Class CommonDropAdapterAssistant
- java.lang.Object
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- org.eclipse.ui.navigator.CommonDropAdapterAssistant
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- Direct Known Subclasses:
ResourceDropAdapterAssistant
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 musthandleDrop(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:
validateDrop(Object, int, TransferData)
: Indicate whether this assistant can handle a drop onto the current viewer.handleDrop(CommonDropAdapter, DropTargetEvent, Object)
: Handle the drop operation onto the current viewer.
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 :
validatePluginTransferDrop(IStructuredSelection, Object)
: Indicate whether this assistant can handle the drop onto another viewer.handlePluginTransferDrop(IStructuredSelection, Object)
: Handle the drop operation onto the other viewer.
Clients may subclass this.
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Constructor Summary
Constructors Constructor Description CommonDropAdapterAssistant()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected void
doInit()
Override to perform any one-time initialization.protected CommonDropAdapter
getCommonDropAdapter()
Returns theCommonDropAdapter
.protected INavigatorContentService
getContentService()
DropTargetEvent
getCurrentEvent()
Returns the currentDropTargetEvent
.protected Shell
getShell()
abstract IStatus
handleDrop(CommonDropAdapter aDropAdapter, DropTargetEvent aDropTargetEvent, Object aTarget)
Carry out the DND operation.IStatus
handlePluginTransferDrop(IStructuredSelection aDragSelection, Object aDropTarget)
Handle the drop operation for the target viewer.void
init(INavigatorContentService aContentService)
Perform any necessary initialization using theINavigatorContentService
.boolean
isSupportedType(TransferData aTransferType)
Clients may extend the supported transfer types beyond the defaultLocalSelectionTransfer.getTransfer()
andPluginTransfer.getInstance()
transfer types.void
setCommonDropAdapter(CommonDropAdapter dropAdapter)
Sets theCommonDropAdapter
.abstract IStatus
validateDrop(Object target, int operation, TransferData transferType)
Validates dropping on the given object.IStatus
validatePluginTransferDrop(IStructuredSelection aDragSelection, Object aDropTarget)
Return true if the client can handle the drop onto the target viewer of the drop operation.
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Method Detail
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init
public final void init(INavigatorContentService aContentService)
Perform any necessary initialization using theINavigatorContentService
.- Parameters:
aContentService
- The instance ofINavigatorContentService
that the current CommonDropAdapterAssistant will be associated with
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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)
.- Parameters:
target
- the object that the mouse is currently hovering over, ornull
if the mouse is hovering over empty spaceoperation
- the current drag operation (copy, move, etc.)transferType
- the current transfer type- Returns:
- A status indicating whether the drop is valid.
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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 theDragSourceListener.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.- Parameters:
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- Returns:
- A status indicating whether the drop completed OK.
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isSupportedType
public boolean isSupportedType(TransferData aTransferType)
Clients may extend the supported transfer types beyond the defaultLocalSelectionTransfer.getTransfer()
andPluginTransfer.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.- Parameters:
aTransferType
- The transfer data from the drop operation- Returns:
- True if the given TransferData can be understood by this assistant.
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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.
- Parameters:
aDragSelection
- The selection dragged from the viewer.aDropTarget
- The target of the drop operation.- Returns:
- OK if the plugin transfer can be handled by this assistant.
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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.
- Parameters:
aDragSelection
- The selection dragged from the viewer.aDropTarget
- The target of the drop operation.- Returns:
- OK if the drop operation succeeded.
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getContentService
protected INavigatorContentService getContentService()
- Returns:
- The associated content service.
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getShell
protected final Shell getShell()
- Returns:
- A shell for the viewer currently used by the
INavigatorContentService
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getCurrentEvent
public DropTargetEvent getCurrentEvent()
Returns the currentDropTargetEvent
.- Returns:
- event the current DropTargetEvent.
- Since:
- 3.4
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setCommonDropAdapter
public void setCommonDropAdapter(CommonDropAdapter dropAdapter)
Sets theCommonDropAdapter
.- Parameters:
dropAdapter
- the drop adapter- Restriction:
- This method is not intended to be referenced by clients.
- Restriction:
- This method is not intended to be re-implemented or extended by clients.
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getCommonDropAdapter
protected CommonDropAdapter getCommonDropAdapter()
Returns theCommonDropAdapter
.- Returns:
- the CommonDropAdapter.
- Since:
- 3.4
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