--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/x11.h	Sun Nov 26 16:27:50 2023 +0100
@@ -0,0 +1,90 @@
+/**
+ * ShaderShark
+ * Copyright © 2023 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <cstring>
+
+#include <X11/Xatom.h>
+#include <X11/XKBlib.h>
+#include <X11/keysymdef.h>
+
+/**
+ * Publish our PID (process ID) through the X11 window property.
+ */
+inline
+void setX11PID(Display* dpy, Window win) {
+	Atom _NET_WM_PID = XInternAtom(dpy, "_NET_WM_PID", False);
+	pid_t pid = getpid();
+	XChangeProperty(dpy, win, _NET_WM_PID, XA_CARDINAL,
+			32, PropModeReplace, (unsigned char *) &pid, 1);
+}
+
+inline
+bool setFullscreen(Display* dpy, Window win, bool fullscreen) {
+	XEvent ev;
+	Atom wmState = XInternAtom(dpy, "_NET_WM_STATE", False);
+	Atom wmFullscreen = XInternAtom(dpy, "_NET_WM_STATE_FULLSCREEN", False);
+	ev.xclient.type = ClientMessage;
+	ev.xclient.serial = 0; // TODO: serial?
+	ev.xclient.send_event = True;
+	ev.xclient.display = dpy;
+	ev.xclient.window = win;
+	ev.xclient.message_type = wmState;
+	ev.xclient.format = 32;
+	ev.xclient.data.l[0] = fullscreen;
+	ev.xclient.data.l[1] = wmFullscreen;
+	ev.xclient.data.l[2] = None;
+	XSendEvent(dpy, DefaultRootWindow(dpy), False, SubstructureNotifyMask, &ev);
+	return fullscreen;
+}
+
+class DecodedKey {
+public:
+	unsigned int code;
+	KeySym symbol;
+	const char* name;
+
+	bool matches(
+			KeySym s1,
+			KeySym s2 = XK_VoidSymbol,
+			KeySym s3 = XK_VoidSymbol,
+			KeySym s4 = XK_VoidSymbol,
+			KeySym s5 = XK_VoidSymbol,
+			KeySym s6 = XK_VoidSymbol,
+			KeySym s7 = XK_VoidSymbol,
+			KeySym s8 = XK_VoidSymbol
+			) {
+		return symbol == s1
+				|| symbol == s2
+				|| symbol == s3
+				|| symbol == s4
+				|| symbol == s5
+				|| symbol == s6
+				|| symbol == s7
+				|| symbol == s8;
+	}
+};
+
+inline
+const DecodedKey decodeKeycode(Display * dpy, KeyCode keyCode) {
+	DecodedKey dk = {};
+	dk.code = keyCode;
+	dk.symbol = XkbKeycodeToKeysym(dpy, keyCode, 0, 0);
+	dk.name = XKeysymToString(dk.symbol);
+	return dk;
+}