如何在Java中旋转imageIcon

Question

ImageIcon imageIcon = new ImageIcon("images\\4-4.png");
Image image = imageIcon.getImage(); 
Image newimg = image.getScaledInstance(60, 120,  java.awt.Image.SCALE_SMOOTH);  
imageIcon = new ImageIcon(newimg);

JLabel img = new JLabel(imageIcon);
img.setBounds(100, 100, 60, 120);
getContentPane().add(img);

Answer 1

旋转一个图像不是琐碎的，即使只是90度也需要一定的工作量。

所以，根据几乎所有其他关于旋转图像的问题，我会从这样的东西开始...

public BufferedImage rotate(BufferedImage image, Double degrees) {
    // Calculate the new size of the image based on the angle of rotaion
    double radians = Math.toRadians(degrees);
    double sin = Math.abs(Math.sin(radians));
    double cos = Math.abs(Math.cos(radians));
    int newWidth = (int) Math.round(image.getWidth() * cos + image.getHeight() * sin);
    int newHeight = (int) Math.round(image.getWidth() * sin + image.getHeight() * cos);

    // Create a new image
    BufferedImage rotate = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2d = rotate.createGraphics();
    // Calculate the "anchor" point around which the image will be rotated
    int x = (newWidth - image.getWidth()) / 2;
    int y = (newHeight - image.getHeight()) / 2;
    // Transform the origin point around the anchor point
    AffineTransform at = new AffineTransform();
    at.setToRotation(radians, x + (image.getWidth() / 2), y + (image.getHeight() / 2));
    at.translate(x, y);
    g2d.setTransform(at);
    // Paint the originl image
    g2d.drawImage(image, 0, 0, null);
    g2d.dispose();
    return rotate;
}

虽然你只旋转90度，但这需要计算新图像所需的大小，以便能够在任何角度绘制旋转的图像。

try {
    BufferedImage original = ImageIO.read(getClass().getResource("domino.jpg"));
    BufferedImage rotated90 = rotate(original, 90.0d);
    BufferedImage rotatedMinus90 = rotate(original, -90.0d);

    JPanel panel = new JPanel();
    panel.add(new JLabel(new ImageIcon(original)));
    panel.add(new JLabel(new ImageIcon(rotated90)));
    panel.add(new JLabel(new ImageIcon(rotatedMinus90)));

    JOptionPane.showMessageDialog(null, panel, null, JOptionPane.PLAIN_MESSAGE, null);
} catch (IOException ex) {
    ex.printStackTrace();
}