bundles/org.eclipse.swt/Eclipse SWT Drag and Drop/carbon/org/eclipse/swt/dnd/DragSource.java - platform/eclipse.platform.swt - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2006 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.custom.*;
 import org.eclipse.swt.graphics.*;
 import org.eclipse.swt.widgets.*;
 import org.eclipse.swt.internal.Callback;
 import org.eclipse.swt.internal.carbon.CGPoint;
 import org.eclipse.swt.internal.carbon.EventRecord;
 import org.eclipse.swt.internal.carbon.OS;
 import org.eclipse.swt.internal.carbon.Point;

 /**
  *
  * <code>DragSource</code> defines the source object for a drag and drop transfer.
  *
  * <p>IMPORTANT: This class is <em>not</em> intended to be subclassed.</p>
  *
  * <p>A drag source is the object which originates a drag and drop operation. For the specified widget,
  * it defines the type of data that is available for dragging and the set of operations that can
  * be performed on that data.  The operations can be any bit-wise combination of DND.MOVE, DND.COPY or
  * DND.LINK.  The type of data that can be transferred is specified by subclasses of Transfer such as
  * TextTransfer or FileTransfer.  The type of data transferred can be a predefined system type or it
  * can be a type defined by the application.  For instructions on how to define your own transfer type,
  * refer to <code>ByteArrayTransfer</code>.</p>
  *
  * <p>You may have several DragSources in an application but you can only have one DragSource
  * per Control.  Data dragged from this DragSource can be dropped on a site within this application
  * or it can be dropped on another application such as an external Text editor.</p>
  *
  * <p>The application supplies the content of the data being transferred by implementing the
  * <code>DragSourceListener</code> and associating it with the DragSource via DragSource#addDragListener.</p>
  *
  * <p>When a successful move operation occurs, the application is required to take the appropriate
  * action to remove the data from its display and remove any associated operating system resources or
  * internal references.  Typically in a move operation, the drop target makes a copy of the data
  * and the drag source deletes the original.  However, sometimes copying the data can take a long
  * time (such as copying a large file).  Therefore, on some platforms, the drop target may actually
  * move the data in the operating system rather than make a copy.  This is usually only done in
  * file transfers.  In this case, the drag source is informed in the DragEnd event that a
  * DROP_TARGET_MOVE was performed.  It is the responsibility of the drag source at this point to clean
  * up its displayed information.  No action needs to be taken on the operating system resources.</p>
  *
  * <p> The following example shows a Label widget that allows text to be dragged from it.</p>
  *
  * <code><pre>
  *	// Enable a label as a Drag Source
  *	Label label = new Label(shell, SWT.NONE);
  *	// This example will allow text to be dragged
  *	Transfer[] types = new Transfer[] {TextTransfer.getInstance()};
  *	// This example will allow the text to be copied or moved to the drop target
  *	int operations = DND.DROP_MOVE | DND.DROP_COPY;
  *
  *	DragSource source = new DragSource(label, operations);
  *	source.setTransfer(types);
  *	source.addDragListener(new DragSourceListener() {
  *		public void dragStart(DragSourceEvent e) {
  *			// Only start the drag if there is actually text in the
  *			// label - this text will be what is dropped on the target.
  *			if (label.getText().length() == 0) {
  *				event.doit = false;
  *			}
  *		};
  *		public void dragSetData(DragSourceEvent event) {
  *			// A drop has been performed, so provide the data of the
  *			// requested type.
  *			// (Checking the type of the requested data is only
  *			// necessary if the drag source supports more than
  *			// one data type but is shown here as an example).
  *			if (TextTransfer.getInstance().isSupportedType(event.dataType)){
  *				event.data = label.getText();
  *			}
  *		}
  *		public void dragFinished(DragSourceEvent event) {
  *			// A Move operation has been performed so remove the data
  *			// from the source
  *			if (event.detail == DND.DROP_MOVE)
  *				label.setText("");
  *		}
  *	});
  * </pre></code>
  *
  *
  * <dl>
  *	<dt><b>Styles</b></dt> <dd>DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK</dd>
  *	<dt><b>Events</b></dt> <dd>DND.DragStart, DND.DragSetData, DND.DragEnd</dd>
  * </dl>
  */
 public class DragSource extends Widget {

 	// info for registering as a drag source
 	Control control;
 	Listener controlListener;
 	Transfer[] transferAgents = new Transfer[0];
 	DragAndDropEffect effect;

 	static final String DRAGSOURCEID = "DragSource"; //$NON-NLS-1$
 	static Callback DragSendDataProc;

 	static {
 		DragSendDataProc = new Callback(DragSource.class, "DragSendDataProc", 4); //$NON-NLS-1$
 		int dragSendDataProcAddress = DragSendDataProc.getAddress();
 		if (dragSendDataProcAddress == 0) SWT.error(SWT.ERROR_NO_MORE_CALLBACKS);
 	}

 /**
  * Creates a new <code>DragSource</code> to handle dragging from the specified <code>Control</code>.
  * Creating an instance of a DragSource may cause system resources to be allocated depending on the platform.
  * It is therefore mandatory that the DragSource instance be disposed when no longer required.
  *
  * @param control the <code>Control</code> that the user clicks on to initiate the drag
  * @param style the bitwise OR'ing of allowed operations; this may be a combination of any of
  *					DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK
  *
  * @exception SWTException <ul>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
  *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
  * </ul>
  * @exception SWTError <ul>
  *    <li>ERROR_CANNOT_INIT_DRAG - unable to initiate drag source; this will occur if more than one
  *        drag source is created for a control or if the operating system will not allow the creation
  *        of the drag source</li>
  * </ul>
  *
  * <p>NOTE: ERROR_CANNOT_INIT_DRAG should be an SWTException, since it is a
  * recoverable error, but can not be changed due to backward compatability.</p>
  *
  * @see Widget#dispose
  * @see DragSource#checkSubclass
  * @see DND#DROP_NONE
  * @see DND#DROP_COPY
  * @see DND#DROP_MOVE
  * @see DND#DROP_LINK
  */
 public DragSource(Control control, int style) {
 	super (control, checkStyle(style));
 	this.control = control;
 	if (control.getData(DRAGSOURCEID) != null) {
 		DND.error(DND.ERROR_CANNOT_INIT_DRAG);
 	}
 	control.setData(DRAGSOURCEID, this);

 	controlListener = new Listener () {
 		public void handleEvent (Event event) {
 			if (event.type == SWT.Dispose) {
 				if (!DragSource.this.isDisposed()) {
 					DragSource.this.dispose();
 				}
 			}
 			if (event.type == SWT.DragDetect) {
 				if (!DragSource.this.isDisposed()) {
 					DragSource.this.drag(event);
 				}
 			}
 		}
 	};
 	control.addListener (SWT.Dispose, controlListener);
 	control.addListener (SWT.DragDetect, controlListener);

 	this.addListener(SWT.Dispose, new Listener() {
 		public void handleEvent(Event e) {
 			onDispose();
 		}
 	});

 	//	 Drag and drop effect
 	if (control instanceof Tree) {
 		effect = new TreeDragAndDropEffect((Tree)control);
 	} else if (control instanceof Table) {
 		effect = new TableDragAndDropEffect((Table)control);
 	} else if (control instanceof StyledText) {
 		effect = new StyledTextDragAndDropEffect((StyledText)control);
 	} else {
 		effect = new NoDragAndDropEffect(control);
 	}
 }

 static int checkStyle (int style) {
 	if (style == SWT.NONE) return DND.DROP_MOVE;
 	return style;
 }

 static int DragSendDataProc(int theType, int dragSendRefCon, int theItemRef, int theDrag) {
 	DragSource source = FindDragSource(dragSendRefCon, theDrag);
 	if (source == null) return OS.cantGetFlavorErr;
 	return source.dragSendDataProc(theType, dragSendRefCon, theItemRef, theDrag);
 }

 static DragSource FindDragSource(int dragSendRefCon, int theDrag) {
 	if (dragSendRefCon == 0) return null;
 	Display display = Display.findDisplay(Thread.currentThread());
 	if (display == null || display.isDisposed()) return null;
 	Widget widget = display.findWidget(dragSendRefCon);
 	if (widget == null) return null;
 	return (DragSource)widget.getData(DRAGSOURCEID);
 }

 /**
  * Adds the listener to the collection of listeners who will
  * be notified when a drag and drop operation is in progress, by sending
  * it one of the messages defined in the <code>DragSourceListener</code>
  * interface.
  *
  * <p><ul>
  * <li><code>dragStart</code> is called when the user has begun the actions required to drag the widget.
  * This event gives the application the chance to decide if a drag should be started.
  * <li><code>dragSetData</code> is called when the data is required from the drag source.
  * <li><code>dragFinished</code> is called when the drop has successfully completed (mouse up
  * over a valid target) or has been terminated (such as hitting the ESC key). Perform cleanup
  * such as removing data from the source side on a successful move operation.
  * </ul></p>
  *
  * @param listener the listener which should be notified
  *
  * @exception IllegalArgumentException <ul>
  *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
  * </ul>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  *
  * @see DragSourceListener
  * @see #removeDragListener
  * @see DragSourceEvent
  */
 public void addDragListener(DragSourceListener listener) {
 	if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
 	DNDListener typedListener = new DNDListener (listener);
 	addListener (DND.DragStart, typedListener);
 	addListener (DND.DragSetData, typedListener);
 	addListener (DND.DragEnd, typedListener);
 }

 protected void checkSubclass () {
 	String name = getClass().getName ();
 	String validName = DragSource.class.getName();
 	if (!validName.equals(name)) {
 		DND.error (SWT.ERROR_INVALID_SUBCLASS);
 	}
 }

 void drag(Event dragEvent) {
 	DNDEvent event = new DNDEvent();
 	event.widget = this;
 	event.x = dragEvent.x;
 	event.y = dragEvent.y;
 	event.time = dragEvent.time;
 	event.doit = true;
 	notifyListeners(DND.DragStart, event);
 	if (!event.doit || transferAgents == null || transferAgents.length == 0) return;

 	int[] theDrag = new int[1];
 	if (OS.NewDrag(theDrag) != OS.noErr) {
 		event = new DNDEvent();
 		event.widget = this;
 		event.time = (int)System.currentTimeMillis();
 		event.doit = false;
 		event.detail = DND.DROP_NONE;
 		notifyListeners(DND.DragEnd, event);
 		return;
 	}

 	Point pt = new Point();
 	OS.GetGlobalMouse (pt);

 	for (int i = 0; i < transferAgents.length; i++) {
 		int[] types = transferAgents[i].getTypeIds();
 		if (transferAgents[i] instanceof FileTransfer) {
 			TransferData transferData = new TransferData();
 			transferData.type = types[0];
 			event = new DNDEvent();
 			event.widget = this;
 			event.time = (int)System.currentTimeMillis();
 			event.dataType = transferData;
 			notifyListeners(DND.DragSetData, event);
 			if (event.data == null) return;
 			Transfer transferAgent = transferAgents[i];
 			for (int j = 0; j < types.length; j++) {
 				transferData.type = types[j];
 				transferAgent.javaToNative(event.data, transferData);
 				if (transferData.result != OS.noErr) return;
 				for (int k = 0; k < transferData.data.length; k++) {
 					byte[] datum = transferData.data[k];
 					OS.AddDragItemFlavor(theDrag[0], 1 + k, types[j], datum, datum.length, 0);
 				}
 			}
 		} else {
 			for (int j = 0; j < types.length; j++) {
 				OS.AddDragItemFlavor(theDrag[0], 1, types[j], null, 0, 0);
 			}
 		}
 	}

 	OS.SetDragSendProc(theDrag[0], DragSendDataProc.getAddress(), control.handle);

 	int theRegion = 0;
 	try {
 		theRegion = OS.NewRgn();
 		OS.SetRectRgn(theRegion, (short)(pt.h), (short)(pt.v), (short)(pt.h+20), (short)(pt.v+20));

 		int operations = opToOsOp(getStyle());
 		//set operations twice - local and not local
 		OS.SetDragAllowableActions(theDrag[0], operations, true);
 		OS.SetDragAllowableActions(theDrag[0], operations, false);

 		ImageData imageData = effect.getDragSourceImage(dragEvent.x, dragEvent.y);
 		Image image = null;
 		try {
 			if (imageData != null) {
 				image = new Image(getDisplay(), imageData);
 				CGPoint imageOffsetPt = new CGPoint();
 				imageOffsetPt.x = 0;
 				imageOffsetPt.y = 0;
 				OS.SetDragImageWithCGImage(theDrag[0], image.handle, imageOffsetPt, OS.kDragStandardTranslucency);
 			}
 			EventRecord theEvent = new EventRecord();
 			theEvent.message = OS.kEventMouseMoved;
 			theEvent.modifiers = (short)OS.GetCurrentEventKeyModifiers();
 			theEvent.what = (short)OS.osEvt;
 			theEvent.where_h = pt.h;
 			theEvent.where_v = pt.v;
 			int result = OS.TrackDrag(theDrag[0], theEvent, theRegion);
 			int operation = DND.DROP_NONE;
 			if (result == OS.noErr) {
 				int[] outAction = new int[1];
 				OS.GetDragDropAction(theDrag[0], outAction);
 				operation = osOpToOp(outAction[0]);
 			}
 			event = new DNDEvent();
 			event.widget = this;
 			event.time = (int)System.currentTimeMillis();
 			event.doit = result == OS.noErr;
 			event.detail = operation;
 			notifyListeners(DND.DragEnd, event);
 		} finally {
 			if (image != null) image.dispose();
 		}
 	} finally {
 		if (theRegion != 0) OS.DisposeRgn(theRegion);
 	}
 	OS.DisposeDrag(theDrag[0]);
 }

 int dragSendDataProc(int theType, int dragSendRefCon, int theItemRef, int theDrag) {
 	if (theType == 0) return OS.badDragFlavorErr;
 	TransferData transferData = new TransferData();
 	transferData.type = theType;
 	DNDEvent event = new DNDEvent();
 	event.widget = this;
 	event.time = (int)System.currentTimeMillis();
 	event.dataType = transferData;
 	notifyListeners(DND.DragSetData, event);
 	Transfer transfer = null;
 	for (int i = 0; i < transferAgents.length; i++) {
 		if (transferAgents[i].isSupportedType(transferData)) {
 			transfer = transferAgents[i];
 			break;
 		}
 	}
 	if (transfer == null) return OS.badDragFlavorErr;
 	transfer.javaToNative(event.data, transferData);
 	if (transferData.result != OS.noErr) return transferData.result;
 	// Except for FileTransfer (see #drag), only one item can be transferred
 	// in a Drag operation
 	byte[] datum = transferData.data[0];
 	if (datum == null) return OS.cantGetFlavorErr;
 	return OS.SetDragItemFlavorData(theDrag, theItemRef, theType, datum, datum.length, 0);
 }

 /**
  * Returns the Control which is registered for this DragSource.  This is the control that the
  * user clicks in to initiate dragging.
  *
  * @return the Control which is registered for this DragSource
  */
 public Control getControl () {
 	return control;
 }

 /**
  * Returns the list of data types that can be transferred by this DragSource.
  *
  * @return the list of data types that can be transferred by this DragSource
  */
 public Transfer[] getTransfer(){
 	return transferAgents;
 }

 void onDispose() {
 	if (control == null)
 		return;
 	if (controlListener != null) {
 		control.removeListener(SWT.Dispose, controlListener);
 		control.removeListener(SWT.DragDetect, controlListener);
 	}
 	controlListener = null;
 	control.setData(DRAGSOURCEID, null);
 	control = null;
 	transferAgents = null;
 }

 int opToOsOp(int operation) {
 	int osOperation = 0;
 	if ((operation & DND.DROP_COPY) != 0){
 		osOperation |= OS.kDragActionCopy;
 	}
 	if ((operation & DND.DROP_LINK) != 0) {
 		osOperation |= OS.kDragActionAlias;
 	}
 	if ((operation & DND.DROP_MOVE) != 0) {
 		osOperation |= OS.kDragActionMove;
 	}
 	if ((operation & DND.DROP_TARGET_MOVE) != 0) {
 		osOperation |= OS.kDragActionDelete;
 	}
 	return osOperation;
 }

 int osOpToOp(int osOperation){
 	int operation = 0;
 	if ((osOperation & OS.kDragActionCopy) != 0){
 		operation |= DND.DROP_COPY;
 	}
 	if ((osOperation & OS.kDragActionAlias) != 0) {
 		operation |= DND.DROP_LINK;
 	}
 	if ((osOperation & OS.kDragActionDelete) != 0) {
 		operation |= DND.DROP_TARGET_MOVE;
 	}
 	if ((osOperation & OS.kDragActionMove) != 0) {
 		operation |= DND.DROP_MOVE;
 	}
 	if (osOperation == OS.kDragActionAll) {
 		operation = DND.DROP_COPY | DND.DROP_MOVE | DND.DROP_LINK;
 	}
 	return operation;
 }

 /**
  * Removes the listener from the collection of listeners who will
  * be notified when a drag and drop operation is in progress.
  *
  * @param listener the listener which should be notified
  *
  * @exception IllegalArgumentException <ul>
  *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
  * </ul>
  * @exception SWTException <ul>
  *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
  *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
  * </ul>
  *
  * @see DragSourceListener
  * @see #addDragListener
  */
 public void removeDragListener(DragSourceListener listener) {
 	if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
 	removeListener (DND.DragStart, listener);
 	removeListener (DND.DragSetData, listener);
 	removeListener (DND.DragEnd, listener);
 }
 /**
  * Specifies the list of data types that can be transferred by this DragSource.
  * The application must be able to provide data to match each of these types when
  * a successful drop has occurred.
  *
  * @param transferAgents a list of Transfer objects which define the types of data that can be
  * dragged from this source
  */
 public void setTransfer(Transfer[] transferAgents){
 	this.transferAgents = transferAgents;
 }

 }
	/*******************************************************************************
	* Copyright (c) 2000, 2006 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.custom.*;
	import org.eclipse.swt.graphics.*;
	import org.eclipse.swt.widgets.*;
	import org.eclipse.swt.internal.Callback;
	import org.eclipse.swt.internal.carbon.CGPoint;
	import org.eclipse.swt.internal.carbon.EventRecord;
	import org.eclipse.swt.internal.carbon.OS;
	import org.eclipse.swt.internal.carbon.Point;

	/**
	*
	* <code>DragSource</code> defines the source object for a drag and drop transfer.
	*
	* <p>IMPORTANT: This class is <em>not</em> intended to be subclassed.</p>
	*
	* <p>A drag source is the object which originates a drag and drop operation. For the specified widget,
	* it defines the type of data that is available for dragging and the set of operations that can
	* be performed on that data. The operations can be any bit-wise combination of DND.MOVE, DND.COPY or
	* DND.LINK. The type of data that can be transferred is specified by subclasses of Transfer such as
	* TextTransfer or FileTransfer. The type of data transferred can be a predefined system type or it
	* can be a type defined by the application. For instructions on how to define your own transfer type,
	* refer to <code>ByteArrayTransfer</code>.</p>
	*
	* <p>You may have several DragSources in an application but you can only have one DragSource
	* per Control. Data dragged from this DragSource can be dropped on a site within this application
	* or it can be dropped on another application such as an external Text editor.</p>
	*
	* <p>The application supplies the content of the data being transferred by implementing the
	* <code>DragSourceListener</code> and associating it with the DragSource via DragSource#addDragListener.</p>
	*
	* <p>When a successful move operation occurs, the application is required to take the appropriate
	* action to remove the data from its display and remove any associated operating system resources or
	* internal references. Typically in a move operation, the drop target makes a copy of the data
	* and the drag source deletes the original. However, sometimes copying the data can take a long
	* time (such as copying a large file). Therefore, on some platforms, the drop target may actually
	* move the data in the operating system rather than make a copy. This is usually only done in
	* file transfers. In this case, the drag source is informed in the DragEnd event that a
	* DROP_TARGET_MOVE was performed. It is the responsibility of the drag source at this point to clean
	* up its displayed information. No action needs to be taken on the operating system resources.</p>
	*
	* <p> The following example shows a Label widget that allows text to be dragged from it.</p>
	*
	* <code><pre>
	* // Enable a label as a Drag Source
	* Label label = new Label(shell, SWT.NONE);
	* // This example will allow text to be dragged
	* Transfer[] types = new Transfer[] {TextTransfer.getInstance()};
	* // This example will allow the text to be copied or moved to the drop target
	* int operations = DND.DROP_MOVE \| DND.DROP_COPY;
	*
	* DragSource source = new DragSource(label, operations);
	* source.setTransfer(types);
	* source.addDragListener(new DragSourceListener() {
	* public void dragStart(DragSourceEvent e) {
	* // Only start the drag if there is actually text in the
	* // label - this text will be what is dropped on the target.
	* if (label.getText().length() == 0) {
	* event.doit = false;
	* }
	* };
	* public void dragSetData(DragSourceEvent event) {
	* // A drop has been performed, so provide the data of the
	* // requested type.
	* // (Checking the type of the requested data is only
	* // necessary if the drag source supports more than
	* // one data type but is shown here as an example).
	* if (TextTransfer.getInstance().isSupportedType(event.dataType)){
	* event.data = label.getText();
	* }
	* }
	* public void dragFinished(DragSourceEvent event) {
	* // A Move operation has been performed so remove the data
	* // from the source
	* if (event.detail == DND.DROP_MOVE)
	* label.setText("");
	* }
	* });
	* </pre></code>
	*
	*
	* <dl>
	* <dt><b>Styles</b></dt> <dd>DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK</dd>
	* <dt><b>Events</b></dt> <dd>DND.DragStart, DND.DragSetData, DND.DragEnd</dd>
	* </dl>
	*/
	public class DragSource extends Widget {

	// info for registering as a drag source
	Control control;
	Listener controlListener;
	Transfer[] transferAgents = new Transfer[0];
	DragAndDropEffect effect;

	static final String DRAGSOURCEID = "DragSource"; //$NON-NLS-1$
	static Callback DragSendDataProc;

	static {
	DragSendDataProc = new Callback(DragSource.class, "DragSendDataProc", 4); //$NON-NLS-1$
	int dragSendDataProcAddress = DragSendDataProc.getAddress();
	if (dragSendDataProcAddress == 0) SWT.error(SWT.ERROR_NO_MORE_CALLBACKS);
	}

	/**
	* Creates a new <code>DragSource</code> to handle dragging from the specified <code>Control</code>.
	* Creating an instance of a DragSource may cause system resources to be allocated depending on the platform.
	* It is therefore mandatory that the DragSource instance be disposed when no longer required.
	*
	* @param control the <code>Control</code> that the user clicks on to initiate the drag
	* @param style the bitwise OR'ing of allowed operations; this may be a combination of any of
	* DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK
	*
	* @exception SWTException <ul>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
	* <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
	* </ul>
	* @exception SWTError <ul>
	* <li>ERROR_CANNOT_INIT_DRAG - unable to initiate drag source; this will occur if more than one
	* drag source is created for a control or if the operating system will not allow the creation
	* of the drag source</li>
	* </ul>
	*
	* <p>NOTE: ERROR_CANNOT_INIT_DRAG should be an SWTException, since it is a
	* recoverable error, but can not be changed due to backward compatability.</p>
	*
	* @see Widget#dispose
	* @see DragSource#checkSubclass
	* @see DND#DROP_NONE
	* @see DND#DROP_COPY
	* @see DND#DROP_MOVE
	* @see DND#DROP_LINK
	*/
	public DragSource(Control control, int style) {
	super (control, checkStyle(style));
	this.control = control;
	if (control.getData(DRAGSOURCEID) != null) {
	DND.error(DND.ERROR_CANNOT_INIT_DRAG);
	}
	control.setData(DRAGSOURCEID, this);

	controlListener = new Listener () {
	public void handleEvent (Event event) {
	if (event.type == SWT.Dispose) {
	if (!DragSource.this.isDisposed()) {
	DragSource.this.dispose();
	}
	}
	if (event.type == SWT.DragDetect) {
	if (!DragSource.this.isDisposed()) {
	DragSource.this.drag(event);
	}
	}
	}
	};
	control.addListener (SWT.Dispose, controlListener);
	control.addListener (SWT.DragDetect, controlListener);

	this.addListener(SWT.Dispose, new Listener() {
	public void handleEvent(Event e) {
	onDispose();
	}
	});

	// Drag and drop effect
	if (control instanceof Tree) {
	effect = new TreeDragAndDropEffect((Tree)control);
	} else if (control instanceof Table) {
	effect = new TableDragAndDropEffect((Table)control);
	} else if (control instanceof StyledText) {
	effect = new StyledTextDragAndDropEffect((StyledText)control);
	} else {
	effect = new NoDragAndDropEffect(control);
	}
	}

	static int checkStyle (int style) {
	if (style == SWT.NONE) return DND.DROP_MOVE;
	return style;
	}

	static int DragSendDataProc(int theType, int dragSendRefCon, int theItemRef, int theDrag) {
	DragSource source = FindDragSource(dragSendRefCon, theDrag);
	if (source == null) return OS.cantGetFlavorErr;
	return source.dragSendDataProc(theType, dragSendRefCon, theItemRef, theDrag);
	}

	static DragSource FindDragSource(int dragSendRefCon, int theDrag) {
	if (dragSendRefCon == 0) return null;
	Display display = Display.findDisplay(Thread.currentThread());
	if (display == null \|\| display.isDisposed()) return null;
	Widget widget = display.findWidget(dragSendRefCon);
	if (widget == null) return null;
	return (DragSource)widget.getData(DRAGSOURCEID);
	}

	/**
	* Adds the listener to the collection of listeners who will
	* be notified when a drag and drop operation is in progress, by sending
	* it one of the messages defined in the <code>DragSourceListener</code>
	* interface.
	*
	* <p><ul>
	* <li><code>dragStart</code> is called when the user has begun the actions required to drag the widget.
	* This event gives the application the chance to decide if a drag should be started.
	* <li><code>dragSetData</code> is called when the data is required from the drag source.
	* <li><code>dragFinished</code> is called when the drop has successfully completed (mouse up
	* over a valid target) or has been terminated (such as hitting the ESC key). Perform cleanup
	* such as removing data from the source side on a successful move operation.
	* </ul></p>
	*
	* @param listener the listener which should be notified
	*
	* @exception IllegalArgumentException <ul>
	* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
	* </ul>
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*
	* @see DragSourceListener
	* @see #removeDragListener
	* @see DragSourceEvent
	*/
	public void addDragListener(DragSourceListener listener) {
	if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
	DNDListener typedListener = new DNDListener (listener);
	addListener (DND.DragStart, typedListener);
	addListener (DND.DragSetData, typedListener);
	addListener (DND.DragEnd, typedListener);
	}

	protected void checkSubclass () {
	String name = getClass().getName ();
	String validName = DragSource.class.getName();
	if (!validName.equals(name)) {
	DND.error (SWT.ERROR_INVALID_SUBCLASS);
	}
	}

	void drag(Event dragEvent) {
	DNDEvent event = new DNDEvent();
	event.widget = this;
	event.x = dragEvent.x;
	event.y = dragEvent.y;
	event.time = dragEvent.time;
	event.doit = true;
	notifyListeners(DND.DragStart, event);
	if (!event.doit \|\| transferAgents == null \|\| transferAgents.length == 0) return;

	int[] theDrag = new int[1];
	if (OS.NewDrag(theDrag) != OS.noErr) {
	event = new DNDEvent();
	event.widget = this;
	event.time = (int)System.currentTimeMillis();
	event.doit = false;
	event.detail = DND.DROP_NONE;
	notifyListeners(DND.DragEnd, event);
	return;
	}

	Point pt = new Point();
	OS.GetGlobalMouse (pt);

	for (int i = 0; i < transferAgents.length; i++) {
	int[] types = transferAgents[i].getTypeIds();
	if (transferAgents[i] instanceof FileTransfer) {
	TransferData transferData = new TransferData();
	transferData.type = types[0];
	event = new DNDEvent();
	event.widget = this;
	event.time = (int)System.currentTimeMillis();
	event.dataType = transferData;
	notifyListeners(DND.DragSetData, event);
	if (event.data == null) return;
	Transfer transferAgent = transferAgents[i];
	for (int j = 0; j < types.length; j++) {
	transferData.type = types[j];
	transferAgent.javaToNative(event.data, transferData);
	if (transferData.result != OS.noErr) return;
	for (int k = 0; k < transferData.data.length; k++) {
	byte[] datum = transferData.data[k];
	OS.AddDragItemFlavor(theDrag[0], 1 + k, types[j], datum, datum.length, 0);
	}
	}
	} else {
	for (int j = 0; j < types.length; j++) {
	OS.AddDragItemFlavor(theDrag[0], 1, types[j], null, 0, 0);
	}
	}
	}

	OS.SetDragSendProc(theDrag[0], DragSendDataProc.getAddress(), control.handle);

	int theRegion = 0;
	try {
	theRegion = OS.NewRgn();
	OS.SetRectRgn(theRegion, (short)(pt.h), (short)(pt.v), (short)(pt.h+20), (short)(pt.v+20));

	int operations = opToOsOp(getStyle());
	//set operations twice - local and not local
	OS.SetDragAllowableActions(theDrag[0], operations, true);
	OS.SetDragAllowableActions(theDrag[0], operations, false);

	ImageData imageData = effect.getDragSourceImage(dragEvent.x, dragEvent.y);
	Image image = null;
	try {
	if (imageData != null) {
	image = new Image(getDisplay(), imageData);
	CGPoint imageOffsetPt = new CGPoint();
	imageOffsetPt.x = 0;
	imageOffsetPt.y = 0;
	OS.SetDragImageWithCGImage(theDrag[0], image.handle, imageOffsetPt, OS.kDragStandardTranslucency);
	}
	EventRecord theEvent = new EventRecord();
	theEvent.message = OS.kEventMouseMoved;
	theEvent.modifiers = (short)OS.GetCurrentEventKeyModifiers();
	theEvent.what = (short)OS.osEvt;
	theEvent.where_h = pt.h;
	theEvent.where_v = pt.v;
	int result = OS.TrackDrag(theDrag[0], theEvent, theRegion);
	int operation = DND.DROP_NONE;
	if (result == OS.noErr) {
	int[] outAction = new int[1];
	OS.GetDragDropAction(theDrag[0], outAction);
	operation = osOpToOp(outAction[0]);
	}
	event = new DNDEvent();
	event.widget = this;
	event.time = (int)System.currentTimeMillis();
	event.doit = result == OS.noErr;
	event.detail = operation;
	notifyListeners(DND.DragEnd, event);
	} finally {
	if (image != null) image.dispose();
	}
	} finally {
	if (theRegion != 0) OS.DisposeRgn(theRegion);
	}
	OS.DisposeDrag(theDrag[0]);
	}

	int dragSendDataProc(int theType, int dragSendRefCon, int theItemRef, int theDrag) {
	if (theType == 0) return OS.badDragFlavorErr;
	TransferData transferData = new TransferData();
	transferData.type = theType;
	DNDEvent event = new DNDEvent();
	event.widget = this;
	event.time = (int)System.currentTimeMillis();
	event.dataType = transferData;
	notifyListeners(DND.DragSetData, event);
	Transfer transfer = null;
	for (int i = 0; i < transferAgents.length; i++) {
	if (transferAgents[i].isSupportedType(transferData)) {
	transfer = transferAgents[i];
	break;
	}
	}
	if (transfer == null) return OS.badDragFlavorErr;
	transfer.javaToNative(event.data, transferData);
	if (transferData.result != OS.noErr) return transferData.result;
	// Except for FileTransfer (see #drag), only one item can be transferred
	// in a Drag operation
	byte[] datum = transferData.data[0];
	if (datum == null) return OS.cantGetFlavorErr;
	return OS.SetDragItemFlavorData(theDrag, theItemRef, theType, datum, datum.length, 0);
	}

	/**
	* Returns the Control which is registered for this DragSource. This is the control that the
	* user clicks in to initiate dragging.
	*
	* @return the Control which is registered for this DragSource
	*/
	public Control getControl () {
	return control;
	}

	/**
	* Returns the list of data types that can be transferred by this DragSource.
	*
	* @return the list of data types that can be transferred by this DragSource
	*/
	public Transfer[] getTransfer(){
	return transferAgents;
	}

	void onDispose() {
	if (control == null)
	return;
	if (controlListener != null) {
	control.removeListener(SWT.Dispose, controlListener);
	control.removeListener(SWT.DragDetect, controlListener);
	}
	controlListener = null;
	control.setData(DRAGSOURCEID, null);
	control = null;
	transferAgents = null;
	}

	int opToOsOp(int operation) {
	int osOperation = 0;
	if ((operation & DND.DROP_COPY) != 0){
	osOperation \|= OS.kDragActionCopy;
	}
	if ((operation & DND.DROP_LINK) != 0) {
	osOperation \|= OS.kDragActionAlias;
	}
	if ((operation & DND.DROP_MOVE) != 0) {
	osOperation \|= OS.kDragActionMove;
	}
	if ((operation & DND.DROP_TARGET_MOVE) != 0) {
	osOperation \|= OS.kDragActionDelete;
	}
	return osOperation;
	}

	int osOpToOp(int osOperation){
	int operation = 0;
	if ((osOperation & OS.kDragActionCopy) != 0){
	operation \|= DND.DROP_COPY;
	}
	if ((osOperation & OS.kDragActionAlias) != 0) {
	operation \|= DND.DROP_LINK;
	}
	if ((osOperation & OS.kDragActionDelete) != 0) {
	operation \|= DND.DROP_TARGET_MOVE;
	}
	if ((osOperation & OS.kDragActionMove) != 0) {
	operation \|= DND.DROP_MOVE;
	}
	if (osOperation == OS.kDragActionAll) {
	operation = DND.DROP_COPY \| DND.DROP_MOVE \| DND.DROP_LINK;
	}
	return operation;
	}

	/**
	* Removes the listener from the collection of listeners who will
	* be notified when a drag and drop operation is in progress.
	*
	* @param listener the listener which should be notified
	*
	* @exception IllegalArgumentException <ul>
	* <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
	* </ul>
	* @exception SWTException <ul>
	* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
	* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
	* </ul>
	*
	* @see DragSourceListener
	* @see #addDragListener
	*/
	public void removeDragListener(DragSourceListener listener) {
	if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
	removeListener (DND.DragStart, listener);
	removeListener (DND.DragSetData, listener);
	removeListener (DND.DragEnd, listener);
	}
	/**
	* Specifies the list of data types that can be transferred by this DragSource.
	* The application must be able to provide data to match each of these types when
	* a successful drop has occurred.
	*
	* @param transferAgents a list of Transfer objects which define the types of data that can be
	* dragged from this source
	*/
	public void setTransfer(Transfer[] transferAgents){
	this.transferAgents = transferAgents;
	}

	}