JAVA图形操作中FPS的计算（附带随机生成乱数球体用例）

2021-08-18 13:52:27

FPS：即帧 /秒(frames per second)的缩写，也称为帧速率。是指1秒钟时间里刷新的图片的帧数，也可以理解为图形处理器每秒钟能够刷新几次。如果具体到手机上就是指每秒钟能够播放（或者录制）多少格画面。同时越高的帧速率可以得到更流畅、更逼真的动画。每秒钟帧数(fps)越多，所显示的动作就会越流畅。

在绝大多数图形程序中（以游戏类为典型），执行效率都以FPS作为评估标准。

由于目前JAVA方面缺少相关用例，故完成功能如下图(在本机测试中，最大fps设定为500，实际达到FPS效率在IDE中280左右，单独运行380左右，受系统配置等因素影响)：

代码如下：

（请变更文件后缀为jar）

FPS部分相关源码：

package org.test;

import java.text.DecimalFormat;

/**
* Title: LoonFramework
* Description:
* Copyright: Copyright (c) 2007
* Company: LoonFramework
* @author chenpeng
* @email：[email]ceponline@yahoo.com.cn[/email]
* @version 0.1
*/
public class FPSListen {
 //设定动画的FPS桢数，此数值越高,动画速度越快。
 public static final int FPS = 500;

 // 换算为运行周期
 public static final long PERIOD = (long) (1.0 / FPS * 1000000000); // 单位: ns(纳秒)

 // FPS最大间隔时间，换算为1s = 10^9ns
 public static long FPS_MAX_INTERVAL = 1000000000L; // 单位: ns

 // 实际的FPS数值
 private double nowFPS = 0.0;

 // FPS累计用间距时间
 private long interval = 0L; // in ns
 private long time;

 //运行桢累计
 private long frameCount = 0;

 //格式化小数位数
 private DecimalFormat df = new DecimalFormat("0.0");

 //开启opengl
 public void opengl(){
 System.setProperty("sun.java2d.opengl", "True");
 System.setProperty("sun.java2d.translaccel", "True");
 }



 /** *//**
 * 制造FPS数据
 *
 */
 public void makeFPS() {
 frameCount++;
 interval += PERIOD;

 //当实际间隔符合时间时。
 if (interval >= FPS_MAX_INTERVAL) {
 //nanoTime()返回最准确的可用系统计时器的当前值，以毫微秒为单位
 long timeNow = System.nanoTime();
 // 获得到目前为止的时间距离
 long realTime = timeNow - time; // 单位: ns

 //换算为实际的fps数值
 nowFPS = ((double) frameCount / realTime) * FPS_MAX_INTERVAL;
 //变更数值
 frameCount = 0L;
 interval = 0L;
 time = timeNow;
 }
 }
 public long getFrameCount() {
 return frameCount;
 }
 public void setFrameCount(long frameCount) {
 this.frameCount = frameCount;
 }
 public long getInterval() {
 return interval;
 }
 public void setInterval(long interval) {
 this.interval = interval;
 }
 public double getNowFPS() {
 return nowFPS;
 }
 public void setNowFPS(double nowFPS) {
 this.nowFPS = nowFPS;
 }
 public long getTime() {
 return time;
 }
 public void setTime(long time) {
 this.time = time;
 }
 public String getFPS(){
 return df.format(nowFPS);
 }

}

球体类相关代码：

package org.test;

import java.awt.Color;
import java.awt.Graphics;

/** *//**
* Title: LoonFramework
* Description:
* Copyright: Copyright (c) 2007
* Company: LoonFramework
* @author chenpeng
* @email：[email]ceponline@yahoo.com.cn[/email]
* @version 0.1
*/
public class Ball {
 private static final int SIZE = 10;
 private int x, y;
 protected int vx, vy;

 public Ball(int x, int y, int vx, int vy) {
 this.x = x;
 this.y = y;
 this.vx = vx;
 this.vy = vy;
 }

 public void move() {
 x += vx;
 y += vy;
 if (x < 0 || x > BallPanel.WIDTH - SIZE) {
 vx = -vx;
 }
 if (y < 0 || y > BallPanel.HEIGHT - SIZE) {
 vy = -vy;
 }
 }

 public void draw(Graphics g) {
 g.setColor(Color.RED);
 g.fillOval(x, y, SIZE, SIZE);
 }


}

FPS及球体处理用代码如下：

package org.test;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Panel;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.image.BufferedImage;
import java.util.Random;

/** *//**
* 
* Title: LoonFramework
* 
* 
* Description:以JAVA获取FPS用演示程序及随机生成乱数球体。(更优化代码内置于loonframework-game框架中)
* 
* 
* Copyright: Copyright (c) 2007
* 
* 
* Company: LoonFramework
* 
*
* @author chenpeng
* @email：[email]ceponline@yahoo.com.cn[/email]
* @version 0.1
*/
public class BallPanel extends Panel implements Runnable {

 /** *//**
 *
 */
 private static final long serialVersionUID = 1L;

 public static final int WIDTH = 360;

 public static final int HEIGHT = 360;

 // 设定最大球体数量
 private static final int NUM_BALLS = 50;

 // 定义球体数组
 private Ball[] ball;

 // 运行状态
 private volatile boolean running = false;

 private Thread gameLoop;

 // 缓存用图形
 private Graphics bg;

 private Image screen = null;

 // 生成随机数
 private Random rand;

 // fps监听
 private FPSListen fps = null;

 public BallPanel() {
 setPreferredSize(new Dimension(WIDTH, HEIGHT));
 screen = new BufferedImage(WIDTH, HEIGHT, 1);
 bg = screen.getGraphics();
 fps = new FPSListen();
 //fps.opengl();
 // 以当前毫秒生成随机数
 rand = new Random(System.currentTimeMillis());
 ball = new Ball[NUM_BALLS];
 // 初始化球体参数
 for (int i = 0; i < NUM_BALLS; i++) {
 int x = rand.nextInt(WIDTH);
 int y = rand.nextInt(HEIGHT);
 int vx = rand.nextInt(10);
 int vy = rand.nextInt(10);
 ball[i] = new Ball(x, y, vx, vy);
 }
 }

 // 加入Notify
 public void addNotify() {
 super.addNotify();
 // 判断循环条件是否成立
 if (gameLoop == null || !running) {
 gameLoop = new Thread(this);
 gameLoop.start();
 }
 }

 /** *//**
 * 进行线程运作。
 */
 public void run() {
 long beforeTime, afterTime, timeDiff, sleepTime;
 long overSleepTime = 0L;
 int noDelays = 0;
 // 获得精确纳秒时间
 beforeTime = System.nanoTime();
 fps.setTime(beforeTime);
 running = true;
 while (running) {
 gameUpdate();
 repaint();
 afterTime = System.nanoTime();
 timeDiff = afterTime - beforeTime;
 // 换算间隔时间
 sleepTime = (FPSListen.PERIOD - timeDiff) - overSleepTime;
 if (sleepTime > 0) {
 // 制造延迟
 try {
 Thread.sleep(sleepTime / 1000000L); // nano->ms
 } catch (InterruptedException e) {
 }
 // 获得延迟时间
 overSleepTime = (System.nanoTime() - afterTime) - sleepTime;
 } else {
 // 重新计算
 overSleepTime = 0L;
 // 判断noDelays值
 if (++noDelays >= 16) {
 Thread.yield(); // 令线程让步
 noDelays = 0;
 }
 }

 // 重新获得beforeTime
 beforeTime = System.nanoTime();

 // 制造FPS结果
 fps.makeFPS();
 }

 }

 /** *//**
 * 变更球体轨迹
 *
 */
 private void gameUpdate() {
 for (int i = 0; i < NUM_BALLS; i++) {
 ball[i].move();
 }
 }

 /** *//**
 * 变更图形
 */
 public void update(Graphics g) {
 paint(g);
 }

 /** *//**
 * 显示图形
 */
 public void paint(Graphics g) {

 // 设定背景为白色，并清空图形
 bg.setColor(Color.WHITE);
 bg.fillRect(0, 0, WIDTH, HEIGHT);

 // FPS数值显示
 bg.setColor(Color.BLUE);
 bg.drawString("FPS: " + fps.getFPS(), 4, 16);

 // 分别绘制相应球体
 for (int i = 0; i < NUM_BALLS; i++) {
 ball[i].draw(bg);
 }
 g.drawImage(screen, 0, 0, this);
 g.dispose();
 }

 public static void main(String[] args) {

 Frame frm = new Frame();
 frm.setTitle("Java FPS速度测试(由Loonframework框架提供)");
 frm.setSize(WIDTH, HEIGHT+20);
 frm.setResizable(false);
 frm.add(new BallPanel());
 frm.setVisible(true);
 frm.addWindowListener(new WindowAdapter(){
 public void windowClosing(WindowEvent e){
 System.exit(0);
 }
 });
 }

}

本文转自 cping 51CTO博客，原文链接:http://blog.51cto.com/cping1982/116709

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