java - 图像不旋转

Question

我正在尝试旋转图像，有些效果，但问题是它无法正常工作。它没有按照我想要的精确旋转。图像以某种混合形式显示。

我的按钮点击代码:

RT90.addActionListener(new ActionListener() 
        {           
            @Override
            public void actionPerformed(ActionEvent arg0) 
            {
                degrees+=90;
                rotateIMG(degrees);
                repaint();
            }
        }); 

rotateIMG() 代码:

public void rotateIMG(double d)
    {
        BufferedImage b ;
        b=a;
        Graphics g;
        g=b.createGraphics();
        Graphics2D g2d = (Graphics2D)g;

        System.out.println(b.getWidth());
        System.out.println(b.getHeight());

        g2d.rotate(Math.toRadians(d), b.getWidth()/2, b.getHeight()/2);
        g2d.drawImage(b,0,0,null);

        ImageIcon rtimg = new ImageIcon(b);
        label.setIcon(rtimg);

    }

知道这段代码有什么错误吗？这里 a 是从图像堆栈加载的缓冲图像，label 是用于显示图像的 JLabel。

Answer 1

您正在覆盖用作源的图像 (b == a)。您需要创建一个新的。

public void rotateIMG(double d) {
    // Consider also using GraphicsConfiguration.createCompatibleImage().
    // I'm just putting here something that should work
    BufferedImage b = new BufferedImage(a.getHeight(), a.getWidth(), BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2d = b.createGraphics();

    g2d.rotate(Math.toRadians(d), a.getWidth()/2, a.getHeight()/2);
    // Note the a instead of b here
    g2d.drawImage(a, 0, 0, null);
    // Do you want to keep the old a or not?
    // a = b;
    ImageIcon rtimg = new ImageIcon(b);
    label.setIcon(rtimg);
}