support touch input on devices

Runtime/engine/WidgetCanvas.cs

         Vector2 _lastMouseMove;
         bool _mouseEntered;
 
-        const int mouseButtonNum = 3;
-        const int mouseScrollId = mouseButtonNum + 1;
-
+
+        const int mouseButtonNum = 3;
+
+            //Disable touch -> mouse event on mobile devices
+            Input.simulateMouseWithTouches = false;
+
             this._displayMetrics = DisplayMetricsProvider.provider();
 
             if (_repaintEvent == null) {
                 this.unfocusIfNeeded();
             }
 
+#if UNITY_IOS || UNITY_ANDROID
+            if (this._mouseEntered && Input.touchCount != 0) {
+                this.handleTouchMove();
+            }
+#else
+#endif
+
+            this._lastMouseMove = Input.mousePosition;
+
-
-
-            this._lastMouseMove = Input.mousePosition;
 
             D.assert(this._windowAdapter != null);
             this._windowAdapter.Update();
             }
         }
 
+        void handleTouchMove() {
+            for (var touchIndex = 0; touchIndex < Input.touchCount; touchIndex++) {
+                var touchEvent = Input.GetTouch(touchIndex);
+                if (touchEvent.phase != TouchPhase.Moved) {
+                    continue;
+                }
+
+                var pos = this.getPointPosition(Input.mousePosition);
+                this._windowAdapter.postPointerEvent(new PointerData(
+                    timeStamp: Timer.timespanSinceStartup,
+                    change: PointerChange.hover,
+                    kind: InputUtils.getPointerDeviceKind(),
+                    device: InputUtils.getTouchFingerKey(touchEvent.fingerId),
+                    physicalX: pos.x,
+                    physicalY: pos.y
+                ));
+            }
+        }
+
         void handleMouseMove() {
             var pos = this.getPointPosition(Input.mousePosition);
             this._windowAdapter.postPointerEvent(new PointerData(
                     Input.mouseScrollDelta.y * scaleFactor,
                     pos.x,
                     pos.y,
-                    this.getScrollButton());
+                    InputUtils.getScrollButtonKey());
             }
 
             var deltaScroll = this._scrollInput.getScrollDelta();
             }
         }
 
-
-        int getScrollButton() {
-            return mouseScrollId;
-        }
-
-                    return key;
+                    return InputUtils.getMouseButtonKey(key);
                 }
             }
 
             this._windowAdapter.postPointerEvent(new PointerData(
                 timeStamp: Timer.timespanSinceStartup,
                 change: PointerChange.down,
-                kind: PointerDeviceKind.mouse,
-                device: (int) eventData.button,
+                kind: InputUtils.getPointerDeviceKind(),
+                device: InputUtils.getPointerDeviceKey(eventData),
                 physicalX: position.x,
                 physicalY: position.y
             ));
             this._windowAdapter.postPointerEvent(new PointerData(
                 timeStamp: Timer.timespanSinceStartup,
                 change: PointerChange.up,
-                kind: PointerDeviceKind.mouse,
-                device: (int) eventData.button,
+                kind: InputUtils.getPointerDeviceKind(),
+                device: InputUtils.getPointerDeviceKey(eventData),
                 physicalX: position.x,
                 physicalY: position.y
             ));
             this._windowAdapter.postPointerEvent(new PointerData(
                 timeStamp: Timer.timespanSinceStartup,
                 change: PointerChange.move,
-                kind: PointerDeviceKind.mouse,
-                device: (int) eventData.button,
+                kind: InputUtils.getPointerDeviceKind(),
+                device: InputUtils.getPointerDeviceKey(eventData),
                 physicalX: position.x,
                 physicalY: position.y
             ));
             this._windowAdapter.postPointerEvent(new PointerData(
                 timeStamp: Timer.timespanSinceStartup,
                 change: PointerChange.hover,
-                kind: PointerDeviceKind.mouse,
-                device: (int) eventData.button,
+                kind: InputUtils.getPointerDeviceKind(),
+                device: InputUtils.getPointerDeviceKey(eventData),
                 physicalX: position.x,
                 physicalY: position.y
             ));
             this._windowAdapter.postPointerEvent(new PointerData(
                 timeStamp: Timer.timespanSinceStartup,
                 change: PointerChange.hover,
-                kind: PointerDeviceKind.mouse,
-                device: (int) eventData.button,
+                kind: InputUtils.getPointerDeviceKind(),
+                device: InputUtils.getPointerDeviceKey(eventData),
                 physicalX: position.x,
                 physicalY: position.y
             ));

Runtime/engine/input_utils.cs

+using Unity.UIWidgets.ui;
+using UnityEngine.EventSystems;
+
+namespace Unity.UIWidgets.engine {
+    public static class InputUtils {
+        const int mouseScrollId = 1;
+        const int preservedPointerKeyNum = 10;
+
+        public static PointerDeviceKind getPointerDeviceKind() {
+#if UNITY_IOS || UNITY_ANDROID
+            return PointerDeviceKind.touch;
+#else
+            return PointerDeviceKind.mouse;
+#endif
+        }
+
+        public static int getPointerDeviceKey(PointerEventData eventData) {
+#if UNITY_IOS || UNITY_ANDROID
+            return getTouchFingerKey(eventData.pointerId);
+#else
+            return getMouseButtonKey((int) eventData.button);
+#endif
+        }
+
+        public static int getScrollButtonKey() {
+            return mouseScrollId;
+        }
+
+        public static int getMouseButtonKey(int buttonId) {
+            return buttonId + preservedPointerKeyNum;
+        }
+
+        public static int getTouchFingerKey(int fingerId) {
+            return fingerId + preservedPointerKeyNum;
+        }
+    }
+}

Runtime/engine/input_utils.cs.meta

+fileFormatVersion: 2
+guid: 59b547839c038453d82019f8bef7d407
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: