Implemented Level indicator

example/lib/main.dart

@@ -35,6 +35,9 @@ class Demo extends StatefulWidget {
 class _DemoState extends State<Demo> {
   bool value = false;
 
+  double sliderValue = 0;
+  double ratingValue = 0;
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -49,6 +52,19 @@ class _DemoState extends State<Demo> {
             child: Text('Button'),
             onPressed: () {},
           ),
+          Padding(
+            padding: const EdgeInsets.all(8.0),
+            child: CapacityIndicator(
+              value: sliderValue,
+              onChanged: (v) => setState(() => sliderValue = v),
+              discrete: true,
+            ),
+          ),
+          RatingIndicator(
+            value: ratingValue,
+            onChanged: (v) => setState(() => ratingValue = v),
+          ),
+          RelevanceIndicator(value: 10),
         ],
       ),
     );

lib/macos_ui.dart

@@ -1,8 +1,7 @@
 library macos_ui;
 
 /// todo: package-level docs
-export 'package:flutter/cupertino.dart'
-    show CupertinoColors, CupertinoDynamicColor;
+export 'package:flutter/widgets.dart';
 export 'package:flutter/material.dart'
     show
         Brightness,
@@ -12,7 +11,9 @@ export 'package:flutter/material.dart'
         PageTransitionsBuilder,
         FlutterLogo,
         CircleAvatar;
-export 'package:flutter/widgets.dart' hide Icon, TextBox;
+
+export 'package:flutter/cupertino.dart'
+    show CupertinoColors, CupertinoDynamicColor, CupertinoIcons;
 
 export 'src/buttons/push_button.dart';
 export 'src/buttons/push_button_theme.dart';
@@ -30,6 +31,12 @@ export 'src/macos_app.dart';
 export 'src/styles/macos_theme.dart';
 export 'src/styles/macos_theme_data.dart';
 export 'src/styles/typography.dart';
+export 'src/layout/scaffold.dart';
+export 'src/buttons/switch.dart';
 export 'src/styles/typography.dart';
 export 'src/util.dart';
 export 'src/util.dart';
+export 'src/indicators/capacity_indicators.dart';
+export 'src/indicators/progress_indicators.dart';
+export 'src/indicators/rating_indicator.dart';
+export 'src/indicators/relevance_indicator.dart';

lib/src/indicators/capacity_indicators.dart

@@ -0,0 +1,184 @@
+import 'package:macos_ui/macos_ui.dart';
+
+/// A capacity indicator illustrates the current level in
+/// relation to a finite capacity. Capacity indicators are
+/// often used when communicating factors like disk and
+/// battery usage. Mail, for example, uses a capacity indicator
+/// to show the percentage of data used in relation to an
+/// email account’s quota.
+///
+/// There are two types of capacity indicators:
+///
+/// * Continuous
+///
+/// A horizontal translucent track that fills with a colored bar
+/// to indicate the current value. Tick marks are often displayed
+/// to provide context.
+///
+/// ![Continuous Capacity Indicator](https://developer.apple.com/design/human-interface-guidelines/macos/images/indicators-continous.png)
+///
+/// * Discrete
+///
+/// A horizontal row of separate, equally sized, rectangular segments.
+/// The number of segments matches the total capacity, and the segments
+/// fill completely—never partially—with color to indicate the current
+/// value.
+///
+/// ![Discrete Capacity Indicator](https://developer.apple.com/design/human-interface-guidelines/macos/images/indicators-discrete.png)
+class CapacityIndicator extends StatelessWidget {
+  /// Creates a capacity indicator.
+  ///
+  /// [value] must be in range of 0 to 100.
+  const CapacityIndicator({
+    Key? key,
+    required this.value,
+    this.onChanged,
+    this.discrete = false,
+    this.splits = 10,
+  })  : assert(value >= 0 && value <= 100),
+        super(key: key);
+
+  /// The current value of the indicator. Must be in range of 0 to 100.
+  final double value;
+
+  /// Called when the current value of the indicator changes.
+  final ValueChanged<double>? onChanged;
+
+  /// Whether the indicator is discrete or not
+  ///
+  /// ![Discrete Capacity Indicator](https://developer.apple.com/design/human-interface-guidelines/macos/images/indicators-discrete.png)
+  final bool discrete;
+
+  /// How many parts the indicator will be splitted in if [discrete]
+  /// is true. Defaults to 10.
+  final int splits;
+
+  void _handleUpdate(Offset lp) {
+    double value = discrete ? lp.dx / splits : lp.dx;
+    if (value.isNegative)
+      value = 0;
+    else if (value > 100) value = 100;
+    onChanged?.call(value);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onPanStart: (event) => _handleUpdate(event.localPosition),
+      onPanUpdate: (event) => _handleUpdate(event.localPosition),
+      onPanDown: (event) => _handleUpdate(event.localPosition),
+      child: Container(
+        constraints: BoxConstraints(minWidth: 100),
+        child: discrete
+            ? LayoutBuilder(builder: (context, consts) {
+                double width = consts.biggest.width;
+                if (width.isInfinite) width = 100;
+                final splitWidth = width / splits;
+                final fillToIndex = (100 - -(value - 100)) * (splits / 10);
+                return SizedBox(
+                  width: width,
+                  child: Row(
+                    children: List.generate(splits, (index) {
+                      return Container(
+                        padding: EdgeInsets.only(
+                          right: index == splits - 1 ? 0 : 2.0,
+                        ),
+                        width: splitWidth,
+                        child: CapacityIndicatorCell(
+                          value:
+                              value > 0 && fillToIndex / 10 >= index ? 100 : 0,
+                        ),
+                      );
+                    }),
+                  ),
+                );
+              })
+            : CapacityIndicatorCell(value: value),
+      ),
+    );
+  }
+}
+
+class CapacityIndicatorCell extends StatelessWidget {
+  const CapacityIndicatorCell({
+    Key? key,
+    this.value = 100,
+    this.color = CupertinoColors.systemGreen,
+    this.borderColor = CupertinoColors.tertiaryLabel,
+    this.backgroundColor = CupertinoColors.tertiarySystemGroupedBackground,
+  })  : assert(value >= 0 && value <= 100),
+        super(key: key);
+
+  final Color color;
+  final Color backgroundColor;
+  final Color borderColor;
+
+  final double value;
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      height: 16,
+      child: CustomPaint(
+        painter: _CapacityCellPainter(
+          color: CupertinoDynamicColor.resolve(color, context),
+          backgroundColor:
+              CupertinoDynamicColor.resolve(backgroundColor, context),
+          borderColor: CupertinoDynamicColor.resolve(borderColor, context),
+          value: value,
+        ),
+      ),
+    );
+  }
+}
+
+class _CapacityCellPainter extends CustomPainter {
+  const _CapacityCellPainter({
+    required this.color,
+    required this.backgroundColor,
+    required this.borderColor,
+    required this.value,
+  });
+
+  final Color color;
+  final Color backgroundColor;
+  final Color borderColor;
+  final double value;
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final radius = 2.0;
+
+    /// Draw background
+    canvas.drawRRect(
+      BorderRadius.circular(radius).toRRect(Offset.zero & size),
+      Paint()..color = backgroundColor,
+    );
+
+    /// Draw inside
+    canvas.drawRRect(
+      BorderRadius.horizontal(
+        left: Radius.circular(radius),
+        right: value == 100 ? Radius.circular(radius) : Radius.zero,
+      ).toRRect(
+        Offset.zero & Size(size.width * (value / 100).clamp(0, 1), size.height),
+      ),
+      Paint()..color = color,
+    );
+
+    /// Draw border
+    canvas.drawRRect(
+      BorderRadius.circular(radius).toRRect(Offset.zero & size),
+      Paint()
+        ..color = borderColor
+        ..style = PaintingStyle.stroke
+        ..strokeWidth = 0.5,
+    );
+  }
+
+  @override
+  bool shouldRepaint(_CapacityCellPainter oldDelegate) => false;
+
+  @override
+  bool shouldRebuildSemantics(_CapacityCellPainter oldDelegate) => false;
+}

lib/src/indicators/rating_indicator.dart

@@ -0,0 +1,87 @@
+import 'package:macos_ui/macos_ui.dart';
+
+/// A rating indicator uses a series of horizontally arranged
+/// graphical symbols to communicate a ranking level. The
+/// default symbol is a star.
+///
+/// A rating indicator doesn’t display partial symbols—its value
+/// is rounded in order to display complete symbols only. Within
+/// a rating indicator, symbols are always the same distance apart
+/// and don't expand or shrink to fit the control.
+class RatingIndicator extends StatelessWidget {
+  /// Creates a rating indicator.
+  ///
+  /// [iconSize] must be non-negative.
+  ///
+  /// [amount] must be greater than 0
+  ///
+  /// [value] must be in range of 0 to [amount]
+  const RatingIndicator({
+    Key? key,
+    required this.value,
+    this.amount = 5,
+    this.ratedIcon = CupertinoIcons.star_fill,
+    this.unratedIcon = CupertinoIcons.star,
+    this.iconColor,
+    this.iconSize = 16,
+    this.onChanged,
+  })  : assert(iconSize >= 0),
+        assert(amount > 0),
+        assert(value >= 0 && value <= amount),
+        super(key: key);
+
+  /// The icon used when the star is rated. [CupertinoIcons.star_fill]
+  /// is used by default. If you must replace the star with a custom
+  /// symbol, ensure that its purpose is clear.
+  final IconData ratedIcon;
+
+  /// The icon used when the star is unrated. [CupertinoIcons.star] is
+  /// used by default. If you must replace the star with a custom symbol,
+  /// ensure that its purpose is clear.
+  final IconData unratedIcon;
+
+  /// The color of the icon. If null, [Style.primaryColor] is used
+  final Color? iconColor;
+
+  /// The size of the icon. Defaults to 16px
+  final double iconSize;
+
+  /// The amount of stars in the indicator. Defaults to 5
+  final int amount;
+
+  /// The current value. It must be in range of 0 to [amount]
+  final double value;
+
+  /// Called when the current value of the indicator changes.
+  final ValueChanged<double>? onChanged;
+
+  void _handleUpdate(Offset lp) {
+    double value = lp.dx / iconSize;
+    if (value.isNegative)
+      value = 0;
+    else if (value > amount) value = amount.toDouble();
+    onChanged?.call(value);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return GestureDetector(
+      onPanStart: (event) => _handleUpdate(event.localPosition),
+      onPanUpdate: (event) => _handleUpdate(event.localPosition),
+      onPanDown: (event) => _handleUpdate(event.localPosition),
+      child: Row(
+        mainAxisSize: MainAxisSize.min,
+        children: List.generate(amount, (index) {
+          final rated = value > index;
+          return Icon(
+            rated ? ratedIcon : unratedIcon,
+            color: iconColor ??
+                context.macosTheme.primaryColor ??
+                CupertinoColors.activeBlue,
+            size: iconSize,
+          );
+        }),
+      ),
+    );
+  }
+}