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/*******************************************************************************
 * Copyright (c) 2000, 2012 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.*;
import org.eclipse.swt.widgets.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.ole.win32.*;
import org.eclipse.swt.internal.win32.*;

/**
 *
 * Class DropTarget defines the target object for a drag and drop transfer.
 *
 * 
IMPORTANT: This class is not intended to be subclassed.

 *
 * 
This class identifies the Control over which the user must position the cursor
 * in order to drop the data being transferred.  It also specifies what data types can be dropped on 
 * this control and what operations can be performed.  You may have several DropTragets in an 
 * application but there can only be a one to one mapping between a Control and a DropTarget.
 * The DropTarget can receive data from within the same application or from other applications 
 * (such as text dragged from a text editor like Word).

 *
 * 
 *	int operations = DND.DROP_MOVE | DND.DROP_COPY | DND.DROP_LINK;
 *	Transfer[] types = new Transfer[] {TextTransfer.getInstance()};
 *	DropTarget target = new DropTarget(label, operations);
 *	target.setTransfer(types);
 * 

*
* 
The application is notified of data being dragged over this control and of when a drop occurs by
* implementing the interface DropTargetListener which uses the class
* DropTargetEvent. The application can modify the type of drag being performed
* on this Control at any stage of the drag by modifying the event.detail field or the
* event.currentDataType field. When the data is dropped, it is the responsibility of
* the application to copy this data for its own purposes.
*
* 
 *	target.addDropListener (new DropTargetListener() {
 *		public void dragEnter(DropTargetEvent event) {};
 *		public void dragOver(DropTargetEvent event) {};
 *		public void dragLeave(DropTargetEvent event) {};
 *		public void dragOperationChanged(DropTargetEvent event) {};
 *		public void dropAccept(DropTargetEvent event) {}
 *		public void drop(DropTargetEvent event) {
 *			// A drop has occurred, copy over the data
 *			if (event.data == null) { // no data to copy, indicate failure in event.detail
 *				event.detail = DND.DROP_NONE;
 *				return;
 *			}
 *			label.setText ((String) event.data); // data copied to label text
 *		}
 * 	});
 * 

*
* 

* 
Styles
 
DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK

* 
Events
 
DND.DragEnter, DND.DragLeave, DND.DragOver, DND.DragOperationChanged,
* DND.DropAccept, DND.Drop 

* 

*
* @see Drag and Drop snippets
* @see SWT Example: DNDExample
* @see Sample code and further information
* @noextend This class is not intended to be subclassed by clients.
*/
public class DropTarget extends Widget {
Control control;
Listener controlListener;
Transfer[] transferAgents = new Transfer[0];
DropTargetEffect dropEffect;
// Track application selections
TransferData selectedDataType;
int selectedOperation;
// workaround - There is no event for "operation changed" so track operation based on key state
int keyOperation = -1;
// workaround - The dataobject address is only passed as an argument in drag enter and drop.
// To allow applications to query the data values during the drag over operations,
// maintain a reference to it.
IDataObject iDataObject;
// interfaces
COMObject iDropTarget;
int refCount;
static final String DEFAULT_DROP_TARGET_EFFECT = "DEFAULT_DROP_TARGET_EFFECT"; //$NON-NLS-1$
/**
* Creates a new DropTarget to allow data to be dropped on the specified
* Control.
* Creating an instance of a DropTarget may cause system resources to be allocated
* depending on the platform. It is therefore mandatory that the DropTarget instance
* be disposed when no longer required.
*
* @param control the Control over which the user positions the cursor to drop the data
* @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 
    
* 
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
    • 
* 
  • ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
    • 
* 

* @exception SWTError 
    
* 
  • ERROR_CANNOT_INIT_DROP - unable to initiate drop target; this will occur if more than one
* drop target is created for a control or if the operating system will not allow the creation
* of the drop target
    • 
* 

*
* 
NOTE: ERROR_CANNOT_INIT_DROP should be an SWTException, since it is a
* recoverable error, but can not be changed due to backward compatibility.

*
* @see Widget#dispose
* @see DropTarget#checkSubclass
* @see DND#DROP_NONE
* @see DND#DROP_COPY
* @see DND#DROP_MOVE
* @see DND#DROP_LINK
*/
public DropTarget(Control control, int style) {
super (control, checkStyle(style));
this.control = control;
if (control.getData(DND.DROP_TARGET_KEY) != null) {
DND.error(DND.ERROR_CANNOT_INIT_DROP);
}
control.setData(DND.DROP_TARGET_KEY, this);
createCOMInterfaces();
this.AddRef();
if (COM.CoLockObjectExternal(iDropTarget.getAddress(), true, true) != COM.S_OK)
DND.error(DND.ERROR_CANNOT_INIT_DROP);
if (COM.RegisterDragDrop( control.handle, iDropTarget.getAddress()) != COM.S_OK)
DND.error(DND.ERROR_CANNOT_INIT_DROP);
controlListener = new Listener () {
public void handleEvent (Event event) {
if (!DropTarget.this.isDisposed()){
DropTarget.this.dispose();
}
}
};
control.addListener (SWT.Dispose, controlListener);
this.addListener(SWT.Dispose, new Listener () {
public void handleEvent (Event event) {
onDispose();
}
});
Object effect = control.getData(DEFAULT_DROP_TARGET_EFFECT);
if (effect instanceof DropTargetEffect) {
dropEffect = (DropTargetEffect) effect;
} else if (control instanceof Table) {
dropEffect = new TableDropTargetEffect((Table) control);
} else if (control instanceof Tree) {
dropEffect = new TreeDropTargetEffect((Tree) control);
}
}
static int checkStyle (int style) {
if (style == SWT.NONE) return DND.DROP_MOVE;
return style;
}
/**
* 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 DropTargetListener
* interface.
*
* 
    
* 
  • dragEnter is called when the cursor has entered the drop target boundaries
* 
  • dragLeave is called when the cursor has left the drop target boundaries and just before
* the drop occurs or is cancelled.
* 
  • dragOperationChanged is called when the operation being performed has changed
* (usually due to the user changing the selected modifier key(s) while dragging)
* 
  • dragOver is called when the cursor is moving over the drop target
* 
  • dropAccept is called just before the drop is performed. The drop target is given
* the chance to change the nature of the drop or veto the drop by setting the event.detail field
* 
  • drop is called when the data is being dropped
* 

*
* @param listener the listener which should be notified
*
* @exception IllegalArgumentException 
    
* 
  • ERROR_NULL_ARGUMENT - if the listener is null
    • 
* 

* @exception SWTException 
    
* 
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
    • 
* 
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
    • 
* 

*
* @see DropTargetListener
* @see #getDropListeners
* @see #removeDropListener
* @see DropTargetEvent
*/
public void addDropListener(DropTargetListener listener) {
if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
DNDListener typedListener = new DNDListener (listener);
typedListener.dndWidget = this;
addListener (DND.DragEnter, typedListener);
addListener (DND.DragLeave, typedListener);
addListener (DND.DragOver, typedListener);
addListener (DND.DragOperationChanged, typedListener);
addListener (DND.Drop, typedListener);
addListener (DND.DropAccept, typedListener);
}
int AddRef() {
refCount++;
return refCount;
}
protected void checkSubclass () {
String name = getClass().getName ();
String validName = DropTarget.class.getName();
if (!validName.equals(name)) {
DND.error (SWT.ERROR_INVALID_SUBCLASS);
}
}
void createCOMInterfaces() {
// register each of the interfaces that this object implements
boolean is32 = C.PTR_SIZEOF == 4;
iDropTarget = new COMObject(new int[]{2, 0, 0, is32 ? 5 : 4, is32 ? 4 : 3, 0, is32 ? 5 : 4}){
public int /*long*/ method0(int /*long*/[] args) {return QueryInterface(args[0], args[1]);}
public int /*long*/ method1(int /*long*/[] args) {return AddRef();}
public int /*long*/ method2(int /*long*/[] args) {return Release();}
public int /*long*/ method3(int /*long*/[] args) {
if (args.length == 5) {
return DragEnter(args[0], (int)/*64*/args[1], (int)/*64*/args[2], (int)/*64*/args[3], args[4]);
} else {
return DragEnter_64(args[0], (int)/*64*/args[1], args[2], args[3]);
}
}
public int /*long*/ method4(int /*long*/[] args) {
if (args.length == 4) {
return DragOver((int)/*64*/args[0], (int)/*64*/args[1], (int)/*64*/args[2], args[3]);
} else {
return DragOver_64((int)/*64*/args[0], args[1], args[2]);
}
}
public int /*long*/ method5(int /*long*/[] args) {return DragLeave();}
public int /*long*/ method6(int /*long*/[] args) {
if (args.length == 5) {
return Drop(args[0], (int)/*64*/args[1], (int)/*64*/args[2], (int)/*64*/args[3], args[4]);
} else {
return Drop_64(args[0], (int)/*64*/args[1], args[2], args[3]);
}
}
};
}
void disposeCOMInterfaces() {
if (iDropTarget != null)
iDropTarget.dispose();
iDropTarget = null;
}
int DragEnter_64(int /*long*/ pDataObject, int grfKeyState, long pt, int /*long*/ pdwEffect) {
POINT point = new POINT();
OS.MoveMemory(point, new long[]{pt}, 8);
return DragEnter(pDataObject, grfKeyState, point.x, point.y, pdwEffect);
}
int DragEnter(int /*long*/ pDataObject, int grfKeyState, int pt_x, int pt_y, int /*long*/ pdwEffect) {
selectedDataType = null;
selectedOperation = DND.DROP_NONE;
if (iDataObject != null) iDataObject.Release();
iDataObject = null;
DNDEvent event = new DNDEvent();
if (!setEventData(event, pDataObject, grfKeyState, pt_x, pt_y, pdwEffect)) {
OS.MoveMemory(pdwEffect, new int[] {COM.DROPEFFECT_NONE}, 4);
return COM.S_FALSE;
}
// Remember the iDataObject because it is not passed into the DragOver callback
iDataObject = new IDataObject(pDataObject);
iDataObject.AddRef();
int allowedOperations = event.operations;
TransferData[] allowedDataTypes = new TransferData[event.dataTypes.length];
System.arraycopy(event.dataTypes, 0, allowedDataTypes, 0, allowedDataTypes.length);
notifyListeners(DND.DragEnter, event);
refresh();
if (event.detail == DND.DROP_DEFAULT) {
event.detail = (allowedOperations & DND.DROP_MOVE) != 0 ? DND.DROP_MOVE : DND.DROP_NONE;
}
selectedDataType = null;
for (int i = 0; i < allowedDataTypes.length; i++) {
if (TransferData.sameType(allowedDataTypes[i], event.dataType)){
selectedDataType = allowedDataTypes[i];
break;
}
}
selectedOperation = DND.DROP_NONE;
if (selectedDataType != null && ((allowedOperations & event.detail) != 0)) {
selectedOperation = event.detail;
}
OS.MoveMemory(pdwEffect, new int[] {opToOs(selectedOperation)}, 4);
return COM.S_OK;
}
int DragLeave() {
keyOperation = -1;
if (iDataObject == null) return COM.S_FALSE;
DNDEvent event = new DNDEvent();
event.widget = this;
event.time = OS.GetMessageTime();
event.detail = DND.DROP_NONE;
notifyListeners(DND.DragLeave, event);
refresh();
iDataObject.Release();
iDataObject = null;
return COM.S_OK;
}
int DragOver_64(int grfKeyState, long pt, int /*long*/ pdwEffect) {
POINT point = new POINT();
OS.MoveMemory(point, new long[]{pt}, 8);
return DragOver(grfKeyState, point.x, point.y, pdwEffect);
}
int DragOver(int grfKeyState, int pt_x, int pt_y, int /*long*/ pdwEffect) {
if (iDataObject == null) return COM.S_FALSE;
int oldKeyOperation = keyOperation;
DNDEvent event = new DNDEvent();
if (!setEventData(event, iDataObject.getAddress(), grfKeyState, pt_x, pt_y, pdwEffect)) {
keyOperation = -1;
OS.MoveMemory(pdwEffect, new int[] {COM.DROPEFFECT_NONE}, 4);
return COM.S_FALSE;
}
int allowedOperations = event.operations;
TransferData[] allowedDataTypes = new TransferData[event.dataTypes.length];
System.arraycopy(event.dataTypes, 0, allowedDataTypes, 0, allowedDataTypes.length);
if (keyOperation == oldKeyOperation) {
event.type = DND.DragOver;
event.dataType = selectedDataType;
event.detail = selectedOperation;
} else {
event.type = DND.DragOperationChanged;
event.dataType = selectedDataType;
}
notifyListeners(event.type, event);
refresh();
if (event.detail == DND.DROP_DEFAULT) {
event.detail = (allowedOperations & DND.DROP_MOVE) != 0 ? DND.DROP_MOVE : DND.DROP_NONE;
}
selectedDataType = null;
for (int i = 0; i < allowedDataTypes.length; i++) {
if (TransferData.sameType(allowedDataTypes[i], event.dataType)){
selectedDataType = allowedDataTypes[i];
break;
}
}
selectedOperation = DND.DROP_NONE;
if (selectedDataType != null && ((allowedOperations & event.detail) == event.detail)) {
selectedOperation = event.detail;
}
OS.MoveMemory(pdwEffect, new int[] {opToOs(selectedOperation)}, 4);
return COM.S_OK;
}
int Drop_64(int /*long*/ pDataObject, int grfKeyState, long pt, int /*long*/ pdwEffect) {
POINT point = new POINT();
OS.MoveMemory(point, new long[]{pt}, 8);
return Drop(pDataObject, grfKeyState, point.x, point.y, pdwEffect);
}
int Drop(int /*long*/ pDataObject, int grfKeyState, int pt_x, int pt_y, int /*long*/ pdwEffect) {
DNDEvent event = new DNDEvent();
event.widget = this;
event.time = OS.GetMessageTime();
if (dropEffect != null) {
event.item = dropEffect.getItem(pt_x, pt_y);
}
event.detail = DND.DROP_NONE;
notifyListeners(DND.DragLeave, event);
refresh();
event = new DNDEvent();
if (!setEventData(event, pDataObject, grfKeyState, pt_x, pt_y, pdwEffect)) {
keyOperation = -1;
OS.MoveMemory(pdwEffect, new int[] {COM.DROPEFFECT_NONE}, 4);
return COM.S_FALSE;
}
keyOperation = -1;
int allowedOperations = event.operations;
TransferData[] allowedDataTypes = new TransferData[event.dataTypes.length];
System.arraycopy(event.dataTypes, 0, allowedDataTypes, 0, allowedDataTypes.length);
event.dataType = selectedDataType;
event.detail = selectedOperation;
notifyListeners(DND.DropAccept,event);
refresh();
selectedDataType = null;
for (int i = 0; i < allowedDataTypes.length; i++) {
if (TransferData.sameType(allowedDataTypes[i], event.dataType)){
selectedDataType = allowedDataTypes[i];
break;
}
}
selectedOperation = DND.DROP_NONE;
if (selectedDataType != null && (allowedOperations & event.detail) == event.detail) {
selectedOperation = event.detail;
}
if (selectedOperation == DND.DROP_NONE){
OS.MoveMemory(pdwEffect, new int[] {COM.DROPEFFECT_NONE}, 4);
return COM.S_OK;
}
// Get Data in a Java format
Object object = null;
for (int i = 0; i < transferAgents.length; i++){
Transfer transfer = transferAgents[i];
if (transfer != null && transfer.isSupportedType(selectedDataType)){
object = transfer.nativeToJava(selectedDataType);
break;
}
}
if (object == null){
selectedOperation = DND.DROP_NONE;
}
event.detail = selectedOperation;
event.dataType = selectedDataType;
event.data = object;
OS.ImageList_DragShowNolock(false);
try {
notifyListeners(DND.Drop,event);
} finally {
OS.ImageList_DragShowNolock(true);
}
refresh();
selectedOperation = DND.DROP_NONE;
if ((allowedOperations & event.detail) == event.detail) {
selectedOperation = event.detail;
}
//notify source of action taken
OS.MoveMemory(pdwEffect, new int[] {opToOs(selectedOperation)}, 4);
return COM.S_OK;
}
/**
* Returns the Control which is registered for this DropTarget. This is the control over which the
* user positions the cursor to drop the data.
*
* @return the Control which is registered for this DropTarget
*/
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 DropTargetListener interface.
*
* @return the listeners who will be notified when a drag and drop
* operation is in progress
*
* @exception SWTException 
    
* 
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
    • 
* 
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
    • 
* 

*
* @see DropTargetListener
* @see #addDropListener
* @see #removeDropListener
* @see DropTargetEvent
*
* @since 3.4
*/
public DropTargetListener[] getDropListeners() {
Listener[] listeners = getListeners(DND.DragEnter);
int length = listeners.length;
DropTargetListener[] dropListeners = new DropTargetListener[length];
int count = 0;
for (int i = 0; i < length; i++) {
Listener listener = listeners[i];
if (listener instanceof DNDListener) {
dropListeners[count] = (DropTargetListener) ((DNDListener) listener).getEventListener();
count++;
}
}
if (count == length) return dropListeners;
DropTargetListener[] result = new DropTargetListener[count];
System.arraycopy(dropListeners, 0, result, 0, count);
return result;
}
/**
* Returns the drop effect for this DropTarget. This drop effect will be
* used during a drag and drop to display the drag under effect on the
* target widget.
*
* @return the drop effect that is registered for this DropTarget
*
* @since 3.3
*/
public DropTargetEffect getDropTargetEffect() {
return dropEffect;
}
int getOperationFromKeyState(int grfKeyState) {
boolean ctrl = (grfKeyState & OS.MK_CONTROL) != 0;
boolean shift = (grfKeyState & OS.MK_SHIFT) != 0;
boolean alt = (grfKeyState & OS.MK_ALT) != 0;
if (alt) {
if (ctrl || shift) return DND.DROP_DEFAULT;
return DND.DROP_LINK;
}
if (ctrl && shift) return DND.DROP_LINK;
if (ctrl)return DND.DROP_COPY;
if (shift)return DND.DROP_MOVE;
return DND.DROP_DEFAULT;
}
/**
* Returns a list of the data types that can be transferred to this DropTarget.
*
* @return a list of the data types that can be transferred to this DropTarget
*/
public Transfer[] getTransfer() {
return transferAgents;
}
void onDispose () {
if (control == null) return;
COM.RevokeDragDrop(control.handle);
if (controlListener != null)
control.removeListener(SWT.Dispose, controlListener);
controlListener = null;
control.setData(DND.DROP_TARGET_KEY, null);
transferAgents = null;
control = null;
COM.CoLockObjectExternal(iDropTarget.getAddress(), false, true);
this.Release();
if (iDataObject != null) {
iDataObject.Release();
}
iDataObject = null;
if (COM.FreeUnusedLibraries) {
COM.CoFreeUnusedLibraries();
}
}
int opToOs(int operation) {
int osOperation = 0;
if ((operation & DND.DROP_COPY) != 0){
osOperation |= COM.DROPEFFECT_COPY;
}
if ((operation & DND.DROP_LINK) != 0) {
osOperation |= COM.DROPEFFECT_LINK;
}
if ((operation & DND.DROP_MOVE) != 0) {
osOperation |= COM.DROPEFFECT_MOVE;
}
return osOperation;
}
int osToOp(int osOperation){
int operation = 0;
if ((osOperation & COM.DROPEFFECT_COPY) != 0){
operation |= DND.DROP_COPY;
}
if ((osOperation & COM.DROPEFFECT_LINK) != 0) {
operation |= DND.DROP_LINK;
}
if ((osOperation & COM.DROPEFFECT_MOVE) != 0) {
operation |= DND.DROP_MOVE;
}
return operation;
}
/* QueryInterface([in] iid, [out] ppvObject)
* Ownership of ppvObject transfers from callee to caller so reference count on ppvObject
* must be incremented before returning. Caller is responsible for releasing ppvObject.
*/
int QueryInterface(int /*long*/ riid, int /*long*/ ppvObject) {
if (riid == 0 || ppvObject == 0)
return COM.E_INVALIDARG;
GUID guid = new GUID();
COM.MoveMemory(guid, riid, GUID.sizeof);
if (COM.IsEqualGUID(guid, COM.IIDIUnknown) || COM.IsEqualGUID(guid, COM.IIDIDropTarget)) {
COM.MoveMemory(ppvObject, new int /*long*/[] {iDropTarget.getAddress()}, OS.PTR_SIZEOF);
AddRef();
return COM.S_OK;
}
COM.MoveMemory(ppvObject, new int /*long*/[] {0}, OS.PTR_SIZEOF);
return COM.E_NOINTERFACE;
}
int Release() {
refCount--;
if (refCount == 0) {
disposeCOMInterfaces();
if (COM.FreeUnusedLibraries) {
COM.CoFreeUnusedLibraries();
}
}
return refCount;
}
void refresh() {
if (control == null || control.isDisposed()) return;
int /*long*/ handle = control.handle;
RECT lpRect = new RECT();
if (OS.GetUpdateRect(handle, lpRect, false)) {
OS.ImageList_DragShowNolock(false);
OS.RedrawWindow(handle, lpRect, 0, OS.RDW_UPDATENOW | OS.RDW_INVALIDATE);
OS.ImageList_DragShowNolock(true);
}
}
/**
* 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 
    
* 
  • ERROR_NULL_ARGUMENT - if the listener is null
    • 
* 

* @exception SWTException 
    
* 
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
    • 
* 
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
    • 
* 

*
* @see DropTargetListener
* @see #addDropListener
* @see #getDropListeners
*/
public void removeDropListener(DropTargetListener listener) {
if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT);
removeListener (DND.DragEnter, listener);
removeListener (DND.DragLeave, listener);
removeListener (DND.DragOver, listener);
removeListener (DND.DragOperationChanged, listener);
removeListener (DND.Drop, listener);
removeListener (DND.DropAccept, listener);
}
/**
* Specifies the drop effect for this DropTarget. This drop effect will be
* used during a drag and drop to display the drag under effect on the
* target widget.
*
* @param effect the drop effect that is registered for this DropTarget
*
* @since 3.3
*/
public void setDropTargetEffect(DropTargetEffect effect) {
dropEffect = effect;
}
boolean setEventData(DNDEvent event, int /*long*/ pDataObject, int grfKeyState, int pt_x, int pt_y, int /*long*/ pdwEffect) {
if (pDataObject == 0 || pdwEffect == 0) return false;
// get allowed operations
int style = getStyle();
int[] operations = new int[1];
OS.MoveMemory(operations, pdwEffect, 4);
operations[0] = osToOp(operations[0]) & style;
if (operations[0] == DND.DROP_NONE) return false;
// get current operation
int operation = getOperationFromKeyState(grfKeyState);
keyOperation = operation;
if (operation == DND.DROP_DEFAULT) {
if ((style & DND.DROP_DEFAULT) == 0) {
operation = (operations[0] & DND.DROP_MOVE) != 0 ? DND.DROP_MOVE : DND.DROP_NONE;
}
} else {
if ((operation & operations[0]) == 0) operation = DND.DROP_NONE;
}
// Get allowed transfer types
TransferData[] dataTypes = new TransferData[0];
IDataObject dataObject = new IDataObject(pDataObject);
dataObject.AddRef();
try {
int /*long*/[] address = new int /*long*/[1];
if (dataObject.EnumFormatEtc(COM.DATADIR_GET, address) != COM.S_OK) {
return false;
}
IEnumFORMATETC enumFormatetc = new IEnumFORMATETC(address[0]);
try {
// Loop over enumerator and save any types that match what we are looking for
int /*long*/ rgelt = OS.GlobalAlloc(OS.GMEM_FIXED | OS.GMEM_ZEROINIT, FORMATETC.sizeof);
try {
int[] pceltFetched = new int[1];
enumFormatetc.Reset();
while (enumFormatetc.Next(1, rgelt, pceltFetched) == COM.S_OK && pceltFetched[0] == 1) {
TransferData transferData = new TransferData();
transferData.formatetc = new FORMATETC();
COM.MoveMemory(transferData.formatetc, rgelt, FORMATETC.sizeof);
transferData.type = transferData.formatetc.cfFormat;
transferData.pIDataObject = pDataObject;
for (int i = 0; i < transferAgents.length; i++){
Transfer transfer = transferAgents[i];
if (transfer != null && transfer.isSupportedType(transferData)){
TransferData[] newDataTypes = new TransferData[dataTypes.length + 1];
System.arraycopy(dataTypes, 0, newDataTypes, 0, dataTypes.length);
newDataTypes[dataTypes.length] = transferData;
dataTypes = newDataTypes;
break;
}
}
}
} finally {
OS.GlobalFree(rgelt);
}
} finally {
enumFormatetc.Release();
}
} finally {
dataObject.Release();
}
if (dataTypes.length == 0) return false;
event.widget = this;
event.x = pt_x;
event.y = pt_y;
event.time = OS.GetMessageTime();
event.feedback = DND.FEEDBACK_SELECT;
event.dataTypes = dataTypes;
event.dataType = dataTypes[0];
if (dropEffect != null) {
event.item = dropEffect.getItem(pt_x, pt_y);
}
event.operations = operations[0];
event.detail = operation;
return true;
}
/**
* Specifies the data types that can be transferred to this DropTarget. If data is
* being dragged that does not match one of these types, the drop target will be notified of
* the drag and drop operation but the currentDataType will be null and the operation
* will be DND.NONE.
*
* @param transferAgents a list of Transfer objects which define the types of data that can be
* dropped on this target
*
* @exception IllegalArgumentException 
    
* 
  • ERROR_NULL_ARGUMENT - if transferAgents is null
    • 
* 

*/
public void setTransfer(Transfer[] transferAgents){
if (transferAgents == null) DND.error(SWT.ERROR_NULL_ARGUMENT);
this.transferAgents = transferAgents;
}
}




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