--- /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.DND;
+import org.eclipse.swt.dnd.DropTargetEvent;
+import org.eclipse.swt.dnd.DropTargetListener;
+import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.widgets.Item;
+import org.eclipse.swt.widgets.TableItem;
+import org.eclipse.swt.widgets.TreeItem;
+
+import org.eclipse.jface.util.Assert;
+import org.eclipse.jface.viewers.StructuredViewer;
+
+/**
+ * A drag and drop adapter to be used together with structured viewers.
+ * The adapater delegates the <code>dragEnter</code>, <code>dragOperationChanged
+ * </code>, <code>dragOver</code> and <code>dropAccept</code> method to the
+ * <code>validateDrop</code> method. Furthermore it adds location feedback.
+ */
+public class JdtViewerDropAdapter implements DropTargetListener {
+
+ /**
+ * Constant describing the position of the mouse cursor relative
+ * to the target object. This means the mouse is positioned
+ * slightly before the target.
+ */
+ protected static final int LOCATION_BEFORE= 1;
+
+ /**
+ * Constant describing the position of the mouse cursor relative
+ * to the target object. This means the mouse is positioned
+ * slightly after the target.
+ */
+ protected static final int LOCATION_AFTER= 2;
+
+ /**
+ * Constant describing the position of the mouse cursor relative
+ * to the target object. This means the mouse is positioned
+ * directly on the target.
+ */
+ protected static final int LOCATION_ON= 3;
+
+ /**
+ * Constant describing the position of the mouse cursor relative
+ * to the target object. This means the mouse is not positioned
+ * over or near any valid target.
+ */
+ protected static final int LOCATION_NONE= 4;
+
+ /**
+ * The threshold used to determine if the mouse is before or after
+ * an item.
+ */
+ private static final int LOCATION_EPSILON= 5;
+
+ /**
+ * Style to enable location feedback.
+ */
+ public static final int INSERTION_FEEDBACK= 1 << 1;
+
+ private StructuredViewer fViewer;
+ private int fFeedback;
+ private boolean fShowInsertionFeedback;
+ private int fRequestedOperation;
+ private int fLastOperation;
+ protected int fLocation;
+ protected Object fTarget;
+
+ public JdtViewerDropAdapter(StructuredViewer viewer, int feedback) {
+ fViewer= viewer;
+ Assert.isNotNull(fViewer);
+ fFeedback= feedback;
+ fLastOperation= -1;
+ }
+
+ /**
+ * Controls whether the drop adapter shows insertion feedback or not.
+ *
+ * @param showInsertionFeedback <code>true</code> if the drop adapter is supposed
+ * to show insertion feedback. Otherwise <code>false</code>
+ */
+ public void showInsertionFeedback(boolean showInsertionFeedback) {
+ fShowInsertionFeedback= showInsertionFeedback;
+ }
+
+ /**
+ * Returns the viewer this adapter is working on.
+ */
+ protected StructuredViewer getViewer() {
+ return fViewer;
+ }
+
+ //---- Hooks to override -----------------------------------------------------
+
+ /**
+ * The actual drop has occurred. Calls <code>drop(Object target, DropTargetEvent event)
+ * </code>.
+ * @see DropTargetListener#drop(org.eclipse.swt.dnd.DropTargetEvent)
+ */
+ public void drop(DropTargetEvent event) {
+ drop(fTarget, event);
+ }
+
+ /**
+ * The actual drop has occurred.
+ * @param target the drop target in form of a domain element.
+ * @param event the drop traget event
+ */
+ public void drop(Object target, DropTargetEvent event) {
+ }
+
+ /**
+ * Checks if the drop is valid. The method calls <code>validateDrop
+ * (Object target, DropTargetEvent event). Implementors can alter the
+ * <code>currentDataType</code> field and the <code>detail</code> field
+ * to give feedback about drop acceptence.
+ */
+ public void validateDrop(DropTargetEvent event) {
+ validateDrop(fTarget, event, fRequestedOperation);
+ }
+
+ /**
+ * Checks if the drop on the current target is valid. The method
+ * can alter the <code>currentDataType</code> field and the <code>
+ * detail</code> field to give feedback about drop acceptence.
+ * @param target the drop target in form of a domain element.
+ * @param event the drop traget event
+ * @param operation the operation requested by the user.
+ */
+ public void validateDrop(Object target, DropTargetEvent event, int operation) {
+ }
+
+ public void dragEnter(DropTargetEvent event) {
+ dragOperationChanged(event);
+ }
+
+ public void dragLeave(DropTargetEvent event) {
+ fTarget= null;
+ fLocation= LOCATION_NONE;
+ }
+
+ public void dragOperationChanged(DropTargetEvent event) {
+ fRequestedOperation= event.detail;
+ fTarget= computeTarget(event);
+ fLocation= computeLocation(event);
+ validateDrop(event);
+ fLastOperation= event.detail;
+ computeFeedback(event);
+ }
+
+ public void dragOver(DropTargetEvent event) {
+ Object oldTarget= fTarget;
+ fTarget= computeTarget(event);
+
+ //set the location feedback
+ int oldLocation= fLocation;
+ fLocation= computeLocation(event);
+ if (oldLocation != fLocation || oldTarget != fTarget || fLastOperation != event.detail) {
+ validateDrop(event);
+ fLastOperation= event.detail;
+ } else {
+ event.detail= fLastOperation;
+ }
+ computeFeedback(event);
+ }
+
+ public void dropAccept(DropTargetEvent event) {
+ fTarget= computeTarget(event);
+ validateDrop(event);
+ fLastOperation= event.detail;
+ }
+
+ /**
+ * Returns the data held by <code>event.item</code>. Inside a viewer
+ * this corresponds to the items data model element.
+ */
+ protected Object computeTarget(DropTargetEvent event) {
+ return event.item == null ? null : event.item.getData();
+ }
+
+ /**
+ * Returns the position of the given coordinates relative to the given target.
+ * The position is determined to be before, after, or on the item, based on
+ * some threshold value. The return value is one of the LOCATION_* constants
+ * defined in this class.
+ */
+ final protected int computeLocation(DropTargetEvent event) {
+ if (!(event.item instanceof Item))
+ return LOCATION_NONE;
+
+ Item item= (Item) event.item;
+ Point coordinates= fViewer.getControl().toControl(new Point(event.x, event.y));
+ Rectangle bounds= getBounds(item);
+ if (bounds == null) {
+ return LOCATION_NONE;
+ }
+ if ((coordinates.y - bounds.y) < LOCATION_EPSILON) {
+ return LOCATION_BEFORE;
+ }
+ if ((bounds.y + bounds.height - coordinates.y) < LOCATION_EPSILON) {
+ return LOCATION_AFTER;
+ }
+ return LOCATION_ON;
+ }
+
+ /**
+ * Returns the bounds of the given item, or <code>null</code> if it is not a
+ * valid type of item.
+ */
+ private Rectangle getBounds(Item item) {
+ if (item instanceof TreeItem)
+ return ((TreeItem) item).getBounds();
+
+ if (item instanceof TableItem)
+ return ((TableItem) item).getBounds(0);
+
+ return null;
+ }
+
+ /**
+ * Sets the drag under feedback corresponding to the value of <code>fLocation</code>
+ * and the <code>INSERTION_FEEDBACK</code> style bit.
+ */
+ protected void computeFeedback(DropTargetEvent event) {
+ if (!fShowInsertionFeedback && fLocation != LOCATION_NONE) {
+ event.feedback= DND.FEEDBACK_SELECT;
+ } else {
+ if (fLocation == LOCATION_BEFORE) {
+ event.feedback= DND.FEEDBACK_INSERT_BEFORE;
+ } else if (fLocation == LOCATION_AFTER) {
+ event.feedback= DND.FEEDBACK_INSERT_AFTER;
+ }
+ }
+ event.feedback|= fFeedback;
+ }
+
+ /**
+ * Sets the drop operation to </code>DROP_NODE<code>.
+ */
+ protected void clearDropOperation(DropTargetEvent event) {
+ event.detail= DND.DROP_NONE;
+ }
+
+ /**
+ * Returns the requested drop operation.
+ */
+ protected int getRequestedOperation() {
+ return fRequestedOperation;
+ }
+}
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