/*******************************************************************************
* Copyright (c) 2000, 2015 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
* EclipseSource - adaptation to RAP
*******************************************************************************/
package org.eclipse.swt.dnd;
import org.eclipse.rap.rwt.internal.lifecycle.WidgetLCA;
import org.eclipse.swt.SWT;
import org.eclipse.swt.SWTError;
import org.eclipse.swt.SWTException;
import org.eclipse.swt.internal.dnd.droptargetkit.DropTargetLCA;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
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>
*
* @noextend This class is not intended to be subclassed by clients.
* @since 1.3
*/
public class DropTarget extends Widget {
Control control;
Listener controlListener;
Transfer[] transferAgents = new Transfer[ 0 ];
DropTargetEffect dropEffect;
// Track application selections
TransferData selectedDataType;
int selectedOperation;
// workaround - There is no event for "operation changed" so track operation based on key state
int keyOperation = -1;
static final String DEFAULT_DROP_TARGET_EFFECT = "DEFAULT_DROP_TARGET_EFFECT"; //$NON-NLS-1$
/**
* 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 ) {
super( control, checkStyle( style ) );
this.control = control;
if( control.getData( DND.DROP_TARGET_KEY ) != null ) {
DND.error( DND.ERROR_CANNOT_INIT_DROP );
}
control.setData( DND.DROP_TARGET_KEY, this );
controlListener = new Listener() {
@Override
public void handleEvent( Event event ) {
if( !DropTarget.this.isDisposed() ) {
DropTarget.this.dispose();
}
}
};
control.addListener( SWT.Dispose, controlListener );
this.addListener( SWT.Dispose, new Listener() {
@Override
public void handleEvent( Event event ) {
onDispose();
}
} );
Object effect = control.getData( DEFAULT_DROP_TARGET_EFFECT );
if( effect instanceof DropTargetEffect ) {
dropEffect = ( DropTargetEffect )effect;
// } else if (control instanceof Table) {
// dropEffect = new TableDropTargetEffect((Table) control);
// } else if (control instanceof Tree) {
// dropEffect = new TreeDropTargetEffect((Tree) control);
}
}
static int checkStyle( int style ) {
if( style == SWT.NONE ) {
return DND.DROP_MOVE;
}
return 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 ) {
if( listener == null ) {
DND.error( SWT.ERROR_NULL_ARGUMENT );
}
DNDListener typedListener = new DNDListener( listener );
typedListener.dndWidget = this;
addListener( DND.DragEnter, typedListener );
addListener( DND.DragLeave, typedListener );
addListener( DND.DragOver, typedListener );
addListener( DND.DragOperationChanged, typedListener );
addListener( DND.Drop, typedListener );
addListener( DND.DropAccept, typedListener );
}
@Override
protected void checkSubclass() {
String name = getClass().getName();
String validName = DropTarget.class.getName();
if( !validName.equals( name ) ) {
DND.error( SWT.ERROR_INVALID_SUBCLASS );
}
}
/**
* 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() {
return control;
}
/**
* 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
*/
public DropTargetListener[] getDropListeners() {
Listener[] listeners = getListeners( DND.DragEnter );
int length = listeners.length;
DropTargetListener[] dropListeners = new DropTargetListener[ length ];
int count = 0;
for( int i = 0; i < length; i++ ) {
Listener listener = listeners[ i ];
if( listener instanceof DNDListener ) {
dropListeners[ count ] = ( DropTargetListener )( ( DNDListener )listener ).getEventListener();
count++ ;
}
}
if( count == length ) {
return dropListeners;
}
DropTargetListener[] result = new DropTargetListener[ count ];
System.arraycopy( dropListeners, 0, result, 0, count );
return result;
}
/**
* 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
*/
public DropTargetEffect getDropTargetEffect() {
return dropEffect;
}
void onDispose() {
if( control == null ) {
return;
}
if( controlListener != null )
control.removeListener( SWT.Dispose, controlListener );
controlListener = null;
control.setData( DND.DROP_TARGET_KEY, null );
transferAgents = null;
control = 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() {
return transferAgents;
}
/**
* 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 ) {
if( listener == null ) {
DND.error( SWT.ERROR_NULL_ARGUMENT );
}
removeListener( DND.DragEnter, listener );
removeListener( DND.DragLeave, listener );
removeListener( DND.DragOver, listener );
removeListener( DND.DragOperationChanged, listener );
removeListener( DND.Drop, listener );
removeListener( DND.DropAccept, listener );
}
/**
* 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
*/
public void setDropTargetEffect( DropTargetEffect effect ) {
dropEffect = effect;
}
/**
* 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 ) {
if( transferAgents == null ) {
DND.error( SWT.ERROR_NULL_ARGUMENT );
}
this.transferAgents = transferAgents;
}
@Override
@SuppressWarnings( "unchecked" )
public <T> T getAdapter( Class<T> adapter ) {
if( adapter == WidgetLCA.class ) {
return ( T )DropTargetLCA.INSTANCE;
}
return super.getAdapter( adapter );
}
}