MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual do Utilizador descarregar pdf (Página 178)

178 Migration Patterns

Using the drag-and-drop feature

When you convert drag-and-drop code, be aware of the following changes:

■ The doDrag() method takes an additional required attribute, mouse_event. This

attribute is the MouseEvent object that contains the mouse information for the start of the

drag.

■ All drag-and-drop-specific events are now DragEvent class events.

■ For a drop target to accept an item for dropping, it must call the acceptDragDrop()

method, not use the

event.handled property.

The following example lets you drag one of two colored canvases onto a larger canvas to apply

the color to the larger canvas:

Flex 1.x:

<?xml version="1.0"?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml">

<mx:Script><![CDATA[

import mx.managers.Dragmanager;

function dragIt(event, text, format) {

var ds:mx.core.DragSource = new mx.core.DragSource();

ds.addData(text, format);

DragManager.doDrag(event.target, ds, mx.containers.Canvas,

{backgroundColor:event.target.getStyle('backgroundColor'),

width:30, height:30});

}

function doDragEnter(event) {

if (event.dragSource.hasFormat('color')) {

event.handled = true;

}

function doDragDrop(event) {

var data = event.dragSource.dataForFormat('color');

myCanvas.setStyle("backgroundColor", data);

}

]]></mx:Script>

<mx:HBox>

<mx:Canvas backgroundColor="#FF0000" borderStyle="solid" width="30"

height="30" mouseMove="dragIt(event, 'red', 'color')"/>

<mx:Canvas backgroundColor="#00FF00" borderStyle="solid" width="30"

height="30" mouseMove="dragIt(event, 'green', 'color')"/>

</mx:HBox>

<mx:Label text="Drag the item into this canvas"/>

<mx:Canvas id="myCanvas" backgroundColor="#FFFFFF" borderStyle="solid"

width="100" height="100" dragEnter="doDragEnter(event)"

dragDrop="doDragDrop(event)"/>

</mx:Application>

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