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/* AnimationApplet.java -- An example of an old-style AWT applet

   Copyright (C) 2006 Free Software Foundation, Inc.

This file is part of GNU Classpath examples.

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. */

package gnu.classpath.examples.awt;

import java.awt.*;

import java.applet.*;

/**

 * AnimationApplet demonstrates the need for Xflush calls in

 * GdkGraphics.c.  To see how this demo can fail in their absence,

 * remove the contents of schedule_flush in GdkGraphics.c.  The

 * animation will be so choppy that it is effectively stopped.

 */

public class AnimationApplet

  extends Applet

  implements Runnable

{

  boolean going = false;

  Thread animThread = null;

  int SPEED = 5;

  int circleX = 0;

  int circleY = 0;

  int circleXold = 0;

  int circleYold = 0;

  int circleXdelta = 0;

  int circleYdelta = 0;

  int circleDiameter = 0;

  int autoCircleX = 0;

  int autoCircleY = 0;

  int autoCircleXold = 0;

  int autoCircleYold = 0;

  int autoCircleXdelta = (int) (0.66 * SPEED);

  int autoCircleYdelta = (int) (1.33 * SPEED);

  int boardWidth = 0;

  int boardHeight = 0;

  int CIRCLE_SIZE = 5;

  private Graphics appletGraphics;

  // Update the circles' location values.

  private void moveCircles()

  {

    circleX += circleXdelta;

    if (circleX < 0)

      circleX = 0;

    if (circleX > boardWidth - circleDiameter)

      circleX = boardWidth - circleDiameter;

    circleY += circleYdelta;

    if (circleY < 0)

      circleY = 0;

    if (circleY > boardHeight - circleDiameter)

      circleY = boardHeight - circleDiameter;

    autoCircleX += autoCircleXdelta;

    if (autoCircleX < 0)

      {

        autoCircleX = 0;

        autoCircleXdelta = -autoCircleXdelta;

      }

    if (autoCircleX > boardWidth - circleDiameter)

      {

        autoCircleX = boardWidth - circleDiameter;

        autoCircleXdelta = -autoCircleXdelta;

      }

    autoCircleY += autoCircleYdelta;

    if (autoCircleY < 0)

      {

        autoCircleY = 0;

        autoCircleYdelta = -autoCircleYdelta;

      }

    if (autoCircleY > boardHeight - circleDiameter)

      {

        autoCircleY = boardHeight - circleDiameter;

        autoCircleYdelta = -autoCircleYdelta;

      }

  }

  // Clear the circle in the old location and paint a new circle

  // in the new location.

  private void paintCircles()

  {

    appletGraphics.setColor(Color.BLUE);

    appletGraphics.fillOval(circleXold, circleYold, circleDiameter,

                            circleDiameter);

    appletGraphics.setColor(Color.YELLOW);

    appletGraphics.fillOval(circleX, circleY, circleDiameter,

                            circleDiameter);

    appletGraphics.setColor(Color.BLUE);

    appletGraphics.fillOval(autoCircleXold, autoCircleYold, circleDiameter,

                            circleDiameter);

    appletGraphics.setColor(Color.WHITE);

    appletGraphics.fillOval(autoCircleX, autoCircleY, circleDiameter,

                            circleDiameter);

  }

  // Override Applet.run.

  public void run()

  {

    while (animThread != null)

      {

        circleXold = circleX;

        circleYold = circleY;

        autoCircleXold = autoCircleX;

        autoCircleYold = autoCircleY;

        moveCircles();

        paintCircles();

        if (animThread != null)

          {

            try

              {

                Thread.sleep(20);

              }

            catch (InterruptedException e)

              {

              }

          }

      }

  }

  // Override Applet.paint.

  public void paint(Graphics g)

  {

    boardWidth = this.getSize().width;

    boardHeight = this.getSize().height;

    g.setColor(Color.BLUE);

    g.fillRect(0, 0, boardWidth, boardHeight);

    if (!going)

      {

        FontMetrics fm = appletGraphics.getFontMetrics();

        appletGraphics.setColor(Color.WHITE);

        String msg = "Click to Start";

        appletGraphics.drawString(msg,

                                  (boardWidth >> 1) - (fm.stringWidth(msg) >> 1),

                                  (boardHeight >> 1) - (fm.getHeight() >> 1));

      }

  }

  // Override Applet.destroy.

  public void destroy()

  {

    // animThread.stop();

    animThread = null;

  }

  // Override Applet.init.

  public void init()

  {

    boardWidth = this.getSize().width;

    boardHeight = this.getSize().height;

    going = false;

    appletGraphics = getGraphics();

    appletGraphics.setFont(new Font(appletGraphics.getFont().getName(),

                                    Font.BOLD, 15));

  }

  // Override Component.preferredSize for when we're run standalone.

  public Dimension preferredSize ()

  {

    return new Dimension (400, 400);

  }

  // Override Applet.handleEvent, the old-style AWT-event handler.

  public boolean handleEvent(Event event)

  {

    switch (event.id)

      {

      case Event.MOUSE_DOWN:

        if (!going)

          {

            going = true;

            circleDiameter = boardWidth / CIRCLE_SIZE;

            circleX = (boardWidth - circleDiameter) >> 1;

            circleY = (boardHeight - circleDiameter) >> 1;

            circleXdelta = 0;

            circleYdelta = 0;

            repaint();

            animThread = new Thread(this);

            animThread.start();

          }

        break;

      case Event.KEY_ACTION:

      case Event.KEY_PRESS:

        if (event.key == Event.LEFT)

          circleXdelta = -SPEED;

        else if (event.key == Event.RIGHT)

          circleXdelta = SPEED;

        else if (event.key == Event.UP)

          circleYdelta = -SPEED;

        else if (event.key == Event.DOWN)

          circleYdelta = SPEED;

        break;

      case Event.KEY_ACTION_RELEASE:

      case Event.KEY_RELEASE:

        if (event.key == Event.LEFT && circleXdelta < 0)

          circleXdelta = 0;

        else if (event.key == Event.RIGHT && circleXdelta > 0)

          circleXdelta = 0;

        else if (event.key == Event.UP && circleYdelta < 0)

          circleYdelta = 0;

        else if (event.key == Event.DOWN && circleYdelta > 0)

          circleYdelta = 0;

        break;

      default:

        break;

      }

    return false;

  }

}