初步优化项目结构

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

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+import 'package:flutter/material.dart';
+/// create by 张风捷特烈 on 2020-03-30
+/// contact me by email 1981462002@qq.com
+/// 说明:
+//    {
+//      "widgetId": 97,
+//      "name": 'Stack基本使用',
+//      "priority": 1,
+//      "subtitle":
+//          "【children】 : 组件列表   【List<Widget>】\n"
+//          "【textDirection】 : 孩子排布方向   【MainAxisAlignment】\n"
+//          "【alignment】 : 对齐方式   【AlignmentGeometry】\n"
+//          "【overflow】 : 溢出模式   【Overflow】\n"
+//          "【fit】 : 适应模式   【StackFit】",
+//    }
+class CustomStack extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    var yellowBox = Container(
+      color: Colors.yellow,
+      height: 100,
+      width: 100,
+    );
+
+    var redBox = Container(
+      color: Colors.red,
+      height: 90,
+      width: 90,
+    );
+
+    var greenBox = Container(
+      color: Colors.green,
+      height: 80,
+      width: 80,
+    );
+
+    var cyanBox = Container(
+      color: Colors.cyanAccent,
+      height: 70,
+      width: 70,
+    );
+
+    return Container(
+      width: 200,
+      height: 120,
+      color: Colors.grey.withAlpha(33),
+      child: Stack(
+        textDirection: TextDirection.rtl,
+        fit: StackFit.loose,
+        alignment: Alignment.topRight,
+        // overflow: Overflow.clip, // 1.22.0 被去除
+        children: <Widget>[yellowBox, redBox, greenBox, cyanBox],
+      ),
+    );
+  }
+}

lib/widget_system/widgets/MultiChildRenderObjectWidget/Stack/node2_positioned.dart

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+import 'package:flutter/material.dart';
+/// create by 张风捷特烈 on 2020-03-30
+/// contact me by email 1981462002@qq.com
+/// 说明:
+//    {
+//      "widgetId": 97,
+//      "name": 'Stack和Positioned结合使用',
+//      "priority": 2,
+//      "subtitle":
+//          "Positioned组件只能用与Stack中，可以指定左上右下的距离对某个组件进行位置精确安放。",
+//    }
+class PositionedStack extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    var yellowBox = Container(
+      color: Colors.yellow,
+      height: 100,
+      width: 100,
+    );
+
+    var redBox = Container(
+      color: Colors.red,
+      height: 90,
+      width: 90,
+    );
+
+    var greenBox = Container(
+      color: Colors.green,
+      height: 80,
+      width: 80,
+    );
+
+    var cyanBox = Container(
+      color: Colors.cyanAccent,
+      height: 70,
+      width: 70,
+    );
+
+    return Container(
+        width: 200,
+        height: 120,
+        color: Colors.grey.withAlpha(33),
+        child: Stack(
+          children: <Widget>[yellowBox, redBox, greenBox,
+            Positioned(
+              child: cyanBox,
+              bottom: 10,
+              right: 10,
+            )
+          ],
+        ));
+  }
+}