org.eclipse.jface.util
Class DelegatingDragAdapter
java.lang.Object
org.eclipse.jface.util.DelegatingDragAdapter
-
All Implemented Interfaces:
-
EventListener,
DragSourceListener, org.eclipse.swt.internal.SWTEventListener
-
public class DelegatingDragAdapter
- extends
Object
- implements
DragSourceListener
A DelegatingDragAdapter
is a DragSourceListener
that
maintains and delegates to a set of
TransferDragSourceListener
s. Each
TransferDragSourceListener can then be implemented as if it were the
DragSource's
only DragSourceListener.
When a drag is started, a subset of all TransferDragSourceListeners
is generated and stored in a list of active listeners. This subset is
calculated by forwarding
DragSourceListener.dragStart(DragSourceEvent)
to
every listener, and checking if the
doit
field is left
set to true
.
The
DragSource
's set of supported Transfer types (
DragSource.setTransfer(Transfer[])
) is updated to reflect the Transfer types
corresponding to the active listener subset.
If and when
dragSetData(DragSourceEvent)
is called, a single
TransferDragSourceListener
is chosen, and only it is allowed to set the
drag data. The chosen listener is the first listener in the subset of active listeners
whose Transfer supports (
Transfer.isSupportedType(TransferData)
) the
dataType
in the DragSourceEvent
.
The following example snippet shows a DelegatingDragAdapter
with two
TransferDragSourceListeners
. One implements drag of text strings,
the other supports file transfer and demonstrates how a listener can be disabled using
the dragStart method.
final TreeViewer viewer = new TreeViewer(shell, SWT.NONE);
DelegatingDragAdapter dragAdapter = new DelegatingDragAdapter();
dragAdapter.addDragSourceListener(new TransferDragSourceListener() {
public Transfer getTransfer() {
return TextTransfer.getInstance();
}
public void dragStart(DragSourceEvent event) {
// always enabled, can control enablement based on selection etc.
}
public void dragSetData(DragSourceEvent event) {
event.data = "Transfer data";
}
public void dragFinished(DragSourceEvent event) {
// no clean-up required
}
});
dragAdapter.addDragSourceListener(new TransferDragSourceListener() {
public Transfer getTransfer() {
return FileTransfer.getInstance();
}
public void dragStart(DragSourceEvent event) {
// enable drag listener if there is a viewer selection
event.doit = !viewer.getSelection().isEmpty();
}
public void dragSetData(DragSourceEvent event) {
File file1 = new File("C:/temp/file1");
File file2 = new File("C:/temp/file2");
event.data = new String[] {file1.getAbsolutePath(), file2.getAbsolutePath()};
}
public void dragFinished(DragSourceEvent event) {
// no clean-up required
}
});
viewer.addDragSupport(DND.DROP_COPY | DND.DROP_MOVE, dragAdapter.getTransfers(), dragAdapter);
-
Since:
- 3.0
Methods inherited from class java.lang.
Object
|
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
|
DelegatingDragAdapter
public DelegatingDragAdapter()
addDragSourceListener
public void addDragSourceListener(
TransferDragSourceListener listener)
- Adds the given
TransferDragSourceListener
.
-
-
-
Parameters:
-
listener
- the new listener
dragFinished
public void dragFinished(
DragSourceEvent event)
- The drop has successfully completed. This event is forwarded to the current
drag listener.
Doesn't update the current listener, since the current listener is already the one
that completed the drag operation.
-
-
Specified by:
-
dragFinished
in interface
DragSourceListener
-
-
Parameters:
-
event
- the drag source event -
See Also:
-
DragSourceListener.dragFinished(DragSourceEvent)
dragSetData
public void dragSetData(
DragSourceEvent event)
- The drop data is requested.
Updates the current listener and then forwards the event to it.
-
-
Specified by:
-
dragSetData
in interface
DragSourceListener
-
-
Parameters:
-
event
- the drag source event -
See Also:
-
DragSourceListener.dragSetData(DragSourceEvent)
dragStart
public void dragStart(
DragSourceEvent event)
- A drag operation has started.
Forwards this event to each listener. A listener must set
event.doit
to false
if it cannot handle the drag operation. If a listener can
handle the drag, it is added to the list of active listeners.
The drag is aborted if there are no listeners that can handle it.
-
-
Specified by:
-
dragStart
in interface
DragSourceListener
-
-
Parameters:
-
event
- the drag source event -
See Also:
-
DragSourceListener.dragStart(DragSourceEvent)
getTransfers
public
Transfer[] getTransfers()
- Returns the
Transfers from every TransferDragSourceListener
.
-
-
Returns:
- the combined
Transfer
s
isEmpty
public boolean isEmpty()
- Returns
true
if there are no listeners to delegate drag events to.
-
-
-
Returns:
-
true
if there are no TransferDragSourceListeners
false
otherwise.
removeDragSourceListener
public void removeDragSourceListener(
TransferDragSourceListener listener)
- Removes the given
TransferDragSourceListener
.
Listeners should not be removed while a drag and drop operation is in progress.
-
-
-
Parameters:
-
listener
- the TransferDragSourceListener
to remove
Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.