glfw: add Window.setAspectRatio

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

glfw/src/Window.zig

@@ -430,6 +430,37 @@ pub inline fn setSizeLimits(self: Window, min: Size, max: Size) Error!void {
     try getError();
 }
 
+/// Sets the aspect ratio of the specified window.
+///
+/// This function sets the required aspect ratio of the content area of the specified window. If
+/// the window is full screen, the aspect ratio only takes effect once it is made windowed. If the
+/// window is not resizable, this function does nothing.
+///
+/// The aspect ratio is specified as a numerator and a denominator and both values must be greater
+/// than zero. For example, the common 16:9 aspect ratio is specified as 16 and 9, respectively.
+///
+/// If the numerator AND denominator is set to `glfw.dont_care` then the aspect ratio limit is
+/// disabled.
+///
+/// The aspect ratio is applied immediately to a windowed mode window and may cause it to be
+/// resized.
+///
+/// Possible errors include glfw.Error.NotInitialized, glfw.Error.InvalidValue and
+/// glfw.Error.PlatformError.
+///
+/// If you set size limits and an aspect ratio that conflict, the results are undefined.
+///
+/// wayland: The aspect ratio will not be applied until the window is actually resized, either by
+/// the user or by the compositor.
+///
+/// @thread_safety This function must only be called from the main thread.
+///
+/// see also: window_sizelimits, glfw.Window.setSizeLimits
+pub inline fn setAspectRatio(self: Window, numerator: usize, denominator: usize) Error!void {
+    c.glfwSetWindowAspectRatio(self.handle, @intCast(c_int, numerator), @intCast(c_int, denominator));
+    try getError();
+}
+
 test "defaultHints" {
     const glfw = @import("main.zig");
     try glfw.init();
@@ -599,3 +630,19 @@ test "setSizeLimits" {
         .{ .width = 1080, .height = 1920 },
     );
 }
+
+test "setAspectRatio" {
+    const glfw = @import("main.zig");
+    try glfw.init();
+    defer glfw.terminate();
+
+    const window = glfw.Window.create(640, 480, "Hello, Zig!", null, null) catch |err| {
+        // return without fail, because most of our CI environments are headless / we cannot open
+        // windows on them.
+        std.debug.print("note: failed to create window: {}\n", .{err});
+        return;
+    };
+    defer window.destroy();
+
+    try window.setAspectRatio(4, 3);
+}