Java（SWING）使用旋转

Question

我有一个可以处理图片的应用程序（只是一个开头有 3 张图片的全屏应用程序），我应该可以移动和旋转这些图片。一切都很完美，直到旋转，如果我旋转一张图片，这张图片的边界将保持 hotizantal -> 所以问题是我如何在 java 中旋转组件边界？

Answer 1

这是我很久以前找到的一些代码：

import java.awt.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.io.*;
import java.net.*;
import javax.imageio.*;
import javax.swing.*;

public class RotateImage {
    public static void main(String[] args) throws IOException {
        URL url = new URL("http://www.oracle.com/us/assets/im04t0-java-logo-1862786.jpg");
        BufferedImage original = ImageIO.read(url);
        GraphicsConfiguration gc = getDefaultConfiguration();
        BufferedImage rotated1 = tilt(original, -Math.PI/2, gc);
        BufferedImage rotated2 = tilt(original, +Math.PI/4, gc);
        BufferedImage rotated3 = tilt(original, Math.PI, gc);
        display(original, rotated1, rotated2, rotated3);
    }

    public static BufferedImage tilt(BufferedImage image, double angle, GraphicsConfiguration gc) {
        double sin = Math.abs(Math.sin(angle)), cos = Math.abs(Math.cos(angle));
        int w = image.getWidth(), h = image.getHeight();
        int neww = (int)Math.floor(w*cos+h*sin), newh = (int)Math.floor(h*cos+w*sin);
        int transparency = image.getColorModel().getTransparency();
        BufferedImage result = gc.createCompatibleImage(neww, newh, transparency);
        Graphics2D g = result.createGraphics();
        g.translate((neww-w)/2, (newh-h)/2);
        g.rotate(angle, w/2, h/2);
        g.drawRenderedImage(image, null);
        return result;
    }

    public static GraphicsConfiguration getDefaultConfiguration() {
        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
        GraphicsDevice gd = ge.getDefaultScreenDevice();
        return gd.getDefaultConfiguration();
    }

    public static void display(BufferedImage im1, BufferedImage im2, BufferedImage im3, BufferedImage im4) {
        JPanel cp = new JPanel(new GridLayout(2,2));
        addImage(cp, im1, "original");
        addImage(cp, im2, "rotate -PI/2");
        addImage(cp, im3, "rotate +PI/4");
        addImage(cp, im4, "rotate PI");

        JFrame f = new JFrame("RotateImage");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setContentPane(cp);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    static void addImage(Container cp, BufferedImage im, String title) {
        JLabel lbl = new JLabel(new ImageIcon(im));
        lbl.setBorder(BorderFactory.createTitledBorder(title));
        cp.add(lbl);
    }
}

编辑：

// BufferedImage result = gc.createCompatibleImage(neww, newh, transparency);
BufferedImage result = gc.createCompatibleImage(neww, newh, Transparency.TRANSLUCENT);