Add ability to assign a menu when creating a window on Windows (#1842)

CHANGELOG.md

@@ -6,6 +6,7 @@
 - On Windows, fix bug causing mouse capture to not be released.
 - On Windows, fix fullscreen not preserving minimized/maximized state.
 - On Android, unimplemented events are marked as unhandled on the native event loop.
+- On Windows, added `WindowBuilderExtWindows::with_menu` to set a custom menu at window creation time.
 - On Android, bump `ndk` and `ndk-glue` to 0.3: use predefined constants for event `ident`.
 
 # 0.24.0 (2020-12-09)

FEATURES.md

@@ -116,6 +116,7 @@ If your PR makes notable changes to Winit's features, please update this section
 ### Windows
 * Setting the taskbar icon
 * Setting the parent window
+* Setting a menu bar
 * `WS_EX_NOREDIRECTIONBITMAP` support
 * Theme the title bar according to Windows 10 Dark Mode setting or set a preferred theme
 

src/platform/windows.rs

@@ -5,7 +5,7 @@ use std::path::Path;
 
 use libc;
 use winapi::shared::minwindef::WORD;
-use winapi::shared::windef::HWND;
+use winapi::shared::windef::{HMENU, HWND};
 
 use crate::{
     dpi::PhysicalSize,
@@ -112,6 +112,16 @@ pub trait WindowBuilderExtWindows {
     /// Sets a parent to the window to be created.
     fn with_parent_window(self, parent: HWND) -> WindowBuilder;
 
+    /// Sets a menu on the window to be created.
+    ///
+    /// Parent and menu are mutually exclusive; a child window cannot have a menu!
+    ///
+    /// The menu must have been manually created beforehand with [`winapi::um::winuser::CreateMenu`] or similar.
+    ///
+    /// Note: Dark mode cannot be supported for win32 menus, it's simply not possible to change how the menus look.
+    /// If you use this, it is recommended that you combine it with `with_theme(Some(Theme::Light))` to avoid a jarring effect.
+    fn with_menu(self, menu: HMENU) -> WindowBuilder;
+
     /// This sets `ICON_BIG`. A good ceiling here is 256x256.
     fn with_taskbar_icon(self, taskbar_icon: Option<Icon>) -> WindowBuilder;
 
@@ -137,6 +147,12 @@ impl WindowBuilderExtWindows for WindowBuilder {
         self
     }
 
+    #[inline]
+    fn with_menu(mut self, menu: HMENU) -> WindowBuilder {
+        self.platform_specific.menu = Some(menu);
+        self
+    }
+
     #[inline]
     fn with_taskbar_icon(mut self, taskbar_icon: Option<Icon>) -> WindowBuilder {
         self.platform_specific.taskbar_icon = taskbar_icon;

src/platform_impl/windows/mod.rs

@@ -1,6 +1,6 @@
 #![cfg(target_os = "windows")]
 
-use winapi::{self, shared::windef::HWND};
+use winapi::{self, shared::windef::HMENU, shared::windef::HWND};
 
 pub use self::{
     event_loop::{EventLoop, EventLoopProxy, EventLoopWindowTarget},
@@ -18,6 +18,7 @@ use crate::window::Theme;
 #[derive(Clone)]
 pub struct PlatformSpecificWindowBuilderAttributes {
     pub parent: Option<HWND>,
+    pub menu: Option<HMENU>,
     pub taskbar_icon: Option<Icon>,
     pub no_redirection_bitmap: bool,
     pub drag_and_drop: bool,
@@ -28,6 +29,7 @@ impl Default for PlatformSpecificWindowBuilderAttributes {
     fn default() -> Self {
         Self {
             parent: None,
+            menu: None,
             taskbar_icon: None,
             no_redirection_bitmap: false,
             drag_and_drop: true,

src/platform_impl/windows/window.rs

@@ -711,6 +711,10 @@ unsafe fn init<T: 'static>(
     window_flags.set(WindowFlags::CHILD, pl_attribs.parent.is_some());
     window_flags.set(WindowFlags::ON_TASKBAR, true);
 
+    if pl_attribs.parent.is_some() && pl_attribs.menu.is_some() {
+        warn!("Setting a menu on windows that have a parent is unsupported");
+    }
+
     // creating the real window this time, by using the functions in `extra_functions`
     let real_window = {
         let (style, ex_style) = window_flags.to_window_styles();
@@ -724,7 +728,7 @@ unsafe fn init<T: 'static>(
             winuser::CW_USEDEFAULT,
             winuser::CW_USEDEFAULT,
             pl_attribs.parent.unwrap_or(ptr::null_mut()),
-            ptr::null_mut(),
+            pl_attribs.menu.unwrap_or(ptr::null_mut()),
             libloaderapi::GetModuleHandleW(ptr::null()),
             ptr::null_mut(),
         );