Subversion Repositories openrisc

/* DropTarget.java --

   Copyright (C) 2002, 2003, 2004  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 java.awt.dnd;

import java.awt.Component;

import java.awt.GraphicsEnvironment;

import java.awt.HeadlessException;

import java.awt.Insets;

import java.awt.Point;

import java.awt.Rectangle;

import java.awt.datatransfer.FlavorMap;

import java.awt.datatransfer.SystemFlavorMap;

import java.awt.dnd.peer.DropTargetPeer;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.peer.ComponentPeer;

import java.awt.peer.LightweightPeer;

import java.io.Serializable;

import java.util.EventListener;

import java.util.TooManyListenersException;

import javax.swing.Timer;

/**

 * @author Michael Koch

 * @since 1.2

 */

public class DropTarget

  implements DropTargetListener, EventListener, Serializable

{

  /**

   * Compatible with JDK 1.2+

   */

  private static final long serialVersionUID = -6283860791671019047L;

  protected static class DropTargetAutoScroller

    implements ActionListener

  {

    /**

     * The threshold that keeps the autoscroller running.

     */

    private static final int HYSTERESIS = 10;

    /**

     * The initial timer delay.

     */

    private static final int DELAY = 100;

    private Component component;

    private Point point;

    /**

     * The timer that triggers autoscrolling.

     */

    private Timer timer;

    /**

     * The outer region of the scroller. This is the component's size.

     */

    private Rectangle outer;

    /**

     * The inner region of the scroller. This is the component size without

     * the autoscroll insets.

     */

    private Rectangle inner;

    protected DropTargetAutoScroller (Component c, Point p)

    {

      component = c;

      point = p;

      timer = new Timer(DELAY, this);

      timer.setCoalesce(true);

      timer.start();

    }

    protected void updateLocation (Point newLocn)

    {

      Point previous = point;

      point = newLocn;

      if (Math.abs(point.x - previous.x) > HYSTERESIS

          || Math.abs(point.y - previous.y) > HYSTERESIS)

        {

          if (timer.isRunning())

            timer.stop();

        }

      else

        {

          if (! timer.isRunning())

            timer.start();

        }

    }

    protected void stop ()

    {

      timer.start();

    }

    public void actionPerformed (ActionEvent e)

    {

      Autoscroll autoScroll = (Autoscroll) component;

      // First synchronize the inner and outer rectangles.

      Insets i = autoScroll.getAutoscrollInsets();

      int width = component.getWidth();

      int height = component.getHeight();

      if (width != outer.width || height != outer.height)

        outer.setBounds(0, 0, width, height);

      if (inner.x != i.left || inner.y != i.top)

        inner.setLocation(i.left, i.top);

      int inWidth = width - i.left - i.right;

      int inHeight = height - i.top - i.bottom;

      if (inWidth != inner.width || inHeight != inner.height)

        inner.setSize(inWidth, inHeight);

      // Scroll if the outer rectangle contains the location, but the

      // inner doesn't.

      if (outer.contains(point) && ! inner.contains(point))

        autoScroll.autoscroll(point);

    }

  }

  private Component component;

  private FlavorMap flavorMap;

  private int actions;

  private DropTargetPeer peer;

  private DropTargetContext dropTargetContext;

  private DropTargetListener dropTargetListener;

  private DropTarget.DropTargetAutoScroller autoscroller;

  private boolean active = true;

  /**

   * Creates a <code>DropTarget</code> object.

   *

   * @exception HeadlessException If GraphicsEnvironment.isHeadless()

   * returns true.

   */

  public DropTarget ()

  {

    this (null, DnDConstants.ACTION_COPY_OR_MOVE, null, true, null);

  }

  /**

   * Creates a <code>DropTarget</code> object.

   *

   * @exception HeadlessException If GraphicsEnvironment.isHeadless()

   * returns true.

   */

  public DropTarget (Component c, DropTargetListener dtl)

  {

    this (c, DnDConstants.ACTION_COPY_OR_MOVE, dtl, true, null);

  }

  /**

   * Creates a <code>DropTarget</code> object.

   *

   * @exception HeadlessException If GraphicsEnvironment.isHeadless()

   * returns true.

   */

  public DropTarget (Component c, int i, DropTargetListener dtl)

  {

    this (c, i, dtl, true, null);

  }

  /**

   * Creates a <code>DropTarget</code> object.

   *

   * @exception HeadlessException If GraphicsEnvironment.isHeadless()

   * returns true.

   */

  public DropTarget (Component c, int i, DropTargetListener dtl, boolean b)

  {

    this (c, i, dtl, b, null);

  }

  /**

   * Creates a <code>DropTarget</code> object.

   *

   * @exception HeadlessException If GraphicsEnvironment.isHeadless()

   * returns true.

   */

  public DropTarget (Component c, int i, DropTargetListener dtl, boolean b,

                     FlavorMap fm)

  {

    if (GraphicsEnvironment.isHeadless ())

      throw new HeadlessException ();

    setComponent(c);

    setDefaultActions(i);

    dropTargetListener = dtl;

    if (fm == null)

      flavorMap = SystemFlavorMap.getDefaultFlavorMap();

    else

      flavorMap = fm;

    setActive (b);

    if (c != null)

      c.setDropTarget(this);

  }

  /**

   * Sets the component associated with this drop target object.

   */

  public void setComponent (Component c)

  {

    if (component != null)

      clearAutoscroll();

    component = c;

  }

  /**

   * Returns the component associated with this drop target object.

   */

  public Component getComponent ()

  {

    return component;

  }

  /**

   * Sets the default actions.

   */

  public void setDefaultActions (int ops)

  {

    actions = ops;

  }

  /**

   * Returns the default actions.

   */

  public int getDefaultActions ()

  {

    return actions;

  }

  public void setActive (boolean active)

  {

    this.active = active;

    if (! active)

      clearAutoscroll();

  }

  public boolean isActive()

  {

    return active;

  }

  /**

   * Adds a new <code>DropTargetListener</code>.

   *

   * @exception TooManyListenersException Sun's JDK does not, despite

   * documentation, throw this exception here when you install an additional

   * <code>DropTargetListener</code>.  So to be compatible, we do the same

   * thing.

   */

  public void addDropTargetListener (DropTargetListener dtl)

    throws TooManyListenersException

  {

    if (dtl == null)

      return;

    if (dtl.equals(this))

      throw new IllegalArgumentException();

    if (dropTargetListener != null)

      throw new TooManyListenersException();

    dropTargetListener = dtl;

  }

  public void removeDropTargetListener(DropTargetListener dtl)

  {

    if (dropTargetListener != null)

      dropTargetListener = null;

  }

  public void dragEnter(DropTargetDragEvent dtde)

  {

    if (active)

      {

        if (dropTargetListener != null)

          dropTargetListener.dragEnter(dtde);

        initializeAutoscrolling(dtde.getLocation());

      }

  }

  public void dragOver(DropTargetDragEvent dtde)

  {

    if (active)

      {

        if (dropTargetListener != null)

          dropTargetListener.dragOver(dtde);

        updateAutoscroll(dtde.getLocation());

      }

  }

  public void dropActionChanged(DropTargetDragEvent dtde)

  {

    if (active)

      {

        if (dropTargetListener != null)

          dropTargetListener.dropActionChanged(dtde);

        updateAutoscroll(dtde.getLocation());

      }

  }

  public void dragExit(DropTargetEvent dte)

  {

    if (active)

      {

        if (dropTargetListener != null)

          dropTargetListener.dragExit(dte);

        clearAutoscroll();

      }

  }

  public void drop(DropTargetDropEvent dtde)

  {

    clearAutoscroll();

    if (dropTargetListener != null)

      dropTargetListener.drop(dtde);

  }

  public FlavorMap getFlavorMap()

  {

    return flavorMap;

  }

  public void setFlavorMap(FlavorMap fm)

  {

    flavorMap = fm;

  }

  public void addNotify(ComponentPeer p)

  {

    Component c = component;

    while (c != null && p instanceof LightweightPeer)

      {

        p = c.getPeer();

        c = c.getParent();

      }

    if (p instanceof DropTargetPeer)

      {

        peer = ((DropTargetPeer) p);

        peer.addDropTarget(this);

      }

    else

      peer = null;

  }

  public void removeNotify(ComponentPeer p)

  {

    ((DropTargetPeer) peer).removeDropTarget(this);

    peer = null;

    p = null;

  }

  public DropTargetContext getDropTargetContext()

  {

    if (dropTargetContext == null)

      dropTargetContext = createDropTargetContext ();

    return dropTargetContext;

  }

  protected DropTargetContext createDropTargetContext()

  {

    if (dropTargetContext == null)

      dropTargetContext = new DropTargetContext (this);

    return dropTargetContext;

  }

  protected DropTarget.DropTargetAutoScroller createDropTargetAutoScroller

                                                       (Component c, Point p)

  {

    return new DropTarget.DropTargetAutoScroller (c, p);

  }

  protected void initializeAutoscrolling(Point p)

  {

    if (component instanceof Autoscroll) // Checks for null too.

      autoscroller = createDropTargetAutoScroller (component, p);

  }

  protected void updateAutoscroll(Point dragCursorLocn)

  {

    if (autoscroller != null)

      autoscroller.updateLocation(dragCursorLocn);

  }

  protected void clearAutoscroll()

  {

    if (autoscroller != null)

      {

        autoscroller.stop();

        autoscroller = null;

      }

  }

} // class DropTarget