/* JScrollPane.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
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package javax.swing;

import java.awt.Component;
import java.awt.ComponentOrientation;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Rectangle;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.accessibility.Accessible;
import javax.accessibility.AccessibleContext;
import javax.swing.border.Border;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.ScrollPaneUI;
import javax.swing.plaf.UIResource;

/**
 * A component that embeds another component and enables it to be scrolled
 * both in horizontal and vertical direction.
 *
 * <table>
 * <tr><th>Property                    </th><th>Stored in       </th><th>Bound?</th></tr>
 * <tr><td>columnHeader                </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>columnHeaderView            </td><td>columnHeader    </td><td>no    </td></tr>
 * <tr><td>componentOrientation        </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>horizontalScrollBar         </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>horizontalScrollBarPolicy   </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>layout                      </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>rowHeader                   </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>rowHeaderView               </td><td>rowHeader       </td><td>no    </td></tr>
 * <tr><td>validateRoot                </td><td>scrollPane      </td><td>no    </td></tr>
 * <tr><td>verticalScrollBar           </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>verticalScrollBarPolicy     </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>viewport                    </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>viewportBorder              </td><td>scrollPane      </td><td>yes   </td></tr>
 * <tr><td>viewportBorderBounds        </td><td>scrollPane      </td><td>no    </td></tr>
 * <tr><td>viewportView                </td><td>viewport        </td><td>no    </td></tr>
 * <tr><td>wheelScrollingEnabled       </td><td>scrollPane      </td><td>yes   </td></tr>
 * </table>
 */
public class JScrollPane extends JComponent
  implements Accessible, ScrollPaneConstants
{
  /**
   * Provides accessibility support for the <code>JScrollPane</code>.
   *
   * @author Roman Kennke (kennke@aicas.com)
   */
  protected class AccessibleJScrollPane extends AccessibleJComponent
    implements ChangeListener, PropertyChangeListener
  {

    /**
     * The viewport of the underlying scrollpane.
     */
    protected JViewport viewPort;

    /**
     * Creates a new <code>AccessibleJScrollPane</code> object. This
     * initializes the <code>viewport</code> field with the current viewport
     * from the scrollpane associated with this
     * <code>AccessibleJScrollPane</code>.
     */
    public AccessibleJScrollPane()
    {
      viewPort = getViewport();
      viewPort.addChangeListener(this);
      viewPort.addPropertyChangeListener(this);
    }

    /**
     * Receives notification when the state of the viewport changes.
     *
     * @param event the change event
     */
    public void stateChanged(ChangeEvent event)
    {
      // TODO: Figure out what should be done here, if anything.
    }

    /**
     * Receives notification if any of the viewport's bound properties changes.
     *
     * @param e the propery change event
     */
    public void propertyChange(PropertyChangeEvent e)
    {
      // TODO: Figure out what should be done here, if anything.
    }

    /**
     * Resets the <code>viewPort</code> field when the scrollpane's viewport
     * changes. This method is called by
     * {@link JScrollPane#setViewport(JViewport)} in order to update the
     * <code>viewPort</code> field and set up the listeners on this viewport
     * correctly.
     */
    public void resetViewPort()
    {
      viewPort.removeChangeListener(this);
      viewPort.removePropertyChangeListener(this);
      viewPort = getViewport();
      viewPort.addChangeListener(this);
      viewPort.addPropertyChangeListener(this);
    }
  }

  private static final long serialVersionUID = 5203525440012340014L;

  protected JViewport columnHeader;
  protected JViewport rowHeader;

  protected Component lowerLeft;
  protected Component lowerRight;
  protected Component upperLeft;
  protected Component upperRight;

  protected JScrollBar horizontalScrollBar;
  protected int horizontalScrollBarPolicy;
  protected JScrollBar verticalScrollBar;
  protected int verticalScrollBarPolicy;

  protected JViewport viewport;

  private Border viewportBorder;

  private boolean wheelScrollingEnabled;

  public JViewport getColumnHeader()
  {
    return columnHeader;
  }

  public Component getCorner(String key)
  {
    if (getComponentOrientation()
        == ComponentOrientation.LEFT_TO_RIGHT)
      {
        if (key == LOWER_LEADING_CORNER)
          key = LOWER_LEFT_CORNER;
        else if (key == LOWER_TRAILING_CORNER)
          key = LOWER_RIGHT_CORNER;
        else if (key == UPPER_LEADING_CORNER)
          key = UPPER_LEFT_CORNER;
        else if (key == UPPER_TRAILING_CORNER)
          key = UPPER_RIGHT_CORNER;
      }
    else if (getComponentOrientation()
             == ComponentOrientation.RIGHT_TO_LEFT)
      {
        if (key == LOWER_LEADING_CORNER)
          key = LOWER_RIGHT_CORNER;
        else if (key == LOWER_TRAILING_CORNER)
          key = LOWER_LEFT_CORNER;
        else if (key == UPPER_LEADING_CORNER)
          key = UPPER_RIGHT_CORNER;
        else if (key == UPPER_TRAILING_CORNER)
          key = UPPER_LEFT_CORNER;
      }

    if (key == LOWER_RIGHT_CORNER)
      return lowerRight;
    else if (key == UPPER_RIGHT_CORNER)
      return upperRight;
    else if (key == LOWER_LEFT_CORNER)
      return lowerLeft;
    else if (key == UPPER_LEFT_CORNER)
      return upperLeft;
    return null;
  }

  public JScrollBar getHorizontalScrollBar()
  {
    return horizontalScrollBar;
  }

  public int getHorizontalScrollBarPolicy()
  {
    return horizontalScrollBarPolicy;
  }

  public JViewport getRowHeader()
  {
    return rowHeader;
  }

  public JScrollBar getVerticalScrollBar()
  {
    return verticalScrollBar;
  }

  public int getVerticalScrollBarPolicy()
  {
    return verticalScrollBarPolicy;
  }

  public JViewport getViewport()
  {
    return viewport;
  }

  public Border getViewportBorder()
  {
    return viewportBorder;
  }

  public Rectangle getViewportBorderBounds()
  {
    if (viewportBorder == null)
      {
        if (getViewport() == null)
          return new Rectangle(0, 0, 0, 0);
        else
          return getViewport().getBounds();
      }
    else
      {
        Insets i = viewportBorder.getBorderInsets(getViewport());
        if (getViewport() == null)
          return new Rectangle(0, 0, i.left + i.right, i.top + i.bottom);
        else
          {
            Rectangle b = getViewport().getBounds();
            return new Rectangle(b.x - i.left,
                                 b.y - i.top,
                                 b.width + i.left + i.right,
                                 b.height + i.top + i.bottom);
          }
      }
  }

  public boolean isWheelScrollingEnabled()
  {
    return wheelScrollingEnabled;
  }


  private void sync()
  {
    LayoutManager m = super.getLayout();
    if (m != null && m instanceof ScrollPaneLayout)
      {
        ScrollPaneLayout sl = (ScrollPaneLayout) m;
        sl.syncWithScrollPane(this);
      }
  }

  private void removeNonNull(Component c)
  {
    if (c != null)
      remove(c);
  }

  private void addNonNull(Component c, Object constraints)
  {
    if (c != null)
      add(c, constraints);
  }

  public void setComponentOrientation(ComponentOrientation co)
  {
    ComponentOrientation old = super.getComponentOrientation();
    super.setComponentOrientation(co);
    firePropertyChange("componentOrientation", old, co);
    sync();
  }

  public void setColumnHeader(JViewport h)
  {
    if (columnHeader == h)
      return;

    JViewport old = columnHeader;
    removeNonNull(old);
    columnHeader = h;
    addNonNull(h, JScrollPane.COLUMN_HEADER);
    firePropertyChange("columnHeader", old, h);
    sync();
  }

  public void setColumnHeaderView(Component c)
  {
    if (columnHeader == null)
      setColumnHeader(createViewport());
    columnHeader.setView(c);
    sync();
  }

  public void setCorner(String key, Component c)
  {
    if (getComponentOrientation()
        == ComponentOrientation.LEFT_TO_RIGHT)
      {
        if (key == LOWER_LEADING_CORNER)
          key = LOWER_LEFT_CORNER;
        else if (key == LOWER_TRAILING_CORNER)
          key = LOWER_RIGHT_CORNER;
        else if (key == UPPER_LEADING_CORNER)
          key = UPPER_LEFT_CORNER;
        else if (key == UPPER_TRAILING_CORNER)
          key = UPPER_RIGHT_CORNER;
      }
    else if (getComponentOrientation()
             == ComponentOrientation.RIGHT_TO_LEFT)
      {
        if (key == LOWER_LEADING_CORNER)
          key = LOWER_RIGHT_CORNER;
        else if (key == LOWER_TRAILING_CORNER)
          key = LOWER_LEFT_CORNER;
        else if (key == UPPER_LEADING_CORNER)
          key = UPPER_RIGHT_CORNER;
        else if (key == UPPER_TRAILING_CORNER)
          key = UPPER_LEFT_CORNER;
      }

    if (key == LOWER_RIGHT_CORNER)
      {
        removeNonNull(lowerRight);
        lowerRight = c;
        addNonNull(c, JScrollPane.LOWER_RIGHT_CORNER);
      }
    else if (key == UPPER_RIGHT_CORNER)
      {
        removeNonNull(upperRight);
        upperRight = c;
        addNonNull(c, JScrollPane.UPPER_RIGHT_CORNER);
      }
    else if (key == LOWER_LEFT_CORNER)
      {
        removeNonNull(lowerLeft);
        lowerLeft = c;
        addNonNull(c, JScrollPane.LOWER_LEFT_CORNER);
      }
    else if (key == UPPER_LEFT_CORNER)
      {
        removeNonNull(upperLeft);
        upperLeft = c;
        addNonNull(c, JScrollPane.UPPER_LEFT_CORNER);
      }
    else
      throw new IllegalArgumentException("unknown corner " + key);
    sync();
  }

  public void setHorizontalScrollBar(JScrollBar h)
  {
    if (horizontalScrollBar == h)
      return;

    JScrollBar old = horizontalScrollBar;
    removeNonNull(old);
    horizontalScrollBar = h;
    addNonNull(h, JScrollPane.HORIZONTAL_SCROLLBAR);
    firePropertyChange("horizontalScrollBar", old, h);
    sync();

  }

  public void setHorizontalScrollBarPolicy(int h)
  {
    if (horizontalScrollBarPolicy == h)
      return;

    if (h != HORIZONTAL_SCROLLBAR_AS_NEEDED
        && h != HORIZONTAL_SCROLLBAR_NEVER
        && h != HORIZONTAL_SCROLLBAR_ALWAYS)
      throw new IllegalArgumentException("unknown horizontal scrollbar policy");

    int old = horizontalScrollBarPolicy;
    horizontalScrollBarPolicy = h;
    firePropertyChange("horizontalScrollBarPolicy", old, h);
    sync();
    revalidate();
  }

  public void setLayout(LayoutManager l)
  {
    LayoutManager old = super.getLayout();
    ScrollPaneLayout tmp = (ScrollPaneLayout) l;
    super.setLayout(l);
    tmp.syncWithScrollPane(this);
    firePropertyChange("layout", old, l);
    sync();
  }

  public void setRowHeader(JViewport v)
  {
    if (rowHeader == v)
      return;

    JViewport old = rowHeader;
    removeNonNull(old);
    rowHeader = v;
    addNonNull(v, JScrollPane.ROW_HEADER);
    firePropertyChange("rowHeader", old, v);
    sync();
  }

  public void setRowHeaderView(Component c)
  {
    if (rowHeader == null)
      setRowHeader(createViewport());
    rowHeader.setView(c);
    sync();
  }

  public void setVerticalScrollBar(JScrollBar v)
  {
    if (verticalScrollBar == v)
      return;

    JScrollBar old = verticalScrollBar;
    removeNonNull(old);
    verticalScrollBar = v;
    addNonNull(v, JScrollPane.VERTICAL_SCROLLBAR);
    firePropertyChange("verticalScrollBar", old, v);
    sync();
  }

  public void setVerticalScrollBarPolicy(int v)
  {
    if (verticalScrollBarPolicy == v)
      return;

    if (v != VERTICAL_SCROLLBAR_AS_NEEDED
        && v != VERTICAL_SCROLLBAR_NEVER
        && v != VERTICAL_SCROLLBAR_ALWAYS)
      throw new IllegalArgumentException("unknown vertical scrollbar policy");

    int old = verticalScrollBarPolicy;
    verticalScrollBarPolicy = v;
    firePropertyChange("verticalScrollBarPolicy", old, v);
    sync();
    revalidate();
  }

  public void setWheelScrollingEnabled(boolean b)
  {
    if (wheelScrollingEnabled == b)
      return;

    boolean old = wheelScrollingEnabled;
    wheelScrollingEnabled = b;
    firePropertyChange("wheelScrollingEnabled", old, b);
    sync();
  }

  public void setViewport(JViewport v)
  {
    if (viewport == v)
      return;

    JViewport old = viewport;
    removeNonNull(old);
    viewport = v;
    addNonNull(v, JScrollPane.VIEWPORT);
    revalidate();
    repaint();
    firePropertyChange("viewport", old, v);
    sync();
    if (accessibleContext != null)
      {
        AccessibleJScrollPane asp = (AccessibleJScrollPane) accessibleContext;
        asp.resetViewPort();
      }
  }

  public void setViewportBorder(Border b)
  {
    if (viewportBorder == b)
      return;

    Border old = viewportBorder;
    viewportBorder = b;
    firePropertyChange("viewportBorder", old, b);
    sync();
  }

  public void setViewportView(Component view)
  {
    if (getViewport() == null)
      {
        setViewport(createViewport());
      }

    if (view != null)
      {
        getViewport().setView(view);
      }
    sync();
  }

  public boolean isValidateRoot()
  {
    return true;
  }

  /**
   * Creates a new <code>JScrollPane</code> without a view. The scrollbar
   * policy is set to {@link #VERTICAL_SCROLLBAR_AS_NEEDED} and
   * {@link #HORIZONTAL_SCROLLBAR_AS_NEEDED}.
   */
  public JScrollPane()
  {
    this(null);
  }

  /**
   * Creates a new <code>JScrollPane</code> that embeds the specified
   * <code>view</code> component, displaying vertical and horizontal scrollbars
   * as needed.
   *
   * @param view the component that is embedded inside the JScrollPane
   */
  public JScrollPane(Component view)
  {
    this(view,
         VERTICAL_SCROLLBAR_AS_NEEDED,
         HORIZONTAL_SCROLLBAR_AS_NEEDED);
  }

  /**
   * Creates a new <code>JScrollPane</code> without a view; The scrollbar
   * policies are set to <code>vsbPolicy</code> and <code>hsbPolicy</code>.
   *
   * @param vsbPolicy the vertical scrollbar policy to set
   * @param hsbPolicy the vertical scrollbar policy to set
   *
   * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_ALWAYS
   * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_AS_NEEDED
   * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_NEVER
   * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_ALWAYS
   * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_AS_NEEDED
   * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_NEVER
   */
  public JScrollPane(int vsbPolicy, int hsbPolicy)
  {
    this(null, vsbPolicy, hsbPolicy);
  }

  /**
   * Creates a new <code>JScrollPane</code> that embeds the specified
   * <code>view</code> component; The scrollbar
   * policies are set to <code>vsbPolicy</code> and <code>hsbPolicy</code>.
   *
   * @param vsbPolicy the vertical scrollbar policy to set
   * @param hsbPolicy the vertical scrollbar policy to set
   *
   * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_ALWAYS
   * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_AS_NEEDED
   * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_NEVER
   * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_ALWAYS
   * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_AS_NEEDED
   * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_NEVER
   */
  public JScrollPane(Component view, int vsbPolicy, int hsbPolicy)
  {
    wheelScrollingEnabled = true;
    setVerticalScrollBarPolicy(vsbPolicy);
    setVerticalScrollBar(createVerticalScrollBar());
    setHorizontalScrollBarPolicy(hsbPolicy);
    setHorizontalScrollBar(createHorizontalScrollBar());
    viewport = createViewport();
    if (view != null)
      getViewport().setView(view);
    add(viewport,0);
    setLayout(new ScrollPaneLayout());
    setOpaque(false);
    updateUI();
  }


  public JScrollBar createHorizontalScrollBar()
  {
    return new ScrollBar(SwingConstants.HORIZONTAL);
  }

  public JScrollBar createVerticalScrollBar()
  {
    return new ScrollBar(SwingConstants.VERTICAL);
  }

  protected JViewport createViewport()
  {
    return new JViewport();
  }

  public String getUIClassID()
  {
    return "ScrollPaneUI";
  }

  public void updateUI()
  {
    setUI((ScrollPaneUI) UIManager.getUI(this));
  }

  /**
   * This method returns the scrollpane's UI delegate.
   *
   * @return The scrollpane's UI delegate.
   */
  public ScrollPaneUI getUI()
  {
    return (ScrollPaneUI) ui;
  }

  /**
   * This method sets the scrollpane's UI delegate.
   *
   * @param ui The scrollpane's UI delegate.
   */
  public void setUI(ScrollPaneUI ui)
  {
    super.setUI(ui);
  }

  protected class ScrollBar
    extends JScrollBar
    implements UIResource
  {
    private static final long serialVersionUID = -42032395320987283L;

    public ScrollBar(int orientation)
    {
      super(orientation);
    }

    public int getBlockIncrement(int direction)
    {
      Component view = JScrollPane.this.getViewport().getView();
      if (view == null || (! (view instanceof Scrollable)))
        return super.getBlockIncrement(direction);
      else
        {
          Scrollable s = (Scrollable) view;
          return s.getScrollableBlockIncrement(JScrollPane.this.getViewport().getViewRect(),
                                               this.getOrientation(),
                                               direction);
        }
    }

    public int getUnitIncrement(int direction)
    {
      Component view = JScrollPane.this.getViewport().getView();
      if (view == null || (! (view instanceof Scrollable)))
        return super.getUnitIncrement(direction);
      else
        {
          Scrollable s = (Scrollable) view;
          return s.getScrollableUnitIncrement(JScrollPane.this.getViewport().getViewRect(),
                                              this.getOrientation(),
                                              direction);
        }
    }
  }

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