/*******************************************************************************
* Copyright (c) 2007, 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.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.widgets.*;
/**
* This class provides a default drag under effect during a drag and drop.
* The current implementation does not provide any visual feedback.
*
* <p>The drop target effect has the same API as the
* <code>DropTargetAdapter</code> so that it can provide custom visual
* feedback when a <code>DropTargetEvent</code> occurs.
* </p>
*
* <p>Classes that wish to provide their own drag under effect
* can extend the <code>DropTargetEffect</code> and override any applicable methods
* in <code>DropTargetAdapter</code> to display their own drag under effect.</p>
*
* <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_EXPAND, FEEDBACK_INSERT_AFTER, FEEDBACK_INSERT_BEFORE,
* FEEDBACK_NONE, FEEDBACK_SELECT, FEEDBACK_SCROLL</dd>
* </dl>
* </p>
*
* @see DropTargetAdapter
* @see DropTargetEvent
* @since 1.3
*/
public class DropTargetEffect extends DropTargetAdapter {
Control control;
/**
* Creates a new <code>DropTargetEffect</code> to handle the drag under effect on the specified
* <code>Control</code>.
*
* @param control the <code>Control</code> over which the user positions the cursor to drop the data
*
* @exception IllegalArgumentException <ul>
* <li>ERROR_NULL_ARGUMENT - if the control is null</li>
* </ul>
*/
public DropTargetEffect(Control control) {
if (control == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
this.control = control;
}
/**
* Returns the Control which is registered for this DropTargetEffect. This is the control over which the
* user positions the cursor to drop the data.
*
* @return the Control which is registered for this DropTargetEffect
*/
public Control getControl() {
return control;
}
/**
* Returns the item at the given x-y coordinate in the receiver
* or null if no such item exists. The x-y coordinate is in the
* display relative coordinates.
*
* @param x the x coordinate used to locate the item
* @param y the y coordinate used to locate the item
* @return the item at the given x-y coordinate, or null if the coordinate is not in a selectable item
*/
public Widget getItem(int x, int y) {
if (control instanceof Table) {
return getItem((Table) control, x, y);
}
if (control instanceof Tree) {
return getItem((Tree) control, x, y);
}
return null;
}
Widget getItem(Table table, int x, int y) {
Point coordinates = new Point(x, y);
coordinates = table.toControl(coordinates);
TableItem item = table.getItem(coordinates);
if (item != null) return item;
Rectangle area = table.getClientArea();
int tableBottom = area.y + area.height;
int itemCount = table.getItemCount();
for (int i=table.getTopIndex(); i<itemCount; i++) {
item = table.getItem(i);
Rectangle rect = item.getBounds();
rect.x = area.x;
rect.width = area.width;
if (rect.contains(coordinates)) return item;
if (rect.y > tableBottom) break;
}
return null;
}
Widget getItem(Tree tree, int x, int y) {
Point point = new Point(x, y);
point = tree.toControl(point);
TreeItem item = tree.getItem(point);
if (item == null) {
Rectangle area = tree.getClientArea();
if (area.contains(point)) {
int treeBottom = area.y + area.height;
// TODO [rh] Tree#getTopItem() is missing
// item = tree.getTopItem();
while (item != null) {
Rectangle rect = item.getBounds();
int itemBottom = rect.y + rect.height;
if (rect.y <= point.y && point.y < itemBottom) return item;
if (itemBottom > treeBottom) break;
item = nextItem(tree, item);
}
return null;
}
}
return item;
}
TreeItem nextItem(Tree tree, TreeItem item) {
if (item == null) return null;
if (item.getExpanded() && item.getItemCount() > 0) return item.getItem(0);
TreeItem childItem = item;
TreeItem parentItem = childItem.getParentItem();
int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
int count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
while (true) {
if (index + 1 < count) return parentItem == null ? tree.getItem(index + 1) : parentItem.getItem(index + 1);
if (parentItem == null) return null;
childItem = parentItem;
parentItem = childItem.getParentItem();
index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
count = parentItem == null ? tree.getItemCount() : parentItem.getItemCount();
}
}
TreeItem previousItem(Tree tree, TreeItem item) {
if (item == null) return null;
TreeItem childItem = item;
TreeItem parentItem = childItem.getParentItem();
int index = parentItem == null ? tree.indexOf(childItem) : parentItem.indexOf(childItem);
if (index == 0) return parentItem;
TreeItem nextItem = parentItem == null ? tree.getItem(index-1) : parentItem.getItem(index-1);
int count = nextItem.getItemCount();
while (count > 0 && nextItem.getExpanded()) {
nextItem = nextItem.getItem(count - 1);
count = nextItem.getItemCount();
}
return nextItem;
}
}