gcc/libjava/classpath/javax/swing/text/DefaultCaret.java

/* 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
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02110-1301 USA.

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permission to link this library with independent modules to produce an
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package javax.swing.text;

import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
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.util.EventListener;

import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;

/**
 * The default implementation of the {@link Caret} interface.
 *
 * @author orgininal author unknown
 * @author Roman Kennke (roman@kennke.org)
 */
public class DefaultCaret extends Rectangle
  implements Caret, FocusListener, MouseListener, MouseMotionListener
{
  /**
   * The serial version UID for DefaultCaret.
   */
  private static final long serialVersionUID = 228155774675466193L;

  /**
   * 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();

  /**
   * 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.
   */
  private boolean visible = true;

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

  /**
   * 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)
  {
    // FIXME: Implement this properly.
  }

  /**
   * 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)
  {
    // FIXME: Implement this properly.
  }

  /**
   * 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)
  {
  }

  /**
   * 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)
  {
    // FIXME: Implement this properly.
  }

  /**
   * 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)
  {
  }

  /**
   * Sets the caret to <code>invisible</code>.
   *
   * @param event the <code>FocusEvent</code>
   */
  public void focusLost(FocusEvent event)
  {
  }

  /**
   * 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)
  {
    // FIXME: Implement this properly.
  }

  /**
   * 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)
  {
    // FIXME: Implement this properly.
  }

  /**
   * 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
   */
  public void deinstall(JTextComponent c)
  {
    textComponent.removeFocusListener(this);
    textComponent.removeMouseListener(this);
    textComponent.removeMouseMotionListener(this);
    textComponent = null;
  }

  /**
   * Installs this <code>Caret</code> on the specified
   * <code>JTextComponent</code>. This registers a couple of listeners
   * on the text component.
   *
   * @param c the text component on which to install this caret
   */
  public void install(JTextComponent c)
  {
    textComponent = c;
    textComponent.addFocusListener(this);
    textComponent.addMouseListener(this);
    textComponent.addMouseMotionListener(this);
    repaint();
  }

  /**
   * Sets the current visual position of this <code>Caret</code>.
   *
   * @param p the Point to use for the saved location. May be <code>null</code>
   *        to indicate that there is no visual location
   */
  public void setMagicCaretPosition(Point p)
  {
    magicCaretPosition = p;
  }

  /**
   * Returns the current visual position of this <code>Caret</code>.
   *
   * @return the current visual position of this <code>Caret</code>
   *
   * @see #setMagicCaretPosition
   */
  public Point getMagicCaretPosition()
  {
    return magicCaretPosition;
  }

  /**
   * Returns the current position of the <code>mark</code>. The
   * <code>mark</code> marks the location in the <code>Document</code> that
   * is the end of a selection. If there is no selection, the <code>mark</code>
   * is the same as the <code>dot</code>.
   *
   * @return the current position of the mark
   */
  public int getMark()
  {
    return mark;
  }

  private void handleHighlight()
  {
    Highlighter highlighter = textComponent.getHighlighter();
    
    if (highlighter == null)
      return;
    
    int p0 = Math.min(dot, mark);
    int p1 = Math.max(dot, mark);
    
    if (selectionVisible && p0 != p1)
      {
	try
	  {
	    if (highlightEntry == null)
	      highlightEntry = highlighter.addHighlight(p0, p1, getSelectionPainter());
	    else
	      highlighter.changeHighlight(highlightEntry, p0, p1);
	  }
	catch (BadLocationException e)
	  {
	    // This should never happen.
	    throw new InternalError();
	  }
      }
    else
      {
	if (highlightEntry != null)
	  {
	    highlighter.removeHighlight(highlightEntry);
	    highlightEntry = null;
	  }
      }
  }

  /**
   * Sets the visiblity state of the selection.
   *
   * @param v <code>true</code> if the selection should be visible,
   *        <code>false</code> otherwise
   */
  public void setSelectionVisible(boolean v)
  {
    if (selectionVisible == v)
      return;
    
    selectionVisible = v;
    handleHighlight();
    repaint();
  }

  /**
   * Returns <code>true</code> if the selection is currently visible,
   * <code>false</code> otherwise.
   *
   * @return <code>true</code> if the selection is currently visible,
   *         <code>false</code> otherwise
   */
  public boolean isSelectionVisible()
  {
    return selectionVisible;
  }

  /**
   * Causes the <code>Caret</code> to repaint itself.
   */
  protected final void repaint()
  {
    // FIXME: Is this good? This possibly causes alot of the component
    // hierarchy to be repainted on every caret blink.
    if (textComponent != null)
      textComponent.repaint();
  }

  /**
   * Paints this <code>Caret</code> using the specified <code>Graphics</code>
   * context.
   *
   * @param g the graphics context to use
   */
  public void paint(Graphics g)
  {
    if (textComponent == null)
      return;

    int dot = getDot();
    Rectangle rect = null;

    try
      {
	rect = textComponent.modelToView(dot);
      }
    catch (BadLocationException e)
      {
	// This should never happen as dot should be always valid.
	return;
      }

    if (rect == null)
      return;
    
    // First we need to delete the old caret.
    // FIXME: Implement deleting of old caret.
    
    // Now draw the caret on the new position if visible.
    if (visible)
      {
	g.setColor(textComponent.getCaretColor());
	g.drawLine(rect.x, rect.y, rect.x, rect.y + rect.height);
      }
  }

  /**
   * Returns all registered event listeners of the specified type.
   *
   * @param listenerType the type of listener to return
   *
   * @return all registered event listeners of the specified type
   */
  public EventListener[] getListeners(Class listenerType)
  {
    return listenerList.getListeners(listenerType);
  }

  /**
   * Registers a {@link ChangeListener} that is notified whenever that state
   * of this <code>Caret</code> changes.
   *
   * @param listener the listener to register to this caret
   */
  public void addChangeListener(ChangeListener listener)
  {
    listenerList.add(ChangeListener.class, listener);
  }

  /**
   * Removes a {@link ChangeListener} from the list of registered listeners.
   *
   * @param listener the listener to remove
   */
  public void removeChangeListener(ChangeListener listener)
  {
    listenerList.remove(ChangeListener.class, listener);
  }

  /**
   * Returns all registered {@link ChangeListener}s of this <code>Caret</code>.
   *
   * @return all registered {@link ChangeListener}s of this <code>Caret</code>
   */
  public ChangeListener[] getChangeListeners()
  {
    return (ChangeListener[]) getListeners(ChangeListener.class);
  }

  /**
   * Notifies all registered {@link ChangeListener}s that the state
   * of this <code>Caret</code> has changed.
   */
  protected void fireStateChanged()
  {
    ChangeListener[] listeners = getChangeListeners();

    for (int index = 0; index < listeners.length; ++index)
      listeners[index].stateChanged(changeEvent);
  }

  /**
   * Returns the <code>JTextComponent</code> on which this <code>Caret</code>
   * is installed.
   *
   * @return the <code>JTextComponent</code> on which this <code>Caret</code>
   *         is installed
   */
  protected final JTextComponent getComponent()
  {
    return textComponent;
  }

  /**
   * Returns the blink rate of this <code>Caret</code> in milliseconds.
   * A value of <code>0</code> means that the caret does not blink.
   *
   * @return the blink rate of this <code>Caret</code> or <code>0</code> if
   *         this caret does not blink
   */
  public int getBlinkRate()
  {
    return blinkRate;
  }

  /**
   * Sets the blink rate of this <code>Caret</code> in milliseconds.
   * A value of <code>0</code> means that the caret does not blink.
   *
   * @param rate the new blink rate to set
   */
  public void setBlinkRate(int rate)
  {
    blinkRate = rate;
  }

  /**
   * Returns the current position of this <code>Caret</code> within the
   * <code>Document</code>.
   *
   * @return the current position of this <code>Caret</code> within the
   *         <code>Document</code>
   */
  public int getDot()
  {
    return dot;
  }

  /**
   * Moves the <code>dot</code> location without touching the
   * <code>mark</code>. This is used when making a selection.
   *
   * @param dot the location where to move the dot
   *
   * @see #setDot(int)
   */
  public void moveDot(int dot)
  {
    this.dot = dot;
    handleHighlight();
    repaint();
  }

  /**
   * Sets the current position of this <code>Caret</code> within the
   * <code>Document</code>. This also sets the <code>mark</code> to the
   * new location.
   *
   * @param dot the new position to be set
   *
   * @see #moveDot(int)
   */
  public void setDot(int dot)
  {
    this.dot = dot;
    this.mark = dot;
    handleHighlight();
    repaint();
  }

  /**
   * Returns <code>true</code> if this <code>Caret</code> is currently visible,
   * and <code>false</code> if it is not.
   *
   * @return <code>true</code> if this <code>Caret</code> is currently visible,
   *         and <code>false</code> if it is not
   */
  public boolean isVisible()
  {
    return visible;
  }

  /**
   * Sets the visibility state of the caret. <code>true</code> shows the
   * <code>Caret</code>, <code>false</code> hides it.
   *
   * @param v the visibility to set
   */  
  public void setVisible(boolean v)
  {
    visible = v;
    repaint();
  }

  /**
   * Returns the {@link Highlighter.HighlightPainter} that should be used
   * to paint the selection.
   *
   * @return the {@link Highlighter.HighlightPainter} that should be used
   *         to paint the selection
   */
  protected Highlighter.HighlightPainter getSelectionPainter()
  {
    return DefaultHighlighter.DefaultPainter;
  }
}