java - 如何修复由于加载图像而导致的屏幕闪烁？

Question

我正在尝试加载并在其上绘制图像，然后将其显示在框架上。我还可以将图像加载到框架上并在框架上绘图，但这会在我的屏幕上产生更多的闪烁。

在下面的代码中，当用户按下任意键时屏幕会闪烁，因为图像会再次加载并在上面绘制球的新位置。

if up_key y--
if down_key y++
if left_key x--
if right_key x++

根据按下的键重新显示图像并更新球的位置。

如何降低闪烁效果使其平滑？

必须替换我在文件构造函数中给出的路径。

import java.awt.*;
import java.io.*;
import java.awt.image.*;
import javax.imageio.ImageIO;
import java.awt.event.*;

class MyFrame extends Frame implements KeyListener 
{
    BufferedImage img;
    int x=100,y=100;
    public MyFrame()
    {
        super("Box");
        this.setSize(1382,784);
        this.setVisible(true);
        this.addKeyListener(this);
        this.requestFocus();
        this.setResizable(false);
    }
    public void make()
    {
        try{
        img=ImageIO.read(new File("c:/users/udesh_2/desktop/Boundary.jpg"));
        Graphics gfx=img.getGraphics();
        gfx.setColor(Color.black);
        gfx.fillOval(x,y,40,40);
        }
        catch(IOException io){}
    }
    @Override
    public void paint(Graphics g)
    {
        make();
        g.drawImage(img,0,0,getWidth(),getHeight(),null);
    }
    public static void main(String $[])
    {
        MyFrame f=new MyFrame();
        f.make();
        f.repaint();
    }

    public void keyPressed(KeyEvent key)
    {
        boolean found=false;

        if(key.getKeyCode()==KeyEvent.VK_UP)
        {
            found=true;
            y--;
        }
        if(key.getKeyCode()==KeyEvent.VK_DOWN)
        {
            found=true;
            y++;
        }
        if(key.getKeyCode()==KeyEvent.VK_LEFT)
        {
            found=true;
            x--;
        }
        if(key.getKeyCode()==KeyEvent.VK_RIGHT)
        {
            found=true;
            x++;
        }
                    if(found)
        repaint();
    }
    public void keyTyped(KeyEvent key){}
    public void keyReleased(KeyEvent key){}
}

Answer 1

每次调用 repaint() 时都会设置变量 img 的值，这会导致闪烁。而是在你的构造函数中初始化它一次。在这种情况下也不需要额外的 make 方法。这应该有效:

import java.awt.*;
import java.io.*;
import java.awt.image.*;
import javax.imageio.ImageIO;
import java.awt.event.*;

class MyFrame extends Frame implements KeyListener {

    BufferedImage img;
    int x = 100, y = 100;

    public MyFrame() {
        super("Box");
        this.setSize(480, 480);
        this.setVisible(true);
        this.addKeyListener(this);
        this.requestFocus();
        this.setResizable(false);
        try {
            img = ImageIO.read(new File("c:/users/udesh_2/desktop/Boundary.jpg"));   
        } catch (IOException io) {
            io.printStackTrace();
        }
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        g.drawImage(img, 0, 0, getWidth(), getHeight(), this);
        g.setColor(Color.black);
        g.fillOval(x, y, 40, 40);
    }

    public static void main(String $[]) {
        MyFrame f = new MyFrame();
        f.repaint();
    }

    public void keyPressed(KeyEvent key) {
        boolean found = false;

        if (key.getKeyCode() == KeyEvent.VK_UP) {
            found = true;
            y--;
        }
        if (key.getKeyCode() == KeyEvent.VK_DOWN) {
            found = true;
            y++;
        }
        if (key.getKeyCode() == KeyEvent.VK_LEFT) {
            found = true;
            x--;
        }
        if (key.getKeyCode() == KeyEvent.VK_RIGHT) {
            found = true;
            x++;
        }
        if (found) {
            repaint();
        }
    }

    public void keyTyped(KeyEvent key) {
    }

    public void keyReleased(KeyEvent key) {
    }
}