Merge branch 'master' into layout

Runtime/editor/editor_utils.cs

         public void OnEnable() {
             this._lastDevicePixelRatio = GameViewUtil.getGameViewDevicePixelRatio();
         }
+
+        public void onViewMetricsChanged() {
+            
+        }
         
         public float devicePixelRatio {
             get { return this._lastDevicePixelRatio; }

Runtime/engine/DisplayMetrics.cs

         void OnEnable();
         void OnGUI();
         void Update();
+        void onViewMetricsChanged();
 
         float devicePixelRatio { get; }
 
         }
 
         public void Update() {
+            
+        }
+
+        public void onViewMetricsChanged() {
-
 
         public float devicePixelRatio {
             get {

Runtime/engine/UIWidgetsPanel.cs

 
         void _handleViewMetricsChanged(string method, List<JSONNode> args) {
             this._windowAdapter.onViewMetricsChanged();
-            this._displayMetrics.Update();
+            this._displayMetrics.onViewMetricsChanged();
         }
 
         protected override void OnEnable() {

Runtime/gestures/long_press.cs

             base(deadline: Constants.kLongPressTimeout, debugOwner: debugOwner, kind: kind) {
         }
 
+        bool _longPressAccepted = false;
+
+        public GestureLongPressUpCallback onLongPressUp;
+
+            this._longPressAccepted = true;
+
             if (this.onLongPress != null) {
                 this.invokeCallback<object>("onLongPress", () => {
                     this.onLongPress();
 
         protected override void handlePrimaryPointer(PointerEvent evt) {
             if (evt is PointerUpEvent) {
-                this.resolve(GestureDisposition.rejected);
+                if (this._longPressAccepted && this.onLongPressUp != null) {
+                    this._longPressAccepted = false;
+                    this.invokeCallback<object>("onLongPressUp", () => {
+                        this.onLongPressUp();
+                        return null;
+                    });
+                }
+                else {
+                    this.resolve(GestureDisposition.rejected);
+                }
+            }
+            else if (evt is PointerDownEvent || evt is PointerCancelEvent) {
+                this._longPressAccepted = false;
             }
         }
 
         Offset _longPressOrigin;
 
         TimeSpan? _longPressStartTimestamp;
-        
+
         public GestureLongPressDragStartCallback onLongPressStart;
 
         public GestureLongPressDragUpdateCallback onLongPressDragUpdate;

Runtime/widgets/gesture_detector.cs

                         throw new UIWidgetsError(
                             "Incorrect GestureDetector arguments.\n" +
                             "Having both a pan gesture recognizer and a scale gesture recognizer is redundant; scale is a superset of pan. Just use the scale gesture recognizer."
-                            );
+                        );
-                    
+
                     string recognizer = havePan ? "pan" : "scale";
                     if (haveVerticalDrag && haveHorizontalDrag) {
                         throw new UIWidgetsError(
                         );
                     }
                 }
-                
+
                 if (haveLongPress && haveLongPressDrag) {
                     throw new UIWidgetsError(
                         "Incorrect GestureDetector arguments.\n" +
                 gestures[typeof(LongPressGestureRecognizer)] =
                     new GestureRecognizerFactoryWithHandlers<LongPressGestureRecognizer>(
                         () => new LongPressGestureRecognizer(debugOwner: this),
-                        instance => { instance.onLongPress = this.onLongPress; }
+                        instance => {
+                            instance.onLongPress = this.onLongPress;
+                            instance.onLongPressUp = this.onLongPressUp;
+                        }
                     );
             }
 

Samples/UIWidgetSample/LongPressSample.cs

-using Unity.UIWidgets.animation;
-using Unity.UIWidgets.engine;
-    public class LongPressSample: UIWidgetsSamplePanel {
-        
-        protected override Widget createWidget()  {
+    public class LongPressSample : UIWidgetsSamplePanel {
+        protected override Widget createWidget() {
             return new WidgetsApp(
                 home: new LongPressSampleWidget(),
                 pageRouteBuilder: this.pageRouteBuilder);
-    public class LongPressSampleWidget: StatefulWidget {
+    public class LongPressSampleWidget : StatefulWidget {
         public override State createState() {
             return new _LongPressSampleWidgetState();
         }
         public override Widget build(BuildContext context) {
             return new GestureDetector(
-                onLongPressDragStart: (value) => {
-                    Debug.Log($"Long Press Drag Start: {value}");
-                },
-                onLongPressDragUpdate: (value) => {
-                    Debug.Log($"Long Press Drag Update: {value}");
-                },
-                onLongPressDragUp: (value) => {
-                    Debug.Log($"Long Press Drag Up: {value}");
-                },
+                onLongPressDragStart: (value) => { Debug.Log($"Long Press Drag Start: {value}"); },
+                onLongPressDragUpdate: (value) => { Debug.Log($"Long Press Drag Update: {value}"); },
+                onLongPressDragUp: (value) => { Debug.Log($"Long Press Drag Up: {value}"); },
+                onLongPressUp: () => { Debug.Log($"Long Press Up"); },
+                onLongPress: () => { Debug.Log($"Long Press"); },
                 child: new Center(
                     child: new Container(
                         width: 200,