com.unity.uiwidgets/Samples/UIWidgetSample/ToDoAppCanvas.cs

using System.Collections.Generic;
using System.Linq;
using Unity.UIWidgets.engine;
using Unity.UIWidgets.foundation;
using Unity.UIWidgets.gestures;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.rendering;
using Unity.UIWidgets.ui;
using Unity.UIWidgets.widgets;
using TextStyle = Unity.UIWidgets.painting.TextStyle;

namespace UIWidgetsSample
{
    public class ToDoAppCanvas : WidgetCanvas
    {
        public class ToDoListApp : StatefulWidget
        {
            public ToDoListApp(Key key = null) : base(key)
            {
            }

            public override State createState()
            {
                return new _ToDoListAppState();
            }
        }

        protected override Widget getWidget()
        {
            return new ToDoListApp();
        }

        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(8.0);
                this.backgroundColor = backgroundColor ?? AsScreenCanvas.CLColors.transparent;
                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 _ToDoListAppState : State<ToDoListApp>
        {
            public class ToDoItem
            {
                public int id;
                public string content;
            }

            private List<ToDoItem> items = new List<ToDoItem>();
            private int nextId = 0;
            private TextEditingController controller = new TextEditingController("");

            private Widget title()
            {
                return new Text("ToDo App", textAlign: TextAlign.center, 
                    style: new TextStyle(fontSize:30, fontWeight: FontWeight.w700));
            }
            
            private Widget textInput()
            {
                return new Container(
                    child: new Row(
                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
                        children: new List<Widget>(
                        )
                        {
                            new Container(
                                width: 300,
                                decoration: new BoxDecoration(border: Border.all(new Color(0xFF000000), 1)), 
                                padding: EdgeInsets.fromLTRB(8, 0, 8, 0),
                                child: new EditableText(maxLines: 1,
                                    controller: controller,
                                   
                                    focusNode: new FocusNode(),
                                    style: new TextStyle(
                                        fontSize: 18,
                                        height: 1.5f,
                                        color: new Color(0xFF1389FD)
                                    ),
                                    selectionColor: Color.fromARGB(255, 255, 0, 0),
                                    cursorColor: Color.fromARGB(255, 0, 0, 0))
                            ),

                            new CustomButton(backgroundColor: Color.fromARGB(255, 0, 204, 204), 
                                padding: EdgeInsets.all(10),
                                child: new Text("Add", style: new TextStyle(
                                fontSize: 20, color: Color.fromARGB(255, 255, 255, 255), fontWeight: FontWeight.w700
                            )), onPressed: () =>
                            {
                                setState(() =>
                                {
                                    if (controller.text != "")
                                    {
                                        items.Add(new ToDoItem() {id = nextId++, content = controller.text});
                                    }
                                });
                            })
                        }
                    )
                );
            }

            private Widget contents()
            {
                var children = items.Select((item) => { return (Widget) new Text(
                    item.content, style: new TextStyle(
                        fontSize: 18,
                        height: 1.5
                        )
                    ); });
                return new Flexible(
                    child: new ListView(
                        physics: new AlwaysScrollableScrollPhysics(),
                        children: children.ToList()
                    )
                );
            }

            public override Widget build(BuildContext context)
            {
                var container = new Container(
                    padding: EdgeInsets.all(10),
                    decoration: new BoxDecoration(color:new Color(0x7F000000), border:Border.all(color: Color.fromARGB(255, 255, 0, 0), width: 5),
                        borderRadius: BorderRadius.all(2)),
                    child: new Column(
                        crossAxisAlignment: CrossAxisAlignment.stretch,
                        children: new List<Widget>
                        {
                            title(),
                            textInput(),
                            contents(),
                        }
                    )
                );
                return container;
            }
        }
    }

    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(8.0);
            this.backgroundColor = backgroundColor ?? AsScreenCanvas.CLColors.transparent;
            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
                )
            );
        }
    }
}