replaced default trigger key code with unspecified key code; updated readme

Author: GammaWolf

README.md

@@ -2,7 +2,7 @@
 
 Scroll without a scroll wheel by moving a pointer (mouse, trackball, touchpad, trackpoint). Enables scrolling with devices without a scroll wheel (e.g. Logitech Marble Trackball). General ergnonomics utility. Command line tool.
 
-Activation:
+Activation (see -s option):
 - hold keyboard key (combo)
 - toggle with keyboard key (combo) on/off
 
@@ -20,3 +20,8 @@ Activation:
 
 ### Fedora / Redhat:
 `sudo dnf install libXi libXtst libXfixes`
+
+# Help
+- exec with option -h to see the options
+- -s option is the shortcut key code. You need to set this, for it to work, although it starts without it.
+  - to find the (xorg) key code to be used with the -s option: start with -d, then press a button. The debug output will print the key code that can be used with -s option.

main.c

@@ -62,13 +62,13 @@ struct Config {
 static const char* PROGRAM_VERSION = "1.0";
 static const int NANOSECOND_TO_MILLISECOND_DIV = 1000000;
 static const int SCROLL_TRIGGER_SPEED_LIMIT_MS = 30; // don't allow scrolling in too quick succession, it can't handle them so fast, so they queue up an play back, also causing more CPU load
+static const int UNSPECIFIED_KEY_CODE = -1;
+
 static int is_active = False;
 static int scrolls_since_active = 0;
 static enum LogLevel log_level = LOG_INFO;
 static struct timespec last_scroll_time;
 
-#define CAPSLOCK_KEY_CODE 66
-
 void logg(enum LogLevel level, const char* fmt, ...)
 {
     va_list args;
@@ -94,7 +94,7 @@ struct Config create_default_config()
                 .show_debug_output = False,
                 .is_toggle_mode_on = False,
                 .release_trigger_button = True,
-                .trigger_key_code = CAPSLOCK_KEY_CODE,
+                .trigger_key_code = UNSPECIFIED_KEY_CODE,
                 .trigger_key_modifiers = 0,
     };
     return cfg;
@@ -163,7 +163,7 @@ void parse_args_into_config(int argc, char** argv, struct Config* cfg) {
             case 'h': // print help
                 printf("Converts X pointer movement (mouse, touchpad, trackpoint, trackball) to scroll wheel events.\n\n");
                 printf("Options:\n");
-                printf("-s [keycode:int] ([modifiers:int])\tshortcut\n");
+                printf("-s [xorg keycode:int] ([modifiers:int])\tshortcut\n");
                 printf("-c [d:int]\tconversion distance (speed): pointer travel distance (in pixels) required to trigger a scroll. Determines how frequently scrolling occurs. A lower number means more frequent scroll events.\n");
                 printf("-r\t\treleases trigger button before first scroll. Example: if ctrl is the trigger key, a scroll would often resize/scale in a program. Releasing it prevents that.\n");
                 printf("-t\t\ttoggle mode: scrolling-mode stays enabled until the combo is pressed again\n");
@@ -449,6 +449,9 @@ int main(int argc, char **argv)
     if (cfg.show_debug_output)
         print_cfg(&cfg);
 
+    if (cfg.trigger_key_code == UNSPECIFIED_KEY_CODE)
+        logg(LOG_WARN, "warning: no trigger key code was specified\n");
+
     Display* display = open_display_or_exit();
     int xi_opcode = ensure_xinput2_or_exit(display);