ErrorHint( 'Instead of performing asynchronous work inside a call to setState(), first ' 'execute the work (without updating the widget state), and then synchronously ' 'update the state inside a call to setState().' ), ]); } // We ignore other types of return values so that you ...
实际上是「Stateful Widget」对应的「Stateful Element」被添加到 Element Tree 时,伴随「Stateful Element」的初始化,createState方法被调用。从后文可知一个 Widget 实例可以对应多个 Element 实例 (也就是同一份配置信息 (Widget) 可以在 Element Tree 上不同位置配置多个 Element 节点),因此,createState方法在「Sta...
Hi, I stumbled upon what it seems to be a bug. I'm using a StreamBuilder in order to build a ListView with messages. If I use a stateless widget than everything works as expected; when adding new items to the database, they are updated i...
实际上是「Stateful Widget」对应的「Stateful Element」被添加到 Element Tree 时,伴随「Stateful Element」的初始化,createState方法被调用。从后文可知一个 Widget 实例可以对应多个 Element 实例 (也就是同一份配置信息 (Widget) 可以在 Element Tree 上不同位置配置多个 Element 节点),因此,createState方法在「Sta...
;}StatefulElement?_element; 由上面的源码可以得出_element其实就是State的bulid方法中的context 3.Flutter渲染原理 实际上,Flutter的UI绘制包含了三个元素,Widget,Element和RenderObject。这三个元素分别组成了三棵树:Widget树,Element树和RenderObject树,在Flutter渲染的流程中Flutter引擎渲染是针对Render树中的对象进行...
below this widget with the widget returned by this method, either by updating the existing subtree or by removing the subtree and inflating a new subtree, depending on whether the widget returned by this method can update the root of the existing subtree, as determined by calling Widget.can...
I have this stateful widget with a GestureDetector that invokes a function UploadImageToStorage from file storage.dart that changes the user profile image at Firebase Storage and change the user`s doc "URL" at Firestore. final db = Provi...
操作步骤：已参考 issue 里的回复修改代码，但仍然无法加载图片 参考：https://gitee.com/openharmony-...
Widget 是 Flutter 功能的抽象描述,是视图的配置信息,同样也是数据的映射,是 Flutter 开发框架中最基本的概念。 两个比较重要的Widget:StatelessWidget和StatefulWidget。 5.2 渲染过程 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...
// This widget is the home page of your application. It is stateful, meaning // that it has a State object (defined below) that contains fields that affect // how it looks. // This class is the configuration for the state. It holds the values (in this ...