+}
+
 bool setup(void)
 {
 	dpy = xcb_connect(NULL, &default_screen);
@@ -331,3 +351,4 @@ void hold(int sig)
 		running = false;
 	}
 }
+

xtitle.h

@@ -12,6 +12,7 @@ int default_screen;
 xcb_window_t root;
 bool running, visible;
 
+void print_usage();
 bool setup(void);
 wchar_t* expand_escapes(const wchar_t *src);
 void output_title(xcb_window_t win, wchar_t *format, bool escaped, int truncate);