用Java旋转缓冲的图像

Question

我正在尝试在java中旋转缓冲的图像。这是我正在使用的代码：

public static BufferedImage rotate(BufferedImage bimg, double angle){
    int w = bimg.getWidth();    
    int h = bimg.getHeight();
    Graphics2D graphic = bimg.createGraphics();
    graphic.rotate(Math.toRadians(angle), w/2, h/2);
    graphic.drawImage(bimg, null, 0, 0);
    graphic.dispose();
    return bimg;
}

我已经看了很多关于这个主题的堆栈溢出问题和答案，并且无法弄清楚为什么图像被切断时我尝试旋转它的方式。这是一个显示加载图像的示例： loaded image

单击旋转按钮后，使用缓冲的图像调用上述函数，然后单击角度为90.0： chopped up image

有人可以帮助我了解正在发生的事情以及如何解决这个问题吗？

谢谢！

Answer 1

一如既往的互联网救援。所以，这是我从其他资源/帖子/博客一起蹒跚而行的一些代码，这些代码将返回一个大小的新图像，以便它包含旋转的图像

public BufferedImage rotateImageByDegrees(BufferedImage img, double angle) {

            double rads = Math.toRadians(angle);
            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 = w / 2;
            int y = h / 2;

            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;
        }

<强>更新

所以，使用这个PNG：

这段代码......

package javaapplication1.pkg040;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

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

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private BufferedImage master;
        private BufferedImage rotated;

        public TestPane() {
            try {
                master = ImageIO.read(new File("/Volumes/Disk02/Dropbox/MegaTokyo/Miho_Small.png"));
                rotated = rotateImageByDegrees(master, 0.0);
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            Timer timer = new Timer(40, new ActionListener() {
                private double angle = 0;
                private double delta = 1.0;

                @Override
                public void actionPerformed(ActionEvent e) {
                    angle += delta;
                    rotated = rotateImageByDegrees(master, angle);
                    repaint();
                }
            });
            timer.start();
        }

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

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (rotated != null) {
                Graphics2D g2d = (Graphics2D) g.create();
                int x = (getWidth() - rotated.getWidth()) / 2;
                int y = (getHeight() - rotated.getHeight()) / 2;
                g2d.drawImage(rotated, x, y, this);
                g2d.dispose();
            }
        }

        public BufferedImage rotateImageByDegrees(BufferedImage img, double angle) {

            double rads = Math.toRadians(angle);
            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 = w / 2;
            int y = h / 2;

            at.rotate(rads, x, y);
            g2d.setTransform(at);
            g2d.drawImage(img, 0, 0, this);
            g2d.dispose();

            return rotated;
        }
    }

}

我可以生成类似......

的内容

Answer 2

此代码从文件中读取图像，将其旋转一定角度，然后写入另一个文件。它适用于 png 透明图像：

public static void main(String[] args) throws IOException {
    BufferedImage image = ImageIO.read(
            Test.class.getResourceAsStream("/resources/image.png"));

    BufferedImage rotated = rotateImage(image, 45);

    ImageIO.write(rotated, "png",
            new FileOutputStream("resources/rotated.png"));
}

private static BufferedImage rotateImage(BufferedImage buffImage, double angle) {
    double radian = Math.toRadians(angle);
    double sin = Math.abs(Math.sin(radian));
    double cos = Math.abs(Math.cos(radian));

    int width = buffImage.getWidth();
    int height = buffImage.getHeight();

    int nWidth = (int) Math.floor((double) width * cos + (double) height * sin);
    int nHeight = (int) Math.floor((double) height * cos + (double) width * sin);

    BufferedImage rotatedImage = new BufferedImage(
            nWidth, nHeight, BufferedImage.TYPE_INT_ARGB);

    Graphics2D graphics = rotatedImage.createGraphics();

    graphics.setRenderingHint(
            RenderingHints.KEY_INTERPOLATION,
            RenderingHints.VALUE_INTERPOLATION_BICUBIC);

    graphics.translate((nWidth - width) / 2, (nHeight - height) / 2);
    // rotation around the center point
    graphics.rotate(radian, (double) (width / 2), (double) (height / 2));
    graphics.drawImage(buffImage, 0, 0, null);
    graphics.dispose();

    return rotatedImage;
}

<头>

image.png	rotated.png (45º) ⟳	rotated.png (-45º) ⟲

Answer 3

由于将旋转后的图像绘制到输入图像本身中，因此会得到图像混乱的结果。相反，您需要从新的BufferedImage创建图形。

public static BufferedImage rotate(BufferedImage bimg, double angle) {

    int w = bimg.getWidth();    
    int h = bimg.getHeight();

    BufferedImage rotated = new BufferedImage(w, h, bimg.getType());  
    Graphics2D graphic = rotated.createGraphics();
    graphic.rotate(Math.toRadians(angle), w/2, h/2);
    graphic.drawImage(bimg, null, 0, 0);
    graphic.dispose();
    return rotated;
}

请注意，如果要避免出现拐角，请调整输出BufferedImage的宽度和高度。

Answer 4

您必须考虑调整大小以及输出的新宽度和高度。请参阅：https://stackoverflow.com/a/4787898/5420880