Added a bit more involved example of Zig and Xlib

3 files changed, 106 insertions, 0 deletions

diff --git a/README.md b/README.md
index 651395b..fa00a94 100644
--- a/README.md
+++ b/README.md
@@ -19,3 +19,4 @@ reference them later if I need to.
 | [zig-telnet](./zig-telnet)       | Connects to Redis server like it is a basic telnet server.     |
 | [zig-x11](./zig-x11)             | Uses X11 to create a basic window without any bindings needed. |
 | [zig-http](./zig-http)           | Basic example of a HTTP 1.1 server without any routing etc.    |
+| [zig-x11-box](./zig-x11-box)     | Move a box around with arrow keys with Xlib and Zig.           |
diff --git a/zig-x11-box/Makefile b/zig-x11-box/Makefile
new file mode 100644
index 0000000..1ebb12c
--- /dev/null
+++ b/zig-x11-box/Makefile
@@ -0,0 +1,2 @@
+default:
+	zig run main.zig -lX11 -lc
diff --git a/zig-x11-box/main.zig b/zig-x11-box/main.zig
new file mode 100644
index 0000000..8cc6ede
--- /dev/null
+++ b/zig-x11-box/main.zig
@@ -0,0 +1,103 @@
+// https://tronche.com/gui/x/xlib/
+
+const std = @import("std");
+const xlib = @cImport({
+    @cInclude("X11/Xlib.h");
+
+    // This should work and pull in header with all the mappings
+    // making xlib.XK_Escape available but it doesn't.
+    @cInclude("X11/keysymdef.h");
+});
+
+// Defining key symbols by hand from keysymdef.h file.
+const KeySym = enum(u32) {
+    ESCAPE = 0xFF1B,
+    LEFT = 0xff51,
+    UP = 0xff52,
+    RIGHT = 0xff53,
+    DOWN = 0xff54,
+};
+
+const Box = struct {
+    x: i32,
+    y: i32,
+};
+
+const StepSize = 30;
+
+pub fn main() !void {
+    const display = xlib.XOpenDisplay(null);
+    if (display == null) {
+        return error.DisplayOpenFailed;
+    }
+
+    const root_window = xlib.XDefaultRootWindow(display);
+
+    const main_window = xlib.XCreateSimpleWindow(
+        display,
+        root_window,
+        0,
+        0,
+        400,
+        800,
+        0,
+        0,
+        0xFFFFFF,
+    );
+
+    _ = xlib.XMapWindow(display, main_window);
+    _ = xlib.XFlush(display);
+
+    _ = xlib.XSelectInput(display, main_window, xlib.KeyPressMask);
+    _ = xlib.XMapWindow(display, main_window);
+
+    _ = xlib.XStoreName(display, main_window, "Moving boxes");
+
+    var gc = xlib.XCreateGC(display, main_window, 0, null) orelse {
+        std.debug.print("Failed to create graphics context\n", .{});
+        return error.CreateGCFailed;
+    };
+    defer {
+        _ = xlib.XFreeGC(display, gc);
+    }
+
+    var box = Box{ .x = 0, .y = 0 };
+
+    var event: xlib.XEvent = undefined;
+    while (true) {
+        _ = xlib.XNextEvent(display, &event);
+        if (event.type == xlib.KeyPress) {
+            var keysym = xlib.XLookupKeysym(&event.xkey, 0);
+
+            // NOTE: There probably is a better way of matching key presses
+            //       without casting. I tried creating enum with type
+            //       c_ulong without luck. More described in link below.
+            //       https://ziglang.org/documentation/0.9.1/#Primitive-Types
+
+            if (keysym == @intFromEnum(KeySym.ESCAPE)) {
+                std.debug.print("Exiting game\n", .{});
+                break;
+            }
+
+            if (keysym == @intFromEnum(KeySym.LEFT)) {
+                box.x -= StepSize;
+            }
+
+            if (keysym == @intFromEnum(KeySym.RIGHT)) {
+                box.x += StepSize;
+            }
+
+            if (keysym == @intFromEnum(KeySym.UP)) {
+                box.y -= StepSize;
+            }
+
+            if (keysym == @intFromEnum(KeySym.DOWN)) {
+                box.y += StepSize;
+            }
+        }
+
+        _ = xlib.XClearWindow(display, main_window);
+        _ = xlib.XDrawString(display, main_window, gc, 150, 150, "Use arrow keys.", 15);
+        _ = xlib.XFillRectangle(display, main_window, gc, box.x, box.y, 100, 100);
+    }
+}