[shutter] shutter layout component (opacity component | clipprect component | padding component)

One 、Opacity Components

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Opacity Components : Used to modify component transparency ;

class Opacity extends SingleChildRenderObjectWidget { 
      const Opacity({ 
        Key key,    @required this.opacity,    this.alwaysIncludeSemantics = false,    Widget child,  }) : assert(opacity != null && opacity >= 0.0 && opacity <= 1.0),       assert(alwaysIncludeSemantics != null),       super(key: key, child: child);}

Opacity Component usage :

• Set transparency : stay opacity Field set transparency value , Value range 0 ~ 1.0 ;
• Set components that adjust transparency : child Field to set the component to adjust the transparency ;

//  Modify the transparency component  Opacity(    opacity:  Transparency value ,        child:  Components to adjust transparency ,),

Code example : modify Image The transparency of the component is 50% transparency ;

//  Modify the transparency component  ,  Set up here  50%  transparency Opacity(    opacity: 0.5,    //  Set up  100x100  Size picture component     child: Image.network("https://img-blog.csdnimg.cn/20210301145757946.png",      width: 100,      height: 100,    ),),

Two 、ClipRRect Components

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ClipRRect Components : Cut the components of the square layout ;

class ClipRRect extends SingleChildRenderObjectWidget { 
      const ClipRRect({ 
        Key key,    this.borderRadius = BorderRadius.zero, //  Rounded corners of the four vertices of the rectangle      this.clipper,    this.clipBehavior = Clip.antiAlias,    Widget child, //  Components to be trimmed   }) : assert(borderRadius != null || clipper != null),       assert(clipBehavior != null),       super(key: key, child: child);}

ClipRRect How to use components :

• Setting fillet : borderRadius Field to set the fillet radius of the four vertices ;
• Set the trimmed components : child Field settings are clipped components

//  Square cutting component  ,  Cut the components into squares child: ClipRRect(  //  Set the clipping fillet   borderRadius:  Fillet Parameters   ( BorderRadius  type  ),  //  Trimmed components   child:  Trimmed components  ( Widget  type  ),),

Code example :

//  Square cutting component  ,  Cut the components into squares child: ClipRRect(  //  Set the clipping fillet ,  Set the radius of the four corners to  10  Fillet of   borderRadius: BorderRadius.all(Radius.circular(10)),  //  Modify the transparency component  ,  Set up here  50%  transparency   child: Opacity(      opacity: 0.5,      //  Set up  100x100  Size picture component       child: Image.network("https://img-blog.csdnimg.cn/20210301145757946.png",        width: 100,        height: 100,      ),  ),),

3、 ... and 、Padding Components

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Padding Components : The main function is to set the inner margin of components ;

class Padding extends SingleChildRenderObjectWidget { 
      const Padding({ 
        Key key,    @required this.padding,    Widget child,  }) : assert(padding != null),       super(key: key, child: child);}

Padding Component usage :

• Set four inner margins : padding Field set inner margin , EdgeInsetsGeometry type ;
• Set the components used by the inner margin : child Field sets the component of the inner margin function , Widget type ;

Padding(  //  Set the inside margin   padding:  padding  ( EdgeInsetsGeometry  type  ),  //  Inner margin action component   child:  Inner margin action component  ( Widget  type  ),),

Code example :

Padding(  //  Set the inside margin  5  padding: EdgeInsets.all(15),  //  Square cutting component  ,  Cut the components into squares   child: ClipRRect(    //  Set the clipping fillet ,  Set the radius of the four corners to  10  Fillet of     borderRadius: BorderRadius.all(Radius.circular(10)),    //  Modify the transparency component  ,  Set up here  50%  transparency     child: Opacity(        opacity: 0.5,        //  Set up  100x100  Size picture component         child: Image.network("https://img-blog.csdnimg.cn/20210301145757946.png",          width: 100,          height: 100,        ),    ),  ),),

Four 、 Complete code example

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Complete code example :

import 'package:flutter/material.dart';class LayoutPage extends StatefulWidget { 
      @override  _LayoutPageState createState() => _LayoutPageState();}class _LayoutPageState extends State<LayoutPage> { 
      ///  The currently selected bottom navigation bar index   int _currentSelectedIndex = 0;  // This widget is the root of your application.  @override  Widget build(BuildContext context) { 
        //  Text component style  ,  Can be set to  Text  Text component     //  Set font size  20,  The color is red     TextStyle textStyle = TextStyle(fontSize: 20, color: Colors.red);    return MaterialApp(      title: ' Example layout components ',      theme: ThemeData(        primarySwatch: Colors.blue,      ),      home: Scaffold(        //  Top title bar         appBar: AppBar(title: Text(' Example layout components '),),        //  Bottom navigation bar  BottomNavigationBar  Set up         // items  You can set multiple  BottomNavigationBarItem        bottomNavigationBar: BottomNavigationBar(          //  Set the currently selected bottom navigation index           currentIndex: _currentSelectedIndex,          //  Set the callback event of clicking the navigation bar at the bottom  , index  The parameter is the index value of the click           onTap: (index){ 
                //  Callback  StatefulWidget  Component's  setState  Method of setting state  ,  Modify the currently selected index             //  after  BottomNavigationBar  The component will automatically update the currently selected tab             setState(() { 
                  //  change  int _currentSelectedIndex  The state of the variable               _currentSelectedIndex = index;            });          },          //  entry           items: [          //  Set the bottom navigation bar entry ,  Each entry can be set with an icon           BottomNavigationBarItem(            //  The default icon             icon: Icon(Icons.home, color: Colors.grey,),            //  Icon in active state             activeIcon: Icon(Icons.home, color: Colors.red,),            //  Set title             title: Text(" Home page ")          ),          //  Set the bottom navigation bar entry ,  Each entry can be set with an icon           BottomNavigationBarItem(            //  The default icon             icon: Icon(Icons.settings, color: Colors.grey,),            //  Icon in active state             activeIcon: Icon(Icons.settings, color: Colors.red,),              //  Set title               title: Text(" Set up ")          )        ],),        //  Set the levitation button         floatingActionButton: FloatingActionButton(          onPressed: (){ 
                print(" Click the hover button ");          },          child: Text(" Levitation button assembly "),        ),        // Container  Container usage         body:        _currentSelectedIndex == 0 ?        //  Refresh indicator component         RefreshIndicator(          //  Display content           child: ListView(            children: <Widget>[              Container( //  Corresponding to the bottom navigation bar settings tab                 //  Set the decorator of the container  , BoxDecoration  Is the most commonly used decorator                 //  You can check it by yourself  BoxDecoration  Properties that can be set in                 decoration: BoxDecoration(color: Colors.white),                //  Set up  child  How the sub components are centered ,  Center                 alignment: Alignment.center,                //  Child components ,  The subcomponent is set to a  Column  Components                 child: Column(                  // Column  Child components ,  Set up here  Text  Text component                   children: <Widget>[                    Text(" Main page tab ,  The drop-down refresh "),                    //  A linear layout arranged horizontally                     Row(                      children: <Widget>[                        //  Original picture ,  For comparison                         Image.network("https://img-blog.csdnimg.cn/20210301145757946.png",                          width: 100,                          height: 100,                        ),                        //  Circular clipping component  ,  take  child  Cut the layout into a circle                         ClipOval(                          //  Use  SizedBox  Component constrains layout size                           child: SizedBox(                            width: 100,                            height: 100,                            //  Use  SizedBox  Constrain this  Image  Component size                             child: Image.network("https://img-blog.csdnimg.cn/20210301145757946.png"),                          ),                        ),                        Padding(                          //  Set the inside margin  5                          padding: EdgeInsets.all(15),                          //  Square cutting component  ,  Cut the components into squares                           child: ClipRRect(                            //  Set the clipping fillet ,  Set the radius of the four corners to  10  Fillet of                             borderRadius: BorderRadius.all(Radius.circular(10)),                            //  Modify the transparency component  ,  Set up here  50%  transparency                             child: Opacity(                                opacity: 0.5,                                //  Set up  100x100  Size picture component                                 child: Image.network("https://img-blog.csdnimg.cn/20210301145757946.png",                                  width: 100,                                  height: 100,                                ),                            ),                          ),                        ),                      ],                    ),                  ],                ),              ),            ],          ),          //  Method of callback during refresh           //  When a drop-down operation occurs in the list ,  Call back the method           //  The callback is  Future  Type of           onRefresh: _refreshIndicatorOnRefresh,        )        :        Container( //  Corresponding to the bottom navigation bar settings tab           //  Set the decorator of the container  , BoxDecoration  Is the most commonly used decorator           //  You can check it by yourself  BoxDecoration  Properties that can be set in           decoration: BoxDecoration(color: Colors.white),          //  Set up  child  How the sub components are centered ,  Center           alignment: Alignment.center,          //  Child components ,  The subcomponent is set to a  Column  Components           child: Column(            // Column  Child components ,  Set up here  Text  Text component             children: <Widget>[              Text(" Set up page tabs ")            ],          ),        ) , //  This setting is related to  _currentSelectedIndex == 0?  Corresponding , ?:  Ternary operator       ),    );  }  /// RefreshIndicator  When a pull-down operation occurs ,  Call back the method   ///  This is an asynchronous method  ,  Add... Before the method body  async  keyword   Future<Null> _refreshIndicatorOnRefresh() async{ 
        //  Pause  500 ms ,  Use  await  Keyword implementation     //  Here  500 ms  Between  ,  The list is in refresh state     // 500 ms  after  ,  The list becomes non refreshed     await Future.delayed(Duration(milliseconds: 500));    return null;  }}

Operation effect display :

5、 ... and 、 Related resources

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Reference material :

• Flutter Official website : https://flutter.dev/
• Flutter Developing documents : https://flutter.cn/docs ( Strongly recommend )
• official GitHub Address : https://github.com/flutter
• Flutter The Chinese community : https://flutter.cn/
• Flutter Practical tutorial : https://flutter.cn/docs/cookbook
• Flutter CodeLab : https://codelabs.flutter-io.cn/
• Dart Chinese document : https://dart.cn/
• Dart Developer website : https://api.dart.dev/
• Flutter Chinese net ( unofficial , The translation is very good ) : https://flutterchina.club/ , http://flutter.axuer.com/docs/
• Flutter Related issues : https://flutterchina.club/faq/ ( It is recommended to watch it at the introductory stage )

Blog source download :

• GitHub Address : https://github.com/han1202012/flutter_cmd ( Keep updating with the progress of the blog , There may not be the source code of this blog )

• Blog source snapshot : https://download.csdn.net/download/han1202012/15484718 ( The source code snapshot of this blog , You can find the source code of this blog )