/*******************************************************************************
* Copyright (c) 2004, 2015 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.ui.internal.dnd;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.eclipse.jface.util.Geometry;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tracker;
import org.eclipse.ui.PlatformUI;
import org.eclipse.ui.internal.DragCursors;
/**
* Provides the methods for attaching drag-and-drop listeners to SWT controls.
*/
public class DragUtil {
private static final String DROP_TARGET_ID = "org.eclipse.ui.internal.dnd.dropTarget"; //$NON-NLS-1$
/**
* The location where all drags will end. If this is non-null, then
* all user input is ignored in drag/drop. If null, we use user input
* to determine where objects should be dropped.
*/
private static TestDropLocation forcedDropTarget = null;
/**
* List of IDragOverListener
*/
private static List defaultTargets = new ArrayList();
/**
* Sets the drop target for the given control. It is possible to add one or more
* targets for a "null" control. This becomes a default target that is used if no
* other targets are found (for example, when dragging objects off the application
* window).
*
* @param control the control that should be treated as a drag target, or null
* to indicate the default target
* @param target the drag target to handle the given control
*/
public static void addDragTarget(Control control, IDragOverListener target) {
if (control == null) {
defaultTargets.add(target);
} else {
List targetList = getTargetList(control);
if (targetList == null) {
targetList = new ArrayList(1);
}
targetList.add(target);
control.setData(DROP_TARGET_ID, targetList);
}
}
/**
* Return the list of 'IDragOverListener' elements associated with
* the given control. If there's a 'global' listener then always
* return it.
*
* @param control
* @return
*/
private static List getTargetList(Control control) {
List result = (List) control.getData(DROP_TARGET_ID);
return result;
}
/**
* Removes a drop target from the given control.
*
* @param control
* @param target
*/
public static void removeDragTarget(Control control,
IDragOverListener target) {
if (control == null) {
defaultTargets.remove(target);
} else {
List targetList = getTargetList(control);
if (targetList != null) {
targetList.remove(target);
if (targetList.isEmpty()) {
control.setData(DROP_TARGET_ID, null);
}
}
}
}
/**
* Shorthand method. Returns the bounding rectangle for the given control, in
* display coordinates. Note that all 'Shell' controls are expected to be 'top level'
* so DO NOT do the origin offset for them.
*
* @param draggedItem
* @param boundsControl
* @return
*/
public static Rectangle getDisplayBounds(Control boundsControl) {
Control parent = boundsControl.getParent();
if (parent == null || boundsControl instanceof Shell) {
return boundsControl.getBounds();
}
return Geometry.toDisplay(parent, boundsControl.getBounds());
}
public static boolean performDrag(final Object draggedItem,
Rectangle sourceBounds, Point initialLocation, boolean allowSnapping) {
IDropTarget target = dragToTarget(draggedItem, sourceBounds,
initialLocation, allowSnapping);
if (target == null) {
return false;
}
target.drop();
// If the target can handle a 'finished' notification then send one
if (target!= null && target instanceof IDropTarget2) {
((IDropTarget2)target).dragFinished(true);
}
return true;
}
/**
* Drags the given item to the given location (in display coordinates). This
* method is intended for use by test suites.
*
* @param draggedItem object being dragged
* @param finalLocation location being dragged to
* @return true iff the drop was accepted
*/
public static boolean dragTo(Display display, Object draggedItem,
Point finalLocation, Rectangle dragRectangle) {
Control currentControl = SwtUtil.findControl(display, finalLocation);
IDropTarget target = getDropTarget(currentControl, draggedItem,
finalLocation, dragRectangle);
if (target == null) {
return false;
}
target.drop();
return true;
}
/**
* Forces all drags to end at the given position (display coordinates). Intended
* for use by test suites. If this method is called, then all subsequent calls
* to performDrag will terminate immediately and behave as though the object were
* dragged to the given location. Calling this method with null cancels this
* behavior and causes performDrag to behave normally.
*
* @param forcedLocation location where objects will be dropped (or null to
* cause drag/drop to behave normally).
*/
public static void forceDropLocation(TestDropLocation forcedLocation) {
forcedDropTarget = forcedLocation;
}
/**
* Drags the given item, given an initial bounding rectangle in display coordinates.
* Due to a quirk in the Tracker class, changing the tracking rectangle when using the
* keyboard will also cause the mouse cursor to move. Since "snapping" causes the tracking
* rectangle to change based on the position of the mouse cursor, it is impossible to do
* drag-and-drop with the keyboard when snapping is enabled.
*
* @param draggedItem object being dragged
* @param sourceBounds initial bounding rectangle for the dragged item
* @param initialLocation initial position of the mouse cursor
* @param allowSnapping true iff the rectangle should snap to the drop location. This must
* be false if the user might be doing drag-and-drop using the keyboard.
*
* @return
*/
static IDropTarget dragToTarget(final Object draggedItem,
final Rectangle sourceBounds, final Point initialLocation,
final boolean allowSnapping) {
final Display display = Display.getCurrent();
// Testing...immediately 'drop' onto the test target
if (forcedDropTarget != null) {
Point location = forcedDropTarget.getLocation();
Control currentControl = SwtUtil.findControl(forcedDropTarget.getShells(), location);
return getDropTarget(currentControl, draggedItem, location,
sourceBounds);
}
// Create a tracker. This is just an XOR rect on the screen.
// As it moves we notify the drag listeners.
final Tracker tracker = new Tracker(display, SWT.NULL);
tracker.setStippled(true);
tracker.addListener(SWT.Move, event -> display.syncExec(() -> {
// Get the curslor location as a point
Point location = new Point(event.x, event.y);
// Select a drop target; use the global one by default
IDropTarget target = null;
Control targetControl = display.getCursorControl();
// Get the drop target for this location
target = getDropTarget(targetControl,
draggedItem, location,
tracker.getRectangles()[0]);
// Set up the tracker feedback based on the target
Rectangle snapTarget = null;
if (target != null) {
snapTarget = target.getSnapRectangle();
tracker.setCursor(target.getCursor());
} else {
tracker.setCursor(DragCursors
.getCursor(DragCursors.INVALID));
}
// If snapping then reset the tracker's rectangle based on the current drop target
if (allowSnapping) {
if (snapTarget == null) {
snapTarget = new Rectangle(sourceBounds.x
+ location.x - initialLocation.x,
sourceBounds.y + location.y
- initialLocation.y,
sourceBounds.width, sourceBounds.height);
}
// Try to prevent flicker: don't change the rectangles if they're already in
// the right location
Rectangle[] currentRectangles = tracker.getRectangles();
if (!(currentRectangles.length == 1 && currentRectangles[0]
.equals(snapTarget))) {
tracker.setRectangles(new Rectangle[] { Geometry.copy(snapTarget) });
}
}
}));
// Setup...when the drag starts we might already be over a valid target, check this...
// If there is a 'global' target then skip the check
IDropTarget target = null;
Control startControl = display.getCursorControl();
if (startControl != null && allowSnapping) {
target = getDropTarget(startControl,
draggedItem, initialLocation,
sourceBounds);
}
// Set up an initial tracker rectangle
Rectangle startRect = sourceBounds;
if (target != null) {
Rectangle rect = target.getSnapRectangle();
if (rect != null) {
startRect = rect;
}
tracker.setCursor(target.getCursor());
}
if (startRect != null) {
tracker.setRectangles(new Rectangle[] { Geometry.copy(startRect)});
}
// Tracking Loop...tracking is preformed on the 'SWT.Move' listener registered
// against the tracker.
// HACK:
// Some control needs to capture the mouse during the drag or other
// controls will interfere with the cursor
Shell shell = PlatformUI.getWorkbench().getActiveWorkbenchWindow().getShell();
if (shell != null) {
shell.setCapture(true);
}
// Run tracker until mouse up occurs or escape key pressed.
boolean trackingOk = tracker.open();
// HACK:
// Release the mouse now
if (shell != null) {
shell.setCapture(false);
}
// Done tracking...
// Get the current drop target
IDropTarget dropTarget = null;
Point finalLocation = display.getCursorLocation();
Control targetControl = display.getCursorControl();
dropTarget = getDropTarget(targetControl, draggedItem,
finalLocation, tracker.getRectangles()[0]);
// Cleanup...
tracker.dispose();
// if we're going to perform a 'drop' then delay the issuing of the 'finished'
// callback until after it's done...
if (trackingOk) {
return dropTarget;
}
else if (dropTarget!= null && dropTarget instanceof IDropTarget2) {
// If the target can handle a 'finished' notification then send one
((IDropTarget2)dropTarget).dragFinished(false);
}
return null;
}
/**
* Given a list of IDragOverListeners and a description of what is being dragged, it returns
* a IDropTarget for the current drop.
*
* @param toSearch
* @param mostSpecificControl
* @param draggedObject
* @param position
* @param dragRectangle
* @return
*/
private static IDropTarget getDropTarget(List toSearch,
Control mostSpecificControl, Object draggedObject, Point position,
Rectangle dragRectangle) {
if (toSearch == null) {
return null;
}
Iterator iter = toSearch.iterator();
while (iter.hasNext()) {
IDragOverListener next = (IDragOverListener) iter.next();
IDropTarget dropTarget = next.drag(mostSpecificControl,
draggedObject, position, dragRectangle);
if (dropTarget != null) {
return dropTarget;
}
}
return null;
}
/**
* Returns the drag target for the given control or null if none.
*
* @param toSearch
* @param e
* @return
*/
public static IDropTarget getDropTarget(Control toSearch,
Object draggedObject, Point position, Rectangle dragRectangle) {
// Search for a listener by walking the control's parent hierarchy
for (Control current = toSearch; current != null; current = current
.getParent()) {
IDropTarget dropTarget = getDropTarget(getTargetList(current),
toSearch, draggedObject, position, dragRectangle);
if (dropTarget != null) {
return dropTarget;
}
// Don't look to parent shells for drop targets
if (current instanceof Shell) {
break;
}
}
// No controls could handle this event -- check for default targets
return getDropTarget(defaultTargets, toSearch, draggedObject, position,
dragRectangle);
}
/**
* Returns the location of the given event, in display coordinates
* @return
*/
public static Point getEventLoc(Event event) {
Control ctrl = (Control) event.widget;
return ctrl.toDisplay(new Point(event.x, event.y));
}
}