protected void checkSubclass() {
String name = getClass().getName();
String validName = DragSource.class.getName();
if (!validName.equals(name)) {
DND.error(SWT.ERROR_INVALID_SUBCLASS);
}
}
/**
* 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>
*
* @param listener the listener which should be notified
* @exception IllegalArgumentException
* <ul>
* <li>ERROR_NULL_ARGUMENT - if the listener is null
* </ul>
*
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
* </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);
}
/**
* 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>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
* </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
* </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.
* @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);
createCOMInterfaces();
this.AddRef();
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) {
DragSource.this.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);
}
}
/**
* 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
* </ul>
*
* @exception SWTException
* <ul>
* <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed
* <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
* </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);
}