defaultcaret.java

gcc的组建

/* DefaultCaret.java --
   Copyright (C) 2002, 2004, 2005 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 javax.swing.text;

import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.EventListener;

import javax.swing.JComponent;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.event.EventListenerList;

/**
 * The default implementation of the {@link Caret} interface.
 *
 * @author orgininal author unknown
 * @author Roman Kennke ([e-mail])
 */
public class DefaultCaret extends Rectangle
  implements Caret, FocusListener, MouseListener, MouseMotionListener
{

  /**
   * Controls the blinking of the caret.
   *
   * @author Roman Kennke ([e-mail])
   * @author Audrius Meskauskas ([e-mail])
   */
  private class BlinkTimerListener implements ActionListener
  {
    /**
     * Forces the next event to be ignored. The next event should be ignored
     * if we force the caret to appear. We do not know how long will it take
     * to fire the comming event; this may be near immediately. Better to leave
     * the caret visible one iteration longer.
     */
    boolean ignoreNextEvent;
    
    /**
     * Receives notification when the blink timer fires and updates the visible
     * state of the caret.
     * 
     * @param event the action event
     */
    public void actionPerformed(ActionEvent event)
    {
      if (ignoreNextEvent)
        ignoreNextEvent = false;
      else
        {
          visible = !visible;
          repaint();
        }
    }
  }

  /**
   * Listens for changes in the text component's document and updates the
   * caret accordingly.
   * 
   * @author Roman Kennke ([e-mail])
   */
  private class DocumentHandler implements DocumentListener
  {
    /**
     * Receives notification that some text attributes have changed. No action
     * is taken here.
     *
     * @param event the document event
     */
    public void changedUpdate(DocumentEvent event)
    {
      // Nothing to do here.
    }

    /**
     * Receives notification that some text has been inserted from the text
     * component. The caret is moved forward accordingly.
     *
     * @param event the document event
     */
    public void insertUpdate(DocumentEvent event)
    {
      if (policy == ALWAYS_UPDATE || 
          (SwingUtilities.isEventDispatchThread() && 
           policy == UPDATE_WHEN_ON_EDT))
        {        
          int dot = getDot();
          setDot(dot + event.getLength());
        }
    }

    /**
     * Receives notification that some text has been removed into the text
     * component. The caret is moved backwards accordingly.
     *
     * @param event the document event
     */
    public void removeUpdate(DocumentEvent event)
    {
      if (policy == ALWAYS_UPDATE || 
          (SwingUtilities.isEventDispatchThread() && 
           policy == UPDATE_WHEN_ON_EDT))
        {
          int dot = getDot();
          setDot(dot - event.getLength());
        }
      else if (policy == NEVER_UPDATE)
        {
          int docLength = event.getDocument().getLength();
          if (getDot() > docLength)
            setDot(docLength);
        }
    }
  }

  /**
   * Listens for property changes on the text document. This is used to add and
   * remove our document listener, if the document of the text component has
   * changed.
   *
   * @author Roman Kennke ([e-mail])
   */
  private class PropertyChangeHandler implements PropertyChangeListener
  {

    /**
     * Receives notification when a property has changed on the text component.
     * This adds/removes our document listener from the text component's
     * document when the document changes.
     *
     * @param e the property change event
     */
    public void propertyChange(PropertyChangeEvent e)
    {
      if (e.getPropertyName().equals("document"))
        {
          Document oldDoc = (Document) e.getOldValue();
          oldDoc.removeDocumentListener(documentListener);
          Document newDoc = (Document) e.getNewValue();
          newDoc.addDocumentListener(documentListener);
        }
    }
    
  }

  /** The serialization UID (compatible with JDK1.5). */
  private static final long serialVersionUID = 4325555698756477346L;
  
  /**
   * Indicates the Caret position should always be updated after Document
   * changes even if the updates are not performed on the Event Dispatching
   * thread.
   * 
   * @since 1.5
   */
  public static final int ALWAYS_UPDATE = 2;

  /**
   * Indicates the Caret position should not be changed unless the Document
   * length becomes less than the Caret position, in which case the Caret
   * is moved to the end of the Document.
   * 
   * @since 1.5
   */
  public static final int NEVER_UPDATE = 1;
  
  /** 
   * Indicates the Caret position should be updated only if Document changes
   * are made on the Event Dispatcher thread.
   *  
   * @since 1.5
   */
  public static final int UPDATE_WHEN_ON_EDT = 0;
  
  /** Keeps track of the current update policy **/
  int policy = UPDATE_WHEN_ON_EDT;
    
  /**
   * The <code>ChangeEvent</code> that is fired by {@link #fireStateChanged()}.
   */
  protected ChangeEvent changeEvent = new ChangeEvent(this);

  /**
   * Stores all registered event listeners.
   */
  protected EventListenerList listenerList = new EventListenerList();

  /**
   * Our document listener.
   */
  DocumentListener documentListener;

  /**
   * Our property listener.
   */
  PropertyChangeListener propertyChangeListener;

  /**
   * The text component in which this caret is installed.
   */
  private JTextComponent textComponent;

  /**
   * Indicates if the selection should be visible or not.
   */
  private boolean selectionVisible = true;

  /**
   * The blink rate of this <code>Caret</code>.
   */
  private int blinkRate = 500;

  /**
   * The current dot position.
   */
  private int dot = 0;

  /**
   * The current mark position.
   */
  private int mark = 0;

  /**
   * The current visual caret position.
   */
  private Point magicCaretPosition = null;

  /**
   * Indicates if this <code>Caret</code> is currently visible or not. This is
   * package private to avoid an accessor method.
   */
  boolean visible = false;

  /**
   * The current highlight entry.
   */
  private Object highlightEntry;

  private Timer blinkTimer;
  
  private BlinkTimerListener blinkListener;

  /**
   * Creates a new <code>DefaultCaret</code> instance.
   */
  public DefaultCaret()
  {
    // Nothing to do here.
  }

  /**
   * Sets the Caret update policy.
   *    
   * @param policy the new policy.  Valid values are:
   * ALWAYS_UPDATE: always update the Caret position, even when Document
   * updates don't occur on the Event Dispatcher thread.
   * NEVER_UPDATE: don't update the Caret position unless the Document
   * length becomes less than the Caret position (then update the
   * Caret to the end of the Document).
   * UPDATE_WHEN_ON_EDT: update the Caret position when the 
   * Document updates occur on the Event Dispatcher thread.  This is the 
   * default.
   * 
   * @since 1.5
   * @throws IllegalArgumentException if policy is not one of the above.
   */
  public void setUpdatePolicy (int policy)
  {
    if (policy != ALWAYS_UPDATE && policy != NEVER_UPDATE
        && policy != UPDATE_WHEN_ON_EDT)
      throw new 
        IllegalArgumentException
        ("policy must be ALWAYS_UPDATE, NEVER__UPDATE, or UPDATE_WHEN_ON_EDT");
    this.policy = policy;
  }
  
  /**
   * Gets the caret update policy.
   * 
   * @return the caret update policy.
   * @since 1.5
   */
  public int getUpdatePolicy ()
  {
    return policy;
  }
  
  /**
   * Moves the caret position when the mouse is dragged over the text
   * component, modifying the selection accordingly.
   *
   * @param event the <code>MouseEvent</code> describing the drag operation
   */
  public void mouseDragged(MouseEvent event)
  {
    moveCaret(event);
  }

  /**
   * Indicates a mouse movement over the text component. Does nothing here.
   *
   * @param event the <code>MouseEvent</code> describing the mouse operation
   */
  public void mouseMoved(MouseEvent event)
  {
    // Nothing to do here.
  }

  /**
   * When the click is received from Button 1 then the following actions
   * are performed here:
   *
   * <ul>
   * <li>If we receive a double click, the caret position (dot) is set
   *   to the position associated to the mouse click and the word at
   *   this location is selected.</li>
   * <li>If we receive a triple click, the caret position (dot) is set
   *   to the position associated to the mouse click and the line at
   *   this location is selected.</li>
   * </ul>
   *
   * @param event the <code>MouseEvent</code> describing the click operation
   */
  public void mouseClicked(MouseEvent event)
  {
    // TODO: Implement double- and triple-click behaviour here.
  }

  /**
   * Indicates that the mouse has entered the text component. Nothing is done
   * here.
   *
   * @param event the <code>MouseEvent</code> describing the mouse operation
   */
  public void mouseEntered(MouseEvent event)
  {
    // Nothing to do here.
  }

  /**
   * Indicates that the mouse has exited the text component. Nothing is done
   * here.
   *
   * @param event the <code>MouseEvent</code> describing the mouse operation
   */
  public void mouseExited(MouseEvent event)
  {
    // Nothing to do here.
  }

  /**
   * If the button 1 is pressed, the caret position is updated to the
   * position of the mouse click and the text component requests the input
   * focus if it is enabled. If the SHIFT key is held down, the caret will
   * be moved, which might select the text between the old and new location.
   *
   * @param event the <code>MouseEvent</code> describing the press operation
   */
  public void mousePressed(MouseEvent event)
  {
    positionCaret(event);
  }

  /**
   * Indicates that a mouse button has been released on the text component.
   * Nothing is done here.
   *
   * @param event the <code>MouseEvent</code> describing the mouse operation
   */
  public void mouseReleased(MouseEvent event)
  {
    // Nothing to do here.
  }

  /**
   * Sets the caret to <code>visible</code> if the text component is editable.
   *
   * @param event the <code>FocusEvent</code>
   */
  public void focusGained(FocusEvent event)
  {
    setVisible(true);
  }

  /**
   * Sets the caret to <code>invisible</code>.
   *
   * @param event the <code>FocusEvent</code>
   */
  public void focusLost(FocusEvent event)
  {
    if (event.isTemporary() == false)
      setVisible(false);
  }

  /**
   * Moves the caret to the position specified in the <code>MouseEvent</code>.
   * This will cause a selection if the dot and mark are different.
   *
   * @param event the <code>MouseEvent</code> from which to fetch the position
   */
  protected void moveCaret(MouseEvent event)
  {
    int newDot = getComponent().viewToModel(event.getPoint());
    moveDot(newDot);
  }

  /**
   * Repositions the caret to the position specified in the
   * <code>MouseEvent</code>.
   *
   * @param event the <code>MouseEvent</code> from which to fetch the position
   */
  protected void positionCaret(MouseEvent event)
  {
    int newDot = getComponent().viewToModel(event.getPoint());
    setDot(newDot);
  }

  /**
   * Deinstalls this <code>Caret</code> from the specified
   * <code>JTextComponent</code>. This removes any listeners that have been
   * registered by this <code>Caret</code>.
   *
   * @param c the text component from which to install this caret
   */