JTextArea.java

/* JTextArea.java --
   Copyright (C) 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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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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package javax.swing;

import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Rectangle;

import javax.accessibility.AccessibleContext;
import javax.accessibility.AccessibleStateSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.Element;
import javax.swing.text.JTextComponent;
import javax.swing.text.PlainDocument;
import javax.swing.text.View;

/**
 * The <code>JTextArea</code> component provides a multi-line area for displaying
 * and editing plain text.  The component is designed to act as a lightweight
 * replacement for the heavyweight <code>java.awt.TextArea</code> component,
 * which provides similar functionality using native widgets.
 * <p>
 *
 * This component has additional functionality to the AWT class.  It follows
 * the same design pattern as seen in other text components, such as
 * <code>JTextField</code>, <code>JTextPane</code> and <code>JEditorPane</code>,
 * and embodied in <code>JTextComponent</code>.  These classes separate the text
 * (the model) from its appearance within the onscreen component (the view).  The
 * text is held within a <code>javax.swing.text.Document</code> object, which can
 * also maintain relevant style information where necessary.  As a result, it is the
 * document that should be monitored for textual changes, via
 * <code>DocumentEvent</code>s delivered to registered
 * <code>DocumentListener</code>s, rather than this component.
 * <p>
 *
 * Unlike <code>java.awt.TextArea</code>, <code>JTextArea</code> does not
 * handle scrolling.  Instead, this functionality is delegated to a
 * <code>JScrollPane</code>, which can contain the text area and handle
 * scrolling when required.  Likewise, the word wrapping functionality
 * of the AWT component is converted to a property of this component
 * and the <code>rows</code> and <code>columns</code> properties
 * are used in calculating the preferred size of the scroll pane's
 * view port.
 *
 * @author Michael Koch  (konqueror@gmx.de)
 * @author Andrew John Hughes  (gnu_andrew@member.fsf.org)
 * @see java.awt.TextArea
 * @see javax.swing.text.JTextComponent
 * @see javax.swing.JTextField
 * @see javax.swing.JTextPane
 * @see javax.swing.JEditorPane
 * @see javax.swing.text.Document
 * @see javax.swing.event.DocumentEvent
 * @see javax.swing.event.DocumentListener
 */

public class JTextArea extends JTextComponent
{
  /**
   * Provides accessibility support for <code>JTextArea</code>.
   *
   * @author Roman Kennke (kennke@aicas.com)
   */
  protected class AccessibleJTextArea extends AccessibleJTextComponent
  {

    /**
     * Creates a new <code>AccessibleJTextArea</code> object.
     */
    protected AccessibleJTextArea()
    {
      super();
    }

    /**
     * Returns the accessible state of this <code>AccessibleJTextArea</code>.
     *
     * @return  the accessible state of this <code>AccessibleJTextArea</code>
     */
    public AccessibleStateSet getAccessibleStateSet()
    {
      AccessibleStateSet state = super.getAccessibleStateSet();
      // TODO: Figure out what state must be added here to the super's state.
      return state;
    }
  }

  /**
   * Compatible with Sun's JDK
   */
  private static final long serialVersionUID = -6141680179310439825L;

  /**
   * The number of rows used by the component.
   */
  private int rows;

  /**
   * The number of columns used by the component.
   */
  private int columns;

  /**
   * Whether line wrapping is enabled or not.
   */
  private boolean lineWrap;

  /**
   * The number of characters equal to a tab within the text.
   */
  private int tabSize = 8;

  private boolean wrapStyleWord;

  /**
   * Creates a new <code>JTextArea</code> object.
   */
  public JTextArea()
  {
    this(null, null, 0, 0);
  }

  /**
   * Creates a new <code>JTextArea</code> object.
   *
   * @param text the initial text
   */
  public JTextArea(String text)
  {
    this(null, text, 0, 0);
  }

  /**
   * Creates a new <code>JTextArea</code> object.
   *
   * @param rows the number of rows
   * @param columns the number of cols
   *
   * @exception IllegalArgumentException if rows or columns are negative
   */
  public JTextArea(int rows, int columns)
  {
    this(null, null, rows, columns);
  }

  /**
   * Creates a new <code>JTextArea</code> object.
   *
   * @param text the initial text
   * @param rows the number of rows
   * @param columns the number of cols
   *
   * @exception IllegalArgumentException if rows or columns are negative
   */
  public JTextArea(String text, int rows, int columns)
  {
    this(null, text, rows, columns);
  }

  /**
   * Creates a new <code>JTextArea</code> object.
   *
   * @param doc the document model to use
   */
  public JTextArea(Document doc)
  {
    this(doc, null, 0, 0);
  }

  /**
   * Creates a new <code>JTextArea</code> object.
   *
   * @param doc the document model to use
   * @param text the initial text
   * @param rows the number of rows
   * @param columns the number of cols
   *
   * @exception IllegalArgumentException if rows or columns are negative
   */
  public JTextArea(Document doc, String text, int rows, int columns)
  {
    setDocument(doc == null ? createDefaultModel() : doc);
    // Only explicitly setText() when there is actual text since
    // setText() might be overridden and not expected to be called
    // from the constructor (as in JEdit).
    if (text != null)
      setText(text);
    setRows(rows);
    setColumns(columns);
  }

  /**
   * Appends the supplied text to the current contents
   * of the document model.
   *
   * @param toAppend the text to append
   */
  public void append(String toAppend)
  {
      try
          {
              getDocument().insertString(getText().length(), toAppend, null);
          }
      catch (BadLocationException exception)
          {
              /* This shouldn't happen in theory -- but, if it does...  */
              throw new RuntimeException("Unexpected exception occurred.", exception);
          }
      if (toAppend != null && toAppend.length() > 0)
        revalidate();
  }

  /**
   * Creates the default document model.
   *
   * @return a new default model
   */
  protected Document createDefaultModel()
  {
    return new PlainDocument();
  }

  /**
   * Returns true if the width of this component should be forced
   * to match the width of a surrounding view port.  When line wrapping
   * is turned on, this method returns true.
   *
   * @return true if lines are wrapped.
   */
  public boolean getScrollableTracksViewportWidth()
  {
    return lineWrap ? true : super.getScrollableTracksViewportWidth();
  }

  /**
   * Returns the increment that is needed to expose exactly one new line
   * of text. This is implemented here to return the values of
   * {@link #getRowHeight} and {@link #getColumnWidth}, depending on
   * the value of the argument <code>direction</code>.
   *
   * @param visibleRect the view area that is visible in the viewport
   * @param orientation either {@link SwingConstants#VERTICAL} or
   *     {@link SwingConstants#HORIZONTAL}
   * @param direction less than zero for up/left scrolling, greater
   *     than zero for down/right scrolling
   *
   * @return the increment that is needed to expose exactly one new row
   *     or column of text
   *
   * @throws IllegalArgumentException if <code>orientation</code> is invalid
   */
  public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation,
                                        int direction)
  {
    if (orientation == SwingConstants.VERTICAL)
      return getRowHeight();
    else if (orientation == SwingConstants.HORIZONTAL)
      return getColumnWidth();
    else
      throw new IllegalArgumentException("orientation must be either "
                                     + "javax.swing.SwingConstants.VERTICAL "
                                     + "or "
                                     + "javax.swing.SwingConstants.HORIZONTAL"
                                     );
  }

  /**
   * Returns the preferred size of that text component in the case
   * it is embedded within a JScrollPane. This uses the column and
   * row settings if they are explicitly set, or fall back to
   * the superclass's behaviour.
   *
   * @return the preferred size of that text component in the case
   *     it is embedded within a JScrollPane
   */
  public Dimension getPreferredScrollableViewportSize()
  {
    if ((rows > 0) && (columns > 0))
      return new Dimension(columns * getColumnWidth(), rows * getRowHeight());
    else
      return super.getPreferredScrollableViewportSize();
  }

  /**
   * Returns the UI class ID string.
   *
   * @return the string "TextAreaUI"
   */
  public String getUIClassID()
  {
    return "TextAreaUI";
  }

  /**
   * Returns the current number of columns.
   *
   * @return number of columns
   */
  public int getColumns()
  {
    return columns;
  }

  /**
   * Sets the number of rows.
   *
   * @param columns number of columns
   *
   * @exception IllegalArgumentException if columns is negative
   */
  public void setColumns(int columns)
  {
    if (columns < 0)
      throw new IllegalArgumentException();

    if (columns != this.columns)
      {
        this.columns = columns;
        revalidate();
      }
  }

  /**
   * Returns the current number of rows.
   *
   * @return number of rows
   */
  public int getRows()
  {
    return rows;
  }

  /**
   * Sets the number of rows.
   *
   * @param rows number of rows
   *
   * @exception IllegalArgumentException if rows is negative
   */
  public void setRows(int rows)
  {
    if (rows < 0)
      throw new IllegalArgumentException();

    if (rows != this.rows)
      {
        this.rows = rows;
        revalidate();
      }
  }

  /**
   * Checks whether line wrapping is enabled.
   *
   * @return <code>true</code> if line wrapping is enabled,
   * <code>false</code> otherwise
   */
  public boolean getLineWrap()
  {
    return lineWrap;
  }

  /**
   * Enables/disables line wrapping.
   *
   * @param flag <code>true</code> to enable line wrapping,
   * <code>false</code> otherwise
   */
  public void setLineWrap(boolean flag)
  {
    if (lineWrap == flag)
      return;

    boolean oldValue = lineWrap;
    lineWrap = flag;
    firePropertyChange("lineWrap", oldValue, lineWrap);
  }

  /**
   * Checks whether word style wrapping is enabled.
   *
   * @return <code>true</code> if word style wrapping is enabled,
   * <code>false</code> otherwise
   */
  public boolean getWrapStyleWord()
  {
    return wrapStyleWord;
  }

  /**
   * Enables/Disables word style wrapping.
   *
   * @param flag <code>true</code> to enable word style wrapping,
   * <code>false</code> otherwise
   */
  public void setWrapStyleWord(boolean flag)
  {
    if (wrapStyleWord == flag)
      return;

    boolean oldValue = wrapStyleWord;
    wrapStyleWord = flag;
    firePropertyChange("wrapStyleWord", oldValue, wrapStyleWord);
  }

  /**
   * Returns the number of characters used for a tab.
   * This defaults to 8.
   *
   * @return the current number of spaces used for a tab.
   */
  public int getTabSize()
  {
    return tabSize;
  }

  /**
   * Sets the number of characters used for a tab to the
   * supplied value.  If a change to the tab size property
   * occurs (i.e. newSize != tabSize), a property change event
   * is fired.
   *
   * @param newSize The new number of characters to use for a tab.
   */
  public void setTabSize(int newSize)
  {
    if (tabSize == newSize)
      return;

    int oldValue = tabSize;
    tabSize = newSize;
    firePropertyChange("tabSize", oldValue, tabSize);
  }

  protected int getColumnWidth()
  {
    FontMetrics metrics = getToolkit().getFontMetrics(getFont());
    return metrics.charWidth('m');
  }

  public int getLineCount()
  {
    return getDocument().getDefaultRootElement().getElementCount();
  }

  public int getLineStartOffset(int line)
     throws BadLocationException
  {
    int lineCount = getLineCount();

    if (line < 0 || line > lineCount)
      throw new BadLocationException("Non-existing line number", line);

    Element lineElem = getDocument().getDefaultRootElement().getElement(line);
    return lineElem.getStartOffset();
  }

  public int getLineEndOffset(int line)
     throws BadLocationException
  {
    int lineCount = getLineCount();

    if (line < 0 || line > lineCount)
      throw new BadLocationException("Non-existing line number", line);

    Element lineElem = getDocument().getDefaultRootElement().getElement(line);
    return lineElem.getEndOffset();
  }

  public int getLineOfOffset(int offset)
    throws BadLocationException
  {
    Document doc = getDocument();

    if (offset < doc.getStartPosition().getOffset()
        || offset >= doc.getEndPosition().getOffset())
      throw new BadLocationException("offset outside of document", offset);

    return doc.getDefaultRootElement().getElementIndex(offset);
  }

  protected int getRowHeight()
  {
    FontMetrics metrics = getToolkit().getFontMetrics(getFont());
    return metrics.getHeight();
  }

  /**
   * Inserts the supplied text at the specified position.  Nothing
   * happens in the case that the model or the supplied string is null
   * or of zero length.
   *
   * @param string The string of text to insert.
   * @param position The position at which to insert the supplied text.
   * @throws IllegalArgumentException if the position is &lt; 0 or greater
   * than the length of the current text.
   */
  public void insert(String string, int position)
  {
    // Retrieve the document model.
    Document doc = getDocument();

    // Check the model and string for validity.
    if (doc == null
        || string == null
        || string.length() == 0)
      return;

    // Insert the text into the model.
    try
      {
        doc.insertString(position, string, null);
      }
    catch (BadLocationException e)
      {
        throw new IllegalArgumentException("The supplied position, "
                                           + position + ", was invalid.");
      }
  }

  public void replaceRange(String text, int start, int end)
  {
    Document doc = getDocument();

    if (start > end
        || start < doc.getStartPosition().getOffset()
        || end >= doc.getEndPosition().getOffset())
      throw new IllegalArgumentException();

    try
      {
        doc.remove(start, end - start);
        doc.insertString(start, text, null);
      }
    catch (BadLocationException e)
      {
        // This cannot happen as we check offset above.
      }
  }

  /**
   * Returns the preferred size for the JTextArea. This is the maximum of
   * the size that is needed to display the content and the requested size
   * as per {@link #getColumns} and {@link #getRows}.
   *
   * @return the preferred size of the JTextArea
   */
  public Dimension getPreferredSize()
  {
    int reqWidth = getColumns() * getColumnWidth();
    int reqHeight = getRows() * getRowHeight();
    View view = getUI().getRootView(this);
    int neededWidth = (int) view.getPreferredSpan(View.HORIZONTAL);
    int neededHeight = (int) view.getPreferredSpan(View.VERTICAL);
    return new Dimension(Math.max(reqWidth, neededWidth),
                          Math.max(reqHeight, neededHeight));
  }

  /**
   * Returns the accessible context associated with the <code>JTextArea</code>.
   *
   * @return the accessible context associated with the <code>JTextArea</code>
   */
  public AccessibleContext getAccessibleContext()
  {
    if (accessibleContext == null)
      accessibleContext = new AccessibleJTextArea();
    return accessibleContext;
  }
}