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/* * @(#)DropTargetContext.java 1.38 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.awt.dnd; import java.awt.Component; import java.awt.datatransfer.DataFlavor; import java.awt.datatransfer.Transferable; import java.awt.datatransfer.UnsupportedFlavorException; import java.awt.dnd.peer.DropTargetContextPeer; import java.io.IOException; import java.io.Serializable; import java.util.Arrays; import java.util.List; /** * A <code>DropTargetContext</code> is created * whenever the logical cursor associated * with a Drag and Drop operation coincides with the visible geometry of * a <code>Component</code> associated with a <code>DropTarget</code>. * The <code>DropTargetContext</code> provides * the mechanism for a potential receiver * of a drop operation to both provide the end user with the appropriate * drag under feedback, but also to effect the subsequent data transfer * if appropriate. * * @version 1.38, 11/17/05 * @since 1.2 */ public class DropTargetContext implements Serializable { private static final long serialVersionUID = -634158968993743371L; /** * Construct a <code>DropTargetContext</code> * given a specified <code>DropTarget</code>. * <P> * @param dt the DropTarget to associate with */ DropTargetContext(DropTarget dt) { super(); dropTarget = dt; } /** * This method returns the <code>DropTarget</code> associated with this * <code>DropTargetContext</code>. * <P> * @return the <code>DropTarget</code> associated with this <code>DropTargetContext</code> */ public DropTarget getDropTarget() { return dropTarget; } /** * This method returns the <code>Component</code> associated with * this <code>DropTargetContext</code>. * <P> * @return the Component associated with this Context */ public Component getComponent() { return dropTarget.getComponent(); } /** * Called when associated with the <code>DropTargetContextPeer</code>. * <P> * @param dtcp the <code>DropTargetContextPeer</code> */ public void addNotify(DropTargetContextPeer dtcp) { dropTargetContextPeer = dtcp; } /** * Called when disassociated with the <code>DropTargetContextPeer</code>. */ public void removeNotify() { dropTargetContextPeer = null; transferable = null; } /** * This method sets the current actions acceptable to * this <code>DropTarget</code>. * <P> * @param actions an <code>int</code> representing the supported action(s) */ protected void setTargetActions(int actions) { DropTargetContextPeer peer = getDropTargetContextPeer(); if (peer != null) { synchronized (peer) { peer.setTargetActions(actions); getDropTarget().doSetDefaultActions(actions); } } else { getDropTarget().doSetDefaultActions(actions); } } /** * This method returns an <code>int</code> representing the * current actions this <code>DropTarget</code> will accept. * <P> * @return the current actions acceptable to this <code>DropTarget</code> */ protected int getTargetActions() { DropTargetContextPeer peer = getDropTargetContextPeer(); return ((peer != null) ? peer.getTargetActions() : dropTarget.getDefaultActions() ); } /** * This method signals that the drop is completed and * if it was successful or not. * <P> * @param success true for success, false if not * <P> * @throws InvalidDnDOperationException if a drop is not outstanding/extant */ public void dropComplete(boolean success) throws InvalidDnDOperationException{ DropTargetContextPeer peer = getDropTargetContextPeer(); if (peer != null) { peer.dropComplete(success); } } /** * accept the Drag. * <P> * @param dragOperation the supported action(s) */ protected void acceptDrag(int dragOperation) { DropTargetContextPeer peer = getDropTargetContextPeer(); if (peer != null) { peer.acceptDrag(dragOperation); } } /** * reject the Drag. */ protected void rejectDrag() { DropTargetContextPeer peer = getDropTargetContextPeer(); if (peer != null) { peer.rejectDrag(); } } /** * called to signal that the drop is acceptable * using the specified operation. * must be called during DropTargetListener.drop method invocation. * <P> * @param dropOperation the supported action(s) */ protected void acceptDrop(int dropOperation) { DropTargetContextPeer peer = getDropTargetContextPeer(); if (peer != null) { peer.acceptDrop(dropOperation); } } /** * called to signal that the drop is unacceptable. * must be called during DropTargetListener.drop method invocation. */ protected void rejectDrop() { DropTargetContextPeer peer = getDropTargetContextPeer(); if (peer != null) { peer.rejectDrop(); } } /** * get the available DataFlavors of the * <code>Transferable</code> operand of this operation. * <P> * @return a <code>DataFlavor[]</code> containing the * supported <code>DataFlavor</code>s of the * <code>Transferable</code> operand. */ protected DataFlavor[] getCurrentDataFlavors() { DropTargetContextPeer peer = getDropTargetContextPeer(); return peer != null ? peer.getTransferDataFlavors() : new DataFlavor[0]; } /** * This method returns a the currently available DataFlavors * of the <code>Transferable</code> operand * as a <code>java.util.List</code>. * <P> * @return the currently available * DataFlavors as a <code>java.util.List</code> */ protected List<DataFlavor> getCurrentDataFlavorsAsList() { return Arrays.asList(getCurrentDataFlavors()); } /** * This method returns a <code>boolean</code> * indicating if the given <code>DataFlavor</code> is * supported by this <code>DropTargetContext</code>. * <P> * @param df the <code>DataFlavor</code> * <P> * @return if the <code>DataFlavor</code> specified is supported */ protected boolean isDataFlavorSupported(DataFlavor df) { return getCurrentDataFlavorsAsList().contains(df); } /** * get the Transferable (proxy) operand of this operation * <P> * @throws InvalidDnDOperationException if a drag is not outstanding/extant * <P> * @return the <code>Transferable</code> */ protected Transferable getTransferable() throws InvalidDnDOperationException { DropTargetContextPeer peer = getDropTargetContextPeer(); if (peer == null) { throw new InvalidDnDOperationException(); } else { if (transferable == null) { Transferable t = peer.getTransferable(); boolean isLocal = peer.isTransferableJVMLocal(); synchronized (this) { if (transferable == null) { transferable = createTransferableProxy(t, isLocal); } } } return transferable; } } /** * Get the <code>DropTargetContextPeer</code> * <P> * @return the platform peer */ DropTargetContextPeer getDropTargetContextPeer() { return dropTargetContextPeer; } /** * Creates a TransferableProxy to proxy for the specified * Transferable. * * @param t the <tt>Transferable</tt> to be proxied * @param local <tt>true</tt> if <tt>t</tt> represents * the result of a local drag-n-drop operation. * @return the new <tt>TransferableProxy</tt> instance. */ protected Transferable createTransferableProxy(Transferable t, boolean local) { return new TransferableProxy(t, local); } /****************************************************************************/ /** * <code>TransferableProxy</code> is a helper inner class that implements * <code>Transferable</code> interface and serves as a proxy for another * <code>Transferable</code> object which represents data transfer for * a particular drag-n-drop operation. * <p> * The proxy forwards all requests to the encapsulated transferable * and automatically performs additional conversion on the data * returned by the encapsulated transferable in case of local transfer. */ protected class TransferableProxy implements Transferable { /** * Constructs a <code>TransferableProxy</code> given * a specified <code>Transferable</code> object representing * data transfer for a particular drag-n-drop operation and * a <code>boolean</code> which indicates whether the * drag-n-drop operation is local (within the same JVM). * <p> * @param t the <code>Transferable</code> object * @param local <code>true</code>, if <code>t</code> represents * the result of local drag-n-drop operation */ TransferableProxy(Transferable t, boolean local) { proxy = new sun.awt.datatransfer.TransferableProxy(t, local); transferable = t; isLocal = local; } /** * Returns an array of DataFlavor objects indicating the flavors * the data can be provided in by the encapsulated transferable. * <p> * @return an array of data flavors in which the data can be * provided by the encapsulated transferable */ public DataFlavor[] getTransferDataFlavors() { return proxy.getTransferDataFlavors(); } /** * Returns whether or not the specified data flavor is supported by * the encapsulated transferable. * @param flavor the requested flavor for the data * @return <code>true</code> if the data flavor is supported, * <code>false</code> otherwise */ public boolean isDataFlavorSupported(DataFlavor flavor) { return proxy.isDataFlavorSupported(flavor); } /** * Returns an object which represents the data provided by * the encapsulated transferable for the requested data flavor. * <p> * In case of local transfer a serialized copy of the object * returned by the encapsulated transferable is provided when * the data is requested in application/x-java-serialized-object * data flavor. * * @param df the requested flavor for the data * @throws IOException if the data is no longer available * in the requested flavor. * @throws UnsupportedFlavorException if the requested data flavor is * not supported. */ public Object getTransferData(DataFlavor df) throws UnsupportedFlavorException, IOException { return proxy.getTransferData(df); } /* * fields */ // We don't need to worry about client code changing the values of // these variables. Since TransferableProxy is a protected class, only // subclasses of DropTargetContext can access it. And DropTargetContext // cannot be subclassed by client code because it does not have a // public constructor. /** * The encapsulated <code>Transferable</code> object. */ protected Transferable transferable; /** * A <code>boolean</code> indicating if the encapsulated * <code>Transferable</code> object represents the result * of local drag-n-drop operation (within the same JVM). */ protected boolean isLocal; private sun.awt.datatransfer.TransferableProxy proxy; } /****************************************************************************/ /* * fields */ /** * The DropTarget associated with this DropTargetContext. * * @serial */ private DropTarget dropTarget; private transient DropTargetContextPeer dropTargetContextPeer; private transient Transferable transferable; }