jlist.java

来自「纯java操作系统jnode,安装简单和操作简单的个人使用的Java操作系统」· Java 代码 · 共 654 行 · 第 1/2 页

    }

    /** Returns the highest selected item index.
     */
    public int getMaxSelectionIndex() {
	return _selectionModel.getMaxSelectionIndex();
    }

    /**
     * Sets the flag that determines whether this list allows multiple
     * selections.
     * @param mode_ the selection mode. Allowed values are:<p>
     * <ul>
     * <li> ListSelectionModel.SINGLE_SELECTION. Only one list index 
     * can be selected at a time.
     * <li> ListSelectionModel.SINGLE_INTERVAL_SELECTION. 
     * <li> ListSelectionModel.MULTIPLE_INTERVAL_SELECTION. Any number 
     * of list items can be selected simultaneously.
     * </ul>
     */
    public void setSelectionMode(int mode_) { 
	_selectionModel.setSelectionMode(mode_);
    }

    /**
     * Determines whether this list allows multiple selections.
     */
    public int getSelectionMode() { 
	return _selectionModel.getSelectionMode();
    }

    /** Determines if the specified item in this scrolling list is selected.
     */
    public boolean isIndexSelected(int index_) {
	return _selectionModel.isSelectedIndex(index_);
    }

    /**
     * Called by LayoutManager.
     */
    public Dimension minimumSize() {

	/* Calculate the minimum number of columns that will contain all the
	 * items in the list.
	 */
	_columns = 1;
	for (int i=0; i< _listModel.getSize(); i++) {
	    String c = _listModel.getElementAt(i).toString();
	    if (c.length() > _columns)
		_columns = c.length();
	}

	/* Take into account the border inherited from the JComponent
	 * superclass.
	 */
	Insets insets = super.getInsets();
	return new Dimension(_columns + insets.left + insets.right, 
		_visibleRows + insets.top + insets.bottom);
    }

    public void requestFocus() {
	/* Generate the FOCUS_GAINED event.
	 */
	super.requestFocus();

	/* Get the absolute origin of this component 
	 */
	Point origin = getLocationOnScreen();
	Insets insets = super.getInsets();
	origin.translate(insets.left, insets.top);
	Toolkit.getDefaultToolkit().setCursor(
		origin.addOffset(0, _currentRow));
    }

    /** Draws this component. Overrides draw() in Component.
     */
    public void draw() {

	/* This situation can occur if the ListModel has been changed.
	 */
	if (_currentRow >= _listModel.getSize()) {
	    if (_listModel.getSize() == 0)
		_currentRow = 0;
	    else
		_currentRow = _listModel.getSize() - 1;
	}

	/* Draw the border if it exists
	 */
	super.draw();

	/* Get the absolute origin of this component.
	 */
	Point origin = getLocationOnScreen();
	Insets insets = super.getInsets();
	origin.translate(insets.left, insets.top);

	Toolkit term = Toolkit.getDefaultToolkit();

	int colorpair = getCursesColor();
	int attribute;

	StringBuffer blanks = new StringBuffer();
	for (int j=0; j<_columns; j++)
	    blanks.append(' ');

	for (int i = 0; i < _listModel.getSize(); i++) {

	    term.setCursor(origin.x, origin.y + i);

	    if (isIndexSelected(i))
		attribute = Toolkit.A_REVERSE;
	    else
		attribute = 0;

	    if (i == _currentRow)
		attribute += Toolkit.A_BOLD;

	    String item = _listModel.getElementAt(i).toString();

	    StringBuffer buffer = new StringBuffer(item);
	    for (int k=item.length(); k<_columns; k++)
		buffer.append(' ');

	    term.addString(buffer.toString(), attribute, colorpair);
	}	// end FOR loop

	for (int i = _listModel.getSize(); i < _visibleRows; i++) {
	    term.setCursor(origin.x, origin.y + i);
	    term.addString(blanks.toString(), 0, colorpair);
	}
    }

    public void processKeyEvent(KeyEvent ke_) {
	/* First call all KeyListener objects that may have been registered
	 * for this component. 
	 */
	super.processKeyEvent(ke_);

	/* Check if any of the KeyListeners consumed the KeyEvent.
	 */
	if (ke_.isConsumed())
	    return;

	Toolkit term = Toolkit.getDefaultToolkit();
	EventQueue evtqueue = term.getSystemEventQueue();
	int key = ke_.getKeyCode();
	switch (key) {
	    case '\t':
		getParent().nextFocus();
		return;

	    case KeyEvent.VK_BACK_TAB:
		getParent().previousFocus();
		return;

	    case KeyEvent.VK_DOWN:
		/* If we are already at the bottom of the list, ignore
		 * this keystroke.
		 */
		if (_currentRow >= _listModel.getSize() -1)
		    return;

		evtqueue.postEvent(
		    new ScrollEvent(this, ScrollEvent.UP, 
			new Point(0, ++_currentRow)));
		break;

	    case KeyEvent.VK_PAGE_DOWN:
		_currentRow += _visibleRows;
		if (_currentRow >= _listModel.getSize())
		    _currentRow = _listModel.getSize() -1;

		evtqueue.postEvent(
		    new ScrollEvent(this, ScrollEvent.UP, 
			new Point(0, _currentRow)));
		break;

	    case KeyEvent.VK_END:
		_currentRow = _listModel.getSize() - 1;
		evtqueue.postEvent(new ScrollEvent(
		        this, ScrollEvent.UP, new Point(0, _currentRow)));
		break;

	    case KeyEvent.VK_UP:
		/* If we are already at the top of the list, ignore
		 * this keystroke.
		 */
		if (_currentRow < 1)
		    return;

		evtqueue.postEvent(new ScrollEvent(
		        this, ScrollEvent.DOWN, new Point(0, --_currentRow)));
		break;

	    case KeyEvent.VK_PAGE_UP:
		_currentRow -= _visibleRows;
		if (_currentRow < 0)
		    _currentRow = 0;

		evtqueue.postEvent(new ScrollEvent(this, ScrollEvent.DOWN, 
			new Point(0, _currentRow)));
		break;

	    case KeyEvent.VK_ENTER:
		_doSelect();
		break;

	    case KeyEvent.VK_HOME:
		_currentRow = 0;
		break;
	}

	if ((getParent() instanceof JViewport) == false) {
	    draw();
	    requestFocus();
	    super.requestSync();
	}
    }

    private void _doSelect() {
	/* Pressing ENTER or double-clicking on a row selects/deselects 
	 * the current row. If the list is empty, ignore the keystroke.
	 */
	if (_listModel.getSize() == 0)
	    return;

	if (isIndexSelected(_currentRow))
	    removeSelectionInterval(_currentRow, _currentRow);
	else {
	    int mode = getSelectionMode();
	    if (mode == ListSelectionModel.SINGLE_SELECTION)
		setSelectedIndex(_currentRow);
	    else
		addSelectionInterval(_currentRow, _currentRow);
	}
	repaint();
    }

    public void processMouseEvent(MouseEvent e_) {
	super.processMouseEvent(e_);

	if (e_.getButton() == MouseEvent.BUTTON1 &&
		e_.getModifiers() == MouseEvent.MOUSE_CLICKED &&
		this.isFocusTraversable()) {

	    if (e_.getClickCount() == 1) {
		int y = e_.getY();
		Point origin = getLocationOnScreen();
		Container parent = getParent();
		if (parent instanceof JViewport) {
		    _currentRow = y - origin.y;
		    repaint();
		}
	    }
	    else
		_doSelect();
	}
    }

    /**
     * Register a ScrollListener object for this JList.
     */
    public void addScrollListener(ScrollListener sl_) {
	if (_scrollListeners == null)
	    _scrollListeners = new Vector();
	_scrollListeners.add(sl_);
    }

    /**
     * Remove a ScrollListener object that is registered for this JList.
     */
    public void removeScrollListener(ScrollListener sl_) {
	if (_scrollListeners == null)
	    return;
	_scrollListeners.remove(sl_);
    }

    /** Process scroll events generated by this JList.
     */
    public void processScrollEvent(ScrollEvent e_) {
	if (_scrollListeners != null) {
	    for (Enumeration e = _scrollListeners.elements(); 
		    e.hasMoreElements(); ) {

		ScrollListener sl = (ScrollListener) e.nextElement();
		sl.scroll(e_);
	    }
	}
    }

    /** Outputs a textual description of this component to stderr.
     */
    public void debug(int level_) {
	for (int i=0; i<level_; i++)
	    System.err.print("    ");
	System.err.println("JList origin=" + _origin + 
	    " size=" + minimumSize());
    }

    //================================================================
    // INSTANCE VARIABLES

    private int _visibleRows = 5;
    private int _columns = 10;

    /** Offset (from start of list) of the item under the cursor (i.e. the
     * item that will be selected/deselected if the user presses ENTER)
     */
    protected int _currentRow = 0;

    /** The ListSelectionModel used by this JList.
     */
    protected ListSelectionModel _selectionModel = 
	    new DefaultListSelectionModel();

    /** The ListModel that holds the items that are displayed by
     * this JList.
     */
    protected ListModel _listModel;

    /** A list of ScrollListeners registered for this JList.
     */
    private Vector _scrollListeners = null;

}