import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;

/* Class that creates three scroll bars.  Each controls a different color (red, green, or blue).  These are mixed together and displayed on a canvas. */
public class CheckColors extends Applet
{
     private TextField colorValues = new TextField (30);
     private Scrollbar red, green, blue;
     private Label redLabel, greenLabel, blueLabel;
     private Canvas canvas = new Canvas ();
     private Panel southPanel = new Panel ();
     private int r, g, b;

    public void init ()
    {
        red = new Scrollbar (Scrollbar.HORIZONTAL, 0, 1, 0, 255);
        redLabel = new Label ("Red", Label.RIGHT);
        red.addAdjustmentListener (new ScrollbarListener (0));

        green = new Scrollbar (Scrollbar.HORIZONTAL, 0, 1, 0, 255);
        greenLabel = new Label ("Green", Label.RIGHT);
        green.addAdjustmentListener (new ScrollbarListener (1));

        blue = new Scrollbar (Scrollbar.HORIZONTAL, 0, 1, 0, 255);
        blueLabel = new Label ("Blue", Label.RIGHT);
        blue.addAdjustmentListener (new ScrollbarListener (2));

        setLayout (new BorderLayout ());
        canvas.setBackground (Color.cyan);
        add (canvas, "Center");

        southPanel.setLayout (new GridLayout (3, 2, 10, 10));

        southPanel.add (redLabel);
        southPanel.add (red);

        southPanel.add (greenLabel);
        southPanel.add (green);

        southPanel.add (blueLabel);
        southPanel.add (blue);

        add (colorValues, "North");
        add (southPanel, "South");

        r = 0; g = 0; b = 0;
     } // method init

     // Inner class that is used to determine the values of the scroll bars.
     class ScrollbarListener implements AdjustmentListener
     {
          Color color;
          int colorValue, colorBar;
 
          public ScrollbarListener (int colorBar)
          {
               this.colorBar = colorBar;
          } // constructor

          public void adjustmentValueChanged (AdjustmentEvent event)
          {
               colorValue = event.getValue ();
               switch (colorBar)
               {
                    case 0: r = colorValue; break;
                    case 1: g = colorValue; break;
                    case 2:  b = colorValue; break;
               } // switch

               color = new Color (r, g, b);
               canvas.setBackground (color);
               colorValues.setText ("red = " + r + "green = "+ g +"blue = "+ b);
          }
     } // class ScrollbarListener
} // class CheckColors