source: trunk/gcc/libjava/java/awt/Toolkit.java@ 3148

/* Toolkit.java -- AWT Toolkit superclass
   Copyright (C) 1999, 2000, 2001, 2002 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., 59 Temple Place, Suite 330, Boston, MA
02111-1307 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 java.awt;

import java.awt.datatransfer.Clipboard;
import java.awt.dnd.DragGestureEvent;
import java.awt.dnd.DragGestureListener;
import java.awt.dnd.DragGestureRecognizer;
import java.awt.dnd.DragSource;
import java.awt.dnd.peer.DragSourceContextPeer;
import java.awt.event.AWTEventListener;
import java.awt.event.KeyEvent;
import java.awt.im.InputMethodHighlight;
import java.awt.image.ColorModel;
import java.awt.image.ImageObserver;
import java.awt.image.ImageProducer;
import java.awt.peer.ButtonPeer;
import java.awt.peer.CanvasPeer;
import java.awt.peer.CheckboxPeer;
import java.awt.peer.CheckboxMenuItemPeer;
import java.awt.peer.ChoicePeer;
import java.awt.peer.DialogPeer;
import java.awt.peer.FileDialogPeer;
import java.awt.peer.FontPeer;
import java.awt.peer.FramePeer;
import java.awt.peer.LabelPeer;
import java.awt.peer.LightweightPeer;
import java.awt.peer.ListPeer;
import java.awt.peer.MenuPeer;
import java.awt.peer.MenuBarPeer;
import java.awt.peer.MenuItemPeer;
import java.awt.peer.PanelPeer;
import java.awt.peer.PopupMenuPeer;
import java.awt.peer.ScrollbarPeer;
import java.awt.peer.ScrollPanePeer;
import java.awt.peer.TextAreaPeer;
import java.awt.peer.TextFieldPeer;
import java.awt.peer.WindowPeer;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.net.URL;
import java.util.Map;
import java.util.Properties;

/**
 * The AWT system uses a set of native peer objects to implement its
 * widgets.  These peers are provided by a peer toolkit, that is accessed
 * via a subclass of this superclass.  The system toolkit is retrieved
 * by the static methods <code>getDefaultToolkit</code>.  This method
 * determines the system toolkit by examining the system property
 * <code>awt.toolkit</code>.  That property is set to the name of the
 * <code>Toolkit</code> subclass for the specified peer set.  If the
 * <code>awt.toolkit</code> property is not set, then the default
 * toolkit <code>gnu.java.awt.peer.gtk.GtkToolkit</code> is used.  This
 * toolkit creates its peers using the GTK+ toolkit.
 *
 * @author Aaron M. Renn <[email protected]>
 */
public abstract class Toolkit
{
  /** The default toolkit name. */
  private static String default_toolkit_name
    = "gnu.awt.gtk.GtkToolkit";

  /**
   * The toolkit in use.  Once we load it, we don't ever change it
   * if the awt.toolkit property is set.
   */
  private static Toolkit toolkit;

  /** The toolkit properties. */
  private static Properties props = new Properties();

  protected final Map desktopProperties = new Properties();

  protected final PropertyChangeSupport desktopPropsSupport
    = new PropertyChangeSupport(this);

  /**
   * Default constructor for subclasses.
   */
  public Toolkit()
  {
  }

  /**
   * Creates a peer object for the specified <code>Button</code>.
   *
   * @param target The <code>Button</code> to create the peer for.
   * 
   * @return The peer for the specified <code>Button</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract ButtonPeer createButton(Button target);

  /**
   * Creates a peer object for the specified <code>TextField</code>.
   *
   * @param target The <code>TextField</code> to create the peer for.
   * @return The peer for the specified <code>TextField</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract TextFieldPeer createTextField(TextField target);

  /**
   * Creates a peer object for the specified <code>Label</code>.
   *
   * @param target The <code>Label</code> to create the peer for.
   * @return The peer for the specified <code>Label</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract LabelPeer createLabel(Label target);

  /**
   * Creates a peer object for the specified <code>List</code>.
   *
   * @param target The <code>List</code> to create the peer for.
   * @return The peer for the specified <code>List</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract ListPeer createList(List target);

  /**
   * Creates a peer object for the specified <code>Checkbox</code>.
   *
   * @param target The <code>Checkbox</code> to create the peer for.
   * @return The peer for the specified <code>Checkbox</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract CheckboxPeer createCheckbox(Checkbox target);

  /**
   * Creates a peer object for the specified <code>Scrollbar</code>.
   *
   * @param target The <code>Scrollbar</code> to create the peer for.
   * @return The peer for the specified <code>Scrollbar</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract ScrollbarPeer createScrollbar(Scrollbar target);

  /**
   * Creates a peer object for the specified <code>ScrollPane</code>.
   *
   * @param target The <code>ScrollPane</code> to create the peer for.
   * @return The peer for the specified <code>ScrollPane</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract ScrollPanePeer createScrollPane(ScrollPane target);

  /**
   * Creates a peer object for the specified <code>TextArea</code>.
   *
   * @param target The <code>TextArea</code> to create the peer for.
   * @return The peer for the specified <code>TextArea</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract TextAreaPeer createTextArea(TextArea target);

  /**
   * Creates a peer object for the specified <code>Choice</code>.
   *
   * @param target The <code>Choice</code> to create the peer for.
   * @return The peer for the specified <code>Choice</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract ChoicePeer createChoice(Choice target);

  /**
   * Creates a peer object for the specified <code>Frame</code>.
   *
   * @param target The <code>Frame</code> to create the peer for.
   * @return The peer for the specified <code>Frame</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract FramePeer createFrame(Frame target);

  /**
   * Creates a peer object for the specified <code>Canvas</code>.
   *
   * @param target The <code>Canvas</code> to create the peer for.
   * @return The peer for the specified <code>Canvas</code> object.
   */
  protected abstract CanvasPeer createCanvas(Canvas target);

  /**
   * Creates a peer object for the specified <code>Panel</code>.
   *
   * @param target The <code>Panel</code> to create the peer for.
   * @return The peer for the specified <code>Panel</code> object.
   */
  protected abstract PanelPeer createPanel(Panel target);

  /**
   * Creates a peer object for the specified <code>Window</code>.
   *
   * @param target The <code>Window</code> to create the peer for.
   * @return The peer for the specified <code>Window</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract WindowPeer createWindow(Window target);

  /**
   * Creates a peer object for the specified <code>Dialog</code>.
   *
   * @param target The dialog to create the peer for
   * @return The peer for the specified font name.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract DialogPeer createDialog(Dialog target);

  /**
   * Creates a peer object for the specified <code>MenuBar</code>.
   *
   * @param target The <code>MenuBar</code> to create the peer for.
   * @return The peer for the specified <code>MenuBar</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract MenuBarPeer createMenuBar(MenuBar target);

  /**
   * Creates a peer object for the specified <code>Menu</code>.
   *
   * @param target The <code>Menu</code> to create the peer for.
   * @return The peer for the specified <code>Menu</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract MenuPeer createMenu(Menu target);

  /**
   * Creates a peer object for the specified <code>PopupMenu</code>.
   *
   * @param target The <code>PopupMenu</code> to create the peer for.
   * @return The peer for the specified <code>PopupMenu</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract PopupMenuPeer createPopupMenu(PopupMenu target);

  /**
   * Creates a peer object for the specified <code>MenuItem</code>.
   *
   * @param target The <code>MenuItem</code> to create the peer for.
   * @return The peer for the specified <code>MenuItem</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract MenuItemPeer createMenuItem(MenuItem target);

  /**
   * Creates a peer object for the specified <code>FileDialog</code>.
   *
   * @param target The <code>FileDialog</code> to create the peer for.
   * @return The peer for the specified <code>FileDialog</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract FileDialogPeer createFileDialog(FileDialog target);

  /**
   * Creates a peer object for the specified <code>CheckboxMenuItem</code>.
   *
   * @param target The <code>CheckboxMenuItem</code> to create the peer for.
   * @return The peer for the specified <code>CheckboxMenuItem</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected abstract CheckboxMenuItemPeer
    createCheckboxMenuItem(CheckboxMenuItem target);

  /**
   * Creates a peer object for the specified <code>Component</code>.  The
   * peer returned by this method is not a native windowing system peer
   * with its own native window.  Instead, this method allows the component
   * to draw on its parent window as a "lightweight" widget.
   *
   * XXX: FIXME
   *
   * @param target The <code>Component</code> to create the peer for.
   * @return The peer for the specified <code>Component</code> object.
   */
  protected LightweightPeer createComponent(Component target)
  {
    return null;
  }

  /**
   * Creates a peer object for the specified font name.
   *
   * @param name The font to create the peer for.
   * @param style The font style to create the peer for.
   * @return The peer for the specified font name.
   */
  protected abstract FontPeer getFontPeer(String name, int style);

  /**
   * Copies the current system colors into the specified array.  This is
   * the interface used by the <code>SystemColors</code> class.
   *
   * @param colors The array to copy the system colors into.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected void loadSystemColors(int systemColors[])
  {
    // XXX Implement.
  }

  /**
   * @since 1.4
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  public void setDynamicLayout(boolean dynamic)
  {
  }

  /**
   * @since 1.4
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  protected boolean isDynamicLayoutSet()
  {
    return false;
  }

  /**
   * @since 1.4
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  public boolean isDynamicLayoutActive()
  {
    return false;
  }

  /**
   * Returns the dimensions of the screen in pixels.
   *
   * @return The dimensions of the screen in pixels.
   * 
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  public abstract Dimension getScreenSize();

  /**
   * Returns the screen resolution in dots per square inch.
   *
   * @return The screen resolution in dots per square inch.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   */
  public abstract int getScreenResolution();

  /**
   * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true.
   *
   * @since 1.4
   */
  public Insets getScreenInsets(GraphicsConfiguration gc)
  {
    return null;
  }

  /**
   * Returns the color model of the screen.
   *
   * @return The color model of the screen.