/*******************************************************************************
* Copyright (c) 2000, 2012 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
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.dnd;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Widget;
/**
*
* Class <code>DropTarget</code> defines the target object for a drag and drop
* transfer.
*
* <p>
* IMPORTANT: This class is <em>not</em> intended to be subclassed.
* </p>
*
* <p>
* This class identifies the <code>Control</code> over which the user must
* position the cursor in order to drop the data being transferred. It also
* specifies what data types can be dropped on this control and what operations
* can be performed. You may have several DropTragets in an application but
* there can only be a one to one mapping between a <code>Control</code> and a
* <code>DropTarget</code>. The DropTarget can receive data from within the same
* application or from other applications (such as text dragged from a text
* editor like Word).
* </p>
*
* <code><pre>
* int operations = DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_LINK;
* Transfer[] types = new Transfer[] {TextTransfer.getInstance()};
* DropTarget target = new DropTarget(label, operations);
* target.setTransfer(types);
* </code></pre>
*
* <p>
* The application is notified of data being dragged over this control and of
* when a drop occurs by implementing the interface
* <code>DropTargetListener</code> which uses the class
* <code>DropTargetEvent</code>. The application can modify the type of drag
* being performed on this Control at any stage of the drag by modifying the
* <code>event.detail</code> field or the <code>event.currentDataType</code>
* field. When the data is dropped, it is the responsibility of the application
* to copy this data for its own purposes.
*
* <code><pre>
* target.addDropListener (new DropTargetListener() {
* public void dragEnter(DropTargetEvent event) {};
* public void dragOver(DropTargetEvent event) {};
* public void dragLeave(DropTargetEvent event) {};
* public void dragOperationChanged(DropTargetEvent event) {};
* public void dropAccept(DropTargetEvent event) {}
* public void drop(DropTargetEvent event) {
* // A drop has occurred, copy over the data
* if (event.data == null) { // no data to copy, indicate failure in event.detail
* event.detail = DND.DROP_NONE;
* return;
* }
* label.setText ((String) event.data); // data copied to label text
* }
* });
* </pre></code>
*
* <dl>
* <dt><b>Styles</b></dt>
* <dd>DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK</dd>
* <dt><b>Events</b></dt>
* <dd>DND.DragEnter, DND.DragLeave, DND.DragOver, DND.DragOperationChanged,
* DND.DropAccept, DND.Drop</dd>
* </dl>
*
* @see <a href="http://www.eclipse.org/swt/snippets/#dnd">Drag and Drop
* snippets</a>
* @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example:
* DNDExample</a>
* @see <a href="http://www.eclipse.org/swt/">Sample code and further
* information</a>
* @noextend This class is not intended to be subclassed by clients.
*/
public class DropTarget extends Widget {
/**
* Creates a new <code>DropTarget</code> to allow data to be dropped on the
* specified <code>Control</code>. Creating an instance of a DropTarget may
* cause system resources to be allocated depending on the platform. It is
* therefore mandatory that the DropTarget instance be disposed when no
* longer required.
*
* @param control
* the <code>Control</code> over which the user positions the
* cursor to drop the data
* @param style
* the bitwise OR'ing of allowed operations; this may be a
* combination of any of DND.DROP_NONE, DND.DROP_COPY,
* DND.DROP_MOVE, DND.DROP_LINK
*
* @exception SWTException
* <ul>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the parent</li>
* <li>ERROR_INVALID_SUBCLASS - if this class is not an
* allowed subclass</li>
* </ul>
* @exception SWTError
* <ul>
* <li>ERROR_CANNOT_INIT_DROP - unable to initiate drop
* target; this will occur if more than one drop target is
* created for a control or if the operating system will not
* allow the creation of the drop target</li>
* </ul>
*
* <p>
* NOTE: ERROR_CANNOT_INIT_DROP should be an SWTException,
* since it is a recoverable error, but can not be changed
* due to backward compatibility.
* </p>
*
* @see Widget#dispose
* @see DropTarget#checkSubclass
* @see DND#DROP_NONE
* @see DND#DROP_COPY
* @see DND#DROP_MOVE
* @see DND#DROP_LINK
*/
public DropTarget(Control control, int style) {
// TODO
super(control, style);
}
/**
* Adds the listener to the collection of listeners who will be notified
* when a drag and drop operation is in progress, by sending it one of the
* messages defined in the <code>DropTargetListener</code> interface.
*
* <p>
* <ul>
* <li><code>dragEnter</code> is called when the cursor has entered the drop
* target boundaries
* <li><code>dragLeave</code> is called when the cursor has left the drop
* target boundaries and just before the drop occurs or is cancelled.
* <li><code>dragOperationChanged</code> is called when the operation being
* performed has changed (usually due to the user changing the selected
* modifier key(s) while dragging)
* <li><code>dragOver</code> is called when the cursor is moving over the
* drop target
* <li><code>dropAccept</code> is called just before the drop is performed.
* The drop target is given the chance to change the nature of the drop or
* veto the drop by setting the <code>event.detail</code> field
* <li><code>drop</code> is called when the data is being dropped
* </ul>
* </p>
*
* @param listener
* the listener which should be notified
*
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been
* disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
*
* @see DropTargetListener
* @see #getDropListeners
* @see #removeDropListener
* @see DropTargetEvent
*/
public void addDropListener(DropTargetListener listener) {
// TODO
}
/**
* Returns the Control which is registered for this DropTarget. This is the
* control over which the user positions the cursor to drop the data.
*
* @return the Control which is registered for this DropTarget
*/
public Control getControl() {
// TODO
return null;
}
/**
* Returns an array of listeners who will be notified when a drag and drop
* operation is in progress, by sending it one of the messages defined in
* the <code>DropTargetListener</code> interface.
*
* @return the listeners who will be notified when a drag and drop operation
* is in progress
*
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been
* disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
*
* @see DropTargetListener
* @see #addDropListener
* @see #removeDropListener
* @see DropTargetEvent
*
* @since 3.4
*/
public DropTargetListener[] getDropListeners() {
// TODO
return null;
}
/**
* Returns the drop effect for this DropTarget. This drop effect will be
* used during a drag and drop to display the drag under effect on the
* target widget.
*
* @return the drop effect that is registered for this DropTarget
*
* @since 3.3
*/
public DropTargetEffect getDropTargetEffect() {
// TODO
return null;
}
/**
* Returns a list of the data types that can be transferred to this
* DropTarget.
*
* @return a list of the data types that can be transferred to this
* DropTarget
*/
public Transfer[] getTransfer() {
// TODO
return null;
}
/**
* Removes the listener from the collection of listeners who will be
* notified when a drag and drop operation is in progress.
*
* @param listener
* the listener which should no longer be notified
*
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
* </ul>
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been
* disposed</li>
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the
* thread that created the receiver</li>
* </ul>
*
* @see DropTargetListener
* @see #addDropListener
* @see #getDropListeners
*/
public void removeDropListener(DropTargetListener listener) {
// TODO
}
/**
* Specifies the data types that can be transferred to this DropTarget. If
* data is being dragged that does not match one of these types, the drop
* target will be notified of the drag and drop operation but the
* currentDataType will be null and the operation will be DND.NONE.
*
* @param transferAgents
* a list of Transfer objects which define the types of data that
* can be dropped on this target
*
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if transferAgents is null</li>
* </ul>
*/
public void setTransfer(Transfer[] transferAgents) {
// TODO
}
/**
* Specifies the drop effect for this DropTarget. This drop effect will be
* used during a drag and drop to display the drag under effect on the
* target widget.
*
* @param effect
* the drop effect that is registered for this DropTarget
*
* @since 3.3
*/
public void setDropTargetEffect(DropTargetEffect effect) {
// TODO
}
}