document the public API

lib/src/bar.dart

@@ -23,11 +23,16 @@ const double BAR_HEIGHT = 50;
 /// Default distance that the child's top edge is inset from the top of the stack.
 const double CURVE_TOP = -25;
 
+/// Default size for active tab
 const double ACTION_LAYOUT_SIZE = 60;
+
+/// Default size for active icon in tab
 const double ACTION_INNER_BUTTON_SIZE = 40;
-const int CURVE_INDEX = -1;
+
+/// default elevation of [ConvexAppBar]
 const double ELEVATION = 2;
 
+/// Tab style which supported internal.
 enum TabStyle {
   /// convex shape fixed center, see [FixedTabStyle]
   ///
@@ -75,6 +80,7 @@ class ConvexAppBar extends StatefulWidget {
   /// TAB item builder
   final DelegateBuilder itemBuilder;
 
+  /// Badge chip builder
   final ChipBuilder chipBuilder;
 
   /// Tab Click handler
@@ -285,6 +291,7 @@ abstract class DelegateBuilder {
   }
 }
 
+/// State of [ConvexAppBar]
 class ConvexAppBarState extends State<ConvexAppBar>
     with TickerProviderStateMixin {
   int _currentIndex;
@@ -309,6 +316,7 @@ class ConvexAppBarState extends State<ConvexAppBar>
     }
   }
 
+  /// change active tab index; can be used with [PageView]
   Future<void> animateTo(int index) async {
     _initAnimation(from: _currentIndex, to: index);
     _controller?.forward();
@@ -429,6 +437,7 @@ class ConvexAppBarState extends State<ConvexAppBar>
     );
   }
 
+  /// whether the tab shape are fixed or not
   bool isFixed() => widget.itemBuilder.fixed();
 
   Widget _barContent(double height, double paddingBottom, int curveTabIndex) {
@@ -476,6 +485,12 @@ class ConvexAppBarState extends State<ConvexAppBar>
   }
 }
 
+/// Tab callback, [index] are tab index which is being clicked
 typedef GestureTapIndexCallback = void Function(int index);
+
+/// Tab builder;
+/// * [context] BuildContent instance
+/// * [index] index of tab
+/// * [active] active state for tab index
 typedef CustomTabBuilder = Widget Function(
     BuildContext context, int index, bool active);

lib/src/chip_builder.dart

@@ -1,16 +1,32 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 
+/// Interface to apply any custom badge chip
 abstract class ChipBuilder {
+  /// Construct a new widget which represent the tab item with custom badge.
+  ///
+  /// * [context] BuildContext instance
+  /// * [child] the tab item Widget
+  /// * [index] index of the tab item
+  /// * [active] active state for the index
   Widget build(BuildContext context, Widget child, int index, bool active);
 }
 
 /// Simple badge with num inside
 class DefaultChipBuilder extends ChipBuilder {
+  /// key-value map, stands for the badge data
   final Map<int, dynamic> chips;
+
+  /// Color of badge text
   final Color textColor;
+
+  /// Color of the badge chip
   final Color badgeColor;
+
+  /// Padding for badge
   final EdgeInsets padding;
+
+  /// Radius corner for badge
   final double borderRadius;
 
   DefaultChipBuilder(
@@ -33,6 +49,11 @@ class DefaultChipBuilder extends ChipBuilder {
     );
   }
 
+  /// factory method which convert a chip data into [Widget];
+  ///
+  /// * [chip] String, return a [Text] badge;
+  /// * [chip] IconData, return a [Icon] badge;
+  /// * [chip] Widget, return a [Widget] badge;
   Widget asBadge(dynamic chip) {
     if (chip is String) {
       return Positioned.fill(

lib/src/convex_shape.dart

@@ -2,6 +2,15 @@ import 'package:flutter/cupertino.dart';
 import 'package:flutter/painting.dart';
 import 'dart:math' as math;
 
+/// A convex shape which implemented [NotchedShape].
+///
+/// It's used to draw a convex shape for [ConvexAppBar], If you are interested about
+/// the math calculation， please refer to [CircularNotchedRectangle]， it's base
+/// on Bezier curve;
+///
+/// See also:
+///
+///  * [CircularNotchedRectangle], a rectangle with a smooth circular notch.
 class ConvexNotchedRectangle extends NotchedShape {
   const ConvexNotchedRectangle();
 

lib/src/item.dart

@@ -1,6 +1,8 @@
 import 'package:flutter/cupertino.dart';
 
+/// Tab item used for [ConvexAppBar]
 class TabItem<T> {
+  /// tab text
   final String title;
 
   /// IconData or Image

lib/src/painter.dart

@@ -4,14 +4,23 @@ import 'package:flutter/material.dart';
 import 'convex_shape.dart';
 import 'reused_gradient.dart';
 
+/// Custom painter to draw the [ConvexNotchedRectangle] into canvas;
 class ConvexPainter extends CustomPainter {
   final _paint = Paint();
   final _shadowPaint = Paint();
   final _shape = ConvexNotchedRectangle();
   final ReusedGradient _gradient = ReusedGradient();
+
+  /// width of the convex shape
   final double width;
+
+  /// height of the convex shape
   final double height;
+
+  /// position in vertical which describe the offset of shape
   final double top;
+
+  /// position in horizontal which describe the offset of shape
   final Animation<double> leftPercent;
 
   ConvexPainter({

lib/src/reused_gradient.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/cupertino.dart';
 
+/// Wrapper for [Gradient], we don't want to re-create instance frequently in
+/// hot method, such as paint.
 class ReusedGradient {
   Gradient _gradient;
 
@@ -8,11 +10,13 @@ class ReusedGradient {
 
   ReusedGradient();
 
+  /// setter to reset the [Gradient] instance
   set gradient(Gradient gradient) {
     _gradient = gradient;
     _size = null;
   }
 
+  /// update the paint with provided size
   updateWith(Paint paint, {Rect size}) {
     if (size == _size) {
       return;

lib/src/style/blend_image_icon.dart

@@ -9,8 +9,13 @@ class BlendImageIcon<T> extends StatelessWidget {
             'image must be IconData or Widget'),
         super(key: key);
 
+  /// color used for Icon and gradient
   final Color color;
+
+  /// child image
   final T image;
+
+  /// size of icon
   final double size;
 
   @override

lib/src/style/fixed_circle_tab_style.dart

@@ -5,22 +5,26 @@ import 'package:flutter/material.dart';
 
 import '../../convex_bottom_bar.dart';
 import 'blend_image_icon.dart';
+import 'inner_builder.dart';
 
 /// Convex shape is fixed center with circle
-class FixedCircleTabStyle extends DelegateBuilder {
-  final List<TabItem> items;
-  final Color activeColor;
-  final Color color;
+class FixedCircleTabStyle extends InnerBuilder {
+  /// color used as background of appbar and circle icon
   final Color backgroundColor;
+
+  /// index of the centered convex shape
   final int convexIndex;
+
+  /// margin of tab
   final margin = (ACTION_LAYOUT_SIZE - ACTION_INNER_BUTTON_SIZE) / 4;
 
   FixedCircleTabStyle(
-      {this.items,
-      this.activeColor,
-      this.color,
+      {List<TabItem> items,
+      Color activeColor,
+      Color color,
       this.backgroundColor,
-      this.convexIndex});
+      this.convexIndex})
+      : super(items: items, activeColor: activeColor, color: color);
 
   @override
   Widget build(BuildContext context, int index, bool active) {

lib/src/style/fixed_tab_style.dart

@@ -5,17 +5,19 @@ import 'package:flutter/material.dart';
 
 import '../../convex_bottom_bar.dart';
 import 'blend_image_icon.dart';
+import 'inner_builder.dart';
 
 /// Convex shape is fixed center
-class FixedTabStyle extends DelegateBuilder {
-  final List<TabItem> items;
-  final Color activeColor;
-  final Color color;
+class FixedTabStyle extends InnerBuilder {
+  /// index of the centered convex shape
   final int convexIndex;
-  DelegateBuilder tabBuilder;
-  DelegateBuilder convexBuilder;
 
-  FixedTabStyle({this.items, this.activeColor, this.color, this.convexIndex});
+  FixedTabStyle({
+    List<TabItem> items,
+    Color activeColor,
+    Color color,
+    this.convexIndex,
+  }) : super(items: items, activeColor: activeColor, color: color);
 
   @override
   Widget build(BuildContext context, int index, bool active) {

lib/src/style/flip_tab_style.dart

@@ -3,15 +3,20 @@ import 'package:flutter/material.dart';
 
 import '../../convex_bottom_bar.dart';
 import 'blend_image_icon.dart';
+import 'inner_builder.dart';
 import 'transition_container.dart';
 
-class FlipTabStyle extends DelegateBuilder {
-  final List<TabItem> items;
-  final Color activeColor;
-  final Color color;
+/// Tab item are flipped when click
+class FlipTabStyle extends InnerBuilder {
+  /// curve for flip transition
   final Curve curve;
 
-  FlipTabStyle({this.items, this.activeColor, this.color, this.curve});
+  FlipTabStyle({
+    List<TabItem> items,
+    Color activeColor,
+    Color color,
+    this.curve,
+  }) : super(items: items, activeColor: activeColor, color: color);
 
   @override
   Widget build(BuildContext context, int index, bool active) {

lib/src/style/inner_builder.dart

@@ -0,0 +1,17 @@
+import 'dart:ui';
+
+import '../../convex_bottom_bar.dart';
+
+/// Simple builder which extend [DelegateBuilder] to provide some necessary config;
+abstract class InnerBuilder extends DelegateBuilder {
+  /// List of [TabItem] stands for tabs
+  final List<TabItem> items;
+
+  /// color used when tab is active
+  final Color activeColor;
+
+  /// color used for tab
+  final Color color;
+
+  InnerBuilder({this.items, this.activeColor, this.color});
+}

lib/src/style/react_circle_tab_style.dart

@@ -3,24 +3,27 @@ import 'package:flutter/material.dart';
 
 import '../../convex_bottom_bar.dart';
 import 'blend_image_icon.dart';
+import 'inner_builder.dart';
 import 'transition_container.dart';
 
 /// Convex shape is moved after selection
-class ReactCircleTabStyle extends DelegateBuilder {
-  final List<TabItem> items;
-  final Color activeColor;
-  final Color color;
+class ReactCircleTabStyle extends InnerBuilder {
+  /// color used as background of appbar and circle icon
   final Color backgroundColor;
+
+  /// curve for tab transition
   final Curve curve;
+
+  /// margin of tab
   final margin = (ACTION_LAYOUT_SIZE - ACTION_INNER_BUTTON_SIZE) / 4;
 
   ReactCircleTabStyle({
-    this.items,
-    this.activeColor,
-    this.color,
+    List<TabItem> items,
+    Color activeColor,
+    Color color,
     this.backgroundColor,
     this.curve,
-  });
+  }) : super(items: items, activeColor: activeColor, color: color);
 
   @override
   Widget build(BuildContext context, int index, bool active) {

lib/src/style/react_tab_style.dart

@@ -3,16 +3,20 @@ import 'package:flutter/material.dart';
 
 import '../../convex_bottom_bar.dart';
 import 'blend_image_icon.dart';
+import 'inner_builder.dart';
 import 'transition_container.dart';
 
 /// Convex shape is moved after selection
-class ReactTabStyle extends DelegateBuilder {
-  final List<TabItem> items;
-  final Color activeColor;
-  final Color color;
+class ReactTabStyle extends InnerBuilder {
+  /// curve for tab transition
   final Curve curve;
 
-  ReactTabStyle({this.items, this.activeColor, this.color, this.curve});
+  ReactTabStyle({
+    List<TabItem> items,
+    Color activeColor,
+    Color color,
+    this.curve,
+  }) : super(items: items, activeColor: activeColor, color: color);
 
   @override
   Widget build(BuildContext context, int index, bool active) {

lib/src/style/styles.dart

@@ -10,6 +10,7 @@ import 'react_tab_style.dart';
 import 'textin_tab_style.dart';
 import 'titled_tab_style.dart';
 
+/// factory method to return the [DelegateBuilder] for each [TabStyle]
 DelegateBuilder supportedStyle(
   TabStyle style, {
   @required List<TabItem> items,

lib/src/style/textin_tab_style.dart

@@ -3,16 +3,20 @@ import 'package:flutter/material.dart';
 
 import '../../convex_bottom_bar.dart';
 import 'blend_image_icon.dart';
+import 'inner_builder.dart';
 import 'transition_container.dart';
 
 /// tab icon, text animated with pop transition
-class TextInTabStyle extends DelegateBuilder {
-  final List<TabItem> items;
-  final Color activeColor;
-  final Color color;
+class TextInTabStyle extends InnerBuilder {
+  /// curve for tab transition
   final Curve curve;
 
-  TextInTabStyle({this.items, this.activeColor, this.color, this.curve});
+  TextInTabStyle({
+    List<TabItem> items,
+    Color activeColor,
+    Color color,
+    this.curve,
+  }) : super(items: items, activeColor: activeColor, color: color);
 
   @override
   Widget build(BuildContext context, int index, bool active) {