src/java.desktop/share/classes/sun/awt/datatransfer/SunClipboard.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
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 * by Oracle in the LICENSE file that accompanied this code.
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * accompanied this code).
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package sun.awt.datatransfer;

import java.awt.EventQueue;

import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.FlavorTable;
import java.awt.datatransfer.SystemFlavorMap;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.ClipboardOwner;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.FlavorListener;
import java.awt.datatransfer.FlavorEvent;
import java.awt.datatransfer.UnsupportedFlavorException;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import java.util.Arrays;
import java.util.Set;
import java.util.HashSet;

import java.io.IOException;

import sun.awt.AppContext;
import sun.awt.PeerEvent;
import sun.awt.SunToolkit;


/**
 * Serves as a common, helper superclass for the Win32 and X11 system
 * Clipboards.
 *
 * @author Danila Sinopalnikov
 * @author Alexander Gerasimov
 *
 * @since 1.3
 */
public abstract class SunClipboard extends Clipboard
    implements PropertyChangeListener {

    private AppContext contentsContext = null;

    private final Object CLIPBOARD_FLAVOR_LISTENER_KEY;

    /**
     * A number of {@code FlavorListener}s currently registered
     * on this clipboard across all {@code AppContext}s.
     */
    private volatile int numberOfFlavorListeners;

    /**
     * A set of {@code DataFlavor}s that is available on this clipboard. It is
     * used for tracking changes of {@code DataFlavor}s available on this
     * clipboard. Can be {@code null}.
     */
    private volatile long[] currentFormats;

    public SunClipboard(String name) {
        super(name);
        CLIPBOARD_FLAVOR_LISTENER_KEY = new StringBuffer(name + "_CLIPBOARD_FLAVOR_LISTENER_KEY");
    }

    public synchronized void setContents(Transferable contents,
                                         ClipboardOwner owner) {
        // 4378007 : Toolkit.getSystemClipboard().setContents(null, null)
        // should throw NPE
        if (contents == null) {
            throw new NullPointerException("contents");
        }

        initContext();

        final ClipboardOwner oldOwner = this.owner;
        final Transferable oldContents = this.contents;

        try {
            this.owner = owner;
            this.contents = new TransferableProxy(contents, true);

            setContentsNative(contents);
        } finally {
            if (oldOwner != null && oldOwner != owner) {
                EventQueue.invokeLater(() -> oldOwner.lostOwnership(SunClipboard.this, oldContents));
            }
        }
    }

    private synchronized void initContext() {
        final AppContext context = AppContext.getAppContext();

        if (contentsContext != context) {
            // Need to synchronize on the AppContext to guarantee that it cannot
            // be disposed after the check, but before the listener is added.
            synchronized (context) {
                if (context.isDisposed()) {
                    throw new IllegalStateException("Can't set contents from disposed AppContext");
                }
                context.addPropertyChangeListener
                    (AppContext.DISPOSED_PROPERTY_NAME, this);
            }
            if (contentsContext != null) {
                contentsContext.removePropertyChangeListener
                    (AppContext.DISPOSED_PROPERTY_NAME, this);
            }
            contentsContext = context;
        }
    }

    public synchronized Transferable getContents(Object requestor) {
        if (contents != null) {
            return contents;
        }
        return new ClipboardTransferable(this);
    }


    /**
     * @return the contents of this clipboard if it has been set from the same
     *         AppContext as it is currently retrieved or null otherwise
     * @since 1.5
     */
    protected synchronized Transferable getContextContents() {
        AppContext context = AppContext.getAppContext();
        return (context == contentsContext) ? contents : null;
    }


    /**
     * @see java.awt.datatransfer.Clipboard#getAvailableDataFlavors
     * @since 1.5
     */
    public DataFlavor[] getAvailableDataFlavors() {
        Transferable cntnts = getContextContents();
        if (cntnts != null) {
            return cntnts.getTransferDataFlavors();
        }

        long[] formats = getClipboardFormatsOpenClose();

        return DataTransferer.getInstance().
            getFlavorsForFormatsAsArray(formats, getDefaultFlavorTable());
    }

    /**
     * @see java.awt.datatransfer.Clipboard#isDataFlavorAvailable
     * @since 1.5
     */
    public boolean isDataFlavorAvailable(DataFlavor flavor) {
        if (flavor == null) {
            throw new NullPointerException("flavor");
        }

        Transferable cntnts = getContextContents();
        if (cntnts != null) {
            return cntnts.isDataFlavorSupported(flavor);
        }

        long[] formats = getClipboardFormatsOpenClose();

        return formatArrayAsDataFlavorSet(formats).contains(flavor);
    }

    /**
     * @see java.awt.datatransfer.Clipboard#getData
     * @since 1.5
     */
    public Object getData(DataFlavor flavor)
        throws UnsupportedFlavorException, IOException {
        if (flavor == null) {
            throw new NullPointerException("flavor");
        }

        Transferable cntnts = getContextContents();
        if (cntnts != null) {
            return cntnts.getTransferData(flavor);
        }

        long format = 0;
        byte[] data = null;
        Transferable localeTransferable = null;

        openClipboard(null);

        try {

            long[] formats = getClipboardFormats();
            Long lFormat = DataTransferer.getInstance().
                    getFlavorsForFormats(formats, getDefaultFlavorTable()).get(flavor);

            if (lFormat == null) {
                throw new UnsupportedFlavorException(flavor);
            }

            format = lFormat.longValue();
            data = getClipboardData(format);

            if (DataTransferer.getInstance().isLocaleDependentTextFormat(format)) {
                localeTransferable = createLocaleTransferable(formats);
            }

        } finally {
            closeClipboard();
        }

        return DataTransferer.getInstance().
                translateBytes(data, flavor, format, localeTransferable);
    }

    /**
     * The clipboard must be opened.
     *
     * @since 1.5
     */
    protected Transferable createLocaleTransferable(long[] formats) throws IOException {
        return null;
    }

    /**
     * @throws IllegalStateException if the clipboard has not been opened
     */
    public void openClipboard(SunClipboard newOwner) {}
    public void closeClipboard() {}

    public abstract long getID();

    public void propertyChange(PropertyChangeEvent evt) {
        if (AppContext.DISPOSED_PROPERTY_NAME.equals(evt.getPropertyName()) &&
            Boolean.TRUE.equals(evt.getNewValue())) {
            final AppContext disposedContext = (AppContext)evt.getSource();
            lostOwnershipLater(disposedContext);
        }
    }

    protected void lostOwnershipImpl() {
        lostOwnershipLater(null);
    }

    /**
     * Clears the clipboard state (contents, owner and contents context) and
     * notifies the current owner that ownership is lost. Does nothing if the
     * argument is not {@code null} and is not equal to the current
     * contents context.
     *
     * @param disposedContext the AppContext that is disposed or
     *        {@code null} if the ownership is lost because another
     *        application acquired ownership.
     */
    protected void lostOwnershipLater(final AppContext disposedContext) {
        final AppContext context = this.contentsContext;
        if (context == null) {
            return;
        }

        SunToolkit.postEvent(context, new PeerEvent(this, () -> lostOwnershipNow(disposedContext),
                                                    PeerEvent.PRIORITY_EVENT));
    }

    protected void lostOwnershipNow(final AppContext disposedContext) {
        final SunClipboard sunClipboard = SunClipboard.this;
        ClipboardOwner owner = null;
        Transferable contents = null;

        synchronized (sunClipboard) {
            final AppContext context = sunClipboard.contentsContext;

            if (context == null) {
                return;
            }

            if (disposedContext == null || context == disposedContext) {
                owner = sunClipboard.owner;
                contents = sunClipboard.contents;
                sunClipboard.contentsContext = null;
                sunClipboard.owner = null;
                sunClipboard.contents = null;
                sunClipboard.clearNativeContext();
                context.removePropertyChangeListener
                        (AppContext.DISPOSED_PROPERTY_NAME, sunClipboard);
            } else {
                return;
            }
        }
        if (owner != null) {
            owner.lostOwnership(sunClipboard, contents);
        }
    }


    protected abstract void clearNativeContext();

    protected abstract void setContentsNative(Transferable contents);

    /**
     * @since 1.5
     */
    protected long[] getClipboardFormatsOpenClose() {
        return getClipboardFormats();
    }

    /**
     * Returns zero-length array (not null) if the number of available formats is zero.
     *
     * @throws IllegalStateException if formats could not be retrieved
     */
    protected abstract long[] getClipboardFormats();

    protected abstract byte[] getClipboardData(long format) throws IOException;


    private static Set<DataFlavor> formatArrayAsDataFlavorSet(long[] formats) {
        return (formats == null) ? null :
                DataTransferer.getInstance().
                getFlavorsForFormatsAsSet(formats, getDefaultFlavorTable());
    }


    public synchronized void addFlavorListener(FlavorListener listener) {
        if (listener == null) {
            return;
        }
        AppContext appContext = AppContext.getAppContext();
        Set<FlavorListener> flavorListeners = getFlavorListeners(appContext);
        if (flavorListeners == null) {
            flavorListeners = new HashSet<>();
            appContext.put(CLIPBOARD_FLAVOR_LISTENER_KEY, flavorListeners);
        }
        flavorListeners.add(listener);

        if (numberOfFlavorListeners++ == 0) {
            this.currentFormats = getClipboardFormats();

            registerClipboardViewerChecked();
        }
    }

    public synchronized void removeFlavorListener(FlavorListener listener) {
        if (listener == null) {
            return;
        }
        Set<FlavorListener> flavorListeners = getFlavorListeners(AppContext.getAppContext());
        if (flavorListeners == null){
            //else we throw NullPointerException, but it is forbidden
            return;
        }
        if (flavorListeners.remove(listener) && --numberOfFlavorListeners == 0) {
            unregisterClipboardViewerChecked();
            currentFormats = null;
        }
    }

    @SuppressWarnings("unchecked")
    private Set<FlavorListener> getFlavorListeners(AppContext appContext) {
        return (Set<FlavorListener>)appContext.get(CLIPBOARD_FLAVOR_LISTENER_KEY);
    }

    public synchronized FlavorListener[] getFlavorListeners() {
        Set<FlavorListener> flavorListeners = getFlavorListeners(AppContext.getAppContext());
        return flavorListeners == null ? new FlavorListener[0]
                : flavorListeners.toArray(new FlavorListener[flavorListeners.size()]);
    }

    public boolean areFlavorListenersRegistered() {
        return (numberOfFlavorListeners > 0);
    }

    protected abstract void registerClipboardViewerChecked();

    protected abstract void unregisterClipboardViewerChecked();

    /**
     * Checks change of the {@code DataFlavor}s and, if necessary,
     * posts notifications on {@code FlavorEvent}s to the
     * AppContexts' EDTs.
     * The parameter {@code formats} is null iff we have just
     * failed to get formats available on the clipboard.
     *
     * @param formats data formats that have just been retrieved from
     *        this clipboard
     */
    protected final void checkChange(final long[] formats) {
        if (Arrays.equals(formats, currentFormats)) {
            // we've been able to successfully get available on the clipboard
            // DataFlavors this and previous time and they are coincident;
            // don't notify
            return;
        }
        currentFormats = formats;

        for (final AppContext appContext : AppContext.getAppContexts()) {
            if (appContext == null || appContext.isDisposed()) {
                continue;
            }
            Set<FlavorListener> flavorListeners = getFlavorListeners(appContext);
            if (flavorListeners != null) {
                for (FlavorListener listener : flavorListeners) {
                    if (listener != null) {
                        PeerEvent peerEvent = new PeerEvent(this,
                                () -> listener.flavorsChanged(new FlavorEvent(SunClipboard.this)),
                                PeerEvent.PRIORITY_EVENT);
                        SunToolkit.postEvent(appContext, peerEvent);
                    }
                }
            }
        }
    }

    public static FlavorTable getDefaultFlavorTable() {
        return (FlavorTable) SystemFlavorMap.getDefaultFlavorMap();
    }
}