Analysis of updatechild principle of widget update mechanism of fluent

This blog will analyze Widget The update mechanism of , Before reading this article, readers are advised to read Fultter And Element and Widget Correspondence analysis , from Element and Widget Correspondence in this blog post, we can know that there are the following table relationships ：

Widget	explain	give an example
MultiChildRenderObjectWidget	This type of Widget Multiple can be added widget	Row,Column,Stack
SingleChildRenderObjectWidget	This type of widget Only one... Can be added widget	Center,Padding,Container
LeafRenderObjectWidget	This type is the leaf node of the tree , Therefore, it cannot be added widget	Text,Image,Seman