不丢失像素的切图

图片切割

将一个原有图片根据传进来的横切数切成小图。

思路：

获取图片长宽算出切成多少块，然后判断是否丢失像素。

版本一：

File file = new File("btg.jpg"); // 项目目录下有名为btg.jpg的图片

FileInputStream fis = new FileInputStream(file);

BufferedImage image = ImageIO.read(fis); //把文件读到图片缓冲流中

int rows = 4; //定义图片要切分成多少块

int cols = 4;

int chunks = rows * cols;

int chunkWidth = image.getWidth() / cols; // 计算每一块小图片的高度和宽度

int chunkHeight = image.getHeight() / rows;

int count = 0;

BufferedImage imgs[] = new BufferedImage[chunks];

for (int x = 0; x < rows; x++) {
for (int y = 0; y < cols; y++) {
//初始化BufferedImage

imgs[count] = new BufferedImage(chunkWidth, chunkHeight, image.getType());

//画出每一小块图片

Graphics2D gr = imgs[count++].createGraphics();

gr.drawImage(image, 0, 0, chunkWidth, chunkHeight, chunkWidth * y, chunkHeight * x, chunkWidth * y + chunkWidth, chunkHeight * x + chunkHeight, null);

gr.dispose();

}

}

System.out.println("切分完成");

//保存小图片到文件中

for (int i = 0; i < imgs.length; i++) {
ImageIO.write(imgs[i], "jpg", new File("img" + i + ".jpg"));

}

System.out.println("小图片创建完成");
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此时发现一个问题，每个图片都是固定大小。丢掉了一些像素，违背了我们的初衷

思路：

此时我们只能将最右边和最下边的宽高进行计算，右下角的宽高比较特殊，右下角呢个图片宽高=原图宽高-（算出的每格大小 * （列/行 - 1））

具体实现：

方便前段使用将行列都从1开始计数

public static void main(String[] args) throws Exception {
        File file = new File("xxx"); // 项目目录下有名为btg.jpg的图片

        FileInputStream fis = new FileInputStream(file);

        BufferedImage image = ImageIO.read(fis); //把文件读到图片缓冲流中

        //定义图片要切分成多少块
        int rows = 7;

        // 算出每块高度是多少
        int chunkHeight = image.getHeight()/rows;

        // 算出多少列
        int cols = image.getWidth()/chunkHeight;

        // 算出每列多少宽度
        int chunkWidth = image.getWidth()/cols;

        int chunks = rows * cols;

        int count = 0;

        BufferedImage imgs[] = new BufferedImage[chunks];

        for (int i = 1; i <= rows; i++) {
            for (int j = 1; j <= cols; j++) {

                // 判断是不是最后一块
                if (j == cols) {
                    // 算出最后一块宽度是多少
                    int wight = image.getWidth() - (chunkWidth * (j - 1));
                    if (i == rows) {
                        // 算出最后一块宽高
                        int hight = image.getHeight() - (chunkHeight * (i - 1));
                        imgs[count] = new BufferedImage(wight, hight, image.getType());
                        Graphics2D gr = imgs[count++].createGraphics();
                        // image原图 sx2 - sx1 = 图片宽度  sy2 - sy1 = 图片高度
                        gr.drawImage(image, 0, 0, wight, hight,
                                image.getWidth(), chunkHeight * (i - 1),
                                chunkWidth * (j - 1) ,  image.getHeight(), null);
                        gr.dispose();
                        System.out.println("sx1==="+wight+"sy1===="+(chunkHeight * (i - 1))+
                                "sx2===="+image.getWidth()+ "sy2===="+image.getHeight());
                    }else {
                        // 最后一列
                        imgs[count] = new BufferedImage(wight, chunkHeight, image.getType());
                        Graphics2D gr = imgs[count++].createGraphics();
                        // image原图 sx2 - sx1 = 图片宽度  sy2 - sy1 = 图片高度
                        gr.drawImage(image, 0, 0, wight, chunkHeight,
                                chunkWidth * (j - 1), chunkHeight * (i - 1),
                                image.getWidth(), (chunkHeight * (i - 1)) + chunkHeight, null);
                        gr.dispose();
                        System.out.println("sx1==="+(chunkWidth * (j - 1))+"sy1===="+(chunkHeight * (i - 1)) +
                                "sx2===="+ image.getWidth()+"sy2===="+((chunkHeight * (i - 1)) + chunkHeight));
                    }
                }else {
                    if (i == rows) {
                        int hight = image.getHeight() - (chunkHeight * (i - 1));
                        imgs[count] = new BufferedImage(chunkWidth, hight, image.getType());
                        Graphics2D gr = imgs[count++].createGraphics();
                        gr.drawImage(image, 0, 0, chunkWidth, hight,
                                chunkWidth * (j-1), chunkHeight * (i-1),
                                chunkWidth * (j-1)+chunkWidth,  image.getHeight(), null);
                        gr.dispose();
                        System.out.println("sx1==="+(chunkWidth * (j-1)+chunkWidth)+"sy1===="+(chunkHeight * (i-1))+"sx2===="+chunkWidth * (j-1)+chunkWidth
                                +"sy2===="+image.getHeight());
                    }else {
                        imgs[count] = new BufferedImage(chunkWidth, chunkHeight, image.getType());
                        Graphics2D gr = imgs[count++].createGraphics();
                        gr.drawImage(image, 0, 0, chunkWidth, chunkHeight,
                                chunkWidth * (j-1), chunkHeight * (i-1),
                                (chunkWidth * (j-1)) + chunkWidth, (chunkHeight * (i-1)) + chunkHeight, null);
                        gr.dispose();
                        System.out.println("sx1==="+(chunkWidth * (j-1))+
                                "sy1===="+(chunkHeight * (i-1))+
                                "sx2===="+(chunkWidth * (j-1) + chunkWidth)
                                +"sy2===="+(chunkHeight * (i-1) + chunkHeight));

                    }
                }
                ImageIO.write(imgs[count-1], "jpg", new File("D:\\bbb\\"+"img" + (count-1) + ".jpg"));
            }
        }
        System.out.println("切分完成");

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