java - 旋转图像对象

Question

我有一个方法 getImage() 需要旋转一个 Image，将它存储在一个新变量中，然后返回那个新的 Image .这是我的尝试，图像似乎是空的或什么的。它只是没有出现在屏幕上:

public Image getImage() {
    buffImage.createGraphics().rotate(direction);
    return buffImage;
}

当我取出 buffImage.createGraphics().rotate(direction); 时，图像在屏幕上绘制得很好，没有任何问题，但当然没有旋转。

Answer 1

因此，基于 this answer 中的示例，您应该能够设计出一种旋转方法，可以将源图像旋转给定的度数，例如...

  // Make sure you actually load some image and assign it to this
  // variable, otherwise you will have a NullPointerException to 
  // deal with
  private BufferedImage source;

  public Image rotateBy(double degrees) {

    // The size of the original image
    int w = source.getWidth();
    int h = source.getHeight();
    // The angel of the rotation in radians
    double rads = Math.toRadians(degrees);
    // Some nice math which demonstrates I have no idea what I'm talking about
    // Okay, this calculates the amount of space the image will need in
    // order not be clipped when it's rotated
    double sin = Math.abs(Math.sin(rads));
    double cos = Math.abs(Math.cos(rads));
    int newWidth = (int) Math.floor(w * cos + h * sin);
    int newHeight = (int) Math.floor(h * cos + w * sin);

    // A new image, into which the original can be painted
    BufferedImage rotated = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2d = rotated.createGraphics();
    // The transformation which will be used to actually rotate the image
    // The translation, actually makes sure that the image is positioned onto
    // the viewable area of the image
    AffineTransform at = new AffineTransform();
    at.translate((newWidth - w) / 2, (newHeight - h) / 2);

    // And we rotate about the center of the image...
    int x = w / 2;
    int y = h / 2;
    at.rotate(rads, x, y);
    g2d.setTransform(at);
    // And we paint the original image onto the new image
    g2d.drawImage(source, 0, 0, null);
    g2d.dispose();

    return rotated;
  }