作为Flutter 开发人员,我相信您在您的开发生活中至少听说过这句流行的句子:“**一切都是widget”。这是 Flutter 的口头禅,它揭示了这个非常好的 SDK 的内在力量! 当我们在widgets目录中,我们可以看到很多小部件,如Padding,Align,SizedBox,等。我们通过组合它们来创建其他小部件,我发现这种方法可扩展、强大且易于理解。
import'package:flutter/material.dart';import'package:flutter/cupertino.dart';voidmain()=>runApp(SFMyApp());classSFMyAppextendsStatelessWidget{@overrideWidgetbuild(BuildContext context){returnMaterialApp(home:SFHomePage());}}classSFHomePageextendsStatelessWidget{@overrideWidgetbuild(BuildContext context){retu...
4、Flutter执行build方法,来看一下我们当前的Widget需要渲染哪些Widget; 5、当前的Widget不再使用时,会调用dispose进行销毁; 6、手动调用setState方法,会根据最新的状态(数据)来重新调用build方法,构建对应的Widgets; 7、执行didUpdateWidget方法是在当父Widget触发重建(rebuild)时,系统会调用didUpdateWidget方法; 我们来...
import'package:flutter/material.dart';voidmain()=>runApp(MyApp());classMyAppextendsStatelessWidget{// This widget is the root of your application.@overrideWidgetbuild(BuildContext context){// final wordPair = new WordPair.random();returnMaterialApp(title:'Flutter 测试标题',theme:newThemeData(prima...
Basic understanding of flutter stateless and stateful widget. Where and in which scenario to use and how to use. - myvsparth/stateless_stateful
每次执行 Build，都会生成一颗由这些一次性对象组成的节点树，也就是 Flutter 官网提到的 Widget Tree。
//定义路由Map<String,WidgetBuilder>datas={'/pageone':(builder){returnPageOne("数据1");},'/pagetwo':(builder)=>PageTwo("数据2"),'/pagethree':(builder){returnPageThree("数据3");},};classMyAppextendsStatelessWidget{@override Widgetbuild(BuildContext context){returnMaterialApp(title:'Flutter ...
Step 4 Testing a use case voidmain(){Widget_wrapWidgetWithMaterialApp({requiredWidgetcolorCard}){returnTestMaterialApp(home:Builder(builder:(BuildContextcontext){SizeConfig().init(context);returncolorCard;}));}import'package:at_common_flutter/at_common_flutter.dart';import'package:at_theme_flutter/...
Widgets describe how to configure a subtree but the same widget can be used to configure multiple subtrees simultaneously because widgets are immutable. AnElementrepresents the use of a widget to configure a specific location in the tree. Over time, the widget associated with a given element can...
5.2.1Flutter引擎不会直接渲染widget树,因为widget是特别不稳定的,会频繁的调用build方法,widget又相互依赖,一旦调用build,后面的widget都会重新创建,直接去解析widget的话会非常消耗性能,布局需要重新计算。由此引出了Element,RenderObject的概念,Flutter引擎解析的是RenderObject树,并非widget。