peer/gtk/GtkClipboard.java

/* GtkClipboard.java
   Copyright (C) 1999, 2005, 2006 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package gnu.java.awt.peer.gtk;

import gnu.java.lang.CPStringBuilder;

import java.awt.Image;

import java.awt.datatransfer.Clipboard;
import java.awt.datatransfer.ClipboardOwner;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.StringSelection;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.InputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Reader;
import java.io.Serializable;
import java.io.UnsupportedEncodingException;

import java.util.List;
import java.util.Iterator;

public class GtkClipboard extends Clipboard
{
  /**
   * The one and only gtk+ clipboard instance for the CLIPBOARD selection.
   */
  final static GtkClipboard clipboard = new GtkClipboard("System Clipboard");

  /**
   * The one and only gtk+ clipboard instance for the PRIMARY selection.
   */
  final static GtkClipboard selection = new GtkClipboard("System Selection");

  // Given to the native side so it can signal special targets that
  // can be converted to one of the special predefined DataFlavors.
  static final String stringMimeType
    = DataFlavor.stringFlavor.getMimeType();
  static final String imageMimeType
    = DataFlavor.imageFlavor.getMimeType();
  static final String filesMimeType
    = DataFlavor.javaFileListFlavor.getMimeType();

  // Indicates whether the results of the clipboard selection can be
  // cached by GtkSelection. True if
  // gdk_display_supports_selection_notification.
  static final boolean canCache = initNativeState(clipboard, selection,
                                                  stringMimeType,
                                                  imageMimeType,
                                                  filesMimeType);

  /**
   * Creates the clipboard and sets the initial contents to the
   * current gtk+ selection.
   */
  private GtkClipboard(String name)
  {
    super(name);
    setContents(new GtkSelection(this), null);
  }

  /**
   * Returns the one and only GtkClipboard instance for the CLIPBOARD
   * selection.
   */
  static GtkClipboard getClipboardInstance()
  {
    return clipboard;
  }

  /**
   * Returns the one and only GtkClipboard instance for the PRIMARY
   * selection.
   */
  static GtkClipboard getSelectionInstance()
  {
    return selection;
  }

  /**
   * Sets the GtkSelection facade as new contents of the clipboard.
   * Called from gtk+ when another application grabs the clipboard and
   * we loose ownership.
   *
   * @param cleared If true this is a clear event (someone takes the
   * clipboard from us) otherwise it is an owner changed event.
   */
  private synchronized void setSystemContents(boolean cleared)
  {
    // We need to notify clipboard owner listeners when we were the
    // owner (the selection was explictly set) and someone takes the
    // clipboard away from us and asks us the clear any held storage,
    // or if we weren't the owner of the clipboard to begin with, but
    // the clipboard contents changed. We could refine this and check
    // whether the actual available formats did in fact change, but we
    // assume listeners will check for that anyway (and if possible we
    // ask to cache the available formats so even if multiple
    // listeners check after a notification the overhead should be
    // minimal).
    boolean owner = ! (contents instanceof GtkSelection);
    boolean needNotification = (cleared && owner) || (! cleared && ! owner);
    if (needNotification)
      GtkClipboardNotifier.announce(this);
  }

  /**
   * Sets the new contents and advertises the available flavors to the
   * gtk+ clipboard.
   */
  public synchronized void setContents(Transferable contents,
                                       ClipboardOwner owner)
  {
    super.setContents(contents, owner);

    if (contents == null)
      {
        advertiseContent(null, false, false, false);
        return;
      }

    // We don't need to do anything for a GtkSelection facade.
    if (contents instanceof GtkSelection)
      return;

    boolean text = false;
    boolean images = false;
    boolean files = false;

    if (contents instanceof StringSelection
        || contents.isDataFlavorSupported(DataFlavor.stringFlavor)
        || contents.isDataFlavorSupported(DataFlavor.plainTextFlavor)
        || contents.isDataFlavorSupported(DataFlavor.getTextPlainUnicodeFlavor()))
      text = true;

    DataFlavor[] flavors = contents.getTransferDataFlavors();
    String[] mimeTargets = new String[flavors.length];
    for (int i = 0; i < flavors.length; i++)
      {
        DataFlavor flavor = flavors[i];
        String mimeType = flavor.getMimeType();
        mimeTargets[i] = mimeType;

        if (! text)
          if ("text".equals(flavor.getPrimaryType())
              || flavor.isRepresentationClassReader())
            text = true;

        if (! images && flavors[i].equals(DataFlavor.imageFlavor))
          {
            try
              {
                Object o = contents.getTransferData(DataFlavor.imageFlavor);
                if (o instanceof Image)
                  images = true;
              }
            catch (UnsupportedFlavorException ufe)
              {
              }
            catch (IOException ioe)
              {
              }
            catch (ClassCastException cce)
              {
              }
          }

        if (flavors[i].equals(DataFlavor.javaFileListFlavor))
          files = true;
      }

    advertiseContent(mimeTargets, text, images, files);
  }

  /**
   * Advertises new contents to the gtk+ clipboard given a string
   * array of (mime-type) targets. When the boolean flags text, images
   * and/or files are set then gtk+ is asked to also advertise the
   * availability of any text, image or uri/file content types it
   * supports. If targets is null (and all flags false) then the
   * selection has explicitly been erased.
   */
  private native void advertiseContent(String[] targets,
                                       boolean text,
                                       boolean images,
                                       boolean files);

  /**
   * Called by the gtk+ clipboard when an application has requested
   * text.  Return a string representing the current clipboard
   * contents or null when no text can be provided.
   */
  private String provideText()
  {
    Transferable contents = this.contents;
    if (contents == null || contents instanceof GtkSelection)
      return null;

    // Handle StringSelection special since that is just pure text.
    if (contents instanceof StringSelection)
      {
        try
          {
            return (String) contents.getTransferData(DataFlavor.stringFlavor);
          }
        catch (UnsupportedFlavorException ufe)
          {
          }
        catch (IOException ioe)
          {
          }
        catch (ClassCastException cce)
          {
          }
      }

    // Try to get a plain text reader for the current contents and
    // turn the result into a string.
    try
      {
        DataFlavor plainText = DataFlavor.getTextPlainUnicodeFlavor();
        Reader r = plainText.getReaderForText(contents);
        if (r != null)
          {
            CPStringBuilder sb = new CPStringBuilder();
            char[] cs = new char[1024];
            int l = r.read(cs);
            while (l != -1)
              {
                sb.append(cs, 0, l);
                l = r.read(cs);
              }
            return sb.toString();
          }
      }
    catch (IllegalArgumentException iae)
      {
      }
    catch (UnsupportedEncodingException iee)
      {
      }
    catch (UnsupportedFlavorException ufe)
      {
      }
    catch (IOException ioe)
      {
      }

    return null;
  }

  /**
   * Called by the gtk+ clipboard when an application has requested an
   * image.  Returns a GtkImage representing the current clipboard
   * contents or null when no image can be provided.
   */
  private GtkImage provideImage()
  {
    Transferable contents = this.contents;
    if (contents == null || contents instanceof GtkSelection)
      return null;

    try
      {
        Object o = contents.getTransferData(DataFlavor.imageFlavor);
        if( o instanceof GtkImage )
          return (GtkImage) o;
        else
          return new GtkImage(((Image)o).getSource());
      }
    catch (UnsupportedFlavorException ufe)
      {
      }
    catch (IOException ioe)
      {
      }
    catch (ClassCastException cce)
      {
      }

    return null;
  }

  /**
   * Called by the gtk+ clipboard when an application has requested a
   * uri-list.  Return a string array containing the URIs representing
   * the current clipboard contents or null when no URIs can be
   * provided.
   */
  private String[] provideURIs()
  {
    Transferable contents = this.contents;
    if (contents == null || contents instanceof GtkSelection)
      return null;

    try
      {
        List list = (List) contents.getTransferData(DataFlavor.javaFileListFlavor);
        String[] uris = new String[list.size()];
        int u = 0;
        Iterator it = list.iterator();
        while (it.hasNext())
          uris[u++] = ((File) it.next()).toURI().toString();
        return uris;
      }
    catch (UnsupportedFlavorException ufe)
      {
      }
    catch (IOException ioe)
      {
      }
    catch (ClassCastException cce)
      {
      }

    return null;
  }

  /**
   * Called by gtk+ clipboard when an application requests the given
   * target mime-type. Returns a byte array containing the requested
   * data, or null when the contents cannot be provided in the
   * requested target mime-type. Only called after any explicit text,
   * image or file/uri requests have been handled earlier and failed.
   */
  private byte[] provideContent(String target)
  {
    // Sanity check. The callback could be triggered just after we
    // changed the clipboard.
    Transferable contents = this.contents;
    if (contents == null || contents instanceof GtkSelection)
      return null;

    // XXX - We are being called from a gtk+ callback. Which means we
    // should return as soon as possible and not call arbitrary code
    // that could deadlock or go bonkers. But we don't really know
    // what DataTransfer contents object we are dealing with. Same for
    // the other provideXXX() methods.
    try
      {
        DataFlavor flavor = new DataFlavor(target);
        Object o = contents.getTransferData(flavor);

        if (o instanceof byte[])
          return (byte[]) o;

        if (o instanceof InputStream)
          {
            InputStream is = (InputStream) o;
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] bs = new byte[1024];
            int l = is.read(bs);
            while (l != -1)
              {
                baos.write(bs, 0, l);
                l = is.read(bs);
              }
            return baos.toByteArray();
          }

        if (o instanceof Serializable)
          {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            ObjectOutputStream oos = new ObjectOutputStream(baos);
            oos.writeObject(o);
            oos.close();
            return baos.toByteArray();
          }
      }
    catch (ClassNotFoundException cnfe)
      {
      }
    catch (UnsupportedFlavorException ufe)
      {
      }
    catch (IOException ioe)
      {
      }
    catch (ClassCastException cce)
      {
      }

    return null;
  }

  /**
   * Initializes the gtk+ clipboards and caches any native side
   * structures needed. Returns whether or not the contents of the
   * Clipboard can be cached (gdk_display_supports_selection_notification).
   */
  private static native boolean initNativeState(GtkClipboard clipboard,
                                                GtkClipboard selection,
                                                String stringTarget,
                                                String imageTarget,
                                                String filesTarget);
}