--- /dev/null
+/*******************************************************************************
+ * Copyright (c) 2000, 2003 IBM Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Common Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/cpl-v10.html
+ *
+ * Contributors:
+ * IBM Corporation - initial API and implementation
+ *******************************************************************************/
+package net.sourceforge.phpdt.internal.ui.dnd;
+
+import org.eclipse.swt.dnd.DropTargetEvent;
+import org.eclipse.swt.dnd.DropTargetListener;
+import org.eclipse.swt.dnd.TransferData;
+
+import org.eclipse.jface.util.Assert;
+
+/**
+ * A delegating drop adapter negotiates between a set of <code>TransferDropTargetListener</code>s
+ * On <code>dragEnter</code> the adapter determines the listener to be used for any further
+ * <code>drag*</code> callback.
+ */
+public class DelegatingDropAdapter implements DropTargetListener {
+
+ private TransferDropTargetListener[] fListeners;
+
+ private TransferDropTargetListener fChosenListener;
+
+ /**
+ * Creates a new delegating drop adapter.
+ *
+ * @param listeners an array of potential listeners
+ */
+ public DelegatingDropAdapter(TransferDropTargetListener[] listeners) {
+ fListeners= listeners;
+ Assert.isNotNull(listeners);
+ }
+
+ /* non Java-doc
+ * @see DropTargetListener
+ */
+ public void dragEnter(DropTargetEvent event) {
+ fChosenListener= null;
+ event.currentDataType= selectPreferredListener(event.dataTypes);
+ if (fChosenListener != null)
+ fChosenListener.dragEnter(event);
+ }
+
+ /* non Java-doc
+ * @see DropTargetListener
+ */
+ public void dragLeave(DropTargetEvent event){
+ if (fChosenListener != null)
+ fChosenListener.dragLeave(event);
+ }
+
+ /* non Java-doc
+ * @see DropTargetListener
+ */
+ public void dragOperationChanged(DropTargetEvent event){
+ if (fChosenListener != null)
+ fChosenListener.dragOperationChanged(event);
+ }
+
+ /* non Java-doc
+ * @see DropTargetListener
+ */
+ public void dragOver(DropTargetEvent event){
+ if (fChosenListener != null)
+ fChosenListener.dragOver(event);
+ }
+
+ /* non Java-doc
+ * @see DropTargetListener
+ */
+ public void drop(DropTargetEvent event){
+ if (fChosenListener != null)
+ fChosenListener.drop(event);
+ fChosenListener= null;
+ }
+
+ /* non Java-doc
+ * @see DropTargetListener
+ */
+ public void dropAccept(DropTargetEvent event){
+ if (fChosenListener != null)
+ fChosenListener.dropAccept(event);
+ }
+
+ private TransferData selectPreferredListener(TransferData[] dataTypes) {
+ for (int i= 0; i < fListeners.length; i++) {
+ TransferData data= computeTransferData(dataTypes, fListeners[i]);
+ if (data != null)
+ return data;
+ }
+ return null;
+ }
+
+ private TransferData computeTransferData(TransferData[] dataTypes, TransferDropTargetListener listener) {
+ for (int i= 0; i < dataTypes.length; i++) {
+ if (listener.getTransfer().isSupportedType(dataTypes[i])) {
+ fChosenListener= listener;
+ return dataTypes[i];
+ }
+ }
+ return null;
+ }
+}