kind of working finally

internal/xhotkey/hotkey_linux.c

@@ -0,0 +1,76 @@
+// 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>
+#include <X11/XKBlib.h>
+#include <unistd.h>
+
+extern void hotkeyDown(uintptr_t hkhandle);
+extern void hotkeyUp(uintptr_t hkhandle);
+extern int checkCancel(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;
+}
+
+// waitHotkey blocks until the hotkey is triggered.
+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;
+	}
+	
+	// Optional: Ask X server to only send one release at the physical end of auto-repeat.
+	Bool supported;
+	XkbSetDetectableAutoRepeat(d, True, &supported);
+
+	int keycode = XKeysymToKeycode(d, key);
+	XGrabKey(d, keycode, mod, DefaultRootWindow(d), False, GrabModeAsync, GrabModeAsync);
+	XSelectInput(d, DefaultRootWindow(d), KeyPressMask | KeyReleaseMask);
+	XEvent ev;
+	
+	while(1) {
+		if (checkCancel(hkhandle) == 1) {
+			break;
+		}
+		if (XPending(d) > 0) {
+			XNextEvent(d, &ev);
+			switch(ev.type) {
+			case KeyPress:
+				hotkeyDown(hkhandle);
+				continue;
+			case KeyRelease:
+				hotkeyUp(hkhandle);
+				continue;
+			}
+		} else {
+			usleep(10000); // Poll every 10ms for snappy responsiveness without high CPU
+		}
+	}
+	
+	XUngrabKey(d, keycode, mod, DefaultRootWindow(d));
+	XCloseDisplay(d);
+	return 0;
+}