Implement ColorsDemo.

Samples/UIWidgetsGallery/gallery/demos.cs

 //                ),
 //
 //                // Style
-//                new GalleryDemo(
-//                    title: "Colors",
-//                    subtitle: "All of the predefined colors",
-//                    icon: GalleryIcons.colors,
-//                    category: GalleryDemoCategory._kStyle,
-//                    routeName: ColorsDemo.routeName,
-//                    buildRoute: (BuildContext context) => ColorsDemo()
-//                ),
+                new GalleryDemo(
+                    title: "Colors",
+                    subtitle: "All of the predefined colors",
+                    icon: GalleryIcons.colors,
+                    category: DemoUtils._kStyle,
+                    routeName: ColorsDemo.routeName,
+                    buildRoute: (BuildContext context) => new ColorsDemo()
+                ),
 //                new GalleryDemo(
 //                    title: "Typography",
 //                    subtitle: "All of the predefined text styles",

Samples/UIWidgetsGallery/demo/colors_demo.cs

+using System.Collections.Generic;
+using System.Linq;
+using Unity.UIWidgets.foundation;
+using Unity.UIWidgets.material;
+using Unity.UIWidgets.painting;
+using Unity.UIWidgets.rendering;
+using Unity.UIWidgets.ui;
+using Unity.UIWidgets.widgets;
+using TextStyle = Unity.UIWidgets.painting.TextStyle;
+
+namespace UIWidgetsGallery.gallery {
+    class ColorDemoConstants {
+        public const float kColorItemHeight = 48.0f;
+
+        public static readonly List<Palette> allPalettes = new List<Palette> {
+            new Palette(name: "RED", primary: Colors.red, accent: Colors.redAccent, threshold: 300),
+            new Palette(name: "PINK", primary: Colors.pink, accent: Colors.pinkAccent, threshold: 200),
+            new Palette(name: "PURPLE", primary: Colors.purple, accent: Colors.purpleAccent, threshold: 200),
+            new Palette(name: "DEEP PURPLE", primary: Colors.deepPurple, accent: Colors.deepPurpleAccent,
+                threshold: 200),
+            new Palette(name: "INDIGO", primary: Colors.indigo, accent: Colors.indigoAccent, threshold: 200),
+            new Palette(name: "BLUE", primary: Colors.blue, accent: Colors.blueAccent, threshold: 400),
+            new Palette(name: "LIGHT BLUE", primary: Colors.lightBlue, accent: Colors.lightBlueAccent, threshold: 500),
+            new Palette(name: "CYAN", primary: Colors.cyan, accent: Colors.cyanAccent, threshold: 600),
+            new Palette(name: "TEAL", primary: Colors.teal, accent: Colors.tealAccent, threshold: 400),
+            new Palette(name: "GREEN", primary: Colors.green, accent: Colors.greenAccent, threshold: 500),
+            new Palette(name: "LIGHT GREEN", primary: Colors.lightGreen, accent: Colors.lightGreenAccent,
+                threshold: 600),
+            new Palette(name: "LIME", primary: Colors.lime, accent: Colors.limeAccent, threshold: 800),
+            new Palette(name: "YELLOW", primary: Colors.yellow, accent: Colors.yellowAccent),
+            new Palette(name: "AMBER", primary: Colors.amber, accent: Colors.amberAccent),
+            new Palette(name: "ORANGE", primary: Colors.orange, accent: Colors.orangeAccent, threshold: 700),
+            new Palette(name: "DEEP ORANGE", primary: Colors.deepOrange, accent: Colors.deepOrangeAccent,
+                threshold: 400),
+            new Palette(name: "BROWN", primary: Colors.brown, threshold: 200),
+            new Palette(name: "GREY", primary: Colors.grey, threshold: 500),
+            new Palette(name: "BLUE GREY", primary: Colors.blueGrey, threshold: 500),
+        };
+    }
+
+    public class Palette {
+        public Palette(string name = null, MaterialColor primary = null, MaterialAccentColor accent = null,
+            int threshold = 900) {
+            this.name = name;
+            this.primary = primary;
+            this.accent = accent;
+            this.threshold = threshold;
+        }
+
+        public readonly string name;
+        public readonly MaterialColor primary;
+        public readonly MaterialAccentColor accent;
+        public readonly int threshold;
+
+        public bool isValid {
+            get { return this.name != null && this.primary != null && this.threshold != null; }
+        }
+    }
+
+
+    public class ColorItem : StatelessWidget {
+        public ColorItem(
+            Key key = null,
+            int? index = null,
+            Color color = null,
+            string prefix = ""
+        ) : base(key: key) {
+            D.assert(index != null);
+            D.assert(color != null);
+            D.assert(prefix != null);
+            this.index = index;
+            this.color = color;
+            this.prefix = prefix;
+        }
+
+
+        public readonly int? index;
+        public readonly Color color;
+        public readonly string prefix;
+
+        string colorString() {
+            return $"#{this.color.value.ToString("X8").ToUpper()}";
+        }
+
+        public override Widget build(BuildContext context) {
+            return new Container(
+                height: ColorDemoConstants.kColorItemHeight,
+                padding: EdgeInsets.symmetric(horizontal: 16.0f),
+                color: this.color,
+                child: new SafeArea(
+                    top: false,
+                    bottom: false,
+                    child: new Row(
+                        mainAxisAlignment: MainAxisAlignment.spaceBetween,
+                        crossAxisAlignment: CrossAxisAlignment.center,
+                        children: new List<Widget> {
+                            new Text($"{this.prefix}{this.index}"),
+                            new Text(this.colorString())
+                        }
+                    )
+                )
+            );
+        }
+    }
+
+    public class PaletteTabView : StatelessWidget {
+        public PaletteTabView(
+            Key key = null,
+            Palette colors = null
+        ) : base(key: key) {
+            D.assert(colors != null && colors.isValid);
+            this.colors = colors;
+        }
+
+        public readonly Palette colors;
+
+        public readonly static List<int> primaryKeys = new List<int> {50, 100, 200, 300, 400, 500, 600, 700, 800, 900};
+        public readonly static List<int> accentKeys = new List<int> {100, 200, 400, 700};
+
+        public override Widget build(BuildContext context) {
+            TextTheme textTheme = Theme.of(context).textTheme;
+            TextStyle whiteTextStyle = textTheme.body1.copyWith(color: Colors.white);
+            TextStyle blackTextStyle = textTheme.body1.copyWith(color: Colors.black);
+            List<Widget> colorItems = primaryKeys.Select<int, Widget>((int index) => {
+                return new DefaultTextStyle(
+                    style: index > this.colors.threshold ? whiteTextStyle : blackTextStyle,
+                    child: new ColorItem(index: index, color: this.colors.primary[index])
+                );
+            }).ToList();
+
+            if (this.colors.accent != null) {
+                colorItems.AddRange(accentKeys.Select<int, Widget>((int index) => {
+                    return new DefaultTextStyle(
+                        style: index > this.colors.threshold ? whiteTextStyle : blackTextStyle,
+                        child: new ColorItem(index: index, color: this.colors.accent[index], prefix: "A")
+                    );
+                }).ToList());
+            }
+
+            return new ListView(
+                itemExtent: ColorDemoConstants.kColorItemHeight,
+                children: colorItems
+            );
+        }
+    }
+
+    public class ColorsDemo : StatelessWidget {
+        public const string routeName = "/colors";
+
+        public override Widget build(BuildContext context) {
+            return new DefaultTabController(
+                length: ColorDemoConstants.allPalettes.Count,
+                child: new Scaffold(
+                    appBar: new AppBar(
+                        elevation: 0.0f,
+                        title: new Text("Colors"),
+                        bottom: new TabBar(
+                            isScrollable: true,
+                            tabs: ColorDemoConstants.allPalettes
+                                .Select<Palette, Widget>((Palette swatch) => new Tab(text: swatch.name)).ToList()
+                        )
+                    ),
+                    body: new TabBarView(
+                        children: ColorDemoConstants.allPalettes.Select<Palette, Widget>((Palette colors) => {
+                            return new PaletteTabView(colors: colors);
+                        }).ToList()
+                    )
+                )
+            );
+        }
+    }
+}

Samples/UIWidgetsGallery/demo/colors_demo.cs.meta

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