Handle touchpad scroll events

native/src/input/mouse.rs

@@ -3,4 +3,4 @@ mod button;
 mod event;
 
 pub use button::Button;
-pub use event::Event;
+pub use event::{Event, ScrollDelta};

native/src/input/mouse/event.rs

@@ -34,11 +34,22 @@ pub enum Event {
     },
 
     /// The mouse wheel was scrolled.
-    WheelScrolled {
+    WheelScrolled { delta: ScrollDelta },
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum ScrollDelta {
+    Lines {
         /// The number of horizontal lines scrolled
-        delta_x: f32,
+        x: f32,
 
         /// The number of vertical lines scrolled
-        delta_y: f32,
+        y: f32,
+    },
+    Pixels {
+        /// The number of horizontal pixels scrolled
+        x: f32,
+        /// The number of vertical pixels scrolled
+        y: f32,
     },
 }

native/src/widget/scrollable.rs

@@ -64,11 +64,16 @@ where
         // TODO: Event capture. Nested scrollables should capture scroll events.
         if is_mouse_over {
             match event {
-                Event::Mouse(mouse::Event::WheelScrolled {
-                    delta_y, ..
-                }) => {
-                    // TODO: Configurable speed (?)
-                    self.state.scroll(delta_y * 15.0, bounds, content_bounds);
+                Event::Mouse(mouse::Event::WheelScrolled { delta }) => {
+                    match delta {
+                        mouse::ScrollDelta::Lines { y, .. } => {
+                            // TODO: Configurable speed (?)
+                            self.state.scroll(y * 15.0, bounds, content_bounds);
+                        }
+                        mouse::ScrollDelta::Pixels { y, .. } => {
+                            self.state.scroll(y, bounds, content_bounds);
+                        }
+                    }
                 }
                 _ => {}
             }

winit/src/application.rs

@@ -123,6 +123,7 @@ pub trait Application {
                 ..
             } => match window_event {
                 WindowEvent::CursorMoved { position, .. } => {
+                    // TODO: Remove when renderer supports HiDPI
                     let physical_position =
                         position.to_physical(window.hidpi_factor());
 
@@ -143,10 +144,28 @@ pub trait Application {
                         delta_y,
                     ) => {
                         events.push(Event::Mouse(
-                            mouse::Event::WheelScrolled { delta_x, delta_y },
+                            mouse::Event::WheelScrolled {
+                                delta: mouse::ScrollDelta::Lines {
+                                    x: delta_x,
+                                    y: delta_y,
+                                },
+                            },
+                        ));
+                    }
+                    winit::event::MouseScrollDelta::PixelDelta(position) => {
+                        // TODO: Remove when renderer supports HiDPI
+                        let physical_position =
+                            position.to_physical(window.hidpi_factor());
+
+                        events.push(Event::Mouse(
+                            mouse::Event::WheelScrolled {
+                                delta: mouse::ScrollDelta::Pixels {
+                                    x: physical_position.x as f32,
+                                    y: physical_position.y as f32,
+                                },
+                            },
                         ));
                     }
-                    _ => {}
                 },
                 WindowEvent::CloseRequested => {
                     *control_flow = ControlFlow::Exit;