feat: support track pad scroll on flutter

flutter/lib/common/widgets/remote_input.dart

@@ -51,6 +51,9 @@ class RawPointerMouseRegion extends StatelessWidget {
         onPointerUp: inputModel.onPointUpImage,
         onPointerMove: inputModel.onPointMoveImage,
         onPointerSignal: inputModel.onPointerSignalImage,
+        onPointerPanZoomStart: inputModel.onPointerPanZoomStart,
+        onPointerPanZoomUpdate: inputModel.onPointerPanZoomUpdate,
+        onPointerPanZoomEnd: inputModel.onPointerPanZoomEnd,
         child: MouseRegion(
             cursor: cursor ?? MouseCursor.defer,
             onEnter: onEnter,

flutter/lib/models/input_model.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:convert';
 import 'dart:math';
 import 'dart:ui' as ui;
@@ -39,6 +40,10 @@ class InputModel {
   var alt = false;
   var command = false;
 
+  // trackpad
+  var trackpadScrollDistance = Offset.zero;
+  Timer? _flingTimer;
+
   // mouse
   final isPhysicalMouse = false.obs;
   int _lastMouseDownButtons = 0;
@@ -236,6 +241,7 @@ class InputModel {
     if (!enter) {
       resetModifiers();
     }
+    _flingTimer?.cancel();
     bind.sessionEnterOrLeave(id: id, enter: enter);
   }
 
@@ -258,6 +264,57 @@ class InputModel {
     }
   }
 
+  int _signOrZero(num x) {
+    if (x == 0) {
+      return 0;
+    } else {
+      return x > 0 ? 1 : -1;
+    }
+  }
+
+  void onPointerPanZoomStart(PointerPanZoomStartEvent e) {}
+
+  // https://docs.flutter.dev/release/breaking-changes/trackpad-gestures
+  // TODO(support zoom in/out)
+  void onPointerPanZoomUpdate(PointerPanZoomUpdateEvent e) {
+    var delta = e.panDelta;
+    trackpadScrollDistance += delta;
+    bind.sessionSendMouse(
+        id: id,
+        msg:
+            '{"type": "trackpad", "x": "${delta.dx.toInt()}", "y": "${delta.dy.toInt()}"}');
+  }
+
+  // Simple simulation for fling.
+  void _scheduleFling(var x, y, dx, dy) {
+    if (dx <= 0 && dy <= 0) {
+      return;
+    }
+    _flingTimer = Timer(Duration(milliseconds: 10), () {
+      bind.sessionSendMouse(
+          id: id, msg: '{"type": "trackpad", "x": "$x", "y": "$y"}');
+      dx--;
+      dy--;
+      if (dx == 0) {
+        x = 0;
+      }
+      if (dy == 0) {
+        y = 0;
+      }
+      _scheduleFling(x, y, dx, dy);
+    });
+  }
+
+  void onPointerPanZoomEnd(PointerPanZoomEndEvent e) {
+    var x = _signOrZero(trackpadScrollDistance.dx);
+    var y = _signOrZero(trackpadScrollDistance.dy);
+    var dx = trackpadScrollDistance.dx.abs() ~/ 40;
+    var dy = trackpadScrollDistance.dy.abs() ~/ 40;
+    _scheduleFling(x, y, dx, dy);
+
+    trackpadScrollDistance = Offset.zero;
+  }
+
   void onPointDownImage(PointerDownEvent e) {
     debugPrint("onPointDownImage");
     if (e.kind != ui.PointerDeviceKind.mouse) {

src/client.rs

@@ -1572,9 +1572,14 @@ pub async fn handle_test_delay(t: TestDelay, peer: &mut Stream) {
     }
 }
 
+/// Whether is track pad scrolling.
 #[inline]
-#[cfg(all(target_os = "macos", not(feature = "flutter")))]
+#[cfg(all(target_os = "macos"))]
 fn check_scroll_on_mac(mask: i32, x: i32, y: i32) -> bool {
+    // flutter version we set mask type bit to 4 when track pad scrolling.
+    if mask & 7 == 4 {
+        return true;
+    }
     if mask & 3 != 3 {
         return false;
     }
@@ -1597,7 +1602,7 @@ fn check_scroll_on_mac(mask: i32, x: i32, y: i32) -> bool {
 ///
 /// * `mask` - Mouse event.
 ///     * mask = buttons << 3 | type
-///     * type, 1: down, 2: up, 3: wheel
+///     * type, 1: down, 2: up, 3: wheel, 4: trackpad
 ///     * buttons, 1: left, 2: right, 4: middle
 /// * `x` - X coordinate.
 /// * `y` - Y coordinate.
@@ -1636,7 +1641,7 @@ pub fn send_mouse(
     if command {
         mouse_event.modifiers.push(ControlKey::Meta.into());
     }
-    #[cfg(all(target_os = "macos", not(feature = "flutter")))]
+    #[cfg(all(target_os = "macos"))]
     if check_scroll_on_mac(mask, x, y) {
         mouse_event.modifiers.push(ControlKey::Scroll.into());
     }

src/flutter_ffi.rs

@@ -156,6 +156,7 @@ pub fn session_reconnect(id: String) {
 
 pub fn session_toggle_option(id: String, value: String) {
     if let Some(session) = SESSIONS.write().unwrap().get_mut(&id) {
+        log::warn!("toggle option {}", value);
         session.toggle_option(value);
     }
 }
@@ -907,6 +908,7 @@ pub fn session_send_mouse(id: String, msg: String) {
                 "down" => 1,
                 "up" => 2,
                 "wheel" => 3,
+                "trackpad" => 4,
                 _ => 0,
             };
         }

src/server/input_service.rs

@@ -513,7 +513,7 @@ pub fn handle_mouse_(evt: &MouseEvent) {
             }
             _ => {}
         },
-        3 => {
+        3 | 4 => {
             #[allow(unused_mut)]
             let mut x = evt.x;
             #[allow(unused_mut)]