Add date picker demo

AwesomeUIWidgets/Assets/Scenes/SimpleWorldSpaceUI.unity

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AwesomeUIWidgets/Assets/Scripts/DateAndTimePicker.cs

+using System;
+using System.Collections.Generic;
+using uiwidgets;
+using Unity.UIWidgets.cupertino;
+using Unity.UIWidgets.engine;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.rendering;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using UnityEngine;
+using Color = Unity.UIWidgets.ui.Color;
+using Text = Unity.UIWidgets.widgets.Text;
+using ui_ = Unity.UIWidgets.widgets.ui_;
+using TextStyle = Unity.UIWidgets.painting.TextStyle;
+
+namespace UIWidgetsSample
+{
+    
+    
+    public class DatePickerDemo : UIWidgetsPanel
+    {
+        protected void OnEnable()
+        {
+            base.OnEnable();
+        }
+
+        protected override void main()
+        {
+            ui_.runApp(new MyApp());
+        }
+
+        class MyApp : StatelessWidget
+        {
+            public override Widget build(BuildContext context)
+            {
+                return new CupertinoApp(
+                    home: new DateAndTimePickerWidget()
+                );
+            }
+        }
+    }
+
+    public class DateAndTimePickerWidget : StatefulWidget {
+       
+        public override State createState() {
+            return new DateAndTimePickerWidgetState();
+        }
+    }
+       
+
+    public class DateAndTimePickerWidgetState : State<DateAndTimePickerWidget>
+    {
+      
+        Widget _buildMenu(List<Widget> children) {
+            return new Container(
+                decoration: new BoxDecoration(
+                    color: CupertinoTheme.of(this.context).scaffoldBackgroundColor,
+                    border: new Border(
+                        top: new BorderSide(color: new Color(0xFFBCBBC1), width: 0.0f),
+                        bottom: new BorderSide(color: new Color(0xFFBCBBC1), width: 0.0f)
+                    )
+                ),
+                height: 44.0f,
+                child: new Padding(
+                    padding: EdgeInsets.symmetric(horizontal: 16.0f),
+                    child: new SafeArea(
+                        top: false,
+                        bottom: false,
+                        child: new Row(
+                            //mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                            children: children
+                        )
+                    )
+                )
+            );
+        }
+        DateTime dateTime = DateTime.Now;
+        
+        Widget _buildBottomPicker(Widget picker) {
+            return new Container(
+                height: 216f,
+                width : 500f,
+                padding: EdgeInsets.only(top: 6.0f),
+                color: Colors.white,
+                child: new DefaultTextStyle(
+                    style: new TextStyle(
+                        color: Colors.red,
+                        fontSize: 12.0f
+                    ),
+                    child: new GestureDetector(
+                        // Blocks taps from propagating to the modal sheet and popping.
+                        onTap: () => { },
+                        child: new SafeArea(
+                            top: false,
+                            child: picker
+                        )
+                    )
+                )
+            );
+        }
+         Widget _buildDateAndTimePicker(BuildContext context) {
+            return new GestureDetector(
+                onTap: () => {
+                    CupertinoRouteUtils.showCupertinoModalPopup(
+                        context: context,
+                        builder: (BuildContext _context) => {
+                            return this._buildBottomPicker(
+                                new CupertinoTheme(
+                                data: new CupertinoThemeData(
+                                    textTheme: new CupertinoTextThemeData(
+                                        dateTimePickerTextStyle: new TextStyle(
+                                            fontSize: 16,
+                                            color: Colors.white
+                                        )
+                                    )
+                                ),
+                                child :new CupertinoDatePicker(
+                                    backgroundColor: Colors.black,
+                                    mode: CupertinoDatePickerMode.dateAndTime,
+                                    initialDateTime: this.dateTime,
+                                    onDateTimeChanged: (DateTime newDateTime) => {
+                                        this.setState(() => this.dateTime = newDateTime);
+                                    }
+                                )
+                            ));
+                        }
+                    );
+                },
+                child: new Text(
+                    this.dateTime.ToString("MMMM dd, yyyy h:mm tt"),
+                    style: new TextStyle(color: Colors.white)
+                
+                )
+            );
+        }
+        public override Widget build(BuildContext context)
+        {
+            return new Container(
+                color : Colors.black,
+                child : this._buildDateAndTimePicker(context)
+            );
+        }
+    }
+}