Accepts first mouse (#2457)

* MacOS: set value for `accepts_first_mouse`

* Update CHANGELOG and FEATURES

* Field doesn't need to be public

* Convert `bool` to `BOOL`

* Fix formatting

* Move flag from window state to view instance

* Feedback from PR

* Fix changelog location

CHANGELOG.md

@@ -8,6 +8,7 @@ And please only add new entries to the top of this list, right below the `# Unre
 
 # Unreleased
 
+- On MacOS, made `accepts_first_mouse` configurable.
 - Migrated `WindowBuilderExtUnix::with_resize_increments` to `WindowBuilder`.
 - Added `Window::resize_increments`/`Window::set_resize_increments` to update resize increments at runtime for X11/macOS.
 - macOS/iOS: Use `objc2` instead of `objc` internally.

FEATURES.md

@@ -129,6 +129,7 @@ If your PR makes notable changes to Winit's features, please update this section
 * Hidden titlebar
 * Hidden titlebar buttons
 * Full-size content view
+* Accepts first mouse
 
 ### Unix
 * Window urgency

src/platform/macos.rs

@@ -111,6 +111,8 @@ pub trait WindowBuilderExtMacOS {
     fn with_fullsize_content_view(self, fullsize_content_view: bool) -> WindowBuilder;
     fn with_disallow_hidpi(self, disallow_hidpi: bool) -> WindowBuilder;
     fn with_has_shadow(self, has_shadow: bool) -> WindowBuilder;
+    /// Window accepts click-through mouse events.
+    fn with_accepts_first_mouse(self, accepts_first_mouse: bool) -> WindowBuilder;
 }
 
 impl WindowBuilderExtMacOS for WindowBuilder {
@@ -164,6 +166,12 @@ impl WindowBuilderExtMacOS for WindowBuilder {
         self.platform_specific.has_shadow = has_shadow;
         self
     }
+
+    #[inline]
+    fn with_accepts_first_mouse(mut self, accepts_first_mouse: bool) -> WindowBuilder {
+        self.platform_specific.accepts_first_mouse = accepts_first_mouse;
+        self
+    }
 }
 
 pub trait EventLoopBuilderExtMacOS {

src/platform_impl/macos/view.rs

@@ -136,6 +136,7 @@ declare_class!(
         _ns_window: IvarDrop<Id<WinitWindow, Shared>>,
         pub(super) state: IvarDrop<Box<ViewState>>,
         marked_text: IvarDrop<Id<NSMutableAttributedString, Owned>>,
+        accepts_first_mouse: bool,
     }
 
     unsafe impl ClassType for WinitView {
@@ -144,8 +145,12 @@ declare_class!(
     }
 
     unsafe impl WinitView {
-        #[sel(initWithId:)]
-        fn init_with_id(&mut self, window: *mut WinitWindow) -> Option<&mut Self> {
+        #[sel(initWithId:acceptsFirstMouse:)]
+        fn init_with_id(
+            &mut self,
+            window: *mut WinitWindow,
+            accepts_first_mouse: bool,
+        ) -> Option<&mut Self> {
             let this: Option<&mut Self> = unsafe { msg_send![super(self), init] };
             this.map(|this| {
                 let state = ViewState {
@@ -165,6 +170,7 @@ declare_class!(
                 );
                 Ivar::write(&mut this.state, Box::new(state));
                 Ivar::write(&mut this.marked_text, NSMutableAttributedString::new());
+                Ivar::write(&mut this.accepts_first_mouse, accepts_first_mouse);
 
                 this.setPostsFrameChangedNotifications(true);
 
@@ -911,14 +917,20 @@ declare_class!(
         #[sel(acceptsFirstMouse:)]
         fn accepts_first_mouse(&self, _event: &NSEvent) -> bool {
             trace_scope!("acceptsFirstMouse:");
-            true
+            *self.accepts_first_mouse
         }
     }
 );
 
 impl WinitView {
-    pub(super) fn new(window: &WinitWindow) -> Id<Self, Shared> {
-        unsafe { msg_send_id![msg_send_id![Self::class(), alloc], initWithId: window] }
+    pub(super) fn new(window: &WinitWindow, accepts_first_mouse: bool) -> Id<Self, Shared> {
+        unsafe {
+            msg_send_id![
+                msg_send_id![Self::class(), alloc],
+                initWithId: window,
+                acceptsFirstMouse: accepts_first_mouse,
+            ]
+        }
     }
 
     fn window(&self) -> Id<WinitWindow, Shared> {

src/platform_impl/macos/window.rs

@@ -79,6 +79,7 @@ pub struct PlatformSpecificWindowBuilderAttributes {
     pub fullsize_content_view: bool,
     pub disallow_hidpi: bool,
     pub has_shadow: bool,
+    pub accepts_first_mouse: bool,
 }
 
 impl Default for PlatformSpecificWindowBuilderAttributes {
@@ -93,6 +94,7 @@ impl Default for PlatformSpecificWindowBuilderAttributes {
             fullsize_content_view: false,
             disallow_hidpi: false,
             has_shadow: true,
+            accepts_first_mouse: true,
         }
     }
 }
@@ -354,7 +356,7 @@ impl WinitWindow {
         })
         .ok_or_else(|| os_error!(OsError::CreationError("Couldn't create `NSWindow`")))?;
 
-        let view = WinitView::new(&this);
+        let view = WinitView::new(&this, pl_attrs.accepts_first_mouse);
 
         // The default value of `setWantsBestResolutionOpenGLSurface:` was `false` until
         // macos 10.14 and `true` after 10.15, we should set it to `YES` or `NO` to avoid