libjava/java/awt/Toolkit.java

/* 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.event.*;
import java.awt.peer.*;
import java.awt.image.*;
import java.awt.datatransfer.Clipboard;
import java.util.Properties;
import java.net.URL;
import java.beans.*;

/**
  * 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 (arenn@urbanophile.com)
  */
public abstract class Toolkit
{

/*
 * Static Variables
 */

// The default toolkit name.
private static String default_toolkit_name = 
  "gnu.java.awt.peer.gtk.GtkToolkit";

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

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

private PropertyChangeSupport changeSupport = new PropertyChangeSupport(this);

private Properties desktopProperties = new Properties();

/*************************************************************************/

/*
 * Static Methods
 */

/**
  * Returns an instance of the default toolkit.  The default toolkit is
  * the subclass of <code>Toolkit</code> specified in the system property
  * <code>awt.toolkit</code>, or <code>gnu.java.awt.peer.gtk.GtkToolkit</code>
  * if the property is not set.
  *
  * @return An instance of the system default toolkit.
  *
  * @error AWTError If the toolkit cannot be loaded.
  */
public static Toolkit
getDefaultToolkit()
{
  if (toolkit != null)
    return(toolkit);

  String toolkit_name = System.getProperty("awt.toolkit",
					   default_toolkit_name);

  try
    {
      Class cls = Class.forName(toolkit_name);
      Object obj = cls.newInstance();

      if (!(obj instanceof Toolkit))
        throw new AWTError(toolkit_name + " is not a subclass of " +
                           "java.awt.Toolkit");

      toolkit = (Toolkit)obj;
      return(toolkit);
    }
  catch(Exception e)
    {
      throw new AWTError("Cannot load AWT toolkit: " + e.getMessage());
    }
}

/*************************************************************************/

/**
  * Returns the value of the property with the specified name, or the
  * default value if the property does not exist.
  *
  * @param key The name of the property to retrieve.
  * @param defThe default value of the property.
  */
public static String
getProperty(String key, String def)
{
  return(props.getProperty(key, def));
}

/*************************************************************************/

/**
  * Returns the native container object of the specified component.  This
  * method is necessary because the parent component might be a lightweight
  * component.
  *
  * @param component The component to fetch the native container for.
  *
  * @return The native container object for this component.
  */
protected static Container
getNativeContainer(Component component)
{
  component = component.getParent();

  for(;;)
    {
      if (component == null)
        return(null);

      if (!(component instanceof Container))
        {
          component = component.getParent();
          continue;
        }

      if (component.getPeer() instanceof LightweightPeer)
        {
          component = component.getParent();
          continue;
        } 

      return((Container)component);
    }
}

/*************************************************************************/

/*
 * Constructors
 */

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

/*************************************************************************/

/*
 * Instance Methods
 */

/**
  * 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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
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.
  */
protected void
loadSystemColors(int systemColors[])
{
}

/*************************************************************************/

/**
  * Returns the dimensions of the screen in pixels.
  *
  * @return The dimensions of the screen in pixels.
  */
public abstract Dimension
getScreenSize();

/*************************************************************************/

/**
  * Returns the screen resolution in dots per square inch.
  *
  * @return The screen resolution in dots per square inch.
  */
public abstract int
getScreenResolution();

/*************************************************************************/

/**
  * Returns the color model of the screen.
  *
  * @return The color model of the screen.
  */
public abstract ColorModel
getColorModel();

/*************************************************************************/

/**
  * Returns the names of the available fonts.
  *
  * @return The names of the available fonts.
  */
public abstract String[]
getFontList();

/*************************************************************************/

/**
  * Return the font metrics for the specified font
  *
  * @param name The name of the font to return metrics for.
  *
  * @return The requested font metrics.
  */
public abstract FontMetrics
getFontMetrics(Font name);

/*************************************************************************/

/**
  * Flushes any buffered data to the screen so that it is in sync with 
  * what the AWT system has drawn to it.
  */
public abstract void
sync();

/*************************************************************************/

/**
  * Returns an image from the specified file, which must be in a 
  * recognized format.  Supported formats vary from toolkit to toolkit.
  *
  * @return name The name of the file to read the image from.
  */
public abstract Image
getImage(String name);

/*************************************************************************/

/**
  * Returns an image from the specified URL, which must be in a 
  * recognized format.  Supported formats vary from toolkit to toolkit.
  *
  * @return url The URl to read the image from.
  */
public abstract Image
getImage(URL url);

/*************************************************************************/

/**
  * Readies an image to be rendered on the screen.  The width and height
  * values can be set to the default sizes for the image by passing -1
  * in those parameters.
  *
  * @param image The image to prepare for rendering.
  * @param width The width of the image.
  * @param height The height of the image.
  * @param observer The observer to receive events about the preparation
  * process.
  *
  * @return <code>true</code> if the image is already prepared for rendering,
  * <code>false</code> otherwise.
  */
public abstract boolean
prepareImage(Image image, int width, int height, ImageObserver observer);

/*************************************************************************/

/**
  * Checks the status of specified image as it is being readied for 
  * rendering.
  *
  * @param image The image to prepare for rendering.
  * @param width The width of the image.
  * @param height The height of the image.
  * @param observer The observer to receive events about the preparation
  * process.
  *
  * @return A union of the bitmasks from 
  * <code>java.awt.image.ImageObserver</code> that indicates the current
  * state of the imaging readying process.
  */
public abstract int
checkImage(Image image, int width, int height, ImageObserver observer);

/*************************************************************************/

/**
  * Creates an image using the specified <code>ImageProducer</code>
  *
  * @param producer The <code>ImageProducer</code> to create the image from.
  *
  * @return The created image.
  */
public abstract Image
createImage(ImageProducer producer);

/*************************************************************************/

/**
  * Creates an image from the specified portion of the byte array passed.
  * The array must be in a recognized format.  Supported formats vary from
  * toolkit to toolkit.
  *
  * @param data The raw image data.
  * @param offset The offset into the data where the image data starts.
  * @param len The length of the image data.
  *
  * @return The created image.
  */
public abstract Image
createImage(byte[] data, int offset, int len);

/*************************************************************************/

/**
  * Creates an image from the specified byte array. The array must be in
  * a recognized format.  Supported formats vary from toolkit to toolkit.
  *
  * @param data The raw image data.
  *
  * @return The created image.
  */
public Image
createImage(byte[] data)
{
  return(createImage(data, 0, data.length));
}

public abstract Image
createImage(String filename);

public abstract Image
createImage(URL url);


/*************************************************************************/

/**
  * Returns a instance of <code>PrintJob</code> for the specified 
  * arguments.
  *
  * @param frame The window initiating the print job.
  * @param title The print job title.
  * @param props The print job properties.
  *
  * @return The requested print job, or <code>null</code> if the job
  * was cancelled.
  */
public abstract PrintJob
getPrintJob(Frame frame, String title, Properties props);

/*************************************************************************/

/**
  * Returns the system clipboard.
  *
  * @return THe system clipboard.
  */
public abstract Clipboard
getSystemClipboard();

/*************************************************************************/

/**
  * Returns the accelerator key mask for menu shortcuts. The default is
  * <code>Event.CTRL_MASK</code>.  A toolkit must override this method
  * to change the default.
  *
  * @return The key mask for the menu accelerator key.
  */
public int
getMenuShortcutKeyMask()
{
  return Event.CTRL_MASK;
}

public boolean
getLockingKeyState(int keyCode)
{
  if (keyCode != KeyEvent.VK_CAPS_LOCK
      && keyCode != KeyEvent.VK_NUM_LOCK
      && keyCode != KeyEvent.VK_SCROLL_LOCK)
    throw new IllegalArgumentException();

  throw new UnsupportedOperationException();
}

public void
setLockingKeyState(int keyCode, boolean on)
{
  if (keyCode != KeyEvent.VK_CAPS_LOCK
      && keyCode != KeyEvent.VK_NUM_LOCK
      && keyCode != KeyEvent.VK_SCROLL_LOCK)
    throw new IllegalArgumentException();

  throw new UnsupportedOperationException();
}

/*************************************************************************/

/**
  * Returns the event queue for the applet.  Despite the word "System"
  * in the name of this method, there is no guarantee that the same queue
  * is shared system wide.
  *
  * @return The event queue for this applet (or application)
  */
public final EventQueue
getSystemEventQueue()
{
  return(getSystemEventQueueImpl());
}

/*************************************************************************/

/**
  * // FIXME: What does this do?
  */
protected abstract EventQueue
getSystemEventQueueImpl();

/*************************************************************************/

/**
  * Causes a "beep" tone to be generated.
  */
public abstract void
beep();

public Cursor
createCustomCursor(Image cursor, Point hotSpot, String name)
  throws IndexOutOfBoundsException
{
  // Presumably the only reason this isn't abstract is for backwards
  // compatibility? FIXME?
  return null;
}

public Dimension
getBestCursorSize(int preferredWidth, int preferredHeight)
{
  return new Dimension (0,0);
}

public int
getMaximumCursorColors()
{
  return 0;
}

public final Object
getDesktopProperty(String propertyName)
{
  return desktopProperties.get(propertyName);
}

protected final void
setDesktopProperty(String name, Object newValue)
{
  Object oldValue = getDesktopProperty(name);
  desktopProperties.put(name, newValue);
  changeSupport.firePropertyChange(name, oldValue, newValue);
}
protected Object
lazilyLoadDesktopProperty(String name)
{
  // FIXME - what is this??
  return null;
}

protected void
initializeDesktopProperties()
{
  // Overridden by toolkit implementation?
}

public void
addPropertyChangeListener(String name, PropertyChangeListener pcl)
{
  changeSupport.addPropertyChangeListener(name, pcl);
}
  
public void
removePropertyChangeListener(String name, PropertyChangeListener pcl)
{
  changeSupport.removePropertyChangeListener(name, pcl);
}

public void
addAWTEventListener(AWTEventListener listener, long eventMask)
{
  // SecurityManager s = System.getSecurityManager();
  // if (s != null)
  //  s.checkPermission(AWTPermission("listenToAllAWTEvents"));

  // FIXME
}

public void
removeAWTEventListener(AWTEventListener listener)
{
  // FIXME
}

} // class Toolkit