Merge pull request #483 from robertknight/rob-precise_scroll_deltas

Specify scroll deltas as either line or pixel-based

examples/cursor.rs

@@ -17,7 +17,7 @@ fn main() { println!("This example requires glutin to be compiled with the `wind
 #[cfg(feature = "window")]
 fn main() {
     
-    let mut window = glutin::Window::new().unwrap();
+    let window = glutin::Window::new().unwrap();
     window.set_title("A fantastic window!");   
     unsafe { window.make_current() };
 

src/api/cocoa/mod.rs

@@ -275,7 +275,15 @@ impl<'a> Iterator for PollEventsIterator<'a> {
                     self.window.delegate.state.pending_events.lock().unwrap().extend(events.into_iter());
                     event
                 },
-                NSScrollWheel           => { Some(MouseWheel(event.scrollingDeltaX() as f64, event.scrollingDeltaY() as f64)) },
+                NSScrollWheel => {
+                    use events::MouseScrollDelta::{LineDelta, PixelDelta};
+                    let delta = if event.hasPreciseScrollingDeltas() == YES {
+                        PixelDelta(event.scrollingDeltaX() as f32, event.scrollingDeltaY() as f32)
+                    } else {
+                        LineDelta(event.scrollingDeltaX() as f32, event.scrollingDeltaY() as f32)
+                    };
+                    Some(MouseWheel(delta))
+                },
                 _                       => { None },
             };
 

src/api/win32/callback.rs

@@ -112,12 +112,13 @@ pub unsafe extern "system" fn callback(window: winapi::HWND, msg: winapi::UINT,
 
         winapi::WM_MOUSEWHEEL => {
             use events::Event::MouseWheel;
+            use events::MouseScrollDelta::LineDelta;
 
             let value = (wparam >> 16) as i16;
             let value = value as i32;
-            let value = value as f64 / winapi::WHEEL_DELTA as f64;
+            let value = value as f32 / winapi::WHEEL_DELTA as f32;
 
-            send_event(window, MouseWheel(0.0, value));
+            send_event(window, MouseWheel(LineDelta(0.0, value)));
 
             0
         },

src/api/x11/window.rs

@@ -219,6 +219,7 @@ impl<'a> Iterator for PollEventsIterator<'a> {
                     use events::Event::{MouseInput, MouseWheel};
                     use events::ElementState::{Pressed, Released};
                     use events::MouseButton::{Left, Right, Middle};
+                    use events::MouseScrollDelta::{LineDelta};
 
                     let event: &ffi::XButtonEvent = unsafe { mem::transmute(&xev) };
 
@@ -229,11 +230,13 @@ impl<'a> Iterator for PollEventsIterator<'a> {
                         ffi::Button2 => Some(Middle),
                         ffi::Button3 => Some(Right),
                         ffi::Button4 => {
-                            self.window.pending_events.lock().unwrap().push_back(MouseWheel(0.0, 1.0));
+                            let delta = LineDelta(0.0, 1.0);
+                            self.window.pending_events.lock().unwrap().push_back(MouseWheel(delta));
                             None
                         }
                         ffi::Button5 => {
-                            self.window.pending_events.lock().unwrap().push_back(MouseWheel(0.0, -1.0));
+                            let delta = LineDelta(0.0, -1.0);
+                            self.window.pending_events.lock().unwrap().push_back(MouseWheel(delta));
                             None
                         }
                         _ => None

src/events.rs

@@ -25,11 +25,8 @@ pub enum Event {
     /// The parameter are the (x,y) coords in pixels relative to the top-left corner of the window.
     MouseMoved((i32, i32)),
 
-    /// Returns the horizontal and vertical mouse scrolling.
-    ///
-    /// A positive value indicates that the wheel was rotated forward, away from the user;
-    /// a negative value indicates that the wheel was rotated backward, toward the user.
-    MouseWheel(f64, f64),
+    /// A mouse wheel movement or touchpad scroll occurred.
+    MouseWheel(MouseScrollDelta),
 
     /// An event from the mouse has been received.
     MouseInput(ElementState, MouseButton),
@@ -57,6 +54,23 @@ pub enum MouseButton {
     Other(u8),
 }
 
+#[derive(Debug, Clone, Copy)]
+pub enum MouseScrollDelta {
+	/// Amount in lines or rows to scroll in the horizontal
+	/// and vertical directions.
+	///
+	/// Positive values indicate movement forward
+	/// (away from the user) or rightwards.
+	LineDelta(f32, f32),
+	/// Amount in pixels to scroll in the horizontal and
+	/// vertical direction.
+	///
+	/// Scroll events are expressed as a PixelDelta if
+	/// supported by the device (eg. a touchpad) and
+	/// platform.
+	PixelDelta(f32, f32)
+}
+
 #[derive(Debug, Hash, PartialEq, Eq, Clone, Copy)]
 pub enum VirtualKeyCode {
     /// The '1' key over the letters.