java连续双缓冲解决方案不起作用

Question

我正在尝试使用AWT在方法paint()中对包含多边形的图像进行双重缓冲。使用Image对象进行缓冲处理，我将图像背景设置为黑色，将多边形绘制到图像上，然后将缓冲图像绘制到屏幕上。然后调用repaint()以再次渲染图像

不幸的是，在重新绘制图像时，我仍然收到伪影。我做错了什么

编辑：作为旁注，我使用的是Java 8。 编辑2:我正在paint()中调用repaint()，因为我需要连续缓冲图像。多边形用于根据用户输入在屏幕上进行平移

import java.applet.Applet;
import java.awt.*;

public class DoubleBuffer extends Applet {
    int xSize = 900;
    int ySize = 600;

    Image bufferImage;
    Graphics bufferG;

    @Override
    public void init() {
        this.setSize(xSize, ySize);

        //Double buffering related variables
        bufferImage = this.createImage(xSize, xSize);
        bufferG = bufferImage.getGraphics();
    }

    //BUFFERING DONE HERE
    @Override
    public void paint(Graphics g){
        //drawing images to external image first (buffering)
        bufferG.setColor(Color.BLACK);
        bufferG.fillRect(0,0,xSize,ySize);
        bufferG.setColor(Color.WHITE);
        bufferG.drawRect(100, 100, 100, 100);

        //draw the image and call repaint
        g.drawImage(bufferImage, 0, 0, this);
        repaint();
    }
}

Answer 1

问题是您没有覆盖update，这是将在响应repaint请求时调用的方法。对于重量级组件，update的默认实现将首先将组件清除为背景色（可能默认为白色），然后调用paint方法

正如其他人所指出的，您不应该从paint方法中调用repaint。您应该使用Timer

清理后，整个类将如下所示：

public class DoubleBuffer extends Applet {
    int xSize = 900;
    int ySize = 600;

    Image bufferImage;
    Graphics bufferG;
    Timer timer=new Timer(200, ev->repaint());

    @Override
    public void init() {
        this.setSize(xSize, ySize);
    }

    @Override
    public void addNotify() {
        super.addNotify();
        //Double buffering related variables
        bufferImage = this.createImage(xSize, xSize);
        bufferG = bufferImage.getGraphics();
        timer.start();
    }

    @Override
    public void removeNotify() {
        super.removeNotify();
        bufferImage = null;
        bufferG = null;
        timer.stop();
    }


    //BUFFERING DONE HERE
    @Override
    public void paint(Graphics g){
        //drawing images to external image first (buffering)
        bufferG.setColor(Color.BLACK);
        bufferG.fillRect(0,0,xSize,ySize);
        bufferG.setColor(Color.WHITE);
        bufferG.drawRect(100, 100, 100, 100);

        //draw the image and call repaint
        g.drawImage(bufferImage, 0, 0, this);
    }

    @Override
    public void update(Graphics g) {
        // now not clearing the background as we expect paint() to fill the entire area
        this.paint(g);
    }
}