From db45e5839011aaa07ae7df15c4deec7311463795 Mon Sep 17 00:00:00 2001
From: Andy Barron <AndrewLBarron@gmail.com>
Date: Thu, 3 Nov 2016 01:31:16 -0700
Subject: [PATCH] Add MouseEntered/MouseLeft for Windows, X11, Wayland, & Cocoa

---
 src/api/wayland/context.rs       | 17 ++++++++++++-----
 src/api/x11/input.rs             |  6 +++---
 src/events.rs                    |  6 ++++++
 src/platform/macos/mod.rs        |  2 ++
 src/platform/windows/callback.rs | 13 ++++++++++---
 5 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/src/api/wayland/context.rs b/src/api/wayland/context.rs
index f98b1e88..b3bd437a 100644
--- a/src/api/wayland/context.rs
+++ b/src/api/wayland/context.rs
@@ -397,9 +397,9 @@ impl wl_pointer::Handler for WaylandEnv {
             if window.equals(surface) {
                 self.mouse_focus = Some(eviter.clone());
                 let (w, h) = self.mouse_location;
-                eviter.lock().unwrap().push_back(
-                    Event::MouseMoved(w, h)
-                );
+                let mut event_queue = eviter.lock().unwrap();
+                event_queue.push_back(Event::MouseEntered);
+                event_queue.push_back(Event::MouseMoved(w, h));
                 break;
             }
         }
@@ -409,9 +409,16 @@ impl wl_pointer::Handler for WaylandEnv {
              _evqh: &mut EventQueueHandle,
              _proxy: &wl_pointer::WlPointer,
              _serial: u32,
-             _surface: &wl_surface::WlSurface)
+             surface: &wl_surface::WlSurface)
     {
-        self.mouse_focus = None
+        self.mouse_focus = None;
+        for &(ref window, ref eviter) in &self.windows {
+            if window.equals(surface) {
+                let mut event_queue = eviter.lock().unwrap();
+                event_queue.push_back(Event::MouseLeft);
+                break;
+            }
+        }
     }
 
     fn motion(&mut self,
diff --git a/src/api/x11/input.rs b/src/api/x11/input.rs
index 310f1bcb..86ce8577 100644
--- a/src/api/x11/input.rs
+++ b/src/api/x11/input.rs
@@ -170,7 +170,7 @@ impl XInputEventHandler {
     }
 
     pub fn translate_event(&mut self, cookie: &ffi::XGenericEventCookie) -> Option<Event> {
-        use events::Event::{Focused, MouseInput, MouseMoved, MouseWheel};
+        use events::Event::{Focused, MouseEntered, MouseInput, MouseLeft, MouseMoved, MouseWheel};
         use events::ElementState::{Pressed, Released};
         use events::MouseButton::{Left, Right, Middle};
         use events::MouseScrollDelta::LineDelta;
@@ -254,9 +254,9 @@ impl XInputEventHandler {
                 // our window however, so clear the previous axis state whenever
                 // the cursor re-enters the window
                 self.current_state.axis_values.clear();
-                None
+                Some(MouseEntered)
             },
-            ffi::XI_Leave => None,
+            ffi::XI_Leave => Some(MouseLeft),
             ffi::XI_FocusIn => Some(Focused(true)),
             ffi::XI_FocusOut => Some(Focused(false)),
             ffi::XI_TouchBegin | ffi::XI_TouchUpdate | ffi::XI_TouchEnd => {
diff --git a/src/events.rs b/src/events.rs
index 7186256c..b6fd7732 100644
--- a/src/events.rs
+++ b/src/events.rs
@@ -30,6 +30,12 @@ pub enum Event {
     /// The parameter are the (x,y) coords in pixels relative to the top-left corner of the window.
     MouseMoved(i32, i32),
 
+    /// The cursor has entered the window.
+    MouseEntered,
+
+    /// The cursor has left the window.
+    MouseLeft,
+
     /// A mouse wheel movement or touchpad scroll occurred.
     MouseWheel(MouseScrollDelta, TouchPhase),
 
diff --git a/src/platform/macos/mod.rs b/src/platform/macos/mod.rs
index 0a8a0e42..2ed0e895 100644
--- a/src/platform/macos/mod.rs
+++ b/src/platform/macos/mod.rs
@@ -683,6 +683,8 @@ unsafe fn NSEventToEvent(window: &Window, nsevent: id) -> Option<Event> {
         appkit::NSLeftMouseUp           => { Some(Event::MouseInput(ElementState::Released, MouseButton::Left)) },
         appkit::NSRightMouseDown        => { Some(Event::MouseInput(ElementState::Pressed, MouseButton::Right)) },
         appkit::NSRightMouseUp          => { Some(Event::MouseInput(ElementState::Released, MouseButton::Right)) },
+        appkit::NSMouseEntered          => { Some(Event::MouseEntered) },
+        appkit::NSMouseExited           => { Some(Event::MouseLeft) },
         appkit::NSMouseMoved            |
         appkit::NSLeftMouseDragged      |
         appkit::NSOtherMouseDragged     |
diff --git a/src/platform/windows/callback.rs b/src/platform/windows/callback.rs
index 6f6bd2cb..26e1e95e 100644
--- a/src/platform/windows/callback.rs
+++ b/src/platform/windows/callback.rs
@@ -125,11 +125,14 @@ pub unsafe extern "system" fn callback(window: winapi::HWND, msg: winapi::UINT,
         }
 
         winapi::WM_MOUSEMOVE => {
-            use events::Event::MouseMoved;
+            use events::Event::{MouseEntered, MouseMoved};
             CONTEXT_STASH.with(|context_stash| {
                 let mut context_stash = context_stash.borrow_mut();
                 if let Some(context_stash) = context_stash.as_mut() {
-                    context_stash.mouse_in_window = true;
+                    if !context_stash.mouse_in_window {
+                        send_event(window, MouseEntered);
+                        context_stash.mouse_in_window = true;
+                    }
                 }
             });
 
@@ -142,10 +145,14 @@ pub unsafe extern "system" fn callback(window: winapi::HWND, msg: winapi::UINT,
         },
 
         winapi::WM_MOUSELEAVE => {
+            use events::Event::MouseLeft;
             CONTEXT_STASH.with(|context_stash| {
                 let mut context_stash = context_stash.borrow_mut();
                 if let Some(context_stash) = context_stash.as_mut() {
-                    context_stash.mouse_in_window = false;
+                    if context_stash.mouse_in_window {
+                        send_event(window, MouseLeft);
+                        context_stash.mouse_in_window = false;
+                    }
                 }
             });