Report mouse motion before click (#1490)

* Report mouse motion before click

This fixes an issue on macOS where a mouse click would be generated,
without ever getting a mouse motion to the position before the click.
This leads to the application thinking the mouse click occurred at a
position other than the actual mouse location.

This happens due to mouse motion above the window not automatically
giving focus to the window, unless it is actually clicked, making it
possible to move the window without motion events.

Fixes #942.

* Add additional mouse motion events

Co-authored-by: Ryan Goldstein <ryan@ryanisaacg.com>

CHANGELOG.md

@@ -29,6 +29,7 @@
 - Revert On macOS, fix not sending ReceivedCharacter event for specific keys combinations.
 - on macOS, fix incorrect ReceivedCharacter events for some key combinations.
 - **Breaking:** Use `i32` instead of `u32` for position type in `WindowEvent::Moved`.
+- On macOS, a mouse motion event is now generated before every mouse click.
 
 # 0.21.0 (2020-02-04)
 

src/platform_impl/macos/view.rs

@@ -869,26 +869,32 @@ fn mouse_click(this: &Object, event: id, button: MouseButton, button_state: Elem
 }
 
 extern "C" fn mouse_down(this: &Object, _sel: Sel, event: id) {
+    mouse_motion(this, event);
     mouse_click(this, event, MouseButton::Left, ElementState::Pressed);
 }
 
 extern "C" fn mouse_up(this: &Object, _sel: Sel, event: id) {
+    mouse_motion(this, event);
     mouse_click(this, event, MouseButton::Left, ElementState::Released);
 }
 
 extern "C" fn right_mouse_down(this: &Object, _sel: Sel, event: id) {
+    mouse_motion(this, event);
     mouse_click(this, event, MouseButton::Right, ElementState::Pressed);
 }
 
 extern "C" fn right_mouse_up(this: &Object, _sel: Sel, event: id) {
+    mouse_motion(this, event);
     mouse_click(this, event, MouseButton::Right, ElementState::Released);
 }
 
 extern "C" fn other_mouse_down(this: &Object, _sel: Sel, event: id) {
+    mouse_motion(this, event);
     mouse_click(this, event, MouseButton::Middle, ElementState::Pressed);
 }
 
 extern "C" fn other_mouse_up(this: &Object, _sel: Sel, event: id) {
+    mouse_motion(this, event);
     mouse_click(this, event, MouseButton::Middle, ElementState::Released);
 }
 
@@ -986,6 +992,9 @@ extern "C" fn mouse_exited(this: &Object, _sel: Sel, _event: id) {
 
 extern "C" fn scroll_wheel(this: &Object, _sel: Sel, event: id) {
     trace!("Triggered `scrollWheel`");
+
+    mouse_motion(this, event);
+
     unsafe {
         let delta = {
             let (x, y) = (event.scrollingDeltaX(), event.scrollingDeltaY());
@@ -1031,6 +1040,9 @@ extern "C" fn scroll_wheel(this: &Object, _sel: Sel, event: id) {
 
 extern "C" fn pressure_change_with_event(this: &Object, _sel: Sel, event: id) {
     trace!("Triggered `pressureChangeWithEvent`");
+
+    mouse_motion(this, event);
+
     unsafe {
         let state_ptr: *mut c_void = *this.get_ivar("winitState");
         let state = &mut *(state_ptr as *mut ViewState);