/*******************************************************************************
* Copyright (c) 2000, 2009 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.internal.wpf.*;
import org.eclipse.swt.*;
import org.eclipse.swt.widgets.*;
/**
*
* <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>
*
* @see <a href="http://www.eclipse.org/swt/snippets/#dnd">Drag and Drop snippets</a>
* @see <a href="http://www.eclipse.org/swt/examples.php">SWT Example: DNDExample</a>
* @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
* @noextend This class is not intended to be subclassed by clients.
*/
public class DragSource extends Widget {
private static final String DEFAULT_DRAG_SOURCE_EFFECT = "DEFAULT_DRAG_SOURCE_EFFECT"; //$NON-NLS-1$
static int checkStyle (int style) {
if (style == SWT.NONE) return DND.DROP_MOVE;
return style;
}
// info for registering as a drag source
private Control control;
private Listener controlListener;
private Transfer[] transferAgents = new Transfer[0];
private DragSourceEffect dragEffect;
private int jniRef;
/**
* 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 compatibility.</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(DND.DRAG_SOURCE_KEY) != null)
DND.error(DND.ERROR_CANNOT_INIT_DRAG);
control.setData(DND.DRAG_SOURCE_KEY, this);
jniRef = OS.NewGlobalRef (this);
if (jniRef == 0) SWT.error(SWT.ERROR_NO_HANDLES);
hookEventHandlers();
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();
}
});
Object effect = control.getData(DEFAULT_DRAG_SOURCE_EFFECT);
if (effect instanceof DragSourceEffect) {
dragEffect = (DragSourceEffect) effect;
} else if (control instanceof Tree) {
dragEffect = new TreeDragSourceEffect((Tree) control);
} else if (control instanceof Table) {
dragEffect = new TableDragSourceEffect((Table) control);
}
}
/**
* 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 #getDragListeners
* @see #removeDragListener
* @see DragSourceEvent
*/
public void addDragListener(DragSourceListener listener) {
if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
DNDListener typedListener = new DNDListener (listener);
typedListener.dndWidget = this;
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 = (int)System.currentTimeMillis();
event.doit = true;
notifyListeners(DND.DragStart,event);
if (!event.doit || transferAgents == null || transferAgents.length == 0 ) return;
int pDataObject = OS.gcnew_DataObject();
for (int i = 0; i < transferAgents.length; i++) {
Transfer transfer = transferAgents[i];
if (transfer != null) {
TransferData supportedTypes[] = transfer.getSupportedTypes();
for (int j = 0; j < supportedTypes.length; j++) {
TransferData transferData = supportedTypes[j];
event = new DNDEvent();
event.widget = this;
event.time = (int)System.currentTimeMillis();
event.dataType = transferData;
notifyListeners(DND.DragSetData, event);
if (!event.doit) return;
transfer.javaToNative(event.data, transferData);
if (transferData.pValue != 0) {
int pFormat = Transfer.getWPFFormat(transferData.type);
OS.DataObject_SetData(pDataObject, pFormat, transferData.pValue, true);
OS.GCHandle_Free(transferData.pValue);
OS.GCHandle_Free(pFormat);
}
}
}
}
int operations = opToOsOp(getStyle());
int result = OS.DragDrop_DoDragDrop(control.handle, pDataObject, operations);
OS.GCHandle_Free(pDataObject);
event = new DNDEvent();
event.widget = this;
event.time = (int)System.currentTimeMillis();
event.doit = (result != OS.DragDropEffects_None);
event.detail = osOpToOp(result);
notifyListeners(DND.DragEnd,event);
}
/**
* 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 an array 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.
*
* @return the listeners who will be notified when a drag and drop
* operation is in progress
*
* @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
* @see #removeDragListener
* @see DragSourceEvent
*
* @since 3.4
*/
public DragSourceListener[] getDragListeners() {
Listener[] listeners = getListeners(DND.DragStart);
int length = listeners.length;
DragSourceListener[] dragListeners = new DragSourceListener[length];
int count = 0;
for (int i = 0; i < length; i++) {
Listener listener = listeners[i];
if (listener instanceof DNDListener) {
dragListeners[count] = (DragSourceListener) ((DNDListener) listener).getEventListener();
count++;
}
}
if (count == length) return dragListeners;
DragSourceListener[] result = new DragSourceListener[count];
System.arraycopy(dragListeners, 0, result, 0, count);
return result;
}
/**
* Returns the drag effect that is registered for this DragSource. This drag
* effect will be used during a drag and drop operation.
*
* @return the drag effect that is registered for this DragSource
*
* @since 3.3
*/
public DragSourceEffect getDragSourceEffect() {
return dragEffect;
}
/**
* 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 hookEventHandlers () {
}
void onDispose() {
if (control == null)
return;
if (controlListener != null) {
control.removeListener(SWT.Dispose, controlListener);
control.removeListener(SWT.DragDetect, controlListener);
}
unhookEventHandlers();
if (jniRef != 0) OS.DeleteGlobalRef (jniRef);
jniRef = 0;
controlListener = null;
control.setData(DND.DRAG_SOURCE_KEY, null);
control = null;
transferAgents = null;
}
int opToOsOp(int operation){
int osOperation = 0;
if ((operation & DND.DROP_COPY) != 0){
osOperation |= OS.DragDropEffects_Copy;
}
if ((operation & DND.DROP_LINK) != 0) {
osOperation |= OS.DragDropEffects_Link;
}
if ((operation & DND.DROP_MOVE) != 0) {
osOperation |= OS.DragDropEffects_Move;
}
return osOperation;
}
int osOpToOp(int osOperation){
int operation = 0;
if ((osOperation & OS.DragDropEffects_Copy) != 0){
operation |= DND.DROP_COPY;
}
if ((osOperation & OS.DragDropEffects_Link) != 0) {
operation |= DND.DROP_LINK;
}
if ((osOperation & OS.DragDropEffects_Move) != 0) {
operation |= DND.DROP_MOVE;
}
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 no longer 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
* @see #getDragListeners
*/
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 drag effect for this DragSource. This drag effect will be
* used during a drag and drop operation.
*
* @param effect the drag effect that is registered for this DragSource
*
* @since 3.3
*/
public void setDragSourceEffect(DragSourceEffect effect) {
dragEffect = effect;
}
/**
* 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;
}
void unhookEventHandlers () {
}
}