通过删除java中的透明像素将图像裁剪为最小尺寸

import javax.media.jai.*;
import java.awt.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.ImageIO;

public class ImageCrop {
    public static void main(String[] args) throws IOException {
        // 读取图像文件
        BufferedImage image = ImageIO.read(new File("input.png"));

        // 获取图像的宽度和高度
        int width = image.getWidth();
        int height = image.getHeight();

        // 创建一个新的图像，用于存储裁剪后的图像
        BufferedImage croppedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);

        // 获取图像的Alpha通道
        WritableRaster alphaRaster = image.getAlphaRaster();

        // 遍历图像的每个像素，找到最小的裁剪尺寸
        int minX = width;
        int minY = height;
        int maxX = 0;
        int maxY = 0;
        for (int y = 0; y< height; y++) {
            for (int x = 0; x< width; x++) {
                int alpha = alphaRaster.getSample(x, y, 0);
                if (alpha != 0) {
                    minX = Math.min(minX, x);
                    minY = Math.min(minY, y);
                    maxX = Math.max(maxX, x);
                    maxY = Math.max(maxY, y);
                }
            }
        }

        // 根据找到的最小裁剪尺寸，裁剪图像
        int cropWidth = maxX - minX + 1;
        int cropHeight = maxY - minY + 1;
        BufferedImage cropImage = new BufferedImage(cropWidth, cropHeight, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = cropImage.createGraphics();
        g2d.drawImage(image, 0, 0, cropWidth, cropHeight, minX, minY, maxX + 1, maxY + 1, null);
        g2d.dispose();

        // 保存裁剪后的图像到文件
        ImageIO.write(cropImage, "png", new File("output.png"));
    }
}