org.eclipse.ui.navigator
Class CommonDropAdapterAssistant
java.lang.Object
org.eclipse.ui.navigator.CommonDropAdapterAssistant
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Direct Known Subclasses:
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ResourceDropAdapterAssistant
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public abstract class CommonDropAdapterAssistant
- extends
Object
Used by the
org.eclipse.ui.navigator.navigatorContent/navigatorContent/commonDropAdapter
extension point to carry out pluggable drop operations.
Each
CommonDropAdapterAssistant is contained by single content
extension. The opportunity for each assistant to handle the drop operation is
determined by the possibleChildren expression of the
org.eclipse.ui.navigator.navigatorContent/navigatorContent extension;
whenever every element in the drag set matches the possibleChildren
expression of an extension, it is eligible to handle the drop operation. This
initial set is further culled using the possibleDropTargets
expression of the commonDropAdapter using the current drop target.
If drag operations originate outside of Eclipse, then the set of eligible
drop adapters is determined based on the drop target (using the
possibleDropTargets expression). Each assistant can then indicate
whether
the incoming type is supported.
Whenever a match is found, the assistant will be given an opportunity to
first
validateDrop(Object, int, TransferData), and then if the
assistant returns true, the assist must
handleDrop(CommonDropAdapter, DropTargetEvent, Object). If
multiple assistants match the drop target, then the potential assistants are
ordered based on priority and their override relationships and given an
opportunity to validate the drop operation in turn. The first one to validate
will have the opportunty to carry out the drop.
Clients may handle DND operations that begin and end in the current viewer by
overriding the following methods:
If a user originates a drag operation to another viewer that cannot handle
one of the available drag transfer types, drop assistants may handle the drop
operation for the target viewer. Clients must override :
Clients may subclass this.
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Since:
- 3.2
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See Also:
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INavigatorDnDService,
INavigatorDnDService.findCommonDropAdapterAssistants(Object, TransferData)
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Methods inherited from class java.lang.
Object
|
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
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CommonDropAdapterAssistant
public CommonDropAdapterAssistant()
init
public final void init(
INavigatorContentService aContentService)
- Perform any necessary initialization using the
INavigatorContentService.
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Parameters:
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aContentService - The instance of
INavigatorContentService that the
current CommonDropAdapterAssistant will be associated with
doInit
protected void doInit()
- Override to perform any one-time initialization.
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validateDrop
public abstract
IStatus validateDrop(
Object target,
int operation,
TransferData transferType)
- Validates dropping on the given object. This method is called whenever
some aspect of the drop operation changes.
Subclasses must implement this method to define which drops make sense.
If clients return true, then they will be allowed to handle the drop in
handleDrop(CommonDropAdapter, DropTargetEvent, Object).
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Parameters:
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target - the object that the mouse is currently hovering over, or
null if the mouse is hovering over empty space -
operation - the current drag operation (copy, move, etc.) -
transferType - the current transfer type
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Returns:
- A status indicating whether the drop is valid.
handleDrop
public abstract
IStatus handleDrop(
CommonDropAdapter aDropAdapter,
DropTargetEvent aDropTargetEvent,
Object aTarget)
- Carry out the DND operation.
Note: Contrary to the SWT
DropTargetListener specification, you
must make sure that the aDropTargetEvent.detail is not set to
DND.DROP_MOVE unless actual work is required in the
DragSourceListener.dragFinished(org.eclipse.swt.dnd.DragSourceEvent)
to complete the operation (for example removing the moved file). In
particular for the LocalSelectionTransfer case, DND.DROP_MOVE cannot be
used as it will cause incorrect behavior in some existing drag handlers.
In case of move operations where no action is required on the source side
(e.g. LocalSelectionTransfer) you must set aDropTargetEvent.detail to
DND.DROP_NONE to signal this to the drag source. Even though the SWT
specification says this is canceling the drop, it is not really doing so,
it is only preventing the DND.DROP_MOVE from being passed through to the
dragFinished() method.
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Parameters:
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aDropAdapter - The Drop Adapter contains information that has already been
parsed from the drop event. -
aDropTargetEvent - The drop target event. -
aTarget - The object being dragged onto
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Returns:
- A status indicating whether the drop completed OK.
isSupportedType
public boolean isSupportedType(
TransferData aTransferType)
- Clients may extend the supported transfer types beyond the default
LocalSelectionTransfer.getTransfer() and
PluginTransfer.getInstance() transfer types. When a transfer type
other than one of these is encountered, the DND Service will query the
visible and active descriptors that are enabled
for the drop target of the current operation.
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Parameters:
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aTransferType - The transfer data from the drop operation
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Returns:
- True if the given TransferData can be understood by this
assistant.
validatePluginTransferDrop
public
IStatus validatePluginTransferDrop(
IStructuredSelection aDragSelection,
Object aDropTarget)
- Return true if the client can handle the drop onto the target viewer of
the drop operation.
The default behavior of this method is to return Status.CANCEL_STATUS.
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Parameters:
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aDragSelection - The selection dragged from the viewer. -
aDropTarget - The target of the drop operation.
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Returns:
- OK if the plugin transfer can be handled by this assistant.
handlePluginTransferDrop
public
IStatus handlePluginTransferDrop(
IStructuredSelection aDragSelection,
Object aDropTarget)
- Handle the drop operation for the target viewer.
The default behavior of this method is to return Status.CANCEL_STATUS.
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Parameters:
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aDragSelection - The selection dragged from the viewer. -
aDropTarget - The target of the drop operation.
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Returns:
- OK if the drop operation succeeded.
getContentService
protected
INavigatorContentService getContentService()
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Returns:
- The associated content service.
getShell
protected final
Shell getShell()
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Returns:
- A shell for the viewer currently used by the
INavigatorContentService.
getCurrentEvent
public
DropTargetEvent getCurrentEvent()
- Returns the current
DropTargetEvent.
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Returns:
- event the current DropTargetEvent.
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Since:
- 3.4
setCommonDropAdapter
public void setCommonDropAdapter(
CommonDropAdapter dropAdapter)
- Sets the
CommonDropAdapter.
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Parameters:
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dropAdapter - -
Restriction:
-
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Restriction:
- This method is not intended to be re-implemented or extended by clients.
getCommonDropAdapter
protected
CommonDropAdapter getCommonDropAdapter()
- Returns the
CommonDropAdapter.
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Returns:
- the CommonDropAdapter.
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Since:
- 3.4
Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.
