droptarget.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

		selectedOperation = event.detail;
	}
	
	effect.show(event.feedback, event.x, event.y);
	
	OS.MoveMemory(pdwEffect, new int[] {opToOs(selectedOperation)}, 4);
	return COM.S_OK;
}

private int Drop(int pDataObject, int grfKeyState, int pt_x, int pt_y, int pdwEffect) {
	effect.show(DND.FEEDBACK_NONE, 0, 0);

	DNDEvent event = new DNDEvent();
	event.widget = this;
	event.time = OS.GetMessageTime();
	event.detail = DND.DROP_NONE;
	try {
		notifyListeners(DND.DragLeave, event);
	} catch (Throwable e) {}
	
	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_OK;
	}
	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;
	try {
		notifyListeners(DND.DropAccept,event);
	} catch (Throwable e) {
		event.detail = DND.DROP_NONE;
		event.dataType = null;
	}

	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++){
		if (transferAgents[i].isSupportedType(selectedDataType)){
			object = transferAgents[i].nativeToJava(selectedDataType);
			break;
		}
	}
	if (object == null){
		selectedOperation = DND.DROP_NONE;
	}
	
	event.detail = selectedOperation;
	event.dataType = selectedDataType;
	event.data = object;
	try {
		notifyListeners(DND.Drop,event);
		selectedOperation = DND.DROP_NONE;
		if ((allowedOperations & event.detail) == event.detail) {
			selectedOperation = event.detail;
		}
	} catch (Throwable e) {
		selectedOperation = DND.DROP_NONE;
	}
	
	//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;
}

private int getOperationFromKeyState(int grfKeyState) {
	boolean ctrl = (grfKeyState & OS.MK_CONTROL) != 0;
	boolean shift = (grfKeyState & OS.MK_SHIFT) != 0;
	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;
}

public void notifyListeners (int eventType, Event event) {
	Point coordinates = new Point(event.x, event.y);
	coordinates = control.toControl(coordinates);
	if (this.control instanceof Tree) {
		Tree tree = (Tree)control;
		event.item = tree.getItem(coordinates);
		if (event.item == null) {
			Rectangle area = tree.getClientArea();
			if (area.contains(coordinates)) {
				// Scan across the width of the tree.
				for (int x1 = area.x; x1 < area.x + area.width; x1++) {
					Point pt = new Point(x1, coordinates.y);
					event.item = tree.getItem(pt);
					if (event.item != null) {
						break;
					}
				}
			}
		}
	}
	if (this.control instanceof Table) {
		Table table = (Table)control;
		event.item = table.getItem(coordinates);
		if (event.item == null) {
			Rectangle area = table.getClientArea();
			if (area.contains(coordinates)) {
				// Scan across the width of the tree.
				for (int x1 = area.x; x1 < area.x + area.width; x1++) {
					Point pt = new Point(x1, coordinates.y);
					event.item = table.getItem(pt);
					if (event.item != null) {
						break;
					}
				}
			}
		}
	}
	super.notifyListeners(eventType, event);
}

private void onDispose () {	
	if (control == null) return;

	COM.RevokeDragDrop(control.handle);
	
	if (controlListener != null)
		control.removeListener(SWT.Dispose, controlListener);
	controlListener = null;
	control.setData(DROPTARGETID, null);
	transferAgents = null;
	control = null;
	
	COM.CoLockObjectExternal(iDropTarget.getAddress(), false, true);
	
	this.Release();
	
	COM.CoFreeUnusedLibraries();
}

private 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;
}

private 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;
}

private int QueryInterface(int riid, int 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[] {iDropTarget.getAddress()}, 4);
		AddRef();
		return COM.S_OK;
	}

	COM.MoveMemory(ppvObject, new int[] {0}, 4);
	return COM.E_NOINTERFACE;
}

private int Release() {
	refCount--;
	
	if (refCount == 0) {
		disposeCOMInterfaces();
		COM.CoFreeUnusedLibraries();
	}
	
	return refCount;
}

/**
 * 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 be notified
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the listener is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see DropTargetListener
 * @see #addDropListener
 */
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);
}

private boolean setEventData(DNDEvent event, int pDataObject, int grfKeyState, int pt_x, int pt_y, int 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[] address = new int[1];
		if (dataObject.EnumFormatEtc(COM.DATADIR_GET, address) != COM.S_OK) {
			return false;
		}
		IEnumFORMATETC enum = new IEnumFORMATETC(address[0]);
		try {
			// Loop over enumerator and save any types that match what we are looking for
			int rgelt = OS.GlobalAlloc(OS.GMEM_FIXED | OS.GMEM_ZEROINIT, FORMATETC.sizeof);
			try {
				int[] pceltFetched = new int[1];
				enum.Reset();
				while (enum.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++){
						if (transferAgents[i].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 {
			enum.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];
	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 <ul>
 *    <li>ERROR_NULL_ARGUMENT - if transferAgents is null</li>
 * </ul>
 */
public void setTransfer(Transfer[] transferAgents){
	if (transferAgents == null) DND.error(SWT.ERROR_NULL_ARGUMENT);
	this.transferAgents = transferAgents;
}

}