Implement divider, with Demo

Runtime/material/divider.cs

+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.widgets;
+using Color = Unity.UIWidgets.ui.Color;
+
+namespace Unity.UIWidgets.material {
+    public class Divider : StatelessWidget {
+        public Divider(
+            Key key = null,
+            double height = 16.0,
+            double indent = 0.0,
+            Color color = null
+        ) : base(key) {
+            D.assert(height >= 0.0);
+            this.height = height;
+            this.indent = indent;
+            this.color = color;
+        }
+
+        public readonly double height;
+        public readonly double indent;
+        public readonly Color color;
+
+        public static BorderSide createBorderSide(BuildContext context, Color color = null, double width = 0.0) {
+            return new BorderSide(
+                color: Theme.of(context).dividerColor,
+                width: width
+            );
+        }
+
+        public override Widget build(BuildContext context) {
+            return new SizedBox(
+                height: height,
+                child: new Center(
+                    child: new Container(
+                        height: 0.0,
+                        margin: EdgeInsets.only(left: indent),
+                        decoration: new BoxDecoration(
+                            border: new Border(
+                                bottom: createBorderSide(context, color)
+                            )
+                        )
+                    )
+                )
+            );
+        }
+    }
+}

Samples/MaterialSample/DividerDemo.cs

+using System.Collections.Generic;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.engine;
+using Unity.UIWidgets.widgets;
+using Unity.UIWidgets.gestures;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.ui;
+using Color = Unity.UIWidgets.ui.Color;
+using TextStyle = Unity.UIWidgets.painting.TextStyle;
+
+namespace UIWidgetsSample {
+    public class DividerDemo : WidgetCanvas {
+        protected override Widget getWidget() {
+            return new DemoApp();
+        }
+
+        public class DemoApp : StatefulWidget {
+            public DemoApp(Key key = null) : base(key) {
+
+            }
+            public override State createState() {
+                return new _DemoAppState();
+            }
+        }
+
+        public class _DemoAppState : State<DemoApp> {
+            string title = "Hello";
+            string subtitle = "World";
+            bool setTitle = true;
+            TextEditingController controller = new TextEditingController("");
+            public override Widget build(BuildContext context) {
+                return new Container(
+                    height: 200,
+                    padding: EdgeInsets.all(10),
+                    decoration: new BoxDecoration(
+                        color: new Color(0xFFEF1F7F),
+                        border: Border.all(color: Color.fromARGB(255, 0xDF, 0x10, 0x70), width: 5),
+                        borderRadius: BorderRadius.all(20)
+                    ),
+                    child: new Center(
+                        child: new Column(
+                            children: new List<Widget>() {
+                        new Text(title),
+                        new Divider(),
+                        new Text(subtitle),
+                        new Divider(),
+                        new Container(
+                            width: 500,
+                            decoration: new BoxDecoration(border: Border.all(new Color(0xFF00FF00), 1)),
+                            child: new EditableText(
+                                controller: controller,
+                                focusNode: new FocusNode(),
+                                style: new TextStyle(
+                                        fontSize: 18,
+                                        height: 1.5f,
+                                        color: new Color(0xFFFF89FD)),
+                                cursorColor: Color.fromARGB(255, 0, 0, 0)
+                            )
+                        ),
+                        new Divider(),
+                        new Container(
+                            width: 100,
+                            height: 50,
+                            child: new CustomButton(
+                                onPressed: () => {
+                                setState(() => {
+                                        if(setTitle) {
+                                            title = controller.text;
+                                        } else {
+                                            subtitle = controller.text;
+                                        }
+                                        setTitle = !setTitle;
+                                    });
+                                },
+                                padding: EdgeInsets.all(5.0),
+                                child: new Center(
+                                    child: new Text(setTitle? "Set Title": "Set Subtitle")
+                                )
+                            )
+                        )
+                            }
+                        )
+                    )
+                );
+            }
+        }
+
+        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 ?? new Color(0xFFFF00FD);
+                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
+                    )
+                );
+            }
+        }
+    }
+}