Flex 拖拽

Flex由于在其Framwork里加入了DragDrop管理器，可以使得开发者在Flex应用中实现类似桌面的效果，默认情况下，Flex的拖拽管理器是针对List等控件的，实现这类控件之间的Item拖拽非常容易。下面是一个很简单的小例子：

代码如下：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" width="450" height="350" creationComplete="initApp()" backgroundColor="#FFFFFF" fontSize="12">
<mx:Script>
  <![CDATA[
    private function initApp():void{
      words.dataProvider=['Water','水','Car','汽车','House','房屋','Book','书籍','Music','音乐','Sandwich','三明治'];
      english.dataProvider=[];
      chinese.dataProvider=[];
    }
  ]]>
</mx:Script>
  <mx:Panel x="0" y="0" width="450" height="350" layout="absolute" title="Sort Words By Language">
    <mx:Label x="7" y="3" text="Drag to Correct Language"/>
    <mx:List x="7" y="25" id="words" width="200" height="275" allowMultipleSelection="true" dragEnabled="true"></mx:List>
    <mx:Label x="223" y="6" text="English"/>
    <mx:List x="223" y="25" id="english" width="200" height="120" dropEnabled="true"></mx:List>
    <mx:Label x="223" y="150" text="中文"/>
    <mx:List x="223" y="177" id="chinese" width="200" height="120" dropEnabled="true"></mx:List>
  </mx:Panel>
</mx:Application>

但是，拖拽管理器还能定制化到特定的控件之上，比如Image，Datagrid等，下面则是一个定制化的例子：

代码如下：

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" width="400" height="400" backgroundColor="#FFFFFF" creationComplete="initApp()" layout="absolute">
  <mx:Script>
    <![CDATA[
      import mx.controls.DataGrid;
      import mx.controls.Image;
      import mx.collections.ArrayCollection;
      import mx.events.DragEvent;
      import mx.managers.DragManager;
      import mx.core.DragSource;
      [Bindable]
      public var total:Number=0;
      [Bindable]
      public var cartContents:ArrayCollection;
      private function initApp():void{
        this.cartContents=new ArrayCollection();
      }
      private function dragIt(event:MouseEvent,name:String,price:Number):void{
        //CurrentTarget指定要实现拖拽事件的初始化目标
        var dragInitiator:Image=event.currentTarget as Image;
        //指定一个dragSource来包括拖拽过程中包含的数据的对象
        var dragSource:DragSource=new DragSource();
        //向对象添加数据
        dragSource.addData(name,'name');
        dragSource.addData(price,'price');
        //创建一个拖拽对象的代理作为拷贝
        var dragProxy:Image=new Image();
        dragProxy.source=event.currentTarget.source;
        //使用DragManager静态方法doDrag开始拖拽
        DragManager.doDrag(dragInitiator,dragSource,event,dragProxy);
      }
      private function dragEnterHandler(event:DragEvent):void{
        var dropTarget:DataGrid=event.currentTarget as DataGrid;
        if (event.dragSource.hasFormat('name') && event.dragSource.hasFormat('price')){
          DragManager.acceptDragDrop(dropTarget);
        }
      }
      private function dragDropHandler(event:DragEvent):void{
        var name:String= String(event.dragSource.dataForFormat('name'));
        var price:Number=Number(event.dragSource.dataForFormat('price'));
        this.cartContents.addItem({name:String(event.dragSource.dataForFormat('name')),price:String(event.dragSource.dataForFormat('price'))});
        total+=price;
      }
    ]]>
  </mx:Script>
  <mx:Canvas x="19" y="10">
  <mx:Image x="23" y="35" width="64" height="64" mouseMove="dragIt(event,'Dreamweaver',499);" source="@Embed(source='../assets/056.png')"/>
  <mx:Label x="41" y="107" text="499"/>
  <mx:Image x="23" y="133" width="64" height="64" mouseMove="dragIt(event,'Fireworks',299);"  source="@Embed(source='../assets/057.png')"/>
  <mx:Label x="41" y="205" text="299"/>
  <mx:Image x="23" y="231" width="64" height="64" mouseMove="dragIt(event,'Flash',599);" source="@Embed(source='../assets/059.png')"/>
  <mx:Label x="41" y="303" text="599"/>
  </mx:Canvas>
  <mx:Label x="210" y="61" text="购物篮" fontSize="12"/>
  <mx:DataGrid x="129.5" y="102" id="cart" dataProvider="{cartContents}" dragEnter="dragEnterHandler(event);" dragDrop="dragDropHandler(event);" height="165" fontSize="12">
    <mx:columns>
      <mx:DataGridColumn headerText="产品" dataField="name"/>
      <mx:DataGridColumn headerText="价格" dataField="price"/>
    </mx:columns>
  </mx:DataGrid>
  <mx:Label x="186" y="292" text="总计：{total}" fontSize="12"/>
  <mx:Label x="129.5" y="0" text="拖拽物品放入购物篮中" fontSize="12"/>
  <mx:HRule x="5" y="20" width="390"/>

</mx:Application>

对于刚刚用拖拽管理器的朋友，这2个例子应该足够了。

Flex 拖拽范例