feat: LayoutBuilder

Author: DIVINER-only

docs/widget/regular/layoutbuilder/index.md

@@ -0,0 +1,17 @@
+## **LayoutBuilder**
+
+>
+构建可依赖于父控件大小的控件树
+
+### 构造方法
+``` dart
+ const LayoutBuilder({
+  Key key,
+  @required this.builder
+})
+```
+
+### 属性介绍
+* builder: 传入一个LayoutWidgetBuilder类，builder: (BuildContext context, BoxConstraints viewportConstraints)
+  * 通过viewportConstraints可以获取到父控件的尺寸
+  * builder: 在布局时调用来构造小部件树,该构建器不得返回nul

lib/widget/regular/index.dart

@@ -14,6 +14,7 @@ import 'flow/index.dart' as Flow;
 import 'stack/index.dart' as Stack;
 import 'listview/index.dart' as ListView;
 import 'listbody/index.dart' as ListBody;
+import 'layoutbuilder/index.dart' as LayoutBuilder;
 
 const nameSpaces = '/regular_';
 
@@ -92,6 +93,11 @@ List widgets = [
     widget: ListBody.Index(),
     code: 57440, // art_track
     title: ListBody.Index.title
+  ),
+  ItemInfo(
+    widget: LayoutBuilder.Index(),
+    code: 59484, // assessment
+    title: LayoutBuilder.Index.title
   )
 ];
 

lib/widget/regular/layoutbuilder/demo.dart

@@ -0,0 +1,61 @@
+import 'package:flutter/material.dart';
+
+class Index extends StatefulWidget {
+  @override
+  _IndexState createState() => _IndexState();
+}
+
+class _IndexState extends State<Index> {
+ var height = 360.0;
+ 
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: Text('LayoutBuilder'),),
+      body: ListView(
+        children: <Widget>[
+          InkWell(
+            onTap: () {
+              this.setState(() {
+                height == 360.0 ? height = 200.0 : height = 360.0;
+              });
+            },
+            child: Text('父视口高度: $height', style: TextStyle(fontSize: 16.0),),
+          ),
+          Container(
+            width: double.infinity,
+            height: height,
+            color: Colors.blueGrey,
+            margin: EdgeInsets.only(top: 10.0),
+            child: LayoutBuilder(
+              builder: (BuildContext context, BoxConstraints viewportConstraints) {
+                return SingleChildScrollView(
+                  child: ConstrainedBox(
+                    constraints:
+                        BoxConstraints(minHeight: viewportConstraints.maxHeight),
+                    child: Column(
+                      mainAxisSize: MainAxisSize.min,
+                      mainAxisAlignment: MainAxisAlignment.spaceAround,
+                      children: <Widget>[
+                        Container(
+                          child: Image.network('http://pic1.win4000.com/wallpaper/2019-02-15/5c664c3e1d90c.jpg', fit: BoxFit.cover,),
+                          height: 120,
+                          width: double.infinity,
+                        ),
+                        Container(
+                          child: Image.network('http://pic1.win4000.com/wallpaper/2019-02-15/5c664c48c73d0.jpg', fit: BoxFit.cover,),
+                          height: 160,
+                          width: double.infinity,
+                        )
+                      ],
+                    ),
+                  ),
+                );
+              }
+            ),
+          )
+        ],
+      )
+    );
+  }
+}

lib/widget/regular/layoutbuilder/index.dart

@@ -0,0 +1,26 @@
+import 'package:flutter/material.dart';
+import 'package:efox_flutter/components/widgetComp.dart' as WidgetComp;
+import 'demo.dart' as Demo;
+
+class Index extends StatefulWidget {
+  static String title = 'LayoutBuilder';
+  static String originCodeUrl = 'https://docs.flutter.io/flutter/widgets/LayoutBuilder-class.html';
+  static String mdUrl = 'docs/widget/regular/layoutbuilder/index.md';
+
+  @override
+  _IndexState createState() => _IndexState();
+}
+
+class _IndexState extends State<Index> {
+  @override
+  Widget build(BuildContext context) {
+    return WidgetComp.Index(
+      title: Index.title,
+      originCodeUrl: Index.originCodeUrl,
+      mdUrl: Index.mdUrl,
+      demoChild: <Widget>[
+        Demo.Index()
+      ],
+    );
+  }
+}

pubspec.yaml

@@ -77,6 +77,7 @@ flutter:
       - docs/widget/regular/stack/
       - docs/widget/regular/listview/
       - docs/widget/regular/listbody/
+      - docs/widget/regular/layoutbuilder/
       - docs/widget/navigator/appbar/
       - docs/widget/navigator/scaffold/
   # An image asset can refer to one or more resolution-specific "variants", see