/*******************************************************************************
* Copyright (c) 2000, 2008 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.SWT;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.internal.Callback;
import org.eclipse.swt.internal.carbon.DataBrowserCallbacks;
import org.eclipse.swt.internal.carbon.OS;
import org.eclipse.swt.widgets.*;
/**
* This class provides a default drag under effect (eg. select, insert and scroll)
* when a drag occurs over a <code>Table</code>.
*
* <p>Classes that wish to provide their own drag under effect for a <code>Table</code>
* can extend the <code>TableDropTargetEffect</code> and override any applicable methods
* in <code>TableDropTargetEffect</code> to display their own drag under effect.</p>
*
* Subclasses that override any methods of this class must call the corresponding
* <code>super</code> method to get the default drag under effect implementation.
*
* <p>The feedback value is either one of the FEEDBACK constants defined in
* class <code>DND</code> which is applicable to instances of this class,
* or it must be built by <em>bitwise OR</em>'ing together
* (that is, using the <code>int</code> "|" operator) two or more
* of those <code>DND</code> effect constants.
* </p>
* <p>
* <dl>
* <dt><b>Feedback:</b></dt>
* <dd>FEEDBACK_SELECT, FEEDBACK_SCROLL</dd>
* </dl>
* </p>
*
* @see DropTargetAdapter
* @see DropTargetEvent
* @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
*
* @since 3.3
*/
public class TableDropTargetEffect extends DropTargetEffect {
static final int SCROLL_HYSTERESIS = 150; // milli seconds
TableItem scrollItem;
long scrollBeginTime;
DataBrowserCallbacks callbacks = null;
static Callback AcceptDragProc;
static {
AcceptDragProc = new Callback(TableDropTargetEffect.class, "AcceptDragProc", 5); //$NON-NLS-1$
int acceptDragProc = AcceptDragProc.getAddress();
if (acceptDragProc == 0) SWT.error(SWT.ERROR_NO_MORE_CALLBACKS);
}
static int AcceptDragProc(int theControl, int itemID, int property, int theRect, int theDrag) {
DropTarget target = FindDropTarget(theControl, theDrag);
if (target == null) return 0;
return (target.feedback & DND.FEEDBACK_SELECT) != 0 ? 1 : 0;
}
static DropTarget FindDropTarget(int theControl, int theDrag) {
if (theControl == 0) return null;
Display display = Display.findDisplay(Thread.currentThread());
if (display == null || display.isDisposed()) return null;
Widget widget = display.findWidget(theControl);
if (widget == null) return null;
return (DropTarget)widget.getData(DND.DROP_TARGET_KEY);
}
/**
* Creates a new <code>TableDropTargetEffect</code> to handle the drag under effect on the specified
* <code>Table</code>.
*
* @param table the <code>Table</code> over which the user positions the cursor to drop the data
*/
public TableDropTargetEffect(Table table) {
super(table);
}
int checkEffect(int effect) {
// Some effects are mutually exclusive. Make sure that only one of the mutually exclusive effects has been specified.
if ((effect & DND.FEEDBACK_SELECT) != 0) effect = effect & ~DND.FEEDBACK_INSERT_AFTER & ~DND.FEEDBACK_INSERT_BEFORE;
if ((effect & DND.FEEDBACK_INSERT_BEFORE) != 0) effect = effect & ~DND.FEEDBACK_INSERT_AFTER;
return effect;
}
/**
* This implementation of <code>dragEnter</code> provides a default drag under effect
* for the feedback specified in <code>event.feedback</code>.
*
* For additional information see <code>DropTargetAdapter.dragEnter</code>.
*
* Subclasses that override this method should call <code>super.dragEnter(event)</code>
* to get the default drag under effect implementation.
*
* @param event the information associated with the drag enter event
*
* @see DropTargetAdapter
* @see DropTargetEvent
*/
public void dragEnter(DropTargetEvent event) {
if (callbacks == null) {
Table table = (Table) control;
DataBrowserCallbacks callbacks = new DataBrowserCallbacks ();
OS.GetDataBrowserCallbacks (table.handle, callbacks);
callbacks.v1_acceptDragCallback = AcceptDragProc.getAddress();
OS.SetDataBrowserCallbacks(table.handle, callbacks);
}
scrollBeginTime = 0;
scrollItem = null;
}
/**
* This implementation of <code>dragLeave</code> provides a default drag under effect
* for the feedback specified in <code>event.feedback</code>.
*
* For additional information see <code>DropTargetAdapter.dragLeave</code>.
*
* Subclasses that override this method should call <code>super.dragLeave(event)</code>
* to get the default drag under effect implementation.
*
* @param event the information associated with the drag leave event
*
* @see DropTargetAdapter
* @see DropTargetEvent
*/
public void dragLeave(DropTargetEvent event) {
scrollBeginTime = 0;
scrollItem = null;
}
/**
* This implementation of <code>dragOver</code> provides a default drag under effect
* for the feedback specified in <code>event.feedback</code>. The class description
* lists the FEEDBACK constants that are applicable to the class.
*
* For additional information see <code>DropTargetAdapter.dragOver</code>.
*
* Subclasses that override this method should call <code>super.dragOver(event)</code>
* to get the default drag under effect implementation.
*
* @param event the information associated with the drag over event
*
* @see DropTargetAdapter
* @see DropTargetEvent
* @see DND#FEEDBACK_SELECT
* @see DND#FEEDBACK_SCROLL
*/
public void dragOver(DropTargetEvent event) {
Table table = (Table) control;
int effect = checkEffect(event.feedback);
TableItem item = (TableItem)getItem(table, event.x, event.y);
if ((effect & DND.FEEDBACK_SCROLL) == 0) {
scrollBeginTime = 0;
scrollItem = null;
} else {
if (item != null && item.equals(scrollItem) && scrollBeginTime != 0) {
if (System.currentTimeMillis() >= scrollBeginTime) {
Rectangle area = table.getClientArea();
int headerHeight = table.getHeaderHeight();
int itemHeight= table.getItemHeight();
Point pt = new Point(event.x, event.y);
pt = table.getDisplay().map(null, table, pt);
TableItem nextItem = null;
if (pt.y < area.y + headerHeight + 2 * itemHeight) {
int index = Math.max(0, table.indexOf(item)-1);
nextItem = table.getItem(index);
}
if (pt.y > area.y + area.height - 2 * itemHeight) {
int index = Math.min(table.getItemCount()-1, table.indexOf(item)+1);
nextItem = table.getItem(index);
}
if (nextItem != null) table.showItem(nextItem);
scrollBeginTime = 0;
scrollItem = null;
}
} else {
scrollBeginTime = System.currentTimeMillis() + SCROLL_HYSTERESIS;
scrollItem = item;
}
}
// store current effect for selection feedback
((DropTarget)event.widget).feedback = effect;
}
}