Question

我从列表中有两个BufferedImages（this.docList）。在我的paintComponent方法中，我将它们绘制到JPanel，同时在'this.createdImage上绘制它们。

@Override
protected void paintComponent(Graphics g){
    super.paintComponent(g);
    this.createdImage = newBufferedImage(this.getWidth(),this.getHeight(), BufferedImage.TYPE_INT_ARGB); Graphics g2 = this.createdImage.getGraphics();
    if (controlWhichImage == 1){
        for(BufferedImage eachImage : docList){
            g2.drawImage(eachImage,0,inty,imageWidth,imageHeight,null);
            g.drawImage(eachImage, 0,inty,imageWidth,imageHeight,null);
            intx += eachImage.getWidth();
            inty += eachImage.getHeight() * zoomAdd;
            }

        if (intx >= this.getWidth() || inty >= this.getHeight()){
            inty = 0;
        }

我的问题是，当我使用createdImage时，我得到的只是一个空白面板。

if (controlWhichImage == 2){
     g.drawImage(this.createdImage,this.getWidth(),this.getHeight(),null);
}

Answer 1

每次调用paintComponent时，您都会创建BufferedImage的新实例，如果controlWhichImage为1，则会将图像绘制到BufferedImage，如果它是2它画的，没什么。

基本上你的代码基本上就像......一样......

Override
protected void paintComponent(Graphics g){
    super.paintComponent(g);
    this.createdImage = newBufferedImage(this.getWidth(),this.getHeight(), BufferedImage.TYPE_INT_ARGB); 
    Graphics g2 = this.createdImage.getGraphics();
    if (controlWhichImage == 1){
        for(BufferedImage eachImage : docList){
            g2.drawImage(eachImage,0,inty,imageWidth,imageHeight,null);
            g.drawImage(eachImage, 0,inty,imageWidth,imageHeight,null);
            intx += eachImage.getWidth();
            inty += eachImage.getHeight() * zoomAdd;
        }

        if (intx >= this.getWidth() || inty >= this.getHeight()){
            inty = 0;
        }
    } else if (controlWhichImage == 2){
         g.drawImage(this.createdImage,this.getWidth(),this.getHeight(),null);
    }

当createdImaeg为controlWhichImage

时，您应该只创建1的实例

Override
protected void paintComponent(Graphics g){
    super.paintComponent(g);
    if (controlWhichImage == 1){
        this.createdImage = newBufferedImage(this.getWidth(),this.getHeight(), BufferedImage.TYPE_INT_ARGB); 
        Graphics g2 = this.createdImage.getGraphics();
        for(BufferedImage eachImage : docList){
            g2.drawImage(eachImage,0,inty,imageWidth,imageHeight,this);
            g.drawImage(eachImage, 0,inty,imageWidth,imageHeight,this);
            intx += eachImage.getWidth();
            inty += eachImage.getHeight() * zoomAdd;
        }

        if (intx >= this.getWidth() || inty >= this.getHeight()){
            inty = 0;
        }
        g2.dispose(); // This is kind of important...
    } else if (controlWhichImage == 2){
         g.drawImage(this.createdImage,this.getWidth(),this.getHeight(),this);
    }

或当createdImage为空时......

Override
protected void paintComponent(Graphics g){
    super.paintComponent(g);
    if (createdImage == null){
        this.createdImage = newBufferedImage(this.getWidth(),this.getHeight(), BufferedImage.TYPE_INT_ARGB); 
        Graphics g2 = this.createdImage.getGraphics();
        for(BufferedImage eachImage : docList){
            g2.drawImage(eachImage,0,inty,imageWidth,imageHeight,this);
            intx += eachImage.getWidth();
            inty += eachImage.getHeight() * zoomAdd;
        }

        if (intx >= this.getWidth() || inty >= this.getHeight()){
            inty = 0;
        }
        g2.dispose(); // This is kind of important...
    }
    g.drawImage(this.createdImage,this.getWidth(),this.getHeight(),this);

如何将JPanel的内容复制到BufferedImage

1 个答案: