com.unity.uiwidgets/Samples/UIWidgetsSamples_2019_4/Assets/UIWidgetsGallery/demo/material/buttons_demo.cs

using System;
using System.Collections.Generic;
using System.Linq;
using UIWidgetsGallery.gallery;
using Unity.UIWidgets.material;
using Unity.UIWidgets.painting;
using Unity.UIWidgets.rendering;
using Unity.UIWidgets.widgets;

namespace UIWidgetsGallery.demo.material
{
    public static class ButtonsDemoUtils
    {
        public static readonly string _raisedText =
            "Raised buttons add dimension to mostly flat layouts. They emphasize " +
                "functions on busy or wide spaces.";

        public static readonly string _raisedCode = "buttons_raised";

        public static readonly string _flatText = "A flat button displays an ink splash on press " +
            "but does not lift. Use flat buttons on toolbars, in dialogs and " +
            "inline with padding";

        public static readonly string _flatCode = "buttons_flat";

        public static readonly string _outlineText =
            "Outline buttons become opaque and elevate when pressed. They are often " +
                "paired with raised buttons to indicate an alternative, secondary action.";

        public static readonly string _outlineCode = "buttons_outline";

        public static readonly string _dropdownText =
            "A dropdown button displays a menu that\"s used to select a value from a " +
                "small set of values. The button displays the current value and a down " +
                "arrow.";

        public static readonly string _dropdownCode = "buttons_dropdown";

        public static readonly string _iconText =
            "IconButtons are appropriate for toggle buttons that allow a single choice " +
                "to be selected or deselected, such as adding or removing an item\"s star.";

        public static readonly string _iconCode = "buttons_icon";

        public static readonly string _actionText =
            "Floating action buttons are used for a promoted action. They are " +
                "distinguished by a circled icon floating above the UI and can have motion " +
                "behaviors that include morphing, launching, and a transferring anchor " +
                "point.";

        public static readonly string _actionCode = "buttons_action";
    }
    
    class ButtonsDemo : StatefulWidget {
    public static readonly string routeName = "/material/buttons";

    public override State createState() => new _ButtonsDemoState();
    }
    
    class _ButtonsDemoState : State<ButtonsDemo> {
  ShapeBorder _buttonShape;

  public override Widget build(BuildContext context)
  {
    ButtonThemeData buttonTheme = ButtonTheme.of(context).copyWith(
      shape: _buttonShape
    );

    List<ComponentDemoTabData> demos = new List<ComponentDemoTabData>{
      new ComponentDemoTabData(
        tabName: "RAISED",
        description: ButtonsDemoUtils._raisedText,
        demoWidget: ButtonTheme.fromButtonThemeData(
          data: buttonTheme,
          child: buildRaisedButton()
        ),
        exampleCodeTag: ButtonsDemoUtils._raisedCode,
        documentationUrl: "https://docs.flutter.io/flutter/material/RaisedButton-class.html"
      ),
      new ComponentDemoTabData(
        tabName: "FLAT",
        description: ButtonsDemoUtils._flatText,
        demoWidget: ButtonTheme.fromButtonThemeData(
          data: buttonTheme,
          child: buildFlatButton()
        ),
        exampleCodeTag: ButtonsDemoUtils._flatCode,
        documentationUrl: "https://docs.flutter.io/flutter/material/FlatButton-class.html"
      ),
      new ComponentDemoTabData(
        tabName: "OUTLINE",
        description: ButtonsDemoUtils._outlineText,
        demoWidget: ButtonTheme.fromButtonThemeData(
          data: buttonTheme,
          child: buildOutlineButton()
        ),
        exampleCodeTag: ButtonsDemoUtils._outlineCode,
        documentationUrl: "https://docs.flutter.io/flutter/material/OutlineButton-class.html"
      ),
      new ComponentDemoTabData(
        tabName: "DROPDOWN",
        description: ButtonsDemoUtils._dropdownText,
        demoWidget: buildDropdownButton(),
        exampleCodeTag: ButtonsDemoUtils._dropdownCode,
        documentationUrl: "https://docs.flutter.io/flutter/material/DropdownButton-class.html"
      ),
      new ComponentDemoTabData(
        tabName: "ICON",
        description: ButtonsDemoUtils._iconText,
        demoWidget: buildIconButton(),
        exampleCodeTag: ButtonsDemoUtils._iconCode,
        documentationUrl: "https://docs.flutter.io/flutter/material/IconButton-class.html"
      ),
      new ComponentDemoTabData(
        tabName: "ACTION",
        description: ButtonsDemoUtils._actionText,
        demoWidget: buildActionButton(),
        exampleCodeTag: ButtonsDemoUtils._actionCode,
        documentationUrl: "https://docs.flutter.io/flutter/material/FloatingActionButton-class.html"
      )
  };

  return new TabbedComponentDemoScaffold(
      title: "Buttons",
      demos: demos,
      actions: new List<Widget>{
        new IconButton(
          icon: new Icon(Icons.sentiment_very_satisfied),
          onPressed: () => {
            setState(() => {
              _buttonShape = _buttonShape == null ? new StadiumBorder() : null;
            });
          }
        )
      }
    );
  }

  Widget buildRaisedButton() {
    return new Align(
      alignment: new Alignment(0.0f, -0.2f),
      child: new Column(
        mainAxisSize: MainAxisSize.min,
        children: new List<Widget>{
          new ButtonBar(
            mainAxisSize: MainAxisSize.min,
            children: new List<Widget>{
              new RaisedButton(
                child: new Text("RAISED BUTTON"),
                onPressed: () => {
                  // Perform some action
                }
              ),
              new RaisedButton(
                child: new Text("DISABLED"),
                onPressed: null
              )
            }
          ),
          new ButtonBar(
            mainAxisSize: MainAxisSize.min,
            children: new List<Widget>{
              RaisedButton.icon(
                icon: new Icon(Icons.add, size: 18.0f),
                label: new Text("RAISED BUTTON"),
                onPressed: () => {
                  // Perform some action
                }
              ),
              RaisedButton.icon(
                icon: new Icon(Icons.add, size: 18.0f),
                label: new Text("DISABLED"),
                onPressed: null
              )
            }
          )
        }
      )
    );
  }

  Widget buildFlatButton() {
    return new Align(
      alignment: new Alignment(0.0f, -0.2f),
      child: new Column(
        mainAxisSize: MainAxisSize.min,
        children: new List<Widget>{
          new ButtonBar(
            mainAxisSize: MainAxisSize.min,
            children: new List<Widget>{
              new FlatButton(
                child: new Text("FLAT BUTTON"),
                onPressed: () => {
                  // Perform some action
                }
              ),
              new FlatButton(
                child: new Text("DISABLED"),
                onPressed: null
              )
            }
          ),
          new ButtonBar(
            mainAxisSize: MainAxisSize.min,
            children: new List<Widget>{
              FlatButton.icon(
                icon: new Icon(Icons.add_circle_outline, size: 18.0f),
                label: new Text("FLAT BUTTON"),
                onPressed: () => {
                  // Perform some action
                }
              ),
              FlatButton.icon(
                icon: new Icon(Icons.add_circle_outline, size: 18.0f),
                label: new Text("DISABLED"),
                onPressed: null
              )
            }
          )
        }
      )
    );
  }

  Widget buildOutlineButton() {
    return new Align(
      alignment: new Alignment(0.0f, -0.2f),
      child: new Column(
        mainAxisSize: MainAxisSize.min,
        children: new List<Widget>{
          new ButtonBar(
            mainAxisSize: MainAxisSize.min,
            children: new List<Widget>{
              new OutlineButton(
                child: new Text("OUTLINE BUTTON"),
                onPressed: () => {
                  // Perform some action
                }
              ),
              new OutlineButton(
                child: new Text("DISABLED"),
                onPressed: null
              )
            }
          ),
          new ButtonBar(
            mainAxisSize: MainAxisSize.min,
            children: new List<Widget>{
              OutlineButton.icon(
                icon: new Icon(Icons.add, size: 18.0f),
                label: new Text("OUTLINE BUTTON"),
                onPressed: () => {
                  // Perform some action
                }
              ),
              OutlineButton.icon(
                icon: new Icon(Icons.add, size: 18.0f),
                label: new Text("DISABLED"),
                onPressed: null
              )
            }
          )
        }
      )
    );
  }

  // https://en.wikipedia.org/wiki/Free_Four
  string dropdown1Value = "Free";
  string dropdown2Value = null;
  string dropdown3Value = "Four";

  Widget buildDropdownButton() {
    return new Padding(
      padding:  EdgeInsets.all(24.0f),
      child: new Column(
        mainAxisAlignment: MainAxisAlignment.start,
        children: new List<Widget>{
          new ListTile(
            title: new Text("Simple dropdown:"),
            trailing: new DropdownButton<string>(
              value: dropdown1Value,
              onChanged: (string newValue) => {
                setState(() => {
                  dropdown1Value = newValue;
                });
              },
              items: new List<string>{"One", "Two", "Free", "Four"}.Select<string, DropdownMenuItem<string>>((string value) => {
                return new DropdownMenuItem<string>(
                  value: value,
                  child: new Text(value)
                );
              }).ToList()
            )
          ), 
          new SizedBox(
            height: 24.0f
          ),
          new ListTile(
            title: new Text("Dropdown with a hint:"),
            trailing: new DropdownButton<string>(
              value: dropdown2Value,
              hint: new Text("Choose"),
              onChanged: (string newValue) => {
                setState(() => {
                  dropdown2Value = newValue;
                });
              },
              items: new List<string>{"One", "Two", "Free", "Four"}.Select<string, DropdownMenuItem<string>>((string value) => {
                return new DropdownMenuItem<string>(
                  value: value,
                  child: new Text(value)
                );
              }).ToList()
            )
          ),
          new SizedBox(
            height: 24.0f
          ),
          new ListTile(
            title: new Text("Scrollable dropdown:"),
            trailing: new DropdownButton<string>(
              value: dropdown3Value,
              onChanged: (string newValue) => {
                setState(() => {
                  dropdown3Value = newValue;
                });
              },
              items: new List<string>{
                  "One", "Two", "Free", "Four", "Can", "I", "Have", "A", "Little",
                  "Bit", "More", "Five", "Six", "Seven", "Eight", "Nine", "Ten",
                 }
                .Select<string, DropdownMenuItem<string>>((string value) => {
                  return new DropdownMenuItem<string>(
                    value: value,
                    child: new Text(value)
                  );
                })
                .ToList()
             )
          )
        }
      )
    );
  }

  bool iconButtonToggle = false;

  Widget buildIconButton() {
    return new Align(
      alignment: new Alignment(0.0f, -0.2f),
      child: new Row(
        mainAxisSize: MainAxisSize.min,
        children: new List<Widget>{
          new IconButton(
            icon: new Icon(
              Icons.thumb_up
            ),
            onPressed: () =>{
              setState(() => iconButtonToggle = !iconButtonToggle);
            },
            color: iconButtonToggle ? Theme.of(context).primaryColor : null
          ),
          new IconButton(
            icon: new Icon(
              Icons.thumb_up
            ),
            onPressed: null
          )
        }
        .Select<Widget, Widget>((Widget button) => new SizedBox(width: 64.0f, height: 64.0f, child: button))
        .ToList()
      )
    );
  }

  Widget buildActionButton() {
    return new Align(
      alignment: new Alignment(0.0f, -0.2f),
      child: new FloatingActionButton(
        child: new Icon(Icons.add),
        onPressed: () => {
          // Perform some action
        },
        tooltip: "floating action button"
      )
    );
  }
}
}