🎨 Optimize hotkey service

internal/common/hotkey/hotkey_linux.c

@@ -0,0 +1,77 @@
+// Copyright 2021 The golang.design Initiative Authors.
+// All rights reserved. Use of this source code is governed
+// by a MIT license that can be found in the LICENSE file.
+//
+// Written by Changkun Ou <changkun.de>
+
+//go:build linux
+
+#include <stdint.h>
+#include <stdio.h>
+#include <X11/Xlib.h>
+#include <X11/Xutil.h>
+
+extern void hotkeyDown(uintptr_t hkhandle);
+extern void hotkeyUp(uintptr_t hkhandle);
+
+int displayTest() {
+	Display* d = NULL;
+	for (int i = 0; i < 42; i++) {
+		d = XOpenDisplay(0);
+		if (d == NULL) continue;
+		break;
+	}
+	if (d == NULL) {
+		return -1;
+	}
+	return 0;
+}
+
+// FIXME: handle bad access properly.
+// int handleErrors( Display* dpy, XErrorEvent* pErr )
+// {
+//     printf("X Error Handler called, values: %d/%lu/%d/%d/%d\n",
+//         pErr->type,
+//         pErr->serial,
+//         pErr->error_code,
+//         pErr->request_code,
+//         pErr->minor_code );
+//     if( pErr->request_code == 33 ){  // 33 (X_GrabKey)
+//         if( pErr->error_code == BadAccess ){
+//             printf("ERROR: key combination already grabbed by another client.\n");
+//             return 0;
+//         }
+//     }
+//     return 0;
+// }
+
+// waitHotkey blocks until the hotkey is triggered.
+// this function crashes the program if the hotkey already grabbed by others.
+int waitHotkey(uintptr_t hkhandle, unsigned int mod, int key) {
+	Display* d = NULL;
+	for (int i = 0; i < 42; i++) {
+		d = XOpenDisplay(0);
+		if (d == NULL) continue;
+		break;
+	}
+	if (d == NULL) {
+		return -1;
+	}
+	int keycode = XKeysymToKeycode(d, key);
+	XGrabKey(d, keycode, mod, DefaultRootWindow(d), False, GrabModeAsync, GrabModeAsync);
+	XSelectInput(d, DefaultRootWindow(d), KeyPressMask);
+	XEvent ev;
+	while(1) {
+		XNextEvent(d, &ev);
+		switch(ev.type) {
+		case KeyPress:
+			hotkeyDown(hkhandle);
+			continue;
+		case KeyRelease:
+			hotkeyUp(hkhandle);
+			XUngrabKey(d, keycode, mod, DefaultRootWindow(d));
+			XCloseDisplay(d);
+			return 0;
+		}
+	}
+}