当放大到超过8k像素时，缓冲图像占用cpu

Question

在将缓存图像从1920 x 224缩放到8777 x 1024并以30 fps绘制时，我遇到了cpu占用完整处理器的问题。

我尝试使用。

仅显示jpanel的高度和宽度

drawImage(img, dx1, dy1, dx2, dy2, sx1, sy1, sx2, sy2, observer)

但仍然是cpu的主要飙升。

我的测试代码如下：

package test;

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

import javax.swing.*;
import javax.imageio.ImageIO;

import java.net.URL;
import java.util.Timer;
import java.util.TimerTask;

public class GamePanel extends JPanel{

int frame = 0;
BufferedImage srcImg;
BufferedImage backgroundImg;
Timer timer = new Timer();

public GamePanel(){
try {
    srcImg = ImageIO.read(new URL("http://i.stack.imgur.com/6TJPy.png"));
} catch (Exception e) {
    e.printStackTrace();
}

backgroundImg = new BufferedImage(8777, 1024, BufferedImage.TRANSLUCENT);
Graphics2D g2 = backgroundImg.createGraphics();
g2.setRenderingHint(
    RenderingHints.KEY_INTERPOLATION,
    RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
g2.drawImage(srcImg, 0, 0,8777, 1024, null);
g2.dispose();

timer.scheduleAtFixedRate(new TimerTask() {
  @Override
  public void run() {
    repaint();
  }
}, 1000/30, 1000/30);
}

@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
frame++;
//g.drawImage(backgroundImg, frame%backgroundImg.getWidth(),0, this);
g.drawImage(backgroundImg, 0, 0, 600, 1024, frame, 0, frame+this.getWidth(), backgroundImg.getHeight(),null);
g.setColor(Color.WHITE);
g.drawString("" + frame, 20, 50);
}

@Override
public Dimension getPreferredSize() {
return new Dimension(600,1024);
}


public static void main(String[] args){
GamePanel panel = new GamePanel();

JFrame f = new JFrame();

//f.setBounds(0,0,400,400);
f.getContentPane().add(panel);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.pack();
f.setVisible(true);

}

}

编辑：我发现这种方式减少了cpu但只减少了大约20％，我希望将其降低到仅使用0 - 10％cpu，就像我没有显示如此大的图像一样

我的问题是绘制缓冲图像的最有效的方法是什么。

Answer 1

尝试从代码中形成的这个SSCCE，看看它是否表现得像你期望的那样。这似乎很快：

import java.awt.*;
import java.awt.image.*;
import javax.swing.*;
import javax.imageio.ImageIO;
import java.net.URL;

public class GamePanel extends JPanel implements Runnable{

int frame = 0;
BufferedImage srcImg;
BufferedImage backgroundImg;

public GamePanel(){
    try {
        srcImg = ImageIO.read(new URL("http://i.stack.imgur.com/6TJPy.png"));
    } catch (Exception e) {
        e.printStackTrace();
    }

    backgroundImg = new BufferedImage(8777, 1024, BufferedImage.TRANSLUCENT);
    Graphics2D g2 = backgroundImg.createGraphics();
    g2.setRenderingHint(
        RenderingHints.KEY_INTERPOLATION,
        RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
    g2.drawImage(srcImg, 0, 0,8777, 1024, null);
    g2.dispose();
}

@Override
public void paintComponent(Graphics g){
    super.paintComponent(g);
    frame--;
    g.drawImage(backgroundImg, frame%backgroundImg.getWidth(),0, this);
    g.setColor(Color.WHITE);
    g.drawString("" + frame, 20, 50);
}

@Override
public Dimension getPreferredSize() {
    return new Dimension(600,1024);
}

@Override
public void run() {
    while(true){
        repaint();
        try {
            Thread.sleep(1000/30);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

public static void main(String[] args){
    GamePanel panel = new GamePanel();
    Thread thread = new Thread(panel);

    JFrame f = new JFrame();

    //f.setBounds(0,0,400,400);
    f.getContentPane().add(panel);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.pack();
    f.setVisible(true);
    thread.start();
}

}

以下是使用基于Swing的Timer的等效项。好吧，不是更好，但仍然是更好的练习。

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;
import javax.imageio.ImageIO;
import java.net.URL;

public class GamePanel extends JPanel {

int frame = 0;
BufferedImage srcImg;
BufferedImage backgroundImg;

public GamePanel(){
    try {
        srcImg = ImageIO.read(new URL("http://i.stack.imgur.com/6TJPy.png"));
    } catch (Exception e) {
        e.printStackTrace();
    }

    backgroundImg = new BufferedImage(8777, 1024, BufferedImage.TRANSLUCENT);
    Graphics2D g2 = backgroundImg.createGraphics();
    g2.setRenderingHint(
        RenderingHints.KEY_INTERPOLATION,
        RenderingHints.VALUE_INTERPOLATION_NEAREST_NEIGHBOR);
    g2.drawImage(srcImg, 0, 0,8777, 1024, null);
    g2.dispose();
    ActionListener al = new ActionListener()  {
        public void actionPerformed(ActionEvent ae) {
            repaint();
        }
    };
    Timer timer = new Timer(1000/30, al);
    timer.start();
}

@Override
public void paintComponent(Graphics g){
    super.paintComponent(g);
    frame--;
    g.drawImage(backgroundImg, frame%backgroundImg.getWidth(),0, this);
    g.setColor(Color.WHITE);
    g.drawString("" + frame, 20, 50);
}

@Override
public Dimension getPreferredSize() {
    return new Dimension(600,1024);
}

public static void main(String[] args){
    GamePanel panel = new GamePanel();

    JFrame f = new JFrame();

    f.getContentPane().add(panel);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.pack();
    f.setVisible(true);
}

}