Merge pull request #187 from Unity-Technologies/handle_touches_on_mobile

Handle touches on mobile

com.unity.uiwidgets/Runtime/Plugins/x86_64/libUIWidgets.dll.meta

   validateReferences: 1
   platformData:
   - first:
+      : Any
+    second:
+      enabled: 0
+      settings:
+        Exclude Android: 1
+        Exclude Editor: 0
+        Exclude Linux64: 0
+        Exclude OSXUniversal: 0
+        Exclude Win: 0
+        Exclude Win64: 0
+        Exclude iOS: 1
+  - first:
+      Android: Android
+    second:
+      enabled: 0
+      settings:
+        CPU: ARMv7
+  - first:
-      enabled: 1
+      enabled: 0
-      enabled: 0
+      enabled: 1
+        OS: AnyOS
-        CPU: x86_64
+        CPU: AnyCPU
-      enabled: 0
+      enabled: 1
-      enabled: 0
+      enabled: 1
       settings:
         CPU: None
   - first:
       settings:
         CPU: AnyCPU
+  - first:
+      iPhone: iOS
+    second:
+      enabled: 0
+      settings:
+        AddToEmbeddedBinaries: false
+        CPU: AnyCPU
+        CompileFlags: 
+        FrameworkDependencies: 
   userData: 
   assetBundleName: 
   assetBundleVariant: 

com.unity.uiwidgets/Runtime/engine/UIWidgetsPanelWrapper.cs

             if (pos == null) {
                 return;
             }
-
-            UIWidgetsPanel_onMouseMove(ptr: _ptr, x: pos.Value.x, y: pos.Value.y);
+            
+            UIWidgetsPanel_onMouseMove(ptr: _ptr, x: pos.Value.x, y: pos.Value.y, -1);
         }
 
         public void OnMouseScroll(Vector2 delta, Vector2? pos) {
 
             // mouse event
             if (pointerId < 0) {
-                UIWidgetsPanel_onMouseMove(ptr: _ptr, x: pos.Value.x, y: pos.Value.y);
+                UIWidgetsPanel_onMouseMove(ptr: _ptr, x: pos.Value.x, y: pos.Value.y, pointerId);
             }
         }
 
         static extern void UIWidgetsPanel_onMouseUp(IntPtr ptr, float x, float y, int button);
 
         [DllImport(dllName: NativeBindings.dllName)]
-        static extern void UIWidgetsPanel_onMouseMove(IntPtr ptr, float x, float y);
+        static extern void UIWidgetsPanel_onMouseMove(IntPtr ptr, float x, float y, int button);
 
         [DllImport(dllName: NativeBindings.dllName)]
         static extern void UIWidgetsPanel_onMouseLeave(IntPtr ptr);

engine/Scripts/lib_build.py

     global flutter_root_path
     flutter_root_path = os.getenv('FLUTTER_ROOT_PATH', 'null')
     if flutter_root_path == 'null':
-        os.environ["FLUTTER_ROOT_PATH"] = engine_path + "/engine/src"
+        os.environ["FLUTTER_ROOT_PATH"] = os.path.join(engine_path, "engine","src")
         flutter_root_path = os.getenv('FLUTTER_ROOT_PATH')
     else:
         print("This environment variable has been set, skip")

engine/src/shell/platform/unity/android/uiwidgets_panel.cc

     vsync_batons_.push_back(baton);
   }
 
-  void UIWidgetsPanel::SetEventPhaseFromCursorButtonState(
-      UIWidgetsPointerEvent *event_data)
-  {
-    MouseState state = GetMouseState();
-    event_data->phase = state.buttons == 0
-                            ? state.state_is_down ? UIWidgetsPointerPhase::kUp
-                                                  : UIWidgetsPointerPhase::kHover
-                        : state.state_is_down ? UIWidgetsPointerPhase::kMove
-                                              : UIWidgetsPointerPhase::kDown;
-  }
+  void UIWidgetsPanel::dispatchTouches(float x, float y, int button, UIWidgetsTouchPhase phase)
+{
+  PointerData pointer_data;
+  pointer_data.Clear();
-  void UIWidgetsPanel::SendMouseMove(float x, float y)
-  {
-    UIWidgetsPointerEvent event = {};
-    event.x = x;
-    event.y = y;
-    SetEventPhaseFromCursorButtonState(&event);
-    SendPointerEventWithData(event);
-  }
+  auto packet = std::make_unique<PointerDataPacket>(1);
-  void UIWidgetsPanel::SendMouseDown(float x, float y)
-  {
-    UIWidgetsPointerEvent event = {};
-    SetEventPhaseFromCursorButtonState(&event);
-    event.x = x;
-    event.y = y;
-    SendPointerEventWithData(event);
-    SetMouseStateDown(true);
-  }
+  pointer_data.time_stamp = std::chrono::duration_cast<std::chrono::microseconds>(
+            std::chrono::high_resolution_clock::now().time_since_epoch())
+            .count();
+  
+  pointer_data.change = UIWidgetsPanel::PointerDataChangeFromUITouchPhase(phase);
+  pointer_data.kind = UIWidgetsPanel::DeviceKindFromTouchType();
+  pointer_data.device = -button;
+  pointer_data.pointer_identifier = 0;
+  pointer_data.physical_x = x;
+  pointer_data.physical_y = y;
+  pointer_data.physical_delta_x = 0.0;
+  pointer_data.physical_delta_y = 0.0;
+  pointer_data.pressure = 1.0;
+  pointer_data.pressure_max = 1.0;
+  pointer_data.signal_kind = PointerData::SignalKind::kNone;
+  packet->SetPointerData(0, pointer_data);
-  void UIWidgetsPanel::SendMouseUp(float x, float y)
-  {
-    UIWidgetsPointerEvent event = {};
-    SetEventPhaseFromCursorButtonState(&event);
-    event.x = x;
-    event.y = y;
-    SendPointerEventWithData(event);
-    if (event.phase == UIWidgetsPointerPhase::kUp)
-    {
-      SetMouseStateDown(false);
-    }
-  }
+  reinterpret_cast<EmbedderEngine*>(engine_)->DispatchPointerDataPacket(
+             std::move(packet));
+}
-  void UIWidgetsPanel::SendMouseLeave()
-  {
-    UIWidgetsPointerEvent event = {};
-    event.phase = UIWidgetsPointerPhase::kRemove;
-    SendPointerEventWithData(event);
+PointerData::Change UIWidgetsPanel::PointerDataChangeFromUITouchPhase(UIWidgetsTouchPhase phase)
+{
+  switch(phase) {
+    case TouchBegan:
+      return PointerData::Change::kDown;
+    case TouchMoved:
+      return PointerData::Change::kMove;
+    case TouchEnded:
+      return PointerData::Change::kUp;
+    case TouchCancelled:
+      return PointerData::Change::kCancel;
+    default:
+      std::cerr << "Unhandled touch phase: " << phase << std::endl;
+      break;
-  void UIWidgetsPanel::SendPointerEventWithData(
-      const UIWidgetsPointerEvent &event_data)
-  {
-    MouseState mouse_state = GetMouseState();
-    // If sending anything other than an add, and the pointer isn't already added,
-    // synthesize an add to satisfy Flutter's expectations about events.
-    if (!mouse_state.state_is_added &&
-        event_data.phase != UIWidgetsPointerPhase::kAdd)
-    {
-      UIWidgetsPointerEvent event = {};
-      event.phase = UIWidgetsPointerPhase::kAdd;
-      event.x = event_data.x;
-      event.y = event_data.y;
-      event.buttons = 0;
-      SendPointerEventWithData(event);
-    }
-    // Don't double-add (e.g., if events are delivered out of order, so an add has
-    // already been synthesized).
-    if (mouse_state.state_is_added &&
-        event_data.phase == UIWidgetsPointerPhase::kAdd)
-    {
-      return;
-    }
+  return PointerData::Change::kCancel;
+}
-    UIWidgetsPointerEvent event = event_data;
-    event.device_kind = kUIWidgetsPointerDeviceKindMouse;
-    event.buttons = mouse_state.buttons;
-
-    // Set metadata that's always the same regardless of the event.
-    event.struct_size = sizeof(event);
-    event.timestamp =
-        std::chrono::duration_cast<std::chrono::microseconds>(
-            std::chrono::high_resolution_clock::now().time_since_epoch())
-            .count();
-
-    UIWidgetsEngineSendPointerEvent(engine_, &event, 1);
-
-    if (event_data.phase == UIWidgetsPointerPhase::kAdd)
-    {
-      SetMouseStateAdded(true);
-    }
-    else if (event_data.phase == UIWidgetsPointerPhase::kRemove)
-    {
-      SetMouseStateAdded(false);
-      ResetMouseState();
-    }
-  }
+PointerData::DeviceKind UIWidgetsPanel::DeviceKindFromTouchType()
+{
+  return PointerData::DeviceKind::kTouch;
+}
 
   void UIWidgetsPanel::OnKeyDown(int keyCode, bool isKeyDown)
   {
     }
   }
 
-  void UIWidgetsPanel::OnMouseMove(float x, float y)
+  void UIWidgetsPanel::OnMouseMove(float x, float y, int button)
-      SendMouseMove(x, y);
-    }
-  }
-
-  static uint64_t ConvertToUIWidgetsButton(int button)
-  {
-    switch (button)
-    {
-    case -1:
-      return kUIWidgetsPointerButtonMousePrimary;
-    case -2:
-      return kUIWidgetsPointerButtonMouseSecondary;
-    case -3:
-      return kUIWidgetsPointerButtonMouseMiddle;
+      dispatchTouches(x, y, button, TouchMoved);
-    std::cerr << "Mouse button not recognized: " << button << std::endl;
-    return 0;
   }
 
   void UIWidgetsPanel::OnMouseDown(float x, float y, int button)
-      uint64_t uiwidgets_button = ConvertToUIWidgetsButton(button);
-      if (uiwidgets_button != 0)
-      {
-        uint64_t mouse_buttons = GetMouseState().buttons | uiwidgets_button;
-        SetMouseButtons(mouse_buttons);
-        SendMouseDown(x, y);
-      }
+      dispatchTouches(x, y, button, TouchBegan);
     }
   }
 
     {
-      uint64_t uiwidgets_button = ConvertToUIWidgetsButton(button);
-      if (uiwidgets_button != 0)
-      {
-        uint64_t mouse_buttons = GetMouseState().buttons & ~uiwidgets_button;
-        SetMouseButtons(mouse_buttons);
-        SendMouseUp(x, y);
-      }
+      dispatchTouches(x, y, button, TouchEnded);
-    if (process_events_)
-    {
-      SendMouseLeave();
-    }
+    //there should not be mouse leave events on iPhone!
+    std::cerr << "Invalid input on iPhone: mouse leave" << std::endl;
   }
 
   UIWIDGETS_API(UIWidgetsPanel *)
   }
 
   UIWIDGETS_API(void)
-  UIWidgetsPanel_onMouseMove(UIWidgetsPanel *panel, float x, float y)
+  UIWidgetsPanel_onMouseMove(UIWidgetsPanel *panel, float x, float y, int button)
-    panel->OnMouseMove(x, y);
+    panel->OnMouseMove(x, y, button);
   }
 
   UIWIDGETS_API(void)

engine/src/shell/platform/unity/android/uiwidgets_panel.h

 #include <flutter/fml/memory/ref_counted.h>
 
 #include "shell/platform/unity/gfx_worker_task_runner.h"
+#include "lib/ui/window/pointer_data.h"
 #include "runtime/mono_api.h"
 #include "unity_surface_manager.h"
 #include "android_task_runner.h"
   GameObjectPanel = 1,
   EditorWindowPanel = 2
 };
-struct MouseState {
-  bool state_is_down = false;
-  bool state_is_added = false;
-  uint64_t buttons = 0;
+
+enum UIWidgetsTouchPhase
+{
+  TouchBegan,
+  TouchEnded,
+  TouchMoved,
+  TouchCancelled
 };
 
 class UIWidgetsPanel : public fml::RefCountedThreadSafe<UIWidgetsPanel> {
   
   void OnKeyDown(int keyCode, bool isKeyDown);
 
-  void OnMouseMove(float x, float y);
+  void OnMouseMove(float x, float y, int button);
 
   void OnMouseDown(float x, float y, int button);
 
  private:
   UIWidgetsPanel(Mono_Handle handle, UIWidgetsWindowType window_type, EntrypointCallback entrypoint_callback);
 
-  MouseState GetMouseState() { return mouse_state_; }
-
-  void ResetMouseState() { mouse_state_ = MouseState(); }
+  void dispatchTouches(float x, float y, int button, UIWidgetsTouchPhase evtType);
-  void SetMouseStateDown(bool is_down) { mouse_state_.state_is_down = is_down; }
-
-  void SetMouseStateAdded(bool is_added) {
-    mouse_state_.state_is_added = is_added;
-  }
-
-  void SetMouseButtons(uint64_t buttons) { mouse_state_.buttons = buttons; }
-
-  void SendMouseMove(float x, float y);
-
-  void SendMouseDown(float x, float y);
-
-  void SendMouseUp(float x, float y);
-
-  void SendMouseLeave();
-
-  void SetEventPhaseFromCursorButtonState(UIWidgetsPointerEvent* event_data);
-
-  void SendPointerEventWithData(const UIWidgetsPointerEvent& event_data);
-
+  static PointerData::Change PointerDataChangeFromUITouchPhase(UIWidgetsTouchPhase phase);
+  
+  static PointerData::DeviceKind DeviceKindFromTouchType();
+  
   Mono_Handle handle_;
   UIWidgetsWindowType window_type_;
   EntrypointCallback entrypoint_callback_;
 
   std::vector<intptr_t> vsync_batons_;
 
-  MouseState mouse_state_;
   bool process_events_ = false;
 };
 

engine/src/shell/platform/unity/darwin/ios/uiwidgets_panel.h

 
 #include <flutter/fml/memory/ref_counted.h>
 #include "shell/platform/unity/gfx_worker_task_runner.h"
+#include "lib/ui/window/pointer_data.h"
 #include "runtime/mono_api.h"
 #include "cocoa_task_runner.h"
 #include "unity_surface_manager.h"
   EditorWindowPanel = 2
 };
 
-struct MouseState {
-  bool state_is_down = false;
-  bool state_is_added = false;
-  uint64_t buttons = 0;
+enum UIWidgetsTouchPhase
+{
+  TouchBegan,
+  TouchEnded,
+  TouchMoved,
+  TouchCancelled
 };
 
 class UIWidgetsPanel : public fml::RefCountedThreadSafe<UIWidgetsPanel> {
 
   void OnKeyDown(int keyCode, bool isKeyDown);
 
-  void OnMouseMove(float x, float y);
+  void OnMouseMove(float x, float y, int button);
 
   void OnScroll(float x, float y, float px, float py);
 
 
   void CreateInternalUIWidgetsEngine(size_t width, size_t height, float device_pixel_ratio, const char* streaming_assets_path, const char* settings);
 
-  MouseState GetMouseState() { return mouse_state_; }
-
-  void ResetMouseState() { mouse_state_ = MouseState(); }
-
-  void SetMouseStateDown(bool is_down) { mouse_state_.state_is_down = is_down; }
-
-  void SetMouseStateAdded(bool is_added) {
-    mouse_state_.state_is_added = is_added;
-  }
-
-  void SetMouseButtons(uint64_t buttons) { mouse_state_.buttons = buttons; }
-
-  void SendMouseMove(float x, float y);
-
-  void SendMouseDown(float x, float y);
-
-  void SendMouseUp(float x, float y);
+  void dispatchTouches(float x, float y, int button, UIWidgetsTouchPhase evtType);
-  void SendMouseLeave();
+  static PointerData::Change PointerDataChangeFromUITouchPhase(UIWidgetsTouchPhase phase);
-  void SendScroll(float delta_x, float delta_y, float px, float py);
-
-  void SetEventPhaseFromCursorButtonState(UIWidgetsPointerEvent* event_data);
-
-  void SendPointerEventWithData(const UIWidgetsPointerEvent& event_data);
+  static PointerData::DeviceKind DeviceKindFromTouchType();
 
   Mono_Handle handle_;
   EntrypointCallback entrypoint_callback_;
 
   std::vector<intptr_t> vsync_batons_;
 
-  MouseState mouse_state_;
   bool process_events_ = false;
 };
 

engine/src/shell/platform/unity/darwin/ios/uiwidgets_panel.mm

   vsync_batons_.push_back(baton);
 }
 
-void UIWidgetsPanel::SetEventPhaseFromCursorButtonState(
-    UIWidgetsPointerEvent* event_data) {
-  MouseState state = GetMouseState();
-  event_data->phase = state.buttons == 0
-                          ? state.state_is_down ? UIWidgetsPointerPhase::kUp
-                                                : UIWidgetsPointerPhase::kHover
-                          : state.state_is_down ? UIWidgetsPointerPhase::kMove
-                                                : UIWidgetsPointerPhase::kDown;
-}
+void UIWidgetsPanel::dispatchTouches(float x, float y, int button, UIWidgetsTouchPhase phase)
+{
+  PointerData pointer_data;
+  pointer_data.Clear();
-void UIWidgetsPanel::SendMouseMove(float x, float y) {
-  UIWidgetsPointerEvent event = {};
-  event.x = x;
-  event.y = y;
-  SetEventPhaseFromCursorButtonState(&event);
-  SendPointerEventWithData(event);
-}
+  auto packet = std::make_unique<PointerDataPacket>(1);
-void UIWidgetsPanel::SendMouseDown(float x, float y) {
-  UIWidgetsPointerEvent event = {};
-  SetEventPhaseFromCursorButtonState(&event);
-  event.x = x;
-  event.y = y;
-  SendPointerEventWithData(event);
-  SetMouseStateDown(true);
-}
+  pointer_data.time_stamp = std::chrono::duration_cast<std::chrono::microseconds>(
+            std::chrono::high_resolution_clock::now().time_since_epoch())
+            .count();
+  
+  pointer_data.change = UIWidgetsPanel::PointerDataChangeFromUITouchPhase(phase);
+  pointer_data.kind = UIWidgetsPanel::DeviceKindFromTouchType();
+  pointer_data.device = -button;
+  pointer_data.pointer_identifier = 0;
+  pointer_data.physical_x = x;
+  pointer_data.physical_y = y;
+  pointer_data.physical_delta_x = 0.0;
+  pointer_data.physical_delta_y = 0.0;
+  pointer_data.pressure = 1.0;
+  pointer_data.pressure_max = 1.0;
+  pointer_data.signal_kind = PointerData::SignalKind::kNone;
+  packet->SetPointerData(0, pointer_data);
-void UIWidgetsPanel::SendMouseUp(float x, float y) {
-  UIWidgetsPointerEvent event = {};
-  SetEventPhaseFromCursorButtonState(&event);
-  event.x = x;
-  event.y = y;
-  SendPointerEventWithData(event);
-  if (event.phase == UIWidgetsPointerPhase::kUp) {
-    SetMouseStateDown(false);
-  }
-}
-
-void UIWidgetsPanel::SendMouseLeave() {
-  UIWidgetsPointerEvent event = {};
-  event.phase = UIWidgetsPointerPhase::kRemove;
-  SendPointerEventWithData(event);
-}
-
-void UIWidgetsPanel::SendScroll(float delta_x, float delta_y, float px, float py) {
-  UIWidgetsPointerEvent event = {};
- // TODO: this is a native method, use unity position instead.
-  event.x = px;
-  event.y = py;
-  SetEventPhaseFromCursorButtonState(&event);
-  event.signal_kind = UIWidgetsPointerSignalKind::kUIWidgetsPointerSignalKindScroll;
-  // TODO: See if this can be queried from the OS; this value is chosen
-  // arbitrarily to get something that feels reasonable.
-  const int kScrollOffsetMultiplier = 20;
-  event.scroll_delta_x = delta_x * kScrollOffsetMultiplier;
-  event.scroll_delta_y = delta_y * kScrollOffsetMultiplier;
-  SendPointerEventWithData(event);
+  reinterpret_cast<EmbedderEngine*>(engine_)->DispatchPointerDataPacket(
+             std::move(packet));
-void UIWidgetsPanel::SendPointerEventWithData(
-    const UIWidgetsPointerEvent& event_data) {
-  MouseState mouse_state = GetMouseState();
-  // If sending anything other than an add, and the pointer isn't already added,
-  // synthesize an add to satisfy Flutter's expectations about events.
-  if (!mouse_state.state_is_added &&
-      event_data.phase != UIWidgetsPointerPhase::kAdd) {
-    UIWidgetsPointerEvent event = {};
-    event.phase = UIWidgetsPointerPhase::kAdd;
-    event.x = event_data.x;
-    event.y = event_data.y;
-    event.buttons = 0;
-    SendPointerEventWithData(event);
-  }
-  // Don't double-add (e.g., if events are delivered out of order, so an add has
-  // already been synthesized).
-  if (mouse_state.state_is_added &&
-      event_data.phase == UIWidgetsPointerPhase::kAdd) {
-    return;
+PointerData::Change UIWidgetsPanel::PointerDataChangeFromUITouchPhase(UIWidgetsTouchPhase phase)
+{
+  switch(phase) {
+    case TouchBegan:
+      return PointerData::Change::kDown;
+    case TouchMoved:
+      return PointerData::Change::kMove;
+    case TouchEnded:
+      return PointerData::Change::kUp;
+    case TouchCancelled:
+      return PointerData::Change::kCancel;
+    default:
+      std::cerr << "Unhandled touch phase: " << phase << std::endl;
+      break;
-  UIWidgetsPointerEvent event = event_data;
-  event.device_kind = kUIWidgetsPointerDeviceKindMouse;
-  event.buttons = mouse_state.buttons;
+  return PointerData::Change::kCancel;
+}
-  // Set metadata that's always the same regardless of the event.
-  event.struct_size = sizeof(event);
-  event.timestamp =
-      std::chrono::duration_cast<std::chrono::microseconds>(
-          std::chrono::high_resolution_clock::now().time_since_epoch())
-          .count();
-
-  UIWidgetsEngineSendPointerEvent(engine_, &event, 1);
-
-  if (event_data.phase == UIWidgetsPointerPhase::kAdd) {
-    SetMouseStateAdded(true);
-  } else if (event_data.phase == UIWidgetsPointerPhase::kRemove) {
-    SetMouseStateAdded(false);
-    ResetMouseState();
-  }
+PointerData::DeviceKind UIWidgetsPanel::DeviceKindFromTouchType()
+{
+  return PointerData::DeviceKind::kTouch;
 }
 
 void UIWidgetsPanel::OnKeyDown(int keyCode, bool isKeyDown) {
   }
 }
 
-void UIWidgetsPanel::OnMouseMove(float x, float y) {
+void UIWidgetsPanel::OnMouseMove(float x, float y, int button) {
-    SendMouseMove(x, y);
+    dispatchTouches(x, y, button, TouchMoved);
-  if (process_events_) {
-    SendScroll(x, y, px, py);
-  }
-}
-
-static uint64_t ConvertToUIWidgetsButton(int button) {
-  switch (button) {
-    case -1:
-      return kUIWidgetsPointerButtonMousePrimary;
-    case -2:
-      return kUIWidgetsPointerButtonMouseSecondary;
-    case -3:
-      return kUIWidgetsPointerButtonMouseMiddle;
-  }
-  std::cerr << "Mouse button not recognized: " << button << std::endl;
-  return 0;
+  //there should not be scroll events on iPhone!
+  std::cerr << "Invalid input on iPhone: scroll" << std::endl;
-    uint64_t uiwidgets_button = ConvertToUIWidgetsButton(button);
-    if (uiwidgets_button != 0) {
-      uint64_t mouse_buttons = GetMouseState().buttons | uiwidgets_button;
-      SetMouseButtons(mouse_buttons);
-      SendMouseDown(x, y);
-    }
+    dispatchTouches(x, y, button, TouchBegan);
-    uint64_t uiwidgets_button = ConvertToUIWidgetsButton(button);
-    if (uiwidgets_button != 0) {
-      uint64_t mouse_buttons = GetMouseState().buttons & ~uiwidgets_button;
-      SetMouseButtons(mouse_buttons);
-      SendMouseUp(x, y);
-    }
+    dispatchTouches(x, y, button, TouchEnded);
-  if (process_events_) {
-    SendMouseLeave();
-  }
+  //there should not be mouse leave events on iPhone!
+  std::cerr << "Invalid input on iPhone: mouse leave" << std::endl;
 }
 
 UIWIDGETS_API(UIWidgetsPanel*)
 }
 
 UIWIDGETS_API(void)
-UIWidgetsPanel_onMouseMove(UIWidgetsPanel* panel, float x, float y) {
-  panel->OnMouseMove(x, y);
+UIWidgetsPanel_onMouseMove(UIWidgetsPanel* panel, float x, float y, int button) {
+  panel->OnMouseMove(x, y, button);
 }
 
 UIWIDGETS_API(void)

engine/src/shell/platform/unity/darwin/macos/uiwidgets_panel.mm

 }
 
 UIWIDGETS_API(void)
-UIWidgetsPanel_onMouseMove(UIWidgetsPanel* panel, float x, float y) {
+UIWidgetsPanel_onMouseMove(UIWidgetsPanel* panel, float x, float y, int button) {
+  //button id is not useful for desktop since the motions happens on the mouse (including all buttons)
   panel->OnMouseMove(x, y);
 }
 

engine/src/shell/platform/unity/windows/uiwidgets_panel.cc

 }
 
 UIWIDGETS_API(void)
-UIWidgetsPanel_onMouseMove(UIWidgetsPanel* panel, float x, float y) {
+UIWidgetsPanel_onMouseMove(UIWidgetsPanel* panel, float x, float y, int button) {
+  //button id is not useful for desktop since the motions happens on the mouse (including all buttons)
   panel->OnMouseMove(x, y);
 }
 

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/MobileTouchSample.cs

+using System;
+using System.Collections.Generic;
+using uiwidgets;
+using Unity.UIWidgets.engine;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.material;
+using Unity.UIWidgets.rendering;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using UnityEngine;
+using UnityEngine.Networking;
+using Image = Unity.UIWidgets.widgets.Image;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+
+namespace UIWidgetsSample
+{
+    public class MobileTouchSample : UIWidgetsPanel
+    {
+        protected override void main()
+        {
+            ui_.runApp(new MaterialApp(
+                title: "Http Request Sample",
+                home: new Scaffold(
+                    body: new MobileTouchWidget()
+                )
+            ));
+        }
+    }
+
+    public class MobileTouchWidget : StatefulWidget
+    {
+        public MobileTouchWidget(Key key = null) : base(key)
+        {
+        }
+
+        public override State createState()
+        {
+            return new MobileTouchWidgetState();
+        }
+    }
+
+    class MobileTouchWidgetState : State<MobileTouchWidget>
+    {
+        private float scale = 1;
+        private int frameNo = 0;
+        private float rotation = 0;
+
+        public override Widget build(BuildContext context)
+        {
+            return new Column(
+                crossAxisAlignment: CrossAxisAlignment.center,
+                children: new List<Widget>()
+                {
+                    new Text("Frame: " + frameNo),
+                    new Text("Scale: " + scale),
+                    new Text("Rotation: " + rotation),
+                    new GestureDetector(
+                        child: new Container(height: 300, color: Colors.blue),
+                        onScaleStart: details => { },
+                        onScaleUpdate: details =>
+                        {
+                            scale = details.scale;
+                            rotation = details.rotation;
+                            frameNo += 1;
+                            setState(() => { });
+                        },
+                        onScaleEnd: details => { }
+                    )
+                });
+        }
+    }
+}