初步优化项目结构

lib/widget_system/widgets/MultiChildRenderObjectWidget/CustomMultiChildLayout/node1_base.dart

@@ -0,0 +1,92 @@
+import 'package:flutter/material.dart';
+
+/// create by 张风捷特烈 on 2020/6/6
+/// contact me by email 1981462002@qq.com
+/// 说明:
+
+//    {
+//      "widgetId": 341,
+//      "name": 'CustomMultiChildLayout基本使用',
+//      "priority": 1,
+//      "subtitle":
+//          "【children】 : 子组件集   【List<Widget>】\n"
+//          "【delegate】 : 布局代理   【MultiChildLayoutDelegate】",
+//    }
+
+
+class CustomMultiChildLayoutDemo extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      width: 300,
+      height: 150,
+      color: Colors.grey.withAlpha(33),
+      child: CustomMultiChildLayout(
+        delegate: CornerCustomMultiChildLayout(
+          padding:EdgeInsets.only(left: 10,top: 5,right: 10,bottom: 5),
+        ),
+        children: [
+           LayoutId(id: CornerType.topLeft, child: Box50(Colors.red)),
+           LayoutId(id: CornerType.topRight, child: Box50(Colors.yellow)),
+           LayoutId(id: CornerType.bottomLeft, child: Box50(Colors.blue)),
+           LayoutId(id: CornerType.bottomRight, child: Box50(Colors.green)),
+        ],
+      ),
+    );
+  }
+}
+
+// 50 颜射盒
+class Box50 extends StatelessWidget {
+  final Color color;
+  Box50(this.color);
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      width: 50,
+      height: 50,
+      color: color,
+    );
+  }
+}
+
+
+enum CornerType{
+  topLeft,
+  topRight,
+  bottomLeft,
+  bottomRight
+}
+
+
+class CornerCustomMultiChildLayout extends MultiChildLayoutDelegate{
+  final EdgeInsets padding;
+  
+  CornerCustomMultiChildLayout({this.padding = EdgeInsets.zero});
+
+  @override
+  void performLayout(Size size) {
+    if (hasChild(CornerType.topLeft)) {
+      layoutChild(CornerType.topLeft, BoxConstraints.loose(size));
+      positionChild(CornerType.topLeft, Offset.zero.translate(padding.left, padding.top));
+    }
+    if (hasChild(CornerType.topRight)) {
+      var childSize = layoutChild(CornerType.topRight, BoxConstraints.loose(size));
+      positionChild(CornerType.topRight, Offset(size.width-childSize.width,0).translate(-padding.right, padding.top));
+    }
+    if (hasChild(CornerType.bottomLeft)) {
+      var childSize = layoutChild(CornerType.bottomLeft, BoxConstraints.loose(size));
+      positionChild(CornerType.bottomLeft, Offset(0,size.height-childSize.height).translate(padding.left, -padding.bottom));
+    }
+    if (hasChild(CornerType.bottomRight)) {
+      var childSize = layoutChild(CornerType.bottomRight, BoxConstraints.loose(size));
+      positionChild(CornerType.bottomRight, Offset(size.width-childSize.width,size.height-childSize.height).translate(-padding.right, -padding.bottom));
+    }
+  }
+
+  @override
+  bool shouldRelayout(CornerCustomMultiChildLayout oldDelegate) => oldDelegate.padding!=padding;
+  
+}
+