ei: Handle scroll events

src/backend/libei/mod.rs

@@ -103,7 +103,7 @@ fn disconnected(
 impl InputBackend for EiInput {
     type Device = request::Device;
     type KeyboardKeyEvent = request::KeyboardKey;
-    type PointerAxisEvent = request::ScrollDelta; // XXX?
+    type PointerAxisEvent = ScrollEvent;
     type PointerButtonEvent = request::Button;
     type PointerMotionEvent = request::PointerMotion;
     type PointerMotionAbsoluteEvent = request::PointerMotionAbsolute;
@@ -190,21 +190,74 @@ impl input::KeyboardKeyEvent<EiInput> for request::KeyboardKey {
     }
 }
 
-impl input::PointerAxisEvent<EiInput> for request::ScrollDelta {
-    fn amount(&self, _axis: input::Axis) -> Option<f64> {
-        todo!()
+pub enum ScrollEvent {
+    Delta(request::ScrollDelta),
+    Cancel(request::ScrollCancel),
+    Discrete(request::ScrollDiscrete),
+    Stop(request::ScrollStop),
+}
+
+impl input::Event<EiInput> for ScrollEvent {
+    fn time(&self) -> u64 {
+        match self {
+            Self::Delta(evt) => evt.time(),
+            Self::Cancel(evt) => evt.time(),
+            Self::Discrete(evt) => evt.time(),
+            Self::Stop(evt) => evt.time(),
+        }
+    }
+
+    fn device(&self) -> request::Device {
+        match self {
+            Self::Delta(evt) => evt.device(),
+            Self::Cancel(evt) => evt.device(),
+            Self::Discrete(evt) => evt.device(),
+            Self::Stop(evt) => evt.device(),
+        }
+    }
+}
+
+impl input::PointerAxisEvent<EiInput> for ScrollEvent {
+    fn amount(&self, axis: input::Axis) -> Option<f64> {
+        match self {
+            Self::Delta(evt) => match axis {
+                input::Axis::Horizontal if evt.dx != 0.0 => Some(evt.dx.into()),
+                input::Axis::Vertical if evt.dy != 0.0 => Some(evt.dy.into()),
+                _ => None,
+            },
+            // Same as Mutter
+            Self::Cancel(evt) => match axis {
+                input::Axis::Horizontal if evt.x => Some(0.01),
+                input::Axis::Vertical if evt.y => Some(0.01),
+                _ => None,
+            },
+            Self::Discrete(_evt) => None,
+            Self::Stop(evt) => match axis {
+                input::Axis::Horizontal if evt.x => Some(0.0),
+                input::Axis::Vertical if evt.y => Some(0.0),
+                _ => None,
+            },
+        }
     }
 
     fn amount_v120(&self, axis: input::Axis) -> Option<f64> {
-        todo!()
+        match self {
+            Self::Discrete(evt) => match axis {
+                input::Axis::Horizontal if evt.discrete_dx != 0 => Some(evt.discrete_dx.into()),
+                input::Axis::Vertical if evt.discrete_dy != 0 => Some(evt.discrete_dy.into()),
+                _ => None,
+            },
+            _ => None,
+        }
     }
 
     fn source(&self) -> input::AxisSource {
-        todo!()
+        // Mutter seems to also use wheel for all the scroll events
+        input::AxisSource::Wheel
     }
 
     fn relative_direction(&self, _axis: input::Axis) -> input::AxisRelativeDirection {
-        todo!()
+        input::AxisRelativeDirection::Identical
     }
 }
 
@@ -421,6 +474,18 @@ fn convert_request(request: EisRequest) -> Option<InputEvent<EiInput>> {
         EisRequest::PointerMotion(event) => Some(InputEvent::PointerMotion { event }),
         EisRequest::PointerMotionAbsolute(event) => Some(InputEvent::PointerMotionAbsolute { event }),
         EisRequest::Button(event) => Some(InputEvent::PointerButton { event }),
+        EisRequest::ScrollDelta(event) => Some(InputEvent::PointerAxis {
+            event: ScrollEvent::Delta(event),
+        }),
+        EisRequest::ScrollStop(event) => Some(InputEvent::PointerAxis {
+            event: ScrollEvent::Stop(event),
+        }),
+        EisRequest::ScrollCancel(event) => Some(InputEvent::PointerAxis {
+            event: ScrollEvent::Cancel(event),
+        }),
+        EisRequest::ScrollDiscrete(event) => Some(InputEvent::PointerAxis {
+            event: ScrollEvent::Discrete(event),
+        }),
         _ => None,
     }
 }