///*******************************************************************************
// * Copyright (c) 2000, 2007 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.jface.util;
//
//import java.util.ArrayList;
//import java.util.Iterator;
//import java.util.List;
//
//import org.eclipse.swt.dnd.DND;
//import org.eclipse.swt.dnd.DropTargetEvent;
//import org.eclipse.swt.dnd.DropTargetListener;
//import org.eclipse.swt.dnd.Transfer;
//import org.eclipse.swt.dnd.TransferData;
//
///**
// * A <code>DelegatingDropAdapter</code> is a <code>DropTargetListener</code> that
// * maintains and delegates to a set of {@link TransferDropTargetListener}s. Each
// * <code>TransferDropTargetListener</code> can then be implemented as if it were
// * the DropTarget's only <code>DropTargetListener</code>.
// * <p>
// * On <code>dragEnter</code>, <code>dragOperationChanged</code>, <code>dragOver</code>
// * and <code>drop</code>, a <i>current</i> listener is obtained from the set of all
// * <code>TransferDropTargetListeners</code>. The current listener is the first listener
// * to return <code>true</code> for
// * {@link TransferDropTargetListener#isEnabled(DropTargetEvent)}.
// * The current listener is forwarded all <code>DropTargetEvents</code> until some other
// * listener becomes the current listener, or the drop terminates.
// * </p>
// * <p>
// * After adding all <code>TransferDropTargetListeners</code> to the
// * <code>DelegatingDropAdapter</code> the combined set of <code>Transfers</code> should
// * be set in the SWT <code>DropTarget</code>. <code>#getTransfers()</code> provides the
// * set of <code>Transfer</code> types of all <code>TransferDropTargetListeners</code>.
// * </p>
// * <p>
// * The following example snippet shows a <code>DelegatingDropAdapter</code> with two
// * <code>TransferDropTargetListeners</code>. One supports dropping resources and
// * demonstrates how a listener can be disabled in the isEnabled method.
// * The other listener supports text transfer.
// * </p>
// * <code><pre>
// * final TreeViewer viewer = new TreeViewer(shell, SWT.NONE);
// * DelegatingDropAdapter dropAdapter = new DelegatingDropAdapter();
// * dropAdapter.addDropTargetListener(new TransferDropTargetListener() {
// * public Transfer getTransfer() {
// * return ResourceTransfer.getInstance();
// * }
// * public boolean isEnabled(DropTargetEvent event) {
// * // disable drop listener if there is no viewer selection
// * if (viewer.getSelection().isEmpty())
// * return false;
// * return true;
// * }
// * public void dragEnter(DropTargetEvent event) {}
// * public void dragLeave(DropTargetEvent event) {}
// * public void dragOperationChanged(DropTargetEvent event) {}
// * public void dragOver(DropTargetEvent event) {}
// * public void drop(DropTargetEvent event) {
// * if (event.data == null)
// * return;
// * IResource[] resources = (IResource[]) event.data;
// * if (event.detail == DND.DROP_COPY) {
// * // copy resources
// * } else {
// * // move resources
// * }
// *
// * }
// * public void dropAccept(DropTargetEvent event) {}
// * });
// * dropAdapter.addDropTargetListener(new TransferDropTargetListener() {
// * public Transfer getTransfer() {
// * return TextTransfer.getInstance();
// * }
// * public boolean isEnabled(DropTargetEvent event) {
// * return true;
// * }
// * public void dragEnter(DropTargetEvent event) {}
// * public void dragLeave(DropTargetEvent event) {}
// * public void dragOperationChanged(DropTargetEvent event) {}
// * public void dragOver(DropTargetEvent event) {}
// * public void drop(DropTargetEvent event) {
// * if (event.data == null)
// * return;
// * System.out.println(event.data);
// * }
// * public void dropAccept(DropTargetEvent event) {}
// * });
// * viewer.addDropSupport(DND.DROP_COPY | DND.DROP_MOVE, dropAdapter.getTransfers(), dropAdapter);
// * </pre></code>
// * @since 1.0
// */
//public class DelegatingDropAdapter implements DropTargetListener {
// private List listeners = new ArrayList();
//
// private TransferDropTargetListener currentListener;
//
// private int originalDropType;
//
// /**
// * Adds the given <code>TransferDropTargetListener</code>.
// *
// * @param listener the new listener
// */
// public void addDropTargetListener(TransferDropTargetListener listener) {
// listeners.add(listener);
// }
//
// /**
// * The cursor has entered the drop target boundaries. The current listener is
// * updated, and <code>#dragEnter()</code> is forwarded to the current listener.
// *
// * @param event the drop target event
// * @see DropTargetListener#dragEnter(DropTargetEvent)
// */
// public void dragEnter(DropTargetEvent event) {
// // if (Policy.DEBUG_DRAG_DROP)
// // System.out.println("Drag Enter: " + toString()); //$NON-NLS-1$
// originalDropType = event.detail;
// updateCurrentListener(event);
// }
//
// /**
// * The cursor has left the drop target boundaries. The event is forwarded to the
// * current listener.
// *
// * @param event the drop target event
// * @see DropTargetListener#dragLeave(DropTargetEvent)
// */
// public void dragLeave(final DropTargetEvent event) {
// // if (Policy.DEBUG_DRAG_DROP)
// // System.out.println("Drag Leave: " + toString()); //$NON-NLS-1$
// setCurrentListener(null, event);
// }
//
// /**
// * The operation being performed has changed (usually due to the user changing
// * a drag modifier key while dragging). Updates the current listener and forwards
// * this event to that listener.
// *
// * @param event the drop target event
// * @see DropTargetListener#dragOperationChanged(DropTargetEvent)
// */
// public void dragOperationChanged(final DropTargetEvent event) {
// // if (Policy.DEBUG_DRAG_DROP)
// // System.out.println("Drag Operation Changed to: " + event.detail); //$NON-NLS-1$
// originalDropType = event.detail;
// TransferDropTargetListener oldListener = getCurrentListener();
// updateCurrentListener(event);
// final TransferDropTargetListener newListener = getCurrentListener();
// // only notify the current listener if it hasn't changed based on the
// // operation change. otherwise the new listener would get a dragEnter
// // followed by a dragOperationChanged with the exact same event.
// if (newListener != null && newListener == oldListener) {
// SafeRunnable.run(new SafeRunnable() {
// public void run() throws Exception {
// newListener.dragOperationChanged(event);
// }
// });
// }
// }
//
// /**
// * The cursor is moving over the drop target. Updates the current listener and
// * forwards this event to that listener. If no listener can handle the drag
// * operation the <code>event.detail</code> field is set to <code>DND.DROP_NONE</code>
// * to indicate an invalid drop.
// *
// * @param event the drop target event
// * @see DropTargetListener#dragOver(DropTargetEvent)
// */
// public void dragOver(final DropTargetEvent event) {
// TransferDropTargetListener oldListener = getCurrentListener();
// updateCurrentListener(event);
// final TransferDropTargetListener newListener = getCurrentListener();
//
// // only notify the current listener if it hasn't changed based on the
// // drag over. otherwise the new listener would get a dragEnter
// // followed by a dragOver with the exact same event.
// if (newListener != null && newListener == oldListener) {
// SafeRunnable.run(new SafeRunnable() {
// public void run() throws Exception {
// newListener.dragOver(event);
// }
// });
// }
// }
//
// /**
// * Forwards this event to the current listener, if there is one. Sets the
// * current listener to <code>null</code> afterwards.
// *
// * @param event the drop target event
// * @see DropTargetListener#drop(DropTargetEvent)
// */
// public void drop(final DropTargetEvent event) {
// // if (Policy.DEBUG_DRAG_DROP)
// // System.out.println("Drop: " + toString()); //$NON-NLS-1$
// updateCurrentListener(event);
// if (getCurrentListener() != null) {
// SafeRunnable.run(new SafeRunnable() {
// public void run() throws Exception {
// getCurrentListener().drop(event);
// }
// });
// }
// setCurrentListener(null, event);
// }
//
// /**
// * Forwards this event to the current listener if there is one.
// *
// * @param event the drop target event
// * @see DropTargetListener#dropAccept(DropTargetEvent)
// */
// public void dropAccept(final DropTargetEvent event) {
// // if (Policy.DEBUG_DRAG_DROP)
// // System.out.println("Drop Accept: " + toString()); //$NON-NLS-1$
// if (getCurrentListener() != null) {
// SafeRunnable.run(new SafeRunnable() {
// public void run() throws Exception {
// getCurrentListener().dropAccept(event);
// }
// });
// }
// }
//
// /**
// * Returns the listener which currently handles drop events.
// *
// * @return the <code>TransferDropTargetListener</code> which currently
// * handles drop events.
// */
// private TransferDropTargetListener getCurrentListener() {
// return currentListener;
// }
//
// /**
// * Returns the transfer data type supported by the given listener.
// * Returns <code>null</code> if the listener does not support any of the
// * specified data types.
// *
// * @param dataTypes available data types
// * @param listener <code>TransferDropTargetListener</code> to use for testing
// * supported data types.
// * @return the transfer data type supported by the given listener or
// * <code>null</code>.
// */
// private TransferData getSupportedTransferType(TransferData[] dataTypes,
// TransferDropTargetListener listener) {
// for (int i = 0; i < dataTypes.length; i++) {
// if (listener.getTransfer().isSupportedType(dataTypes[i])) {
// return dataTypes[i];
// }
// }
// return null;
// }
//
// /**
// * Returns the combined set of <code>Transfer</code> types of all
// * <code>TransferDropTargetListeners</code>.
// *
// * @return the combined set of <code>Transfer</code> types
// */
// public Transfer[] getTransfers() {
// Transfer[] types = new Transfer[listeners.size()];
// for (int i = 0; i < listeners.size(); i++) {
// TransferDropTargetListener listener = (TransferDropTargetListener) listeners
// .get(i);
// types[i] = listener.getTransfer();
// }
// return types;
// }
//
// /**
// * Returns <code>true</code> if there are no listeners to delegate events to.
// *
// * @return <code>true</code> if there are no <code>TransferDropTargetListeners</code>
// * <code>false</code> otherwise
// */
// public boolean isEmpty() {
// return listeners.isEmpty();
// }
//
// /**
// * Removes the given <code>TransferDropTargetListener</code>.
// * Listeners should not be removed while a drag and drop operation is in progress.
// *
// * @param listener the listener to remove
// */
// public void removeDropTargetListener(TransferDropTargetListener listener) {
// if (currentListener == listener) {
// currentListener = null;
// }
// listeners.remove(listener);
// }
//
// /**
// * Sets the current listener to <code>listener</code>. Sends the given
// * <code>DropTargetEvent</code> if the current listener changes.
// *
// * @return <code>true</code> if the new listener is different than the previous
// * <code>false</code> otherwise
// */
// private boolean setCurrentListener(TransferDropTargetListener listener,
// final DropTargetEvent event) {
// if (currentListener == listener) {
// return false;
// }
// if (currentListener != null) {
// SafeRunnable.run(new SafeRunnable() {
// public void run() throws Exception {
// currentListener.dragLeave(event);
// }
// });
// }
// currentListener = listener;
// // if (Policy.DEBUG_DRAG_DROP)
// // System.out.println("Current drop listener: " + listener); //$NON-NLS-1$
// if (currentListener != null) {
// SafeRunnable.run(new SafeRunnable() {
// public void run() throws Exception {
// currentListener.dragEnter(event);
// }
// });
// }
// return true;
// }
//
// /**
// * Updates the current listener to one that can handle the drop. There can be many
// * listeners and each listener may be able to handle many <code>TransferData</code>
// * types. The first listener found that can handle a drop of one of the given
// * <code>TransferData</code> types will be selected.
// * If no listener can handle the drag operation the <code>event.detail</code> field
// * is set to <code>DND.DROP_NONE</code> to indicate an invalid drop.
// *
// * @param event the drop target event
// */
// private void updateCurrentListener(DropTargetEvent event) {
// int originalDetail = event.detail;
// // revert the detail to the "original" drop type that the User indicated.
// // this is necessary because the previous listener may have changed the detail
// // to something other than what the user indicated.
// event.detail = originalDropType;
//
// Iterator iter = listeners.iterator();
// while (iter.hasNext()) {
// TransferDropTargetListener listener = (TransferDropTargetListener) iter
// .next();
// TransferData dataType = getSupportedTransferType(event.dataTypes,
// listener);
// if (dataType != null) {
// TransferData originalDataType = event.currentDataType;
// // set the data type supported by the drop listener
// event.currentDataType = dataType;
// if (listener.isEnabled(event)) {
// // if the listener stays the same, set its previously determined
// // event detail
// if (!setCurrentListener(listener, event)) {
// event.detail = originalDetail;
// }
// return;
// }
// event.currentDataType = originalDataType;
// }
// }
// setCurrentListener(null, event);
// event.detail = DND.DROP_NONE;
//
// // -always- ensure that expand/scroll are on...otherwise
// // if a valid drop target is a child of an invalid one
// // you can't get there...
// event.feedback = DND.FEEDBACK_EXPAND | DND.FEEDBACK_SCROLL;
// }
//}