grayscale.java

java技术内幕源代码,配合书籍看有事半功倍的效果

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

/*
  <APPLET
      CODE=grayscale.class
      WIDTH=300
      HEIGHT=300 >
  </APPLET>
*/

public class grayscale extends Applet {
    Image image, image2;

    public void init() 
    {
        image = getImage(getDocumentBase(), "whirl1.gif");
        int pixels[] = new int[248 * 248];

        PixelGrabber pg = new PixelGrabber(image, 0, 0, 248, 248, pixels, 0, 248);
        try {
            pg.grabPixels();
        }
        catch (InterruptedException e) {}

      for (int loop_index = 0; loop_index < 248 * 248; loop_index++){
          int p = pixels[loop_index];
          int red = (0xff & (p >> 16));
          int green = (0xff & (p >> 8));
          int blue = (0xff & p);
          int avg = (int) ((red + green + blue) / 3);
          pixels[loop_index] = (0xff000000 | avg << 16 | avg << 8 | avg);
      }

        image2 = createImage(new MemoryImageSource(248, 248, pixels, 0 , 248));
    }

    public void paint(Graphics g) 
    {
        g.drawImage(image2, 10, 10, this);
    }
}