package com.util.test;


import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;


public class RotateImage {


public static BufferedImage Rotate(Image src, int angel) {
int src_width = src.getWidth(null);
int src_height = src.getHeight(null);
// calculate the new image size
Rectangle rect_des = CalcRotatedSize(new Rectangle(new Dimension(
src_width, src_height)), angel);


BufferedImage res = null;
res = new BufferedImage(rect_des.width, rect_des.height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = res.createGraphics();
// transform
g2.translate((rect_des.width - src_width) / 2,
(rect_des.height - src_height) / 2);
g2.rotate(Math.toRadians(angel), src_width / 2, src_height / 2);


g2.drawImage(src, null, null);
return res;
}


public static Rectangle CalcRotatedSize(Rectangle src, int angel) {
// if angel is greater than 90 degree, we need to do some conversion
if (angel >= 90) {
if(angel / 90 % 2 == 1){
int temp = src.height;
src.height = src.width;
src.width = temp;
}
angel = angel % 90;
}


double r = Math.sqrt(src.height * src.height + src.width * src.width) / 2;
double len = 2 * Math.sin(Math.toRadians(angel) / 2) * r;
double angel_alpha = (Math.PI - Math.toRadians(angel)) / 2;
double angel_dalta_width = Math.atan((double) src.height / src.width);
double angel_dalta_height = Math.atan((double) src.width / src.height);


int len_dalta_width = (int) (len * Math.cos(Math.PI - angel_alpha
- angel_dalta_width));
int len_dalta_height = (int) (len * Math.cos(Math.PI - angel_alpha
- angel_dalta_height));
int des_width = src.width + len_dalta_width * 2;
int des_height = src.height + len_dalta_height * 2;
return new java.awt.Rectangle(new Dimension(des_width, des_height));
}

}

測試方法

package com.util.test;


import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;


import javax.imageio.ImageIO;






public class RotateImageTest {
    
public static void main(String[] args) throws IOException {
BufferedImage src = ImageIO.read(new File("e:/test/dog2.jpg"));
BufferedImage des = RotateImage.Rotate(src,5);
ImageIO.write(des, "jpg", new File("e:/test/dog2.jpg"));
}
}