add Flow widget.

Author: nb312

lib/const/page_item_const.dart

@@ -162,4 +162,9 @@ const PAGE_ITEMS = [
     "img": PageImage.FLUTTER_OPEN,
     "click": PageName.EXPANDED,
   },
+  {
+    "title": PageName.FLOW,
+    "img": PageImage.FLUTTER_OPEN,
+    "click": PageName.FLOW,
+  },
 ];

lib/const/page_name_const.dart

@@ -37,4 +37,5 @@ class PageName {
   static const MIX_SINGLE_LAYOUT = "MixLayout";
   static const INDEX_STACK = "IndexedStack";
   static const EXPANDED = "Expanded";
+  static const FLOW = "Flow";
 }

lib/main.dart

@@ -51,6 +51,7 @@ class FlutterOpenApp extends StatelessWidget {
         PageName.MIX_SINGLE_LAYOUT: (context) => MixPage(),
         PageName.INDEX_STACK: (context) => IndexStackPage(),
         PageName.EXPANDED: (context) => ExpandPage(),
+        PageName.FLOW: (context) => FlowPage(),
       },
     );
   }

lib/page/muti/FlowPage.dart

@@ -0,0 +1,51 @@
+///
+/// Created by NieBin on 2019/5/24
+/// Github: https://github.com/nb312
+/// Email: [email protected]
+///
+import "package:flutter/material.dart";
+import 'package:flutter_widgets/const/_const.dart';
+
+class FlowPage extends StatefulWidget {
+  @override
+  FlowState createState() => FlowState();
+}
+
+class FlowState extends State<FlowPage> {
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(PageName.FLOW),
+      ),
+      body: Flow(
+        delegate: MFlowDelegate(),
+        children: <Widget>[
+          Container(
+            constraints: BoxConstraints.expand(height: 100),
+            color: RED,
+          ),
+          Container(
+            constraints: BoxConstraints.expand(height: 100, width: 100),
+            alignment: Alignment.center,
+            color: BLUE,
+          )
+        ],
+      ),
+    );
+  }
+}
+
+class MFlowDelegate extends FlowDelegate {
+  @override
+  void paintChildren(FlowPaintingContext context) {
+    context.paintChild(0, transform: Matrix4.rotationZ(1));
+    context.paintChild(1,
+        transform: Matrix4.translationValues(100, 0, 0)..rotateZ(1));
+  }
+
+  @override
+  bool shouldRepaint(MFlowDelegate oldDelegate) {
+    return true;
+  }
+}

lib/page/muti/_muti.dart

@@ -5,3 +5,4 @@
 ///
 export "IndexStackPage.dart";
 export "ExpandPage.dart";
+export 'FlowPage.dart';