Java实现图片任意角度旋转

文章参照http://blog.csdn.net/heliang7/article/details/7309394

原文写得相当详细,所以请大家使用上述链接访问原文. 这里我只是为了做一个笔记.方便日后查询.

 

旋转代码:

package org.jerval.test.image;

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));
    }
}

测试代码:

package org.jerval.test.image;

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

import javax.imageio.ImageIO;

import org.testng.Assert;
import org.testng.annotations.Test;

public class RotateImageTest {

    @Test
    public void testRotate() throws IOException {

        BufferedImage src = ImageIO.read(new File("d:/dog.jpg"));
        BufferedImage des = RotateImage.rotate(src, 30);
        Assert.assertNotNull(des);
        Assert.assertTrue(ImageIO.write(des, "jpg", new File("d:/dog2.jpg")));

        // bigger angel
        des = RotateImage.rotate(src, 150);
        Assert.assertNotNull(des);
        Assert.assertTrue(ImageIO.write(des, "jpg", new File("d:/dog3.jpg")));

        // bigger angel
        des = RotateImage.rotate(src, 270);
        Assert.assertNotNull(des);
        Assert.assertTrue(ImageIO.write(des, "jpg", new File("d:/dog4.jpg")));

    }

}