房产网站建设方案论文国外网站seo

CustomWidget的自定义组件的注释还是比较清晰的
参考文档Flutter实战

import 'package:flutter/cupertino.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
/*
* 如果组件不会包含子组件，则我们可以直接继承自 LeafRenderObjectWidget ，它是 RenderObjectWidget
* LeafRenderObjectWidget 适用于 没有子 Widget 的 RenderObject（例如 Container）。
* */
class CustomWidget extends LeafRenderObjectWidget{//创建RenderObjec,返回 RenderObject@overrideRenderObject createRenderObject(BuildContext context) {// TODO: implement createRenderObjectreturn RenderCustomObject();}//更新RenderObj@overridevoid updateRenderObject(BuildContext context, covariant RenderObject renderObject) {// TODO: implement updateRenderObjectsuper.updateRenderObject(context, renderObject);}@overrideLeafRenderObjectElement createElement() {// TODO: implement createElementreturn super.createElement();}}//RenderBox 是 Flutter 最常见的渲染对象，用于 布局 和 绘制
//画个红色的盒子
class RenderCustomObject extends RenderBox{Color color = Colors.red;//实现布局逻辑@overridevoid performLayout() {// TODO: implement performLayoutsize = const Size(100, 100);}//实现绘制,绘制内容
@overridevoid paint(PaintingContext context, Offset offset) {// TODO: implement paintfinal paint = Paint()..color = color;context.canvas.drawRect(offset & size, paint);}//允许点击事件命中当前控件，拦截响应链上的响应@overridebool hitTestSelf(Offset position) {// TODO: implement hitTestSelfreturn true;}//处理点击事件，监听点击事件，改变颜色，并调用 markNeedsPaint() 触发重绘@overridevoid handleEvent(PointerEvent event, HitTestEntry entry) {if (event is PointerDownEvent) {color = color == Colors.blue ? Colors.green : Colors.blue;markNeedsPaint(); // 重新绘制}}}