utilities.java

gcc的组建

   */
  public static final int getNextWord(JTextComponent c, int offs)
      throws BadLocationException
  {
    if (offs < 0 || offs > (c.getText().length() - 1))
      throw new BadLocationException("invalid offset specified", offs);
    String text = c.getText();
    BreakIterator wb = BreakIterator.getWordInstance();
    wb.setText(text);
    int last = wb.following(offs);
    int current = wb.next();
    while (current != BreakIterator.DONE)
      {
        for (int i = last; i < current; i++)
          {
            // FIXME: Should use isLetter(int) and text.codePointAt(int)
            // instead, but isLetter(int) isn't implemented yet
            if (Character.isLetter(text.charAt(i)))
              return last;
          }
        last = current;
        current = wb.next();
      }
    return BreakIterator.DONE;
  }

  /**
   * Finds the start of the previous word for the given offset.
   * 
   * @param c
   *          the text component
   * @param offs
   *          the offset in the document
   * @return the location in the model of the start of the previous word.
   * @throws BadLocationException
   *           if the offset is invalid.
   */
  public static final int getPreviousWord(JTextComponent c, int offs)
      throws BadLocationException
  {
    if (offs < 0 || offs > (c.getText().length() - 1))
      throw new BadLocationException("invalid offset specified", offs);
    String text = c.getText();
    BreakIterator wb = BreakIterator.getWordInstance();
    wb.setText(text);
    int last = wb.preceding(offs);
    int current = wb.previous();

    while (current != BreakIterator.DONE)
      {
        for (int i = last; i < offs; i++)
          {
            // FIXME: Should use isLetter(int) and text.codePointAt(int)
            // instead, but isLetter(int) isn't implemented yet
            if (Character.isLetter(text.charAt(i)))
              return last;
          }
        last = current;
        current = wb.previous();
      }
    return 0;
  }
  
  /**
   * Finds the start of a word for the given location.
   * @param c the text component
   * @param offs the offset location
   * @return the location of the word beginning
   * @throws BadLocationException if the offset location is invalid
   */
  public static final int getWordStart(JTextComponent c, int offs)
      throws BadLocationException
  {
    if (offs < 0 || offs >= c.getText().length())
      throw new BadLocationException("invalid offset specified", offs);
    
    String text = c.getText();
    BreakIterator wb = BreakIterator.getWordInstance();
    wb.setText(text);
    if (wb.isBoundary(offs))
      return offs;
    return wb.preceding(offs);
  }
  
  /**
   * Finds the end of a word for the given location.
   * @param c the text component
   * @param offs the offset location
   * @return the location of the word end
   * @throws BadLocationException if the offset location is invalid
   */
  public static final int getWordEnd(JTextComponent c, int offs)
      throws BadLocationException
  {
    if (offs < 0 || offs >= c.getText().length())
      throw new BadLocationException("invalid offset specified", offs);
    
    String text = c.getText();
    BreakIterator wb = BreakIterator.getWordInstance();
    wb.setText(text);
    return wb.following(offs);
  }
  
  /**
   * Get the model position of the end of the row that contains the 
   * specified model position.  Return null if the given JTextComponent
   * does not have a size.
   * @param c the JTextComponent
   * @param offs the model position
   * @return the model position of the end of the row containing the given 
   * offset
   * @throws BadLocationException if the offset is invalid
   */
  public static final int getRowEnd(JTextComponent c, int offs)
      throws BadLocationException
  {
    String text = c.getText();
    if (text == null)
      return -1;

    // Do a binary search for the smallest position X > offs
    // such that that character at positino X is not on the same
    // line as the character at position offs
    int high = offs + ((text.length() - 1 - offs) / 2);
    int low = offs;
    int oldHigh = text.length() + 1;
    while (true)
      {
        if (c.modelToView(high).y != c.modelToView(offs).y)
          {
            oldHigh = high;
            high = low + ((high + 1 - low) / 2);
            if (oldHigh == high)
              return high - 1;
          }
        else
          {
            low = high;
            high += ((oldHigh - high) / 2);
            if (low == high)
              return low;
          }
      }
  }
      
  /**
   * Get the model position of the start of the row that contains the specified
   * model position. Return null if the given JTextComponent does not have a
   * size.
   * 
   * @param c the JTextComponent
   * @param offs the model position
   * @return the model position of the start of the row containing the given
   *         offset
   * @throws BadLocationException if the offset is invalid
   */
  public static final int getRowStart(JTextComponent c, int offs)
      throws BadLocationException
  {
    String text = c.getText();
    if (text == null)
      return -1;

    // Do a binary search for the greatest position X < offs
    // such that the character at position X is not on the same
    // row as the character at position offs
    int high = offs;
    int low = 0;
    int oldLow = 0;
    while (true)
      {
        if (c.modelToView(low).y != c.modelToView(offs).y)
          {
            oldLow = low;
            low = high - ((high + 1 - low) / 2);
            if (oldLow == low)
              return low + 1;
          }
        else
          {
            high = low;
            low -= ((low - oldLow) / 2);
            if (low == high)
              return low;
          }
      }
  }
  
  /**
   * Determine where to break the text in the given Segment, attempting to find
   * a word boundary.
   * @param s the Segment that holds the text
   * @param metrics the font metrics used for calculating the break point
   * @param x0 starting view location representing the start of the text
   * @param x the target view location
   * @param e the TabExpander used for expanding tabs (if this is null tabs
   * are expanded to 1 space)
   * @param startOffset the offset in the Document of the start of the text
   * @return the offset at which we should break the text
   */
  public static final int getBreakLocation(Segment s, FontMetrics metrics,
                                           int x0, int x, TabExpander e,
                                           int startOffset)
  {
    int mark = Utilities.getTabbedTextOffset(s, metrics, x0, x, e, startOffset);
    BreakIterator breaker = BreakIterator.getWordInstance();
    breaker.setText(s.toString());
    
    // If mark is equal to the end of the string, just use that position
    if (mark == s.count)
      return mark;
    
    // Try to find a word boundary previous to the mark at which we 
    // can break the text
    int preceding = breaker.preceding(mark + 1);
    
    if (preceding != 0)
      return preceding;
    else
      // If preceding is 0 we couldn't find a suitable word-boundary so
      // just break it on the character boundary
      return mark;
  }

  /**
   * Returns the paragraph element in the text component <code>c</code> at
   * the specified location <code>offset</code>.
   *
   * @param c the text component
   * @param offset the offset of the paragraph element to return
   *
   * @return the paragraph element at <code>offset</code>
   */
  public static final Element getParagraphElement(JTextComponent c, int offset)
  {
    Document doc = c.getDocument();
    Element par = null;
    if (doc instanceof StyledDocument)
      {
        StyledDocument styledDoc = (StyledDocument) doc;
        par = styledDoc.getParagraphElement(offset);
      }
    else
      {
        Element root = c.getDocument().getDefaultRootElement();
        int parIndex = root.getElementIndex(offset);
        par = root.getElement(parIndex);
      }
    return par;
  }

  /**
   * Returns the document position that is closest above to the specified x
   * coordinate in the row containing <code>offset</code>.
   *
   * @param c the text component
   * @param offset the offset
   * @param x the x coordinate
   *
   * @return  the document position that is closest above to the specified x
   *          coordinate in the row containing <code>offset</code>
   *
   * @throws BadLocationException if <code>offset</code> is not a valid offset
   */
  public static final int getPositionAbove(JTextComponent c, int offset, int x)
    throws BadLocationException
  {
    View rootView = c.getUI().getRootView(c);
    Rectangle r = c.modelToView(offset);
    int offs = c.viewToModel(new Point(x, r.y));
    int pos = rootView.getNextVisualPositionFrom(c, offs,
                                                 Position.Bias.Forward,
                                                 SwingConstants.NORTH,
                                                 new Position.Bias[1]);
    return pos;
  }

  /**
   * Returns the document position that is closest below to the specified x
   * coordinate in the row containing <code>offset</code>.
   *
   * @param c the text component
   * @param offset the offset
   * @param x the x coordinate
   *
   * @return  the document position that is closest above to the specified x
   *          coordinate in the row containing <code>offset</code>
   *
   * @throws BadLocationException if <code>offset</code> is not a valid offset
   */
  public static final int getPositionBelow(JTextComponent c, int offset, int x)
    throws BadLocationException
  {
    View rootView = c.getUI().getRootView(c);
    Rectangle r = c.modelToView(offset);
    int offs = c.viewToModel(new Point(x, r.y));
    int pos = rootView.getNextVisualPositionFrom(c, offs,
                                                 Position.Bias.Forward,
                                                 SwingConstants.SOUTH,
                                                 new Position.Bias[1]);
    return pos;
  }
}