package TimerDemo;

import java.util.Random;

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;

public class StarCanvas extends Canvas {

	Image offScreen;//緩沖區(qū)對象

	Graphics drawOffScreen;

	int width, height;

	private Random random;

	protected StarCanvas() {

		random = new Random();
		width = this.getWidth();
		height = this.getHeight();
		offScreen = Image.createImage(width, height);
		drawOffScreen = offScreen.getGraphics();

	}

	protected void paint(Graphics g) {

		drawOffScreen.setColor(0, 0, 0);
		drawOffScreen.fillRect(0, 0, width, height);

		drawOffScreen.setColor(255, 255, 255);
		//每隔4行隨機(jī)畫星星
		for (int j = 0; j < height; j=j+4) {
			for (int i = 0; i < width; ++i) {
				int test = Math.abs(random.nextInt()) % 100;
				if (test < 5) {
					drawOffScreen.drawLine(i, j, i, j);
				}
			}
		}

		g.drawImage(offScreen, 0, 0, Graphics.TOP | Graphics.LEFT);

	}

}