# Drop Actions

###### Identifier:

org.eclipse.ui.dropActions

###### Description:

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

point CDATA #REQUIRED

id CDATA #IMPLIED

name CDATA #IMPLIED

>

- point - a fully qualified identifier of the target extension point
- id - an optional identifier of the extension instance
- name - an optional name of the extension instance

<!ELEMENT action EMPTY>

<!ATTLIST action

id CDATA #REQUIRED

class CDATA #REQUIRED

>

- id - a unique identifier that can be used to reference this action
- class - the name of the fully qualified class that implements `org.eclipse.ui.part.IDropActionDelegate`.

###### Examples:

The following is an example of a drop action extension:

        <extension point="org.eclipse.ui.dropActions">
            <action
                id="my_drop_action"
                class="com.xyz.eclipse.TestDropAction">
            </action>
        </extension>

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