邋遢居

在 help 中查到：

public interface TransferDropTargetListener

extends TransferDropTargetListener

A DropTragetListener that handles one type of SWT Transfer. The purpose of a TransferDropTargetListener is to:

• Determine enablement for a Drop operation. Enablement is often a function drop location, and/or criteria.

• When enabled, optionally showing feedback on the DropTarget.

• Performing the actualy Drop

DelegatingDropAdapter allows these functions to be implemented separately for unrelated types of Drags. DelegatingDropAdapter then combines the function of each TransferDropTargetListener, while allowing them to be implemented as if they were the only DragSourceListener.

偷下懶，就不翻譯了。

創(chuàng)建如下類來實(shí)現(xiàn)這個(gè)接口：

public class TreeNodeTransferDropTargetListener extends

AbstractTransferDropTargetListener {

public TreeNodeTransferDropTargetListener(EditPartViewer editPartViewer) {

// 改類默認(rèn)是處理 TextTransfer 類型的拖拽事件

super (editPartViewer,TextTransfer.getInstance());

// TODO Auto-generated constructor stub

}

@Override

protected void updateTargetRequest() {

}

}

我們這個(gè)拖拽想是讓他執(zhí)行一個(gè) create 命令。所以下面就是要重載他的 createTargetRequest() 用來處理 create 對(duì)象的請(qǐng)求（ CreateRequestion ）。 CreateRequetion 需要使用到一個(gè)類，幫助我們創(chuàng)建對(duì)象的工廠類。 GEF 給了我們這樣的一個(gè)接口 CreationFactory 。下面我們?nèi)?shí)現(xiàn)他就好了。

package org.eclipse.gef.examples.shapes.rcp.views;

import org.eclipse.gef.examples.shapes.model.EllipticalShape;

import org.eclipse.gef.requests.CreationFactory;

public class TypeCreationFactory implements CreationFactory {

public Object getNewObject() {

// TODO Auto-generated method stub

EllipticalShape label = new EllipticalShape();

return label;

}

public Object getObjectType() {

return EllipticalShape. class ;

}

}

注意：這里的 getNewObject 是返回要?jiǎng)?chuàng)建類的一個(gè)對(duì)象實(shí)例。 GetObjectType 需要返回需要?jiǎng)?chuàng)建對(duì)象的類。這個(gè)可不要搞反了。

這樣我們就可以把我們的 TreeNodeTransferDropTargetListener 類中的 createTargetRequest 方法加上了。

private TypeCreationFactory factory = new TypeCreationFactory();

protected Request createTargetRequest() {

CreateRequest request = new CreateRequest();

request.setFactory( factory );

return request;

}

好了這個(gè)時(shí)候不要客氣了，加上

protected void handleDragOver() {

getCurrentEvent(). detail = DND. DROP_MOVE |DND. DROP_COPY ;

super .handleDragOver();

}

@Override

protected void handleDrop() {

//String s = (String)getCurrentEvent().data;

//factory.setText(s);

super .handleDrop();

}

這樣的方法吧。

這樣這個(gè)功能就完成了。

參考文獻(xiàn)：

http://www.aygfsteel.com/weidagang2046/archive/2006/09/05/67707.html

http://www.eclipse.org/articles/Article-GEF-dnd/GEF-dnd.html