laserpic.java

Java案例开发集锦,里面提供了很好的学习例子

import java.applet.Applet;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Point;
import java.awt.image.PixelGrabber;
import java.util.Random;

public class LaserPic extends Applet {
	private Image image;

	private int x = 25, y = 25;

	private Random random;

	private int width, height, w, h, image_size, pixels[];

	public void init() {
		//初始化applet
		random = new Random();
		//从网页获取图片文件名参数
		String imageName = getParameter("Image");
		//加载图片
		image = getImage(getDocumentBase(), imageName);
		MediaTracker imageTracker = new MediaTracker(this);
		imageTracker.addImage(image, 0);
		try {
			imageTracker.waitForID(0);
		} catch (InterruptedException e) {

		}
	}

	public void start() {
		//启动applet,然后调用paint()方法

		width = getSize().width; //applet宽度
		height = getSize().height; //applet高度
		w = image.getWidth(this); //图片宽度
		h = image.getHeight(this); //图片高度
		//图片输出位置
		x = (width - w) / 2;
		y = (height - h) / 2;
		//图片大小
		image_size = w * h;
		//创建图片的像素数组
		pixels = new int[image_size];
		//创建一个像素获取器的实例，并将其与像素数组关联
		PixelGrabber pg = new PixelGrabber(image, 0, 0, w, h, pixels, 0, w);
		try {
			//解析图片的像素信息
			pg.grabPixels();
		} catch (InterruptedException e) {

		}
	}

	public void paint(Graphics g) {
		g.setColor(Color.white);
		g.fillRect(0, 0, getSize().width, getSize().height);
		//调用drawImage()方法，在相应的位置输出图片
		drawImage(g, image, x, y);
	}

	private void drawImage(Graphics g, Image image, int x, int y) {
		//输出图片

		while (true) {
			g.setColor(Color.white);
			g.fillRect(0, 0, getSize().width, getSize().height);
			try {
				int one_time = w; //图片宽度
				int S_x = 0, S_y = 0;
				S_x = (int) (random.nextFloat() * width);
				S_y = (int) (random.nextFloat() * height);
				Laser[] nextlot = new Laser[one_time];
				int k = 0, l = 0;
				int step = 1, start = 0;
				float f = random.nextFloat();
				step = (f < 0.8) ? 34759 : (f < 0.9 ? 1 : image_size - 1); //步长
				//start=(int)(random.nextFloat()*image_size); //起始位置
				f = random.nextFloat();
				start = (f < 0.5) ? image_size : 0; //如果f小于0.5,则起始位置为图片大小，否则为0
				int sofar = 0;
				//初始化nextlot数组
				for (k = start; l < image_size; l++, k += step) {
					Thread.sleep(2);
					if (k < 0)
						k += image_size;
					k %= image_size;
					int row = k / w;
					int col = k % w;
					Color colr = new Color(pixels[k]);
					int finishx = x + col;
					int y1 = y + row;
					nextlot[sofar] = new Laser(colr, new Point(S_x, S_y),
							new Point(finishx, y1));
					sofar++;
					if (sofar == one_time) {
						Track(g, nextlot);
						sofar = 0;
					}
				}
			} catch (Exception e) {
			}
			g.setPaintMode();
			g.drawImage(image, x, y, this);
			try {
				Thread.sleep(2000);
			} catch (InterruptedException e) {
			}
		}
	}

	private synchronized void Track(Graphics g, Laser[] nextlot) {
		Color back = Color.white;
		g.setXORMode(back);
		for (int pass = 0; pass < 2; pass++) {
			for (int pixnr = 0; pixnr < nextlot.length; pixnr++) {
				Laser p = nextlot[pixnr];
				if (!close(p.c, back)) {
					g.setColor(p.c);
					g.drawLine(p.start.x, p.start.y, p.finish.x, p.finish.y);
				}
				if (pass == 1) {
					g.setColor(p.c);
					g.drawLine(p.finish.x, p.finish.y, p.finish.x, p.finish.y);
				}
			}
		}
		Thread.yield();
	}

	private boolean close(Color c1, Color c2) {
		return (Math.abs(c1.getRed() - c2.getRed())
				+ Math.abs(c1.getGreen() - c2.getGreen()) + Math.abs(c1
				.getBlue()
				- c2.getBlue())) < 0xff;
	}
}

class Laser {
	public Color c;

	public Point start, finish;

	public Laser(Color c, Point start, Point finish) {
		this.c = c;
		this.start = start;
		this.finish = finish;
	}
}