我在 java 中旋转图像，但想保存旋转后的图像

Question

我正在使用 AffineTransform 旋转图像，我曾尝试通过 ImageIo.write 保存旋转后的图像，它保存的是图像而不是旋转后的图像，它保存的是原始图像。所以请告诉我如何更正它提前致谢。

这是我的旋转和保存图像的代码

public class 图片 {

public static void main(String[] args) {
    new Image();
}

public Image() {
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {
            try {
                UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            } catch (Exception ex) {
            }

            JFrame frame = new JFrame("Test");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.add(new TestPane());
            frame.pack();
            frame.setLocationRelativeTo(null);
            frame.setVisible(true);
        }
    });
}
public class TestPane extends JPanel {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private JSlider slider;
    private BufferedImage image;

    public TestPane() {
        setLayout(new BorderLayout());

        try {
           File imagefile = new File("C:/pics/1206.jpg");
              image = ImageIO.read(imagefile);


              ImageIO.write(image, "jpg",new File("C:/pics"));
              ImageIO.write(image, "bmp",new File("C:/pics"));
              ImageIO.write(image, "gif",new File("C:/picsf"));
              ImageIO.write(image, "png",new File("C:/pics"));
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        slider = new JSlider();
        slider.setMinimum(0);
        slider.setMaximum(360);
        slider.setMinorTickSpacing(5);
        slider.setMajorTickSpacing(10);
        slider.setValue(0);
        add(slider, BorderLayout.SOUTH);
        slider.addChangeListener(new ChangeListener() {
            @Override
            public void stateChanged(ChangeEvent e) {
                repaint();
            }
        });
    }

    @Override
    public Dimension getPreferredSize() {
        return image == null ? new Dimension(200, 200) : new Dimension(image.getWidth(), image.getHeight());
    }

    public double getAngle() {

        return Math.toRadians(slider.getValue());

    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        Graphics2D g2d = (Graphics2D) g.create();

        g2d.setColor(Color.RED);
        g2d.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight());
        g2d.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);

        g2d.setColor(Color.BLACK);
        int x = (getWidth() - image.getWidth()) / 2;
        int y = (getHeight() - image.getHeight()) / 2;
        AffineTransform at = new AffineTransform();
        at.setToRotation(getAngle(), x + (image.getWidth() / 2), y + (image.getHeight() / 2));
        at.translate(x, y);
        g2d.setTransform(at);
        g2d.drawImage(image, 0, 0, this);
        g2d.dispose();
    }
    }
}

Answer 1

让我们开始吧，这不是旋转图像，而是旋转用于显示图像的 Graphics 上下文，它根本不会影响原始图像

@Override
protected void paintComponent(Graphics g) {
    super.paintComponent(g);

    Graphics2D g2d = (Graphics2D) g.create();

    g2d.setColor(Color.RED);
    g2d.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight());
    g2d.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);

    g2d.setColor(Color.BLACK);
    int x = (getWidth() - image.getWidth()) / 2;
    int y = (getHeight() - image.getHeight()) / 2;
    AffineTransform at = new AffineTransform();
    at.setToRotation(getAngle(), x + (image.getWidth() / 2), y + (image.getHeight() / 2));
    at.translate(x, y);
    g2d.setTransform(at);
    g2d.drawImage(image, 0, 0, this);
    g2d.dispose();
}

然后这个...

  try {
        File imagefile = new File("C:/pics/1206.jpg");
        image = ImageIO.read(imagefile);


        ImageIO.write(image, "jpg",new File("C:/pics"));
        ImageIO.write(image, "bmp",new File("C:/pics"));
        ImageIO.write(image, "gif",new File("C:/picsf"));
        ImageIO.write(image, "png",new File("C:/pics"));
  } catch (IOException ex) {
        ex.printStackTrace();
  }

它只是将原始图像保存为多种不同的格式...保存到同一个文件中，但甚至不会对角度的任何变化做出反应

相反，您需要使用从原始图像生成新图像的东西，按您想要的数量旋转...

  public BufferedImage rotateImageByDegrees(BufferedImage img, double degrees) {
        double rads = Math.toRadians(degrees);
        double sin = Math.abs(Math.sin(rads)), cos = Math.abs(Math.cos(rads));
        int w = img.getWidth();
        int h = img.getHeight();
        int newWidth = (int) Math.floor(w * cos + h * sin);
        int newHeight = (int) Math.floor(h * cos + w * sin);

        BufferedImage rotated = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = rotated.createGraphics();
        AffineTransform at = new AffineTransform();
        at.translate((newWidth - w) / 2, (newHeight - h) / 2);

        int x = clickPoint == null ? w / 2 : clickPoint.x;
        int y = clickPoint == null ? h / 2 : clickPoint.y;

        at.rotate(rads, x, y);
        g2d.setTransform(at);
        g2d.drawImage(img, 0, 0, this);
        g2d.setColor(Color.RED);
        g2d.drawRect(0, 0, newWidth - 1, newHeight - 1);
        g2d.dispose();

        return rotated;
  }

那你就可以保存了...

File imagefile = new File("C:/pics/1206.jpg");
image = ImageIO.read(imagefile);

BufferedImage rotated = rotateImageByDegrees(image, 22.5);
ImageIO.write(rotated, "png", new File("RotatedBy225.png"));

因此，下次您使用 my previous examples and I tell you it's not doing what you think/want it to, I hope you will understand my meaning better and look more closly at the other examples 之一时，我们会向您展示

我在 java 中旋转图像，但想保存旋转后的图像

I'm rotating image in java but want to save rotated image

java

swing

image

graphics2d