Merge branch 'dev_1.17.5' of github.com:Unity-Technologies/com.unity.uiwidgets into zxw/gallery

com.unity.uiwidgets/Runtime/material/expansion_panel.cs

         public override Widget build(BuildContext context) {
             List<MergeableMaterialItem> items = new List<MergeableMaterialItem>();
 
-            for (int index = 0; index < widget.children.Count; index++) {
-                int expandIndex = index;
-                if (_isChildExpanded(index) && index != 0 && !_isChildExpanded(index - 1)) {
+            for (int i = 0; i < widget.children.Count; i++) {
+                int expandIndex = i;
+                if (_isChildExpanded(expandIndex) && expandIndex != 0 && !_isChildExpanded(expandIndex - 1)) {
-                        key: new _SaltedKey<BuildContext, int>(context, index * 2 - 1)));
+                        key: new _SaltedKey<BuildContext, int>(context, expandIndex * 2 - 1)));
-                ExpansionPanel child = widget.children[index];
+                ExpansionPanel child = widget.children[expandIndex];
-                    _isChildExpanded(index)
+                    _isChildExpanded(expandIndex)
-                    margin: (EdgeInsets) (EdgeInsetsGeometry) EdgeInsetsDirectional.only(end: 8.0f),
+                    //margin: (EdgeInsets) (EdgeInsetsGeometry) EdgeInsetsDirectional.only(end: 8.0f),
-                        isExpanded: _isChildExpanded(index),
+                        isExpanded: _isChildExpanded(expandIndex),
-                            ? (bool isExpanded) => _handlePressed(isExpanded, index)
+                            ? (bool isExpanded) => _handlePressed(isExpanded, expandIndex)
                             : (ValueChanged<bool>) null
                     )
                 );
                             child: new AnimatedContainer(
                                 duration: widget.animationDuration,
                                 curve: Curves.fastOutSlowIn,
-                                margin: _isChildExpanded(index) ? widget.expandedHeaderPadding : EdgeInsets.zero,
+                                margin: _isChildExpanded(expandIndex) ? widget.expandedHeaderPadding : EdgeInsets.zero,
                                 child: new ConstrainedBox(
                                     constraints: new BoxConstraints(
                                         minHeight: material_._kPanelHeaderCollapsedHeight),
                 );
                 if (child.canTapOnHeader) {
                     header = new InkWell(
-                        onTap: () => _handlePressed(_isChildExpanded(index), index),
+                        onTap: () => _handlePressed(_isChildExpanded(expandIndex), expandIndex),
-                        key: new _SaltedKey<BuildContext, int>(context, index * 2),
+                        key: new _SaltedKey<BuildContext, int>(context, expandIndex * 2),
                         child: new Column(
                             children: new List<Widget> {
                                 header,
                                     firstCurve: new Interval(0.0f, 0.6f, curve: Curves.fastOutSlowIn),
                                     secondCurve: new Interval(0.4f, 1.0f, curve: Curves.fastOutSlowIn),
                                     sizeCurve: Curves.fastOutSlowIn,
-                                    crossFadeState: _isChildExpanded(index)
+                                    crossFadeState: _isChildExpanded(expandIndex)
                                         ? CrossFadeState.showSecond
                                         : CrossFadeState.showFirst,
                                     duration: widget.animationDuration
                     )
                 );
 
-                if (_isChildExpanded(index) && index != widget.children.Count - 1) {
+                if (_isChildExpanded(expandIndex) && expandIndex != widget.children.Count - 1) {
-                        key: new _SaltedKey<BuildContext, int>(context, index * 2 + 1)));
+                        key: new _SaltedKey<BuildContext, int>(context, expandIndex * 2 + 1)));
                 }
             }
 

com.unity.uiwidgets/Runtime/material/flat_button.cs

 
             return new RawMaterialButton(
                 onPressed: onPressed,
-                onLongPress: () => onLongPress(),
+                onLongPress: () => onLongPress?.Invoke(),
                 onHighlightChanged: onHighlightChanged,
                 fillColor: buttonTheme.getFillColor(this),
                 textStyle: theme.textTheme.button.copyWith(color: buttonTheme.getTextColor(this)),

com.unity.uiwidgets/Runtime/material/raised_button.cs

 
             return new RawMaterialButton(
                 onPressed: onPressed,
-                onLongPress: () => onLongPress(),
+                onLongPress: () => onLongPress?.Invoke(),
                 onHighlightChanged: onHighlightChanged,
                 clipBehavior: clipBehavior.Value,
                 fillColor: buttonTheme.getFillColor(this),

com.unity.uiwidgets/Runtime/widgets/animated_size.cs

             TimeSpan? reverseDuration = null,
             TickerProvider vsync = null) : base(key: key, child: child) {
             D.assert(duration != null);
-            D.assert(reverseDuration != null);
             D.assert(vsync != null);
             this.alignment = alignment ?? Alignment.center;
             this.curve = curve ?? Curves.linear;

com.unity.uiwidgets/Runtime/widgets/navigator.cs

         public static Future<T> pushNamed<T>(BuildContext context, string routeName, object arguments = null) {
             return of(context).pushNamed<T>(routeName, arguments: arguments);
         }
+        
+        public static Future pushNamed(BuildContext context, string routeName, object arguments = null) {
+            return of(context).pushNamed(routeName, arguments: arguments);
+        }
 
         public static Future<T> pushReplacementNamed<T,TO>(BuildContext context, string routeName,
             TO result = default , object arguments = null) {
                 name: name,
                 arguments: arguments
             );
-            Route<T> route = widget.onGenerateRoute(settings) as Route<T>;
+
+            var routeee = widget.onGenerateRoute(settings);
+            Route<T> route = routeee as Route<T>;
             if (route == null && !allowNull) {
                 D.assert(() => {
                     if (widget.onUnknownRoute == null) {
             object arguments = null
         ) {
             return push<T>(_routeNamed<T>(routeName, arguments: arguments));
+        }
+        
+        public Future pushNamed(
+            string routeName,
+            object arguments = null
+        ) {
+            return push(_routeNamed(routeName, arguments: arguments));
         }
 
         public Future<T> pushReplacementNamed<T, TO>(

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/CustomPaintSample.cs

+using Unity.UIWidgets.engine2;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+
+namespace UIWidgetsSample {
+    public class CustomPaintSample : UIWidgetsPanel {
+        protected override void main()
+        {
+            ui_.runApp(new MyApp());
+        }
+        
+        class MyApp : StatelessWidget
+        {
+            public override Widget build(BuildContext context)
+            {
+                return new WidgetsApp(
+                    home: new Unity.UIWidgets.widgets.CustomPaint(
+                        child: new Container(width: 300, height: 300, color: new Color(0XFFFFFFFF)),
+                        foregroundPainter: new GridPainter(null)
+                    ),
+                    pageRouteBuilder: (settings, builder) =>
+                        new PageRouteBuilder(
+                            settings: settings,
+                            pageBuilder: (Buildcontext, animation, secondaryAnimation) => builder(context)
+                        )
+                );
+            }
+        }
+
+    }
+    
+    
+    public class GridPainter : AbstractCustomPainter {
+        public GridPainter(Listenable repaint) : base(repaint) {
+        }
+
+        public override void paint(Canvas canvas, Size size) {
+            int numGrid = 4;
+            var paint = new Paint();
+            paint.color = new Color(0xFFFF0000);
+            paint.strokeWidth = 2;
+            paint.style = PaintingStyle.stroke;
+            for (int i = 1; i < numGrid; i++) {
+                float offsetY = size.height * i / numGrid;
+                canvas.drawLine(new Offset(0, offsetY), new Offset(size.width, offsetY),
+                    paint);
+            }
+
+            for (int i = 1; i < numGrid; i++) {
+                float offsetx = size.width * i / numGrid;
+                canvas.drawLine(new Offset(offsetx, 0), new Offset(offsetx, size.height),
+                    paint);
+            }
+
+
+            // draw a arrow line
+            canvas.save();
+            canvas.rotate(0.4f);
+            canvas.scale(2, 2);
+            canvas.translate(50, 50);
+            canvas.drawLine(new Offset(0, 0), new Offset(100, 0),
+                new Paint() {
+                    color = new Color(0xFFFF0000),
+                    strokeWidth = 2,
+                    style = PaintingStyle.stroke
+                });
+            var path = new Path();
+            var arrowPaint = new Paint() {
+                color = new Color(0xFFFF0000),
+                style = PaintingStyle.fill
+            };
+            path.moveTo(100, 0);
+            path.lineTo(100, 5);
+            path.lineTo(120, 0);
+            path.lineTo(100, -5);
+            path.close();
+            canvas.drawPath(path, arrowPaint);
+            canvas.restore();
+        }
+
+        public override bool shouldRepaint(CustomPainter oldDelegate) {
+            return false;
+        }
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/CustomPaintSample.cs.meta

+fileFormatVersion: 2
+guid: 64240ba829347de43abdb2daa8488bc6
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/ExpansionPanelSample.cs

+using System.Collections.Generic;
+using uiwidgets;
+using Unity.UIWidgets.engine;
+using Unity.UIWidgets.engine2;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.material;
+using Unity.UIWidgets.rendering;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using UnityEngine;
+using Material = Unity.UIWidgets.material.Material;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+
+namespace UIWidgetsSample {
+    public class ExpansionPanelSample : UIWidgetsPanel {
+        
+        protected override void main()  {
+            ui_.runApp(new MyApp());
+        }
+        
+        class MyApp : StatelessWidget
+        {
+            int testCaseId = 1;
+
+            readonly List<Widget> testCases = new List<Widget> {
+                new SingleChildScrollWidget(),
+                new ExpansionPanelWidget()
+            };
+
+            public override Widget build(BuildContext context)
+            {
+                return new MaterialApp(
+                    home: this.testCases[this.testCaseId]
+                );
+            }
+        }
+    }
+    
+    
+
+
+    class SingleChildScrollWidget : StatefulWidget {
+        public SingleChildScrollWidget(Key key = null) : base(key) {
+        }
+
+        public override State createState() {
+            return new SingleChildScrollWidgetState();
+        }
+    }
+
+    class SingleChildScrollWidgetState : State<SingleChildScrollWidget> {
+        public override Widget build(BuildContext context) {
+            return new Material(
+                child: new SingleChildScrollView(
+                    child: new Container(
+                        width: 40.0f,
+                        height: 40.0f,
+                        constraints: BoxConstraints.tight(new Size(40, 600)),
+                        color:Colors.red,
+                        child: new Center(child: new Text("Beijing"))
+                    )
+                )
+            );
+        }
+    }
+
+
+    class ExpansionPanelWidget : StatefulWidget {
+        public ExpansionPanelWidget(Key key = null) : base(key) {
+        }
+
+        public override State createState() {
+            return new ExpansionPanelWidgetState();
+        }
+    }
+
+    class ExpansionPanelWidgetState : State<ExpansionPanelWidget> {
+        readonly List<bool> isExpand = new List<bool> {false, false};
+
+        public override Widget build(BuildContext context) {
+            return new Material(
+                child: new SingleChildScrollView(
+                    child: new ExpansionPanelList(
+                        expansionCallback: (int _index, bool _isExpanded) => {
+                            Debug.Log("<tile " + _index + "> from [" + (_isExpanded ? "Open" : "Close") + "]" +
+                                      " to [" + (_isExpanded ? "Close" : "Open") + "]");
+
+                            this.isExpand[_index] = !_isExpanded;
+                            this.setState(() => { });
+                        },
+                        children: new List<ExpansionPanel> {
+                            new ExpansionPanel(
+                                headerBuilder: (BuildContext subContext, bool isExpanded) => {
+                                    return new Container(
+                                        color: Colors.black45,
+                                        child: new Center(
+                                            child: new Text("Beijing")
+                                        )
+                                    );
+                                },
+                                body: new Container(
+                                    child: new Column(
+                                        children: new List<Widget> {
+                                            new Card(
+                                                child: new Container(
+                                                    color: Colors.black38,
+                                                    height: 36,
+                                                    width: 300,
+                                                    child: new Center(
+                                                        child: new Text("Beijing")
+                                                    )
+                                                )
+                                            )
+                                        }
+                                    )
+                                ),
+                                isExpanded: this.isExpand[0]
+                            ),
+                            new ExpansionPanel(
+                                headerBuilder: (BuildContext subContext, bool isExpanded) => {
+                                    return new Container(
+                                        color: Colors.black45,
+                                        child: new Center(
+                                            child: new Text("Hebei")
+                                        )
+                                    );
+                                },
+                                body: new Container(
+                                    child: new Column(
+                                        children: new List<Widget> {
+                                            new Card(
+                                                child: new Container(
+                                                    color: Colors.black38,
+                                                    height: 36,
+                                                    width: 300,
+                                                    child: new Center(
+                                                        child: new Text("Tianjin")
+                                                    )
+                                                )
+                                            ),
+                                            new Card(
+                                                child: new Container(
+                                                    color: Colors.black38,
+                                                    height: 36,
+                                                    width: 300,
+                                                    child: new Center(
+                                                        child: new Text("Shijiazhuang")
+                                                    )
+                                                )
+                                            ),
+                                            new Card(
+                                                child: new Container(
+                                                    color: Colors.black38,
+                                                    height: 36,
+                                                    width: 300,
+                                                    child: new Center(
+                                                        child: new Text("Zhumadian")
+                                                    )
+                                                )
+                                            )
+                                        }
+                                    )
+                                ),
+                                isExpanded: this.isExpand[1]
+                            ),
+                        }
+                    )
+                )
+            );
+        }
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/ExpansionPanelSample.cs.meta

+fileFormatVersion: 2
+guid: 49545bd84f0a8614e866467b68490383
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+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/HttpRequestSample.cs

+using System;
+using System.Collections.Generic;
+using Unity.UIWidgets.engine;
+using Unity.UIWidgets.engine2;
+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 ui_ = Unity.UIWidgets.widgets.ui_;
+
+public class HttpRequestSample : UIWidgetsPanel
+{
+    protected override void main() {
+        ui_.runApp(new MaterialApp(
+            title: "Http Request Sample",
+            home: new Scaffold(
+                body:new AsyncRequestWidget(this.gameObject)
+                )
+        ));
+    }
+}
+
+public class AsyncRequestWidget : StatefulWidget {
+    
+    public readonly GameObject gameObjOfUIWidgetsPanel;
+
+    public AsyncRequestWidget(GameObject gameObjOfUiWidgetsPanel, Key key = null) : base(key) {
+        this.gameObjOfUIWidgetsPanel = gameObjOfUiWidgetsPanel;
+    }
+
+    public override State createState() {
+        return new _AsyncRequestWidgetState();
+    }
+}
+
+[Serializable]
+public class TimeData {
+    public long currentFileTime;
+}
+
+class _AsyncRequestWidgetState : State<AsyncRequestWidget> {
+    
+    long _fileTime;
+    
+    public override Widget build(BuildContext context) {
+        var isolate = Isolate.current;
+        
+        return new Column(
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: new List<Widget>() {
+                new FlatButton(child: new Text("Click To Get Time"), onPressed: () => {
+                    UnityWebRequest www = UnityWebRequest.Get("http://worldclockapi.com/api/json/est/now");
+                    var asyncOperation  = www.SendWebRequest();
+                    asyncOperation.completed += operation => {
+                        var timeData = JsonUtility.FromJson<TimeData>(www.downloadHandler.text);
+                        using(Isolate.getScope(isolate))
+                        {
+                            this.setState(() => { this._fileTime = timeData.currentFileTime; });
+                        }
+                       
+                    };
+                }),
+                new Text($"current file time: {this._fileTime}")
+            });
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/HttpRequestSample.cs.meta

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+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/LongPressSample.cs

+using uiwidgets;
+using Unity.UIWidgets.engine2;
+using Unity.UIWidgets.widgets;
+using UnityEngine;
+
+namespace UIWidgetsSample {
+    public class LongPressSample : UIWidgetsPanel {
+        protected override void main() {
+            ui_.runApp(new MyApp());
+        }
+    }
+    
+    class MyApp : StatelessWidget
+    {
+        public override Widget build(BuildContext context)
+        {
+            return new WidgetsApp(
+                home: new LongPressSampleWidget(),
+                pageRouteBuilder: (settings, builder) =>
+                    new PageRouteBuilder(
+                        settings: settings,
+                        pageBuilder: (Buildcontext, animation, secondaryAnimation) => builder(context)
+                    )
+            );
+        }
+    }
+
+    public class LongPressSampleWidget : StatefulWidget {
+        public override State createState() {
+            return new _LongPressSampleWidgetState();
+        }
+    }
+
+    class _LongPressSampleWidgetState : State<LongPressSampleWidget> {
+        public override Widget build(BuildContext context) {
+            return new GestureDetector(
+                onLongPressStart: (value) => { Debug.Log($"Long Press Drag Start: {value}"); },
+                onLongPressMoveUpdate: (value) => { Debug.Log($"Long Press Drag Update: {value}"); },
+                onLongPressEnd: (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,
+                        height: 200,
+                        color: Colors.blue
+                    )
+                )
+            );
+        }
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/LongPressSample.cs.meta

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+  serializedVersion: 2
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+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/NavigationSample.cs

+using System;
+using System.Collections.Generic;
+using uiwidgets;
+using Unity.UIWidgets.animation;
+using Unity.UIWidgets.engine2;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.gestures;
+using Unity.UIWidgets.material;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.rendering;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using DialogUtils = Unity.UIWidgets.widgets.DialogUtils;
+using TextStyle = Unity.UIWidgets.painting.TextStyle;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+
+namespace UIWidgetsSample {
+    public class NavigationSample : UIWidgetsPanel {
+
+        protected override void main()
+        {
+            ui_.runApp(new MyApp());
+        }
+        
+        
+        
+            
+        class MyApp : StatelessWidget
+        {
+            public override Widget build(BuildContext context)
+            {
+                return new WidgetsApp(
+                    initialRoute: "/",
+                    textStyle: new TextStyle(fontSize: 24),
+                    pageRouteBuilder: (settings, builder) =>
+                        new PageRouteBuilder(
+                            settings: settings,
+                            pageBuilder: (BuildContext subContext, Animation<float> animation,
+                                Animation<float> secondaryAnimation) => builder(subContext),
+                            transitionsBuilder: (BuildContext subContext, Animation<float>
+                                    animation, Animation<float> secondaryAnimation, Widget child) =>
+                                new _FadeUpwardsPageTransition(
+                                    routeAnimation: animation,
+                                    child: child
+                                )
+                        ),
+                    routes: new Dictionary<string, WidgetBuilder> {
+                        {"/", (subContext) => new HomeScreen()},
+                        {"/detail", (subContext) => new DetailScreen()}
+                    }
+                );
+            }
+        }
+    }
+    
+    public class CustomButton : StatelessWidget {
+        public CustomButton(
+            Key key = null,
+            GestureTapCallback onPressed = null,
+            EdgeInsets padding = null,
+            Color backgroundColor = null,
+            Widget child = null
+        ) : base(key: key) {
+            this.onPressed = onPressed;
+            this.padding = padding ?? EdgeInsets.all(8.0f);
+            this.backgroundColor = backgroundColor ?? Colors.white;
+            this.child = child;
+        }
+
+        public readonly GestureTapCallback onPressed;
+        public readonly EdgeInsets padding;
+        public readonly Widget child;
+        public readonly Color backgroundColor;
+
+        public override Widget build(BuildContext context) {
+            return new GestureDetector(
+                onTap: this.onPressed,
+                child: new Container(
+                    padding: this.padding,
+                    color: this.backgroundColor,
+                    child: this.child
+                )
+            );
+        }
+    }
+
+
+    class HomeScreen : StatelessWidget {
+        public override Widget build(BuildContext context) {
+            return new NavigationPage(
+                body: new Container(
+                    color: new Color(0xFF888888),
+                    child: new Center(
+                        child: new CustomButton(onPressed: () => { Navigator.pushNamed(context, "/detail"); },
+                            child: new Text("Go to Detail"))
+                    )),
+                title: "Home"
+            );
+        }
+    }
+
+    class DetailScreen : StatelessWidget {
+        public override Widget build(BuildContext context) {
+            return new NavigationPage(
+                body: new Container(
+                    color: new Color(0xFF1389FD),
+                    child: new Center(
+                        child: new Column(
+                            children: new List<Widget>() {
+                                new CustomButton(onPressed: () => { Navigator.pop<object>(context); }, child: new Text("Back")),
+                                new CustomButton(
+                                    onPressed: () => {
+                                        _Dialog.showDialog(context, builder: (BuildContext c) => new Dialog());
+                                    }, child: new Text("Show Dialog"))
+                            }
+                        )
+                    )),
+                title: "Detail");
+        }
+    }
+
+    class Dialog : StatelessWidget {
+        public override Widget build(BuildContext context) {
+            return new Center(child: new Container(
+                color: new Color(0xFFFF0000),
+                width: 100,
+                height: 80,
+                child: new Center(
+                    child: new Text("Hello Dialog")
+                )));
+        }
+    }
+
+    class _FadeUpwardsPageTransition : StatelessWidget {
+        internal _FadeUpwardsPageTransition(
+            Key key = null,
+            Animation<float> routeAnimation = null, // The route's linear 0.0 - 1.0 animation.
+            Widget child = null
+        ) : base(key: key) {
+            this._positionAnimation = _bottomUpTween.chain(_fastOutSlowInTween).animate(routeAnimation);
+            this._opacityAnimation = _easeInTween.animate(routeAnimation);
+            this.child = child;
+        }
+
+        static Tween<Offset> _bottomUpTween = new OffsetTween(
+            begin: new Offset(0.0f, 0.25f),
+            end: Offset.zero
+        );
+
+        static Animatable<float> _fastOutSlowInTween = new CurveTween(curve: Curves.fastOutSlowIn);
+        static Animatable<float> _easeInTween = new CurveTween(curve: Curves.easeIn);
+
+        readonly Animation<Offset> _positionAnimation;
+        readonly Animation<float> _opacityAnimation;
+        public readonly Widget child;
+
+        public override Widget build(BuildContext context) {
+            return new SlideTransition(
+                position: this._positionAnimation,
+                child: new FadeTransition(
+                    opacity: this._opacityAnimation,
+                    child: this.child
+                )
+            );
+        }
+    }
+
+    class NavigationPage : StatelessWidget {
+        public readonly Widget body;
+        public readonly string title;
+
+        public NavigationPage(Widget body = null, string title = null) {
+            this.title = title;
+            this.body = body;
+        }
+
+        public override Widget build(BuildContext context) {
+            Widget back = null;
+            if (Navigator.of(context).canPop()) {
+                back = new CustomButton(onPressed: () => { Navigator.pop<object>(context); },
+                    child: new Text("Go Back"));
+                back = new Column(mainAxisAlignment: MainAxisAlignment.center, children: new List<Widget>() {back});
+            }
+
+
+            return new Container(
+                child: new Column(
+                    children: new List<Widget>() {
+                        new ConstrainedBox(constraints: new BoxConstraints(maxHeight: 80),
+                            child: new DecoratedBox(
+                                decoration: new BoxDecoration(color: new Color(0XFFE1ECF4)),
+                                child: new NavigationToolbar(leading: back,
+                                    middle: new Text(this.title, textAlign: TextAlign.center)))),
+                        new Flexible(child: this.body)
+                    }
+                )
+            );
+        }
+    }
+
+    static class _Dialog {
+        public static void showDialog(BuildContext context,
+            bool barrierDismissible = true, WidgetBuilder builder = null) {
+            DialogUtils.showGeneralDialog<object>(
+                context: context,
+                pageBuilder: (BuildContext buildContext, Animation<float> animation,
+                    Animation<float> secondaryAnimation) => {
+                    return builder(buildContext);
+                },
+                barrierDismissible: barrierDismissible,
+                barrierColor: new Color(0x8A000000),
+                transitionDuration: TimeSpan.FromMilliseconds(150),
+                transitionBuilder: _buildMaterialDialogTransitions
+            );
+        }
+
+        static Widget _buildMaterialDialogTransitions(BuildContext context,
+            Animation<float> animation, Animation<float> secondaryAnimation, Widget child) {
+            return new FadeTransition(
+                opacity: new CurvedAnimation(
+                    parent: animation,
+                    curve: Curves.easeOut
+                ),
+                child: child
+            );
+        }
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/NavigationSample.cs.meta

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+  userData: 
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+  assetBundleVariant: 

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/PageViewSample.cs

+using System.Collections.Generic;
+using Unity.UIWidgets.engine2;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+
+namespace UIWidgetsSample {
+    public class PageViewSample : UIWidgetsPanel {
+            
+        protected override void main()
+        {
+            ui_.runApp(new MyApp());
+        }
+        
+        class MyApp : StatelessWidget
+        {
+            public override Widget build(BuildContext context)
+            {
+                return new WidgetsApp(
+                    home: new Container(
+                        width: 200,
+                        height: 400,
+                        child: new PageView(
+                            children: new List<Widget>() {
+                                new Container(
+                                    color: new Color(0xFFE91E63)
+                                ),
+                                new Container(
+                                    color: new Color(0xFF00BCD4)
+                                ),
+                                new Container(
+                                    color: new Color(0xFF673AB7)
+                                )
+                            }
+                        )),
+                    pageRouteBuilder: (settings, builder) =>
+                        new PageRouteBuilder(
+                            settings: settings,
+                            pageBuilder: (Buildcontext, animation, secondaryAnimation) => builder(context)
+                        )
+                );
+            }
+        }
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/PageViewSample.cs.meta

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Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/ScrollbarSample.cs

+using System.Collections.Generic;
+using Unity.UIWidgets.engine2;
+using Unity.UIWidgets.material;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+
+namespace UIWidgetsSample {
+    public class ScrollbarSample : UIWidgetsPanel {
+        protected override void main()
+        {
+            ui_.runApp(new MyApp());
+        }
+        
+        class MyApp : StatelessWidget
+        {
+            public override Widget build(BuildContext context)
+            {
+                return new WidgetsApp(
+                    home: new Container(
+                        decoration: new BoxDecoration(
+                            border: Border.all(color: new Color(0xFFFFFF00))
+                        ),
+                        child: new Scrollbar(
+                            child: new ListView(
+                                children: new List<Widget> {
+                                    new Container(height: 40.0f, child: new Text("0")),
+                                    new Container(height: 40.0f, child: new Text("1")),
+                                    new Container(height: 40.0f, child: new Text("2")),
+                                    new Container(height: 40.0f, child: new Text("3")),
+                                    new Container(height: 40.0f, child: new Text("4")),
+                                    new Container(height: 40.0f, child: new Text("5")),
+                                    new Container(height: 40.0f, child: new Text("6")),
+                                    new Container(height: 40.0f, child: new Text("7")),
+                                    new Container(height: 40.0f, child: new Text("8")),
+                                    new Container(height: 40.0f, child: new Text("9")),
+                                    new Container(height: 40.0f, child: new Text("10")),
+                                    new Container(height: 40.0f, child: new Text("11")),
+                                    new Container(height: 40.0f, child: new Text("12")),
+                                    new Container(height: 40.0f, child: new Text("13")),
+                                    new Container(height: 40.0f, child: new Text("14")),
+                                    new Container(height: 40.0f, child: new Text("15")),
+                                    new Container(height: 40.0f, child: new Text("16")),
+                                    new Container(height: 40.0f, child: new Text("17")),
+                                }
+                            )
+                        )
+                    ),
+                    pageRouteBuilder: (settings, builder) =>
+                        new PageRouteBuilder(
+                            settings: settings,
+                            pageBuilder: (Buildcontext, animation, secondaryAnimation) => builder(context)
+                        )
+                );
+            }
+        }
+    }
+}

Samples/UIWidgetsSamples_2019_4/Assets/WidgetsSample/ScrollbarSample.cs.meta

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