merge devlop

lib/widgets/elements/Form/Button/DropdownButton/demo.dart

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+/**
+ * Created with Android Studio.
+ * User: 一晟
+ * Date: 2018/11/22
+ * Time: 上午12:03
+ * email: zhu.yan@alibaba-inc.com
+ * tartget: DropdownButton 的示例
+ */
+import 'dart:math';
+import 'package:flutter/material.dart';
+
+/*
+* DropdownButton 默认按钮的实例
+* isDisabled:是否是禁用，isDisabled 默认为true
+* */
+class DropdownButtonDefault extends StatelessWidget {
+  List<DropdownMenuItem> generateItemList() {
+    List<DropdownMenuItem> items = new List();
+    DropdownMenuItem item1 = new DropdownMenuItem(
+        value: '张三', child: new Text('张三'));
+    DropdownMenuItem item2 = new DropdownMenuItem(
+        value: '李四', child: new Text('李四'));
+    DropdownMenuItem item3 = new DropdownMenuItem(
+        value: '王二', child: new Text('王二'));
+    DropdownMenuItem item4 = new DropdownMenuItem(
+        value: '麻子', child: new Text('麻子'));
+    items.add(item1);
+    items.add(item2);
+    items.add(item3);
+    items.add(item4);
+    return items;
+  }
+
+  var selectItemValue;
+
+  @override
+  Widget build(BuildContext context) {
+    return DropdownButton(
+        hint: new Text('下拉菜单选择一个人名'),
+        //设置这个value之后,选中对应位置的item，
+        //再次呼出下拉菜单，会自动定位item位置在当前按钮显示的位置处
+        value: selectItemValue,
+        items: generateItemList(),
+        onChanged: (T){
+//          setState(() {
+//          selectItemValue=T;
+//          });
+        },
+    );
+  }
+}
+
+List<DropdownMenuItem> getListData(){
+  List<DropdownMenuItem> items=new List();
+  DropdownMenuItem dropdownMenuItem1=new DropdownMenuItem(
+    child:new Text('1'),
+    value: '1',
+  );
+  items.add(dropdownMenuItem1);
+  DropdownMenuItem dropdownMenuItem2=new DropdownMenuItem(
+    child:new Text('2'),
+    value: '2',
+  );
+  items.add(dropdownMenuItem2);
+  DropdownMenuItem dropdownMenuItem3=new DropdownMenuItem(
+    child:new Text('3'),
+    value: '3',
+  );
+  items.add(dropdownMenuItem3);
+  DropdownMenuItem dropdownMenuItem4=new DropdownMenuItem(
+    child:new Text('4'),
+    value: '4',
+  );
+  items.add(dropdownMenuItem4);
+  DropdownMenuItem dropdownMenuItem5=new DropdownMenuItem(
+    child:new Text('5'),
+    value: '5',
+  );
+  items.add(dropdownMenuItem5);
+  DropdownMenuItem dropdownMenuItem6=new DropdownMenuItem(
+    child:new Text('6'),
+    value: '6',
+  );
+  items.add(dropdownMenuItem6);
+  DropdownMenuItem dropdownMenuItem7=new DropdownMenuItem(
+    child:new Text('7'),
+    value: '7',
+  );
+  items.add(dropdownMenuItem7);
+  DropdownMenuItem dropdownMenuItem8=new DropdownMenuItem(
+    child:new Text('8'),
+    value: '8',
+  );
+  items.add(dropdownMenuItem8);
+  DropdownMenuItem dropdownMenuItem9=new DropdownMenuItem(
+    child:new Text('9'),
+    value: '9',
+  );
+  items.add(dropdownMenuItem9);
+  DropdownMenuItem dropdownMenuItem10=new DropdownMenuItem(
+    child:new Text('10'),
+    value: '10',
+  );
+  items.add(dropdownMenuItem10);
+  return items;
+}
+var selectItemValue;
+
+/*
+* DropdownButton 自定义的实例
+* */
+class DropdownButtonCustom extends StatelessWidget {
+  final widget;
+  final parent;
+  const DropdownButtonCustom([this.widget,this.parent])
+      : super();
+
+  @override
+  Widget build(BuildContext context) {
+    return DropdownButton(
+        items: getListData(),
+        //当没有默认值的时候可以设置的提示
+        hint:Text('下拉选择你想要的数据'),
+        //下拉菜单选择完之后显示给用户的值
+        value: selectItemValue,
+        //下拉菜单item点击之后的回调
+        onChanged: (T){
+          parent.setState((){
+            selectItemValue = T;
+          });
+        },
+        //设置阴影的高度
+        elevation: 24,
+        style: TextStyle(//设置文本框里面文字的样式
+            color: Colors.red
+        ),
+        // isDense: true,//减少按钮的高度。默认情况下，此按钮的高度与其菜单项的高度相同。如果isDense为true，则按钮的高度减少约一半。 这个当按钮嵌入添加的容器中时，非常有用
+        // 将下拉列表的内部内容设置为水平填充其父级
+        isExpanded:true,
+        iconSize: 50.0,//设置三角标icon的大小
+    );
+  }
+}