Drop Actions


This extension point is used to add drop behaviour to views defined by other plugins.

Due to the UI layering imposed by the plugin mechanism, views are often not aware of the content and nature of other views. This can make drag and drop operations between plugins difficult. For example, one may wish to provide Java refactoring support whereby the user drags a method from the Java editor's content outliner into another java file in the resource navigator. Since the resource navigator doesn't know anything about Java content, it doesn't know how to behave when java methods are dropped onto it. Similarly, an ISV may want to drop some of their content into one of the Java viewers.

The org.eclipse.ui.dropActions extension point is provided by the Platform to address these situations. This mechanism delegates the drop behaviour back to the originator of the drag operation. This behaviour is contained in an action that must implement org.eclipse.ui.part.IDropActionDelegate. The viewer that is the source of the drag operation must support the org.eclipse.ui.part.PluginTransfer transfer type, and place a PluginTransferData object in the drag event. See org.eclipse.jface.viewers.StructuredViewer#addDragSupport to learn how to add drag support to a viewer.

Configuration Markup:

<!ELEMENT extension (action*)>

<!ATTLIST extension






<!ATTLIST action




The following is an example of a drop action extension:

    <extension point="org.eclipse.ui.dropActions"> 

Here is an example of a drag listener that makes use of the drop action defined above.

class MyDragListener extends DragSourceAdapter { 
    public void dragSetData(DragSourceEvent event) { 
        if (PluginTransfer.getInstance().isSupportedType(event.dataType)) { 
            byte[] dataToSend = ...//enter the data to be sent. 
            event.data = new PluginTransferData( 
                "my_drop_action", dataToSend); 

For a more complete example, see the Platform readme example. In that example, a drop action is defined in ReadmeDropActionDelegate, and it is used by ReadmeContentOutlineDragListener.

API Information:
The value of the class attribute must be a fully qualified name of a Java class that implements org.eclipse.ui.part.IDropActionDelegate. This class is loaded as late as possible to avoid loading the entire plug-in before it is really needed

Supplied Implementation:
The workbench does not provide an implementation for this extension point. Plug-ins can contribute to this extension point to add drop behavior to views defined by other plugins.

Copyright (c) 2002, 2005 IBM Corporation and others.
All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0 which accompanies this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html