gcc/libjava/classpath/javax/swing/plaf/basic/BasicSplitPaneDivider.java

/* BasicSplitPaneDivider.java --
   Copyright (C) 2003, 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.plaf.basic;

import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.JButton;
import javax.swing.JSplitPane;
import javax.swing.SwingConstants;
import javax.swing.border.Border;

/**
 * The divider that separates the two parts of a JSplitPane in the Basic look
 * and feel.
 * 
 * <p>
 * Implementation status: We do not have a real implementation yet. Currently,
 * it is mostly a stub to allow compiling other parts of the
 * javax.swing.plaf.basic package, although some parts are already
 * functional.
 * </p>
 *
 * @author Sascha Brawer (brawer_AT_dandelis.ch)
 */
public class BasicSplitPaneDivider extends Container
  implements PropertyChangeListener
{
  /**
   * Determined using the <code>serialver</code> tool of Apple/Sun JDK 1.3.1
   * on MacOS X 10.1.5.
   */
  static final long serialVersionUID = 1463404307042803342L;

  /**
   * The width and height of the little buttons for showing and hiding parts
   * of a JSplitPane in a single mouse click.
   */
  protected static final int ONE_TOUCH_SIZE = 6;

  /** The distance the one touch buttons will sit from the divider's edges. */
  protected static final int ONE_TOUCH_OFFSET = 2;

  /**
   * An object that performs the tasks associated with an ongoing drag
   * operation, or <code>null</code> if the user is currently not dragging
   * the divider.
   */
  protected DragController dragger;

  /**
   * The delegate object that is responsible for the UI of the
   * <code>JSplitPane</code> that contains this divider.
   */
  protected BasicSplitPaneUI splitPaneUI;

  /** The thickness of the divider in pixels. */
  protected int dividerSize;

  /** A divider that is used for layout purposes. */
  protected Component hiddenDivider;

  /** The JSplitPane containing this divider. */
  protected JSplitPane splitPane;

  /**
   * The listener for handling mouse events from both the divider and the
   * containing <code>JSplitPane</code>.
   * 
   * <p>
   * The reason for also handling MouseEvents from the containing
   * <code>JSplitPane</code> is that users should be able to start a drag
   * gesture from inside the JSplitPane, but slightly outisde the divider.
   * </p>
   */
  protected MouseHandler mouseHandler = new MouseHandler();

  /**
   * The current orientation of the containing <code>JSplitPane</code>, which
   * is either {@link javax.swing.JSplitPane#HORIZONTAL_SPLIT} or {@link
   * javax.swing.JSplitPane#VERTICAL_SPLIT}.
   */
  protected int orientation;

  /**
   * The button for showing and hiding the left (or top) component of the
   * <code>JSplitPane</code>.
   */
  protected JButton leftButton;

  /**
   * The button for showing and hiding the right (or bottom) component of the
   * <code>JSplitPane</code>.
   */
  protected JButton rightButton;

  /**
   * The border of this divider. Typically, this will be an instance of {@link
   * javax.swing.plaf.basic.BasicBorders.SplitPaneDividerBorder}.
   *
   * @see #getBorder()
   * @see #setBorder(javax.swing.border.Border)
   */
  private Border border;

  // This is not a pixel count.
  // This int should be able to take 3 values.
  // left (top), middle, right(bottom)
  //    0          1          2

  /**
   * Keeps track of where the divider should be placed when using one touch
   * expand buttons.
   * This is package-private to avoid an accessor method.
   */
  transient int currentDividerLocation = 1;

  /** DOCUMENT ME! */
  private transient Border tmpBorder = new Border()
    {
      public Insets getBorderInsets(Component c)
      {
	return new Insets(2, 2, 2, 2);
      }

      public boolean isBorderOpaque()
      {
	return false;
      }

      public void paintBorder(Component c, Graphics g, int x, int y,
                              int width, int height)
      {
	Color saved = g.getColor();
	g.setColor(Color.BLACK);

	g.drawRect(x + 2, y + 2, width - 4, height - 4);

	g.setColor(saved);
      }
    };

  /**
   * Constructs a new divider.
   *
   * @param ui the UI delegate of the enclosing <code>JSplitPane</code>.
   */
  public BasicSplitPaneDivider(BasicSplitPaneUI ui)
  {
    setLayout(new DividerLayout());
    setBasicSplitPaneUI(ui);
    setDividerSize(splitPane.getDividerSize());
    setBorder(tmpBorder);
  }

  /**
   * Sets the delegate object that is responsible for the UI of the {@link
   * javax.swing.JSplitPane} containing this divider.
   *
   * @param newUI the UI delegate, or <code>null</code> to release the
   *        connection to the current delegate.
   */
  public void setBasicSplitPaneUI(BasicSplitPaneUI newUI)
  {
    /* Remove the connection to the existing JSplitPane. */
    if (splitPane != null)
      {
	splitPane.removePropertyChangeListener(this);
	splitPane.removeMouseListener(mouseHandler);
	splitPane.removeMouseMotionListener(mouseHandler);
	removeMouseListener(mouseHandler);
	removeMouseMotionListener(mouseHandler);
	splitPane = null;
	hiddenDivider = null;
      }

    /* Establish the connection to the new JSplitPane. */
    splitPaneUI = newUI;
    if (splitPaneUI != null)
      splitPane = newUI.getSplitPane();
    if (splitPane != null)
      {
	splitPane.addPropertyChangeListener(this);
	splitPane.addMouseListener(mouseHandler);
	splitPane.addMouseMotionListener(mouseHandler);
	addMouseListener(mouseHandler);
	addMouseMotionListener(mouseHandler);
	hiddenDivider = splitPaneUI.getNonContinuousLayoutDivider();
	orientation = splitPane.getOrientation();
	oneTouchExpandableChanged();
      }
  }

  /**
   * Returns the delegate object that is responsible for the UI of the {@link
   * javax.swing.JSplitPane} containing this divider.
   *
   * @return The UI for the JSplitPane.
   */
  public BasicSplitPaneUI getBasicSplitPaneUI()
  {
    return splitPaneUI;
  }

  /**
   * Sets the thickness of the divider.
   *
   * @param newSize the new width or height in pixels.
   */
  public void setDividerSize(int newSize)
  {
    this.dividerSize = newSize;
  }

  /**
   * Retrieves the thickness of the divider.
   *
   * @return The thickness of the divider.
   */
  public int getDividerSize()
  {
    return dividerSize;
  }

  /**
   * Sets the border of this divider.
   *
   * @param border the new border. Typically, this will be an instance of
   *        {@link
   *        javax.swing.plaf.basic.BasicBorders.SplitPaneBorder}.
   *
   * @since 1.3
   */
  public void setBorder(Border border)
  {
    if (border != this.border)
      {
	Border oldValue = this.border;
	this.border = border;
	firePropertyChange("border", oldValue, border);
      }
  }

  /**
   * Retrieves the border of this divider.
   *
   * @return the current border, or <code>null</code> if no border has been
   *         set.
   *
   * @since 1.3
   */
  public Border getBorder()
  {
    return border;
  }

  /**
   * Retrieves the insets of the divider. If a border has been installed on
   * the divider, the result of calling its <code>getBorderInsets</code>
   * method is returned. Otherwise, the inherited implementation will be
   * invoked.
   *
   * @see javax.swing.border.Border#getBorderInsets(java.awt.Component)
   */
  public Insets getInsets()
  {
    if (border != null)
      return border.getBorderInsets(this);
    else
      return super.getInsets();
  }

  /**
   * Returns the preferred size of this divider, which is
   * <code>dividerSize</code> by <code>dividerSize</code> pixels.
   *
   * @return The preferred size of the divider.
   */
  public Dimension getPreferredSize()
  {
    return getLayout().preferredLayoutSize(this);
  }

  /**
   * Returns the minimal size of this divider, which is
   * <code>dividerSize</code> by <code>dividerSize</code> pixels.
   *
   * @return The minimal size of the divider.
   */
  public Dimension getMinimumSize()
  {
    return getPreferredSize();
  }

  /**
   * Processes events from the <code>JSplitPane</code> that contains this
   * divider.
   *
   * @param e The PropertyChangeEvent.
   */
  public void propertyChange(PropertyChangeEvent e)
  {
    if (e.getPropertyName().equals(JSplitPane.ONE_TOUCH_EXPANDABLE_PROPERTY))
      oneTouchExpandableChanged();
    else if (e.getPropertyName().equals(JSplitPane.ORIENTATION_PROPERTY))
      {
	orientation = splitPane.getOrientation();
	if (splitPane.isOneTouchExpandable())
	  {
	    layout();
	    repaint();
	  }
      }
    else if (e.getPropertyName().equals(JSplitPane.DIVIDER_SIZE_PROPERTY))
      dividerSize = splitPane.getDividerSize();
  }

  /**
   * Paints the divider by painting its border.
   *
   * @param g The Graphics Object to paint with.
   */
  public void paint(Graphics g)
  {
    Dimension dividerSize;

    super.paint(g);
    if (border != null)
      {
	dividerSize = getSize();
	border.paintBorder(this, g, 0, 0, dividerSize.width, dividerSize.height);
      }
  }

  /**
   * Reacts to changes of the <code>oneToughExpandable</code> property of the
   * containing <code>JSplitPane</code>.
   */
  protected void oneTouchExpandableChanged()
  {
    if (splitPane.isOneTouchExpandable())
      {
	leftButton = createLeftOneTouchButton();
	rightButton = createRightOneTouchButton();
	add(leftButton);
	add(rightButton);

	leftButton.addMouseListener(mouseHandler);
	rightButton.addMouseListener(mouseHandler);

	// Set it to 1.
	currentDividerLocation = 1;
      }
    else
      {
	if (leftButton != null && rightButton != null)
	  {
	    leftButton.removeMouseListener(mouseHandler);
	    rightButton.removeMouseListener(mouseHandler);

	    remove(leftButton);
	    remove(rightButton);
	    leftButton = null;
	    rightButton = null;
	  }
      }
    layout();
    repaint();
  }

  /**
   * Creates a button for showing and hiding the left (or top) part of a
   * <code>JSplitPane</code>.
   *
   * @return The left one touch button.
   */
  protected JButton createLeftOneTouchButton()
  {
    int dir = SwingConstants.WEST;
    if (orientation == JSplitPane.VERTICAL_SPLIT)
      dir = SwingConstants.NORTH;
    JButton button = new BasicArrowButton(dir);
    button.setBorder(null);

    return button;
  }

  /**
   * Creates a button for showing and hiding the right (or bottom) part of a
   * <code>JSplitPane</code>.
   *
   * @return The right one touch button.
   */
  protected JButton createRightOneTouchButton()
  {
    int dir = SwingConstants.EAST;
    if (orientation == JSplitPane.VERTICAL_SPLIT)
      dir = SwingConstants.SOUTH;
    JButton button = new BasicArrowButton(dir);
    button.setBorder(null);
    return button;
  }

  /**
   * Prepares the divider for dragging by calling the
   * <code>startDragging</code> method of the UI delegate of the enclosing
   * <code>JSplitPane</code>.
   *
   * @see BasicSplitPaneUI#startDragging()
   */
  protected void prepareForDragging()
  {
    if (splitPaneUI != null)
      splitPaneUI.startDragging();
  }

  /**
   * Drags the divider to a given location by calling the
   * <code>dragDividerTo</code> method of the UI delegate of the enclosing
   * <code>JSplitPane</code>.
   *
   * @param location the new location of the divider.
   *
   * @see BasicSplitPaneUI#dragDividerTo(int location)
   */
  protected void dragDividerTo(int location)
  {
    if (splitPaneUI != null)
      splitPaneUI.dragDividerTo(location);
  }

  /**
   * Finishes a dragging gesture by calling the <code>finishDraggingTo</code>
   * method of the UI delegate of the enclosing <code>JSplitPane</code>.
   *
   * @param location the new, final location of the divider.
   *
   * @see BasicSplitPaneUI#finishDraggingTo(int location)
   */
  protected void finishDraggingTo(int location)
  {
    if (splitPaneUI != null)
      splitPaneUI.finishDraggingTo(location);
  }

  /**
   * This helper method moves the divider to one of the  three locations when
   * using one touch expand buttons. Location 0 is the left (or top) most
   * location. Location 1 is the middle. Location 2 is the right (or bottom)
   * most location.
   * This is package-private to avoid an accessor method.
   *
   * @param locationIndex The location to move to.
   */
  void moveDividerTo(int locationIndex)
  {
    Insets insets = splitPane.getInsets();
    switch (locationIndex)
      {
      case 1:
	splitPane.setDividerLocation(splitPane.getLastDividerLocation());
	break;
      case 0:
	int top = (orientation == JSplitPane.HORIZONTAL_SPLIT) ? insets.left
	                                                       : insets.top;
	splitPane.setDividerLocation(top);
	break;
      case 2:
	int bottom;
	if (orientation == JSplitPane.HORIZONTAL_SPLIT)
	  bottom = splitPane.getBounds().width - insets.right - dividerSize;
	else
	  bottom = splitPane.getBounds().height - insets.bottom - dividerSize;
	splitPane.setDividerLocation(bottom);
	break;
      }
  }

  /**
   * The listener for handling mouse events from both the divider and the
   * containing <code>JSplitPane</code>.
   * 
   * <p>
   * The reason for also handling MouseEvents from the containing
   * <code>JSplitPane</code> is that users should be able to start a drag
   * gesture from inside the JSplitPane, but slightly outisde the divider.
   * </p>
   *
   * @author Sascha Brawer (brawer_AT_dandelis.ch)
   */
  protected class MouseHandler extends MouseAdapter
    implements MouseMotionListener
  {
    /** Keeps track of whether a drag is occurring. */
    private transient boolean isDragging;

    /**
     * This method is called when the mouse is pressed.
     *
     * @param e The MouseEvent.
     */
    public void mousePressed(MouseEvent e)
    {
      if (splitPane.isOneTouchExpandable())
        {
	  if (e.getSource() == leftButton)
	    {
	      currentDividerLocation--;
	      if (currentDividerLocation < 0)
		currentDividerLocation = 0;
	      moveDividerTo(currentDividerLocation);
	      return;
	    }
	  else if (e.getSource() == rightButton)
	    {
	      currentDividerLocation++;
	      if (currentDividerLocation > 2)
		currentDividerLocation = 2;
	      moveDividerTo(currentDividerLocation);
	      return;
	    }
        }
      isDragging = true;
      currentDividerLocation = 1;
      if (orientation == JSplitPane.HORIZONTAL_SPLIT)
	dragger = new DragController(e);
      else
	dragger = new VerticalDragController(e);
      prepareForDragging();
    }

    /**
     * This method is called when the mouse is released.
     *
     * @param e The MouseEvent.
     */
    public void mouseReleased(MouseEvent e)
    {
      if (isDragging)
	dragger.completeDrag(e);
      isDragging = false;
    }

    /**
     * Repeatedly invoked when the user is dragging the mouse cursor while
     * having pressed a mouse button.
     *
     * @param e The MouseEvent.
     */
    public void mouseDragged(MouseEvent e)
    {
      if (dragger != null)
	dragger.continueDrag(e);
    }

    /**
     * Repeatedly invoked when the user is dragging the mouse cursor without
     * having pressed a mouse button.
     *
     * @param e The MouseEvent.
     */
    public void mouseMoved(MouseEvent e)
    {
      // Do nothing.
    }
  }

  /**
   * Performs the tasks associated with an ongoing drag operation.
   *
   * @author Sascha Brawer (brawer_AT_dandelis.ch)
   */
  protected class DragController
  {
    /**
     * The difference between where the mouse is clicked and the  initial
     * divider location.
     */
    transient int offset;

    /**
     * Creates a new DragController object.
     *
     * @param e The MouseEvent to initialize with.
     */
    protected DragController(MouseEvent e)
    {
      offset = e.getX();
    }

    /**
     * This method returns true if the divider can move.
     *
     * @return True if dragging is allowed.
     */
    protected boolean isValid()
    {
      // Views can always be resized?
      return true;
    }

    /**
     * Returns a position for the divider given the MouseEvent.
     *
     * @param e MouseEvent.
     *
     * @return The position for the divider to move to.
     */
    protected int positionForMouseEvent(MouseEvent e)
    {
      return e.getX() + getX() - offset;
    }

    /**
     * This method returns one of the two paramters for the orientation. In
     * this case, it returns x.
     *
     * @param x The x coordinate.
     * @param y The y coordinate.
     *
     * @return The x coordinate.
     */
    protected int getNeededLocation(int x, int y)
    {
      return x;
    }

    /**
     * This method is called to pass on the drag information to the UI through
     * dragDividerTo.
     *
     * @param newX The x coordinate of the MouseEvent.
     * @param newY The y coordinate of the MouseEvent.
     */
    protected void continueDrag(int newX, int newY)
    {
      if (isValid())
	dragDividerTo(adjust(newX, newY));
    }

    /**
     * This method is called to pass on the drag information  to the UI
     * through dragDividerTo.
     *
     * @param e The MouseEvent.
     */
    protected void continueDrag(MouseEvent e)
    {
      if (isValid())
	dragDividerTo(positionForMouseEvent(e));
    }

    /**
     * This method is called to finish the drag session  by calling
     * finishDraggingTo.
     *
     * @param x The x coordinate of the MouseEvent.
     * @param y The y coordinate of the MouseEvent.
     */
    protected void completeDrag(int x, int y)
    {
      finishDraggingTo(adjust(x, y));
    }

    /**
     * This method is called to finish the drag session  by calling
     * finishDraggingTo.
     *
     * @param e The MouseEvent.
     */
    protected void completeDrag(MouseEvent e)
    {
      finishDraggingTo(positionForMouseEvent(e));
    }

    /**
     * This is a helper method that includes the offset in the needed
     * location.
     *
     * @param x The x coordinate of the MouseEvent.
     * @param y The y coordinate of the MouseEvent.
     *
     * @return The needed location adjusted by the offsets.
     */
    int adjust(int x, int y)
    {
      return getNeededLocation(x, y) + getX() - offset;
    }
  }

  /**
   * This is a helper class that controls dragging when  the orientation is
   * VERTICAL_SPLIT.
   */
  protected class VerticalDragController extends DragController
  {
    /**
     * Creates a new VerticalDragController object.
     *
     * @param e The MouseEvent to initialize with.
     */
    protected VerticalDragController(MouseEvent e)
    {
      super(e);
      offset = e.getY();
    }

    /**
     * This method returns one of the two parameters given the orientation. In
     * this case, it returns y.
     *
     * @param x The x coordinate of the MouseEvent.
     * @param y The y coordinate of the MouseEvent.
     *
     * @return The y coordinate.
     */
    protected int getNeededLocation(int x, int y)
    {
      return y;
    }

    /**
     * This method returns the new location of the divider given a MouseEvent.
     *
     * @param e The MouseEvent.
     *
     * @return The new location of the divider.
     */
    protected int positionForMouseEvent(MouseEvent e)
    {
      return e.getY() + getY() - offset;
    }

    /**
     * This is a helper method that includes the offset in the needed
     * location.
     *
     * @param x The x coordinate of the MouseEvent.
     * @param y The y coordinate of the MouseEvent.
     *
     * @return The needed location adjusted by the offsets.
     */
    int adjust(int x, int y)
    {
      return getNeededLocation(x, y) + getY() - offset;
    }
  }

  /**
   * This helper class acts as the Layout Manager for the divider.
   */
  protected class DividerLayout implements LayoutManager
  {
    /**
     * Creates a new DividerLayout object.
     */
    protected DividerLayout()
    {
      // Nothing to do here.
    }

    /**
     * This method is called when a Component is added.
     *
     * @param string The constraints string.
     * @param c The Component to add.
     */
    public void addLayoutComponent(String string, Component c)
    {
      // Do nothing.
    }

    /**
     * This method is called to lay out the container.
     *
     * @param c The container to lay out.
     */
    public void layoutContainer(Container c)
    {
      if (splitPane.isOneTouchExpandable())
        {
	  changeButtonOrientation();
	  positionButtons();
        }
    }

    /**
     * This method returns the minimum layout size.
     *
     * @param c The container to calculate for.
     *
     * @return The minimum layout size.
     */
    public Dimension minimumLayoutSize(Container c)
    {
      return preferredLayoutSize(c);
    }

    /**
     * This method returns the preferred layout size.
     *
     * @param c The container to calculate for.
     *
     * @return The preferred layout size.
     */
    public Dimension preferredLayoutSize(Container c)
    {
      return new Dimension(dividerSize, dividerSize);
    }

    /**
     * This method is called when a component is removed.
     *
     * @param c The component to remove.
     */
    public void removeLayoutComponent(Component c)
    {
      // Do nothing.
    }

    /**
     * This method changes the button orientation when the orientation of the
     * SplitPane changes.
     */
    private void changeButtonOrientation()
    {
      if (orientation == JSplitPane.HORIZONTAL_SPLIT)
        {
	  ((BasicArrowButton) rightButton).setDirection(SwingConstants.EAST);
	  ((BasicArrowButton) leftButton).setDirection(SwingConstants.WEST);
        }
      else
        {
	  ((BasicArrowButton) rightButton).setDirection(SwingConstants.SOUTH);
	  ((BasicArrowButton) leftButton).setDirection(SwingConstants.NORTH);
        }
    }

    /**
     * This method sizes and positions the buttons.
     */
    private void positionButtons()
    {
      int w = 0;
      int h = 0;
      if (orientation == JSplitPane.HORIZONTAL_SPLIT)
        {
	  rightButton.setLocation(ONE_TOUCH_OFFSET, ONE_TOUCH_OFFSET);
	  leftButton.setLocation(ONE_TOUCH_OFFSET,
	                         ONE_TOUCH_OFFSET + 2 * ONE_TOUCH_SIZE);
	  w = dividerSize - 2 * ONE_TOUCH_OFFSET;
	  h = 2 * ONE_TOUCH_SIZE;
        }
      else
        {
	  leftButton.setLocation(ONE_TOUCH_OFFSET, ONE_TOUCH_OFFSET);
	  rightButton.setLocation(ONE_TOUCH_OFFSET + 2 * ONE_TOUCH_SIZE,
	                          ONE_TOUCH_OFFSET);
	  h = dividerSize - 2 * ONE_TOUCH_OFFSET;
	  w = 2 * ONE_TOUCH_SIZE;
        }
      Dimension dims = new Dimension(w, h);
      leftButton.setSize(dims);
      rightButton.setSize(dims);
    }
  }
}