Add trackpad gesture PointerData types (#28571)

* Implement trackpad gestures in engine

* Remove the platform implementations

* Add new device type for trackpad

* Add back the necessary changes for Android

* Address feedback

* Fix doc typos

Author: moffatman

lib/ui/platform_dispatcher.dart

@@ -341,7 +341,7 @@ class PlatformDispatcher {
   //  * pointer_data.cc
   //  * pointer.dart
   //  * AndroidTouchProcessor.java
-  static const int _kPointerDataFieldCount = 29;
+  static const int _kPointerDataFieldCount = 35;
 
   static PointerDataPacket _unpackPointerDataPacket(ByteData packet) {
     const int kStride = Int64List.bytesPerElement;
@@ -381,6 +381,12 @@ class PlatformDispatcher {
         platformData: packet.getInt64(kStride * offset++, _kFakeHostEndian),
         scrollDeltaX: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
         scrollDeltaY: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
+        panX: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
+        panY: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
+        panDeltaX: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
+        panDeltaY: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
+        scale: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
+        rotation: packet.getFloat64(kStride * offset++, _kFakeHostEndian),
       ));
       assert(offset == (i + 1) * _kPointerDataFieldCount);
     }

lib/ui/pointer.dart

@@ -36,6 +36,15 @@ enum PointerChange {
 
   /// The pointer has stopped making contact with the device.
   up,
+
+  /// A pan/zoom has started on this pointer.
+  panZoomStart,
+
+  /// The pan/zoom on this pointer has updated.
+  panZoomUpdate,
+
+  /// The pan/zoom on this pointer has ended.
+  panZoomEnd,
 }
 
 /// The kind of pointer device.
@@ -52,6 +61,9 @@ enum PointerDeviceKind {
   /// A pointer device with a stylus that has been inverted.
   invertedStylus,
 
+  /// A touch-based pointer device with an indirect surface.
+  trackpad,
+
   /// An unknown pointer device.
   unknown
 }
@@ -101,6 +113,12 @@ class PointerData {
     this.platformData = 0,
     this.scrollDeltaX = 0.0,
     this.scrollDeltaY = 0.0,
+    this.panX = 0.0,
+    this.panY = 0.0,
+    this.panDeltaX = 0.0,
+    this.panDeltaY = 0.0,
+    this.scale = 0.0,
+    this.rotation = 0.0,
   });
 
   /// Unique identifier that ties the [PointerEvent] to embedder event created it.
@@ -265,6 +283,40 @@ class PointerData {
   /// The amount to scroll in the y direction, in physical pixels.
   final double scrollDeltaY;
 
+  /// For events with change of PointerChange.panZoomUpdate:
+  ///
+  /// The current panning magnitude of the pan/zoom in the x direction, in
+  /// physical pixels.
+  final double panX;
+
+  /// For events with change of PointerChange.panZoomUpdate:
+  ///
+  /// The current panning magnitude of the pan/zoom in the y direction, in
+  /// physical pixels.
+  final double panY;
+
+  /// For events with change of PointerChange.panZoomUpdate:
+  ///
+  /// The difference in panning of the pan/zoom in the x direction since the
+  /// latest panZoomUpdate event, in physical pixels.
+  final double panDeltaX;
+
+  /// For events with change of PointerChange.panZoomUpdate:
+  ///
+  /// The difference in panning of the pan/zoom in the y direction since the
+  /// last panZoomUpdate event, in physical pixels.
+  final double panDeltaY;
+
+  /// For events with change of PointerChange.panZoomUpdate:
+  ///
+  /// The current scale of the pan/zoom (unitless), with 1.0 as the initial scale.
+  final double scale;
+
+  /// For events with change of PointerChange.panZoomUpdate:
+  ///
+  /// The current angle of the pan/zoom in radians, with 0.0 as the initial angle.
+  final double rotation;
+
   @override
   String toString() => 'PointerData(x: $physicalX, y: $physicalY)';
 
@@ -298,7 +350,13 @@ class PointerData {
              'tilt: $tilt, '
              'platformData: $platformData, '
              'scrollDeltaX: $scrollDeltaX, '
-             'scrollDeltaY: $scrollDeltaY'
+             'scrollDeltaY: $scrollDeltaY, '
+             'panX: $panX, '
+             'panY: $panY, '
+             'panDeltaX: $panDeltaX, '
+             'panDeltaY: $panDeltaY, '
+             'scale: $scale, '
+             'rotation: $rotation'
            ')';
   }
 }

lib/ui/window/pointer_data.h

@@ -10,7 +10,7 @@
 namespace flutter {
 
 // If this value changes, update the pointer data unpacking code in hooks.dart.
-static constexpr int kPointerDataFieldCount = 29;
+static constexpr int kPointerDataFieldCount = 35;
 static constexpr int kBytesPerField = sizeof(int64_t);
 // Must match the button constants in events.dart.
 enum PointerButtonMouse : int64_t {
@@ -42,6 +42,9 @@ struct alignas(8) PointerData {
     kDown,
     kMove,
     kUp,
+    kPanZoomStart,
+    kPanZoomUpdate,
+    kPanZoomEnd,
   };
 
   // Must match the PointerDeviceKind enum in pointer.dart.
@@ -50,6 +53,7 @@ struct alignas(8) PointerData {
     kMouse,
     kStylus,
     kInvertedStylus,
+    kTrackpad,
   };
 
   // Must match the PointerSignalKind enum in pointer.dart.
@@ -87,6 +91,12 @@ struct alignas(8) PointerData {
   int64_t platformData;
   double scroll_delta_x;
   double scroll_delta_y;
+  double pan_x;
+  double pan_y;
+  double pan_delta_x;
+  double pan_delta_y;
+  double scale;
+  double rotation;
 
   void Clear();
 };

lib/ui/window/pointer_data_packet_converter.cc

@@ -4,6 +4,7 @@
 
 #include "flutter/lib/ui/window/pointer_data_packet_converter.h"
 
+#include <cmath>
 #include <cstring>
 
 #include "flutter/fml/logging.h"
@@ -207,6 +208,88 @@ void PointerDataPacketConverter::ConvertPointerData(
         converted_pointers.push_back(pointer_data);
         break;
       }
+      case PointerData::Change::kPanZoomStart: {
+        // Makes sure we have an existing pointer
+        auto iter = states_.find(pointer_data.device);
+        PointerState state;
+        if (iter == states_.end()) {
+          // Synthesizes add event if the pointer is not previously added.
+          PointerData synthesized_add_event = pointer_data;
+          synthesized_add_event.change = PointerData::Change::kAdd;
+          synthesized_add_event.synthesized = 1;
+          synthesized_add_event.buttons = 0;
+          state = EnsurePointerState(synthesized_add_event);
+          converted_pointers.push_back(synthesized_add_event);
+        } else {
+          state = iter->second;
+        }
+        FML_DCHECK(!state.is_down);
+        FML_DCHECK(!state.is_pan_zoom_active);
+        if (LocationNeedsUpdate(pointer_data, state)) {
+          // Synthesizes a hover event if the location does not match.
+          PointerData synthesized_hover_event = pointer_data;
+          synthesized_hover_event.change = PointerData::Change::kHover;
+          synthesized_hover_event.synthesized = 1;
+          synthesized_hover_event.buttons = 0;
+
+          UpdateDeltaAndState(synthesized_hover_event, state);
+          converted_pointers.push_back(synthesized_hover_event);
+        }
+
+        UpdatePointerIdentifier(pointer_data, state, true);
+        state.is_pan_zoom_active = true;
+        state.pan_x = 0;
+        state.pan_y = 0;
+        state.scale = 1;
+        state.rotation = 0;
+        states_[pointer_data.device] = state;
+        converted_pointers.push_back(pointer_data);
+        break;
+      }
+      case PointerData::Change::kPanZoomUpdate: {
+        // Makes sure we have an existing pointer in pan_zoom_active state
+        auto iter = states_.find(pointer_data.device);
+        FML_DCHECK(iter != states_.end());
+        PointerState state = iter->second;
+        FML_DCHECK(!state.is_down);
+        FML_DCHECK(state.is_pan_zoom_active);
+
+        UpdatePointerIdentifier(pointer_data, state, false);
+        UpdateDeltaAndState(pointer_data, state);
+
+        converted_pointers.push_back(pointer_data);
+        break;
+      }
+      case PointerData::Change::kPanZoomEnd: {
+        // Makes sure we have an existing pointer in pan_zoom_active state
+        auto iter = states_.find(pointer_data.device);
+        FML_DCHECK(iter != states_.end());
+        PointerState state = iter->second;
+        FML_DCHECK(state.is_pan_zoom_active);
+
+        UpdatePointerIdentifier(pointer_data, state, false);
+
+        if (LocationNeedsUpdate(pointer_data, state)) {
+          // Synthesizes an update event if the location does not match.
+          PointerData synthesized_move_event = pointer_data;
+          synthesized_move_event.change = PointerData::Change::kPanZoomUpdate;
+          synthesized_move_event.pan_x = state.pan_x;
+          synthesized_move_event.pan_y = state.pan_y;
+          synthesized_move_event.pan_delta_x = 0;
+          synthesized_move_event.pan_delta_y = 0;
+          synthesized_move_event.scale = state.scale;
+          synthesized_move_event.rotation = state.rotation;
+          synthesized_move_event.synthesized = 1;
+
+          UpdateDeltaAndState(synthesized_move_event, state);
+          converted_pointers.push_back(synthesized_move_event);
+        }
+
+        state.is_pan_zoom_active = false;
+        states_[pointer_data.device] = state;
+        converted_pointers.push_back(pointer_data);
+        break;
+      }
       default: {
         converted_pointers.push_back(pointer_data);
         break;
@@ -261,8 +344,11 @@ PointerState PointerDataPacketConverter::EnsurePointerState(
   PointerState state;
   state.pointer_identifier = 0;
   state.is_down = false;
+  state.is_pan_zoom_active = false;
   state.physical_x = pointer_data.physical_x;
   state.physical_y = pointer_data.physical_y;
+  state.pan_x = 0;
+  state.pan_y = 0;
   states_[pointer_data.device] = state;
   return state;
 }
@@ -271,8 +357,14 @@ void PointerDataPacketConverter::UpdateDeltaAndState(PointerData& pointer_data,
                                                      PointerState& state) {
   pointer_data.physical_delta_x = pointer_data.physical_x - state.physical_x;
   pointer_data.physical_delta_y = pointer_data.physical_y - state.physical_y;
+  pointer_data.pan_delta_x = pointer_data.pan_x - state.pan_x;
+  pointer_data.pan_delta_y = pointer_data.pan_y - state.pan_y;
   state.physical_x = pointer_data.physical_x;
   state.physical_y = pointer_data.physical_y;
+  state.pan_x = pointer_data.pan_x;
+  state.pan_y = pointer_data.pan_y;
+  state.scale = pointer_data.scale;
+  state.rotation = pointer_data.rotation;
   states_[pointer_data.device] = state;
 }
 

lib/ui/window/pointer_data_packet_converter.h

@@ -30,8 +30,13 @@ namespace flutter {
 struct PointerState {
   int64_t pointer_identifier;
   bool is_down;
+  bool is_pan_zoom_active;
   double physical_x;
   double physical_y;
+  double pan_x;
+  double pan_y;
+  double scale;
+  double rotation;
   int64_t buttons;
 };