Create and set up window

CMakeLists.txt

@@ -14,3 +14,6 @@ if(${SANITIZERS})
   target_compile_options(maze-thing PRIVATE -fsanitize=address,undefined)
   target_link_options(maze-thing PRIVATE -fsanitize=address,undefined)
 endif()
+
+find_package(X11 REQUIRED)
+target_link_libraries(maze-thing PRIVATE X11::X11)

main.c

@@ -3,7 +3,53 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+#include <X11/Xlib.h>
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MAZE_SIZE 24
+
+#define GRID_SIZE (2 * MAZE_SIZE - 1)
+#define MARGIN 2
+#define WALL_THICKNESS 1
+#define WINDOW_SIZE (GRID_SIZE + 2 * (WALL_THICKNESS + MARGIN))
+
+#define PX(x) ((x) << 3)
+
 int main(void)
 {
+	XEvent evt;
+	Display *dpy = XOpenDisplay(NULL);
+	assert(dpy);
+
+	// Create window and configure graphics context
+	const int black = BlackPixel(dpy, DefaultScreen(dpy));
+	const int white = WhitePixel(dpy, DefaultScreen(dpy));
+	Window w = XCreateSimpleWindow(
+	    dpy, DefaultRootWindow(dpy), 0, 0, PX(WINDOW_SIZE), PX(WINDOW_SIZE),
+	    0, white, white);
+	Atom del = XInternAtom(dpy, "WM_DELETE_WINDOW", false);
+	XSetWMProtocols(dpy, w, &del, 1);
+	GC gc = DefaultGC(dpy, DefaultScreen(dpy));
+	XSetForeground(dpy, gc, black);
+
+	// Map window
+	XSelectInput(dpy, w, StructureNotifyMask);
+	XMapWindow(dpy, w);
+	do
+		XNextEvent(dpy, &evt);
+	while (MapNotify != evt.type);
+
+	// Wait for window exit
+	bool is_del = false;
+	do {
+		XNextEvent(dpy, &evt);
+		if (ClientMessage == evt.type)
+			is_del = (unsigned long)evt.xclient.data.l[0] == del;
+	} while (!is_del);
+
+	XCloseDisplay(dpy);
 	return EXIT_SUCCESS;
 }