Applet: Spectrum #1

Applet: Spectrum #1

The example applets below generate spectrums of color and draw something with them.

source code

import java.applet.*;
import java.awt.*;

public class DrawingWithColor1 extends Applet {

   int width, height;
   int N = 25;          // the number of colors created
   Color[] spectrum;    // an array of elements, each of type Color
   Color[] spectrum2;   // another array

   public void init() {
      width = getSize().width;
      height = getSize().height;
      setBackground( Color.black );

      // Allocate the arrays; make them "N" elements long
      spectrum = new Color[ N ];
      spectrum2 = new Color[ N ];

      // Generate the colors and store them in the arrays.
      for ( int i = 1; i <= N; ++i ) {
         // The three numbers passed to the Color() constructor
         // are RGB components in the range [0,1].
         // The casting to (float) is done so that the divisions will be
         // done with floating point numbers, yielding fractional quotients.

         // As i goes from 1 to N, this color goes from almost black to white.
         spectrum[ i-1 ] = new Color( i/(float)N, i/(float)N, i/(float)N );

         // As i goes from 1 to N, this color goes from almost pure green to pure red.
         spectrum2[ i-1 ] = new Color( i/(float)N, (N-i)/(float)N, 0 );
      }
   }

   public void paint( Graphics g ) {

      int step = 90 / N;
      for ( int i = 0; i < N; ++i ) {
         g.setColor( spectrum[ i ] );
         g.fillArc( 0, 0, 2*width, 2*height, 90+i*step, step+1 );

         g.setColor( spectrum2[ i ] );
         g.fillArc( width/3, height/3, 4*width/3, 4*height/3, 90+i*step, step+1 );
      }
   }
}

Output: