Merge branch 'develop' into dev/yisheng

# Conflicts:
#	lib/widgets/components/Bar/AppBar/index.dart
#	lib/widgets/components/Bar/BottomAppBar/demo.dart
#	lib/widgets/components/Bar/BottomAppBar/index.dart
#	lib/widgets/components/Bar/ButtonBar/index.dart
#	lib/widgets/components/Bar/FlexibleSpaceBar/index.dart
#	lib/widgets/components/Bar/SliverAppBar/index.dart
#	lib/widgets/components/Bar/SnackBar/index.dart
#	lib/widgets/components/Bar/SnackBarAction/index.dart
#	lib/widgets/components/Card/Card/index.dart
#	lib/widgets/components/LIst/ListBody/index.dart
#	lib/widgets/components/LIst/ListView/index.dart
#	lib/widgets/elements/Form/Button/DropdownButton/index.dart
#	lib/widgets/elements/Form/Button/FlatButton/index.dart
#	lib/widgets/elements/Form/Button/PopupMenuButton/index.dart
#	lib/widgets/elements/Form/CheckBox/Checkbox/index.dart
#	lib/widgets/elements/Form/CheckBox/CheckboxListTile/index.dart
#	lib/widgets/elements/Frame/Axis/crossAxis/index.dart
#	lib/widgets/elements/Frame/Axis/flipAxis/index.dart
#	lib/widgets/elements/Frame/Axis/mainAxis/index.dart
#	lib/widgets/elements/Media/Image/precacheImage/index.dart

lib/widgets/elements/Form/Button/DropdownButton/demo.dart

@@ -6,7 +6,6 @@
  * email: zhu.yan@alibaba-inc.com
  * tartget: DropdownButton 的示例
  */
-import 'dart:math';
 import 'package:flutter/material.dart';
 
 /*
@@ -14,15 +13,15 @@ import 'package:flutter/material.dart';
 * isDisabled:是否是禁用，isDisabled 默认为true
 * */
 class DropdownButtonDefault extends StatelessWidget {
-  List<DropdownMenuItem> generateItemList() {
-    List<DropdownMenuItem> items = new List();
-    DropdownMenuItem item1 = new DropdownMenuItem(
+   List<DropdownMenuItem> generateItemList() {
+    final List<DropdownMenuItem> items = new List();
+    final DropdownMenuItem item1 = new DropdownMenuItem(
         value: '张三', child: new Text('张三'));
-    DropdownMenuItem item2 = new DropdownMenuItem(
+    final DropdownMenuItem item2 = new DropdownMenuItem(
         value: '李四', child: new Text('李四'));
-    DropdownMenuItem item3 = new DropdownMenuItem(
+    final DropdownMenuItem item3 = new DropdownMenuItem(
         value: '王二', child: new Text('王二'));
-    DropdownMenuItem item4 = new DropdownMenuItem(
+    final DropdownMenuItem item4 = new DropdownMenuItem(
         value: '麻子', child: new Text('麻子'));
     items.add(item1);
     items.add(item2);

lib/widgets/elements/Form/Button/DropdownButton/index.dart

@@ -8,6 +8,7 @@
  * 对应文档地址:https://docs.flutter.io/flutter/material/DropdownButton-class.html
  */
 import '../../../../../common/widget_demo.dart';
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_markdown/flutter_markdown.dart';
@@ -56,7 +57,7 @@ class _DemoState extends State<Demo> {
   }
 }
 
-/**
+/*
  * 所有的 DropdownButton 按钮
  */
 Widget allDropdownButtons(BuildContext context,_DemoState that){

lib/widgets/elements/Form/Button/FlatButton/demo.dart

@@ -16,7 +16,7 @@ import 'package:flutter/material.dart';
 class FlatButtonDefault extends StatelessWidget {
   final bool isDisabled;
 
-  const FlatButtonDefault([bool this.isDisabled = true])
+  const FlatButtonDefault([ this.isDisabled = true])
       : assert(isDisabled != null),
         super();
 
@@ -39,7 +39,7 @@ class FlatButtonIconDefault extends StatelessWidget {
   final IconData icon;
 
   const FlatButtonIconDefault(
-      [bool this.isDisabled = true, IconData this.icon = Icons.add_circle])
+      [ this.isDisabled = true,  this.icon = Icons.add_circle])
       : super();
 
   Color _randomColor() {
@@ -73,10 +73,10 @@ class FlatButtonCustom extends StatelessWidget {
   final VoidCallback onPressed;
 
   const FlatButtonCustom([
-    String this.txt = '自定义按钮',
-    Color this.color = Colors.blueAccent,
-    ShapeBorder this.shape,
-    VoidCallback this.onPressed
+     this.txt = '自定义按钮',
+     this.color = Colors.blueAccent,
+     this.shape,
+     this.onPressed
   ]) :super();
 
   @override

lib/widgets/elements/Form/Button/FlatButton/index.dart

@@ -8,39 +8,12 @@
  * 对应文档地址:https://docs.flutter.io/flutter/material/FlatButton-class.html
  */
 import '../../../../../common/widget_demo.dart';
+
 import 'package:flutter/material.dart';
 
 import 'package:flutter_markdown/flutter_markdown.dart';
 import './demo.dart' as flatButton;
 
-const String _markdownData = """# Markdown Example
-Markdown allows you to easily include formatted text, images, and even formatted Dart code in your app.
-## Styling
-Style text as _italic_, __bold__, or `inline code`.
-- Use bulleted lists
-- To better clarify
-- Your points
-## Links
-You can use [hyperlinks](hyperlink) in markdown
-## Images
-You can include images:
-![Flutter logo](https://flutter.io/images/flutter-mark-square-100.png#100x100)
-## Markdown widget
-This is an example of how to create your own Markdown widget:
-    new Markdown(data: 'Hello _world_!');
-## Code blocks
-Formatted Dart code looks really pretty too:
-```
-void main() {
-  runApp(new MaterialApp(
-    home: new Scaffold(
-      body: new Markdown(data: markdownData)
-    )
-  ));
-}
-```
-Enjoy!
-""";
 
 
 const String _flatText0 =
@@ -88,7 +61,7 @@ class _DemoState extends State<Demo> {
   }
 }
 
-/**
+/*
  * 所有的 FlatButton 按钮
  */
 Widget allFlatButtons(BuildContext context){

lib/widgets/elements/Form/Button/FloatingActionButton/demo.dart

@@ -6,7 +6,6 @@
  * email: zhu.yan@alibaba-inc.com
  * tartget: OutlineButton 的示例
  */
-import 'dart:math';
 import 'package:flutter/material.dart';
 
 /*
@@ -16,7 +15,7 @@ import 'package:flutter/material.dart';
 class FloatingActionButtonDefault extends StatelessWidget {
   final bool isDisabled;
 
-  const FloatingActionButtonDefault([bool this.isDisabled = true])
+  const FloatingActionButtonDefault([ this.isDisabled = true])
       : assert(isDisabled != null),
         super();
 
@@ -41,10 +40,10 @@ class FloatingActionButtonCustom extends StatelessWidget {
   final VoidCallback onPressed;
 
   const FloatingActionButtonCustom(
-      [String this.txt = '自定义按钮',
-      Color this.color = Colors.orange,
-      ShapeBorder this.shape,
-      VoidCallback this.onPressed])
+      [ this.txt = '自定义按钮',
+       this.color = Colors.orange,
+       this.shape,
+       this.onPressed])
       : super();
 
   @override
@@ -93,10 +92,10 @@ class FloatingActionButtonCustom2 extends StatelessWidget {
   final VoidCallback onPressed;
 
   const FloatingActionButtonCustom2(
-      [String this.txt = '自定义按钮',
-        Color this.color = Colors.orange,
-        ShapeBorder this.shape,
-        VoidCallback this.onPressed])
+      [ this.txt = '自定义按钮',
+         this.color = Colors.orange,
+         this.shape,
+         this.onPressed])
       : super();
 
   @override

lib/widgets/elements/Form/Button/FloatingActionButton/index.dart

@@ -14,8 +14,6 @@ import 'package:flutter/material.dart';
 import 'package:flutter_markdown/flutter_markdown.dart';
 import './demo.dart' as floatingActionButton;
 
-const String _floatingActionTitle =
-    'FloatingAction Button 示例';
 
 const String _floatingActionText0 =
 """### **简介**
@@ -68,7 +66,7 @@ class _DemoState extends State<Demo> {
   }
 }
 
-/**
+/*
  * 所有的 FloatingActionButton 按钮
  */
 Widget allFloatingActionButtons(BuildContext context,_DemoState that){
@@ -105,26 +103,26 @@ Widget allFloatingActionButtons(BuildContext context,_DemoState that){
   * alert 弹框
   * context:容器的父级
   * */
-void _showMessage(String name, BuildContext context) {
-  showDialog(
-    // alert 的父级
-    context: context,
-    builder: (BuildContext context) {
-      return AlertDialog(
-          title: new Text('提示'),
-          content: new Text(name),
-          actions: <Widget>[
-            new FlatButton(
-              // alert 的取消按钮
-                onPressed: () {
-                  // 取消的事件
-                  Navigator.of(context).pop(true);
-                },
-                child: new Text('取消'))
-          ]);
-    }
-  );
-}
+// void _showMessage(String name, BuildContext context) {
+//   showDialog(
+//     // alert 的父级
+//     context: context,
+//     builder: (BuildContext context) {
+//       return AlertDialog(
+//           title: new Text('提示'),
+//           content: new Text(name),
+//           actions: <Widget>[
+//             new FlatButton(
+//               // alert 的取消按钮
+//                 onPressed: () {
+//                   // 取消的事件
+//                   Navigator.of(context).pop(true);
+//                 },
+//                 child: new Text('取消'))
+//           ]);
+//     }
+//   );
+// }
 
 /*
 * 带align的text

lib/widgets/elements/Form/Button/IconButton/demo.dart

@@ -19,7 +19,7 @@ final  int len = IconNames.Names.length;
 class IconButtonDefault extends StatelessWidget {
   final bool isDisabled;
 
-  const IconButtonDefault([bool this.isDisabled = true])
+  const IconButtonDefault([ this.isDisabled = true])
       : assert(isDisabled != null),
         super();
 
@@ -43,10 +43,10 @@ class IconButtonCustom extends StatelessWidget {
   final VoidCallback onPressed;
 
   const IconButtonCustom(
-      [String this.txt = '自定义按钮',
-      Color this.color = Colors.blueAccent,
-      ShapeBorder this.shape,
-      VoidCallback this.onPressed])
+      [ this.txt = '自定义按钮',
+       this.color = Colors.blueAccent,
+       this.shape,
+       this.onPressed])
       : super();
 
    getIcons(){

lib/widgets/elements/Form/Button/IconButton/index.dart

@@ -60,7 +60,7 @@ class _DemoState extends State<Demo> {
   }
 }
 
-/**
+/*
  * 所有的 IconButton 按钮
  */
 Widget allIconButtons(BuildContext context,_DemoState that){

lib/widgets/elements/Form/Button/OutlineButton/demo.dart

@@ -16,7 +16,7 @@ import 'package:flutter/material.dart';
 class OutlineButtonDefault extends StatelessWidget {
   final bool isDisabled;
 
-  const OutlineButtonDefault([bool this.isDisabled = true])
+  const OutlineButtonDefault([ this.isDisabled = true])
       : assert(isDisabled != null),
         super();
 
@@ -39,7 +39,7 @@ class OutlineButtonIconDefault extends StatelessWidget {
   final IconData icon;
 
   const OutlineButtonIconDefault(
-      [bool this.isDisabled = true, IconData this.icon = Icons.add_circle])
+      [ this.isDisabled = true,  this.icon = Icons.add_circle])
       : super();
 
   @override
@@ -66,10 +66,10 @@ class OutlineButtonCustom extends StatelessWidget {
   final VoidCallback onPressed;
 
   const OutlineButtonCustom(
-      [String this.txt = '自定义按钮',
-      Color this.color = Colors.blueAccent,
-      ShapeBorder this.shape,
-      VoidCallback this.onPressed])
+      [ this.txt = '自定义按钮',
+       this.color = Colors.blueAccent,
+       this.shape,
+       this.onPressed])
       : super();
 
   @override

lib/widgets/elements/Form/Button/OutlineButton/index.dart

@@ -69,7 +69,7 @@ class _DemoState extends State<Demo> {
   }
 }
 
-/**
+/*
  * 所有的 OutlineButton 按钮
  */
 Widget allOutlineButtons(BuildContext context,_DemoState that){
@@ -130,26 +130,26 @@ Widget allOutlineButtons(BuildContext context,_DemoState that){
   * alert 弹框
   * context:容器的父级
   * */
-void _showMessage(String name, BuildContext context) {
-  showDialog(
-    // alert 的父级
-    context: context,
-    builder: (BuildContext context) {
-      return AlertDialog(
-          title: new Text('提示'),
-          content: new Text(name),
-          actions: <Widget>[
-            new FlatButton(
-              // alert 的取消按钮
-                onPressed: () {
-                  // 取消的事件
-                  Navigator.of(context).pop(true);
-                },
-                child: new Text('取消'))
-          ]);
-    }
-  );
-}
+// void _showMessage(String name, BuildContext context) {
+//   showDialog(
+//     // alert 的父级
+//     context: context,
+//     builder: (BuildContext context) {
+//       return AlertDialog(
+//           title: new Text('提示'),
+//           content: new Text(name),
+//           actions: <Widget>[
+//             new FlatButton(
+//               // alert 的取消按钮
+//                 onPressed: () {
+//                   // 取消的事件
+//                   Navigator.of(context).pop(true);
+//                 },
+//                 child: new Text('取消'))
+//           ]);
+//     }
+//   );
+// }
 
 /*
 * 带align的text

lib/widgets/elements/Form/Button/PopupMenuButton/demo.dart

@@ -6,7 +6,6 @@
  * email: zhu.yan@alibaba-inc.com
  * tartget: RaisedButton 的示例
  */
-import 'dart:math';
 import 'package:flutter/material.dart';
 
 /*
@@ -20,7 +19,7 @@ class PopupMenuButtonDefault extends StatelessWidget {
   final String type;
 
   const PopupMenuButtonDefault(
-      [String this.type = 'default1', bool this.isDisabled = true])
+      [ this.type = 'default1',  this.isDisabled = true])
       : assert(isDisabled != null),
         super();
 
@@ -107,7 +106,7 @@ class PopupMenuButtonCustom extends StatelessWidget {
           label: Text(
                 '自定义按钮', style: TextStyle(color: Colors.white),
                 semanticsLabel: 'FLAT BUTTON'),
-          // onPressed:(){} // 激活状态按钮
+          onPressed:(){} // 激活状态按钮
         ),
         // 打开时放置菜单的z坐标。这可以控制菜单下方阴影的大小。
         elevation:10.0,

lib/widgets/elements/Form/Button/PopupMenuButton/index.dart

@@ -9,7 +9,7 @@
  */
 
 import '../../../../../common/widget_demo.dart';
-import 'dart:math';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_markdown/flutter_markdown.dart';
 import './demo.dart' as popupMenuButton;
@@ -37,8 +37,9 @@ const String _titleText2 = """
 class Demo extends StatefulWidget {
   static const String routeName = '/element/Form/Button/PopupMenuButton';
   final Map<String,String> options = {'defaultSelect': '选项二的内容'};
-  @override
   final _DemoState self =  _DemoState();
+
+  @override
   _DemoState createState() => self;
 }
 

lib/widgets/elements/Form/Button/RaisedButton/demo.dart

@@ -16,7 +16,7 @@ import 'package:flutter/material.dart';
 class RaisedButtonDefault extends StatelessWidget {
   final bool isDisabled;
 
-  const RaisedButtonDefault([bool this.isDisabled = true])
+  const RaisedButtonDefault([ this.isDisabled = true])
       : assert(isDisabled != null),
         super();
 
@@ -39,7 +39,7 @@ class RaisedButtonIconDefault extends StatelessWidget {
   final IconData icon;
 
   const RaisedButtonIconDefault(
-      [bool this.isDisabled = true, IconData this.icon = Icons.add_circle])
+      [ this.isDisabled = true,  this.icon = Icons.add_circle])
       : super();
 
   Color _randomColor() {
@@ -73,10 +73,10 @@ class RaisedButtonCustom extends StatelessWidget {
   final VoidCallback onPressed;
 
   const RaisedButtonCustom(
-      [String this.txt = '自定义按钮',
-      Color this.color = Colors.blueAccent,
-      ShapeBorder this.shape,
-      VoidCallback this.onPressed])
+      [ this.txt = '自定义按钮',
+       this.color = Colors.blueAccent,
+       this.shape,
+       this.onPressed])
       : super();
 
   @override

lib/widgets/elements/Form/Button/RaisedButton/index.dart

@@ -69,7 +69,7 @@ class _DemoState extends State<Demo> {
   }
 }
 
-/**
+/*
  * 所有的 RaisedButton 按钮
  */
 Widget allRaisedButtons(BuildContext context,_DemoState that){
@@ -130,26 +130,26 @@ Widget allRaisedButtons(BuildContext context,_DemoState that){
   * alert 弹框
   * context:容器的父级
   * */
-void _showMessage(String name, BuildContext context) {
-  showDialog(
-    // alert 的父级
-    context: context,
-    builder: (BuildContext context) {
-      return AlertDialog(
-          title: new Text('提示'),
-          content: new Text(name),
-          actions: <Widget>[
-            new FlatButton(
-              // alert 的取消按钮
-                onPressed: () {
-                  // 取消的事件
-                  Navigator.of(context).pop(true);
-                },
-                child: new Text('取消'))
-          ]);
-    }
-  );
-}
+// void _showMessage(String name, BuildContext context) {
+//   showDialog(
+//     // alert 的父级
+//     context: context,
+//     builder: (BuildContext context) {
+//       return AlertDialog(
+//           title: new Text('提示'),
+//           content: new Text(name),
+//           actions: <Widget>[
+//             new FlatButton(
+//               // alert 的取消按钮
+//                 onPressed: () {
+//                   // 取消的事件
+//                   Navigator.of(context).pop(true);
+//                 },
+//                 child: new Text('取消'))
+//           ]);
+//     }
+//   );
+// }
 
 /*
 * 带align的text

lib/widgets/elements/Form/Button/RawMaterialButton/demo.dart

@@ -16,7 +16,7 @@ import 'package:flutter/material.dart';
 class RawMaterialButtonDefault extends StatelessWidget {
   final bool isDisabled;
 
-  const RawMaterialButtonDefault([bool this.isDisabled = true])
+  const RawMaterialButtonDefault([ this.isDisabled = true])
       : assert(isDisabled != null),
         super();
 
@@ -39,10 +39,10 @@ class RawMaterialButtonCustom extends StatelessWidget {
   final VoidCallback onPressed;
 
   const RawMaterialButtonCustom(
-      [String this.txt = '自定义按钮',
-      Color this.color = Colors.blueAccent,
-      ShapeBorder this.shape,
-      VoidCallback this.onPressed])
+      [ this.txt = '自定义按钮',
+       this.color = Colors.blueAccent,
+       this.shape,
+       this.onPressed])
       : super();
 
   @override

lib/widgets/elements/Form/Button/RawMaterialButton/index.dart

@@ -58,7 +58,7 @@ class _DemoState extends State<Demo> {
   }
 }
 
-/**
+/*
  * 所有的 RawMaterialButton 按钮
  */
 Widget allRawMaterialButtons(BuildContext context,_DemoState that){
@@ -102,26 +102,26 @@ Widget allRawMaterialButtons(BuildContext context,_DemoState that){
   * alert 弹框
   * context:容器的父级
   * */
-void _showMessage(String name, BuildContext context) {
-  showDialog(
-    // alert 的父级
-    context: context,
-    builder: (BuildContext context) {
-      return AlertDialog(
-          title: new Text('提示'),
-          content: new Text(name),
-          actions: <Widget>[
-            new FlatButton(
-              // alert 的取消按钮
-                onPressed: () {
-                  // 取消的事件
-                  Navigator.of(context).pop(true);
-                },
-                child: new Text('取消'))
-          ]);
-    }
-  );
-}
+// void _showMessage(String name, BuildContext context) {
+//   showDialog(
+//     // alert 的父级
+//     context: context,
+//     builder: (BuildContext context) {
+//       return AlertDialog(
+//           title: new Text('提示'),
+//           content: new Text(name),
+//           actions: <Widget>[
+//             new FlatButton(
+//               // alert 的取消按钮
+//                 onPressed: () {
+//                   // 取消的事件
+//                   Navigator.of(context).pop(true);
+//                 },
+//                 child: new Text('取消'))
+//           ]);
+//     }
+//   );
+// }
 
 /*
 * 带align的text