colorpan.java

exploring Java 2ed edition 附带的例子程序

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

public class ColorPan extends java.applet.Applet { 
	Image img;
	int width, height;
	int [] pixData;

	public void init() {
		width = getSize().width;
		height = getSize().height;
		pixData = new int [width * height];
		int i=0;

        for (int y = 0; y < height; y++) {
            int red = (y * 255) / (height - 1);
            for (int x = 0; x < width; x++) {
                int green = (x * 255) / (width - 1);

				int blue = 128;
				int alpha = 255;
                pixData[i++] = (alpha << 24) | (red << 16) | (green << 8 ) | blue;
            }
        }
	}

	public void paint( Graphics g ) {
		if ( img == null )
			img = createImage( new MemoryImageSource(width, height, pixData, 0, width));
		g.drawImage( img, 0, 0, this );
	}
}