/*
 * Remember, these lines just give us access to all of the
 * graphics functions, so we can take advantage of the 
 * classes that have been defined by the good folks at Sun.
 */
import java.awt.*; 
import java.applet.*; 
import java.awt.event.*; 


/*
 * This is the class that defines the Sketching applet
 */
public class Sketching extends Applet 
    implements MouseListener
{ 
  /*
   *  When the user release the mouse, we'll make changes to these
   *  and then invoke repaint to install them
   *
   * This is a technique known as "double-buffering". It will
   * make this assignment easier to implement than drawign directly onto
   * the active Image. And, it is also better, because the active
   * Image will change, without the redraw being visible.
   */
  private Graphics nextGraphics;
  private Image nextImage;

  /*
   * Dimensions of the applet, itself
   * These come from the HTML page's APPLET tag
   */
  Dimension appletDim;

  /*
   * Start and finish control points for graphics objects, 
   * such as line, oval, rectangle, etc.
   */
  private Point start, finish;


  /*
   * This method is called when the applet is initialized
   */
  public void init()  
  { 
    appletDim = getSize(); // size of the applet, itself

    /*
     * Create the buffer that we'll use to store out changes to
     * the screen, before we actually paint them onto the screen.
     *
     * This involves creating a new Image, and then extracting
     * the Graphics object, the actual screen-map, from it.
     */
    nextImage = createImage (appletDim.width, appletDim.height);
    nextGraphics = nextImage.getGraphics();


    /*
     * Add code here to set the foreground color to white, and then
     * to draw a box the size of the applet. Remember, we want
     * to draw to "nextGraphics". paint() is automatically called
     * after init(), so we don't need to call repaint()
     */



    /*
     * Then, change the color back to something different, maybe black,
     * so that what is drawn on the screen will be visible. 
     */



    /*
     * Instruct the applet to watch for mouse events
     */
    addMouseListener(this); 
   } 

  /*
   * This is used, sometimes automatically, and sometimes
   * explicitly by the program, to redraw the screen 
   * In this case, we prepare "nextImage" in advance. 
   * When we want to redraw the screen, for example after a mouse 
   * event that adds an object, we adjust nextImage, and then 
   * call repaint(), which in turn calls this method.
   */
  public void paint(Graphics g)  
  { 
    g.drawImage (nextImage, 0, 0, this);
  } 


  /*
   * If the mouse is pressed, it is a starting point. 
   * So, we want to mark it with a dot and store it for later,
   * so we can draw the object
   */
  public void mousePressed (MouseEvent me) 
  {
    // Save the current position of the mouse into 
    start = new Point (me.getX(), me.getY());

    /* You might want to draw a dot so the user can see the original 
     * point while moving the mouse to the second point
     *
     * If you want to do this, you can do it by drawing a line 1 pixel
     * long. You want to draw onto "nextGraphics" and then call
     * repaint() to install "nextgraphics" on the screen.
     *
     * Otherwise, you can just save the point and draw the object when
     * the user releases the mouse at the second point.
     */ 
  } 


  /*
   * When the mouse is released it is time to draw the object.
   * So, we find the point, set the color, and draw the right shape
   */
  public void mouseReleased (MouseEvent me) 
  {
    // Save the end point 

    // Draw the shape or line onto "nextGraphics"

    // Call repaint, so the change can be seen.
  } 


  /*
   * We didn't need these actions. But, we do need to
   * define them, or we haven't complied with the
   * MouseAction interface. 
   */

  // This is received, if the user momentarily presses the mouse button
  public void mouseClicked (MouseEvent me) 
  {} 

  // This is received, if the mouse enters the applet area from outside
  public void mouseEntered (MouseEvent me) 
  {} 

  // This is received, if the mouse exits the applet area from outside
  public void mouseExited (MouseEvent me) 
  {}  

}