证件照APP照片间隔排版的实现

某些证件照APP当你上传一张图片后，会自动帮你排版成多张图片。下方代码可以实现这种有间隔的自动排版功能。

运行结果：

 

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class Demo {

    public static void main(String[] args) throws IOException {
        int pageWidth = 105;    //A6尺寸
        int pageHeight = 148;   //A6尺寸
        int photoWidth = 25;    //A1尺寸
        int photoHeight = 35;   //A1尺寸
        int interval = 2;   //间隙大小
        File inFIle = new File("d:/AAfile/yh.jpg");
        File outFIle = new File("d:/AAfile/yhheads.jpg");
        draw(pageWidth,pageHeight,photoWidth,photoHeight,interval,inFIle,outFIle);
    }
    public static void draw(int pageWidth, int pageHeight, int photoWidth, int photoHeight,
                            int interval, File inFile, File outFile) throws IOException {
        //这里pageWidth为什么是减去interval
        int xNum = (pageWidth - interval) / (photoWidth + interval);  //横向放置个数
        int yNum = (pageHeight - interval) / (photoHeight + interval);//纵向放置个数
        int left = (pageWidth + interval - (photoWidth + interval) * xNum) / 2;//横向起始点
        int top = (pageHeight + interval - (photoHeight + interval) * yNum) / 2;//纵向起始点
        int xpixel = getPixel(pageWidth);
        int ypixel = getPixel(pageHeight);
        BufferedImage photo = ImageIO.read(inFile);
        BufferedImage bi = new BufferedImage(xpixel,ypixel,BufferedImage.TYPE_INT_RGB);
        Graphics2D g = bi.createGraphics();
        //填充背景
        g.setColor(Color.white);
        g.fillRect(0,0,xpixel,ypixel);
        //绘制图片

        int xg,yg;
        for (int i = 0; i < yNum; i++){
            yg = getPixel(top + i * (photoHeight + interval));
            for (int j = 0; j < xNum; j++){
                xg = getPixel(left + j * (photoWidth + interval));
                g.drawImage(photo,xg,yg,getPixel(photoWidth),getPixel(photoHeight),null);
            }
        }
        //绘制辅助线 可设置无需辅助线
        g.setColor(Color.black);
        int x,y;
        //纵向
        for (int i = 0; i < xNum; i++){
            xg = getPixel(left + i * (photoWidth + interval));
            g.drawLine(xg,0,xg,ypixel);
            x = xg + getPixel(photoWidth);
            g.drawLine(x,0,x,ypixel);
        }
        //横向
        for (int j = 0; j < yNum; j++){
            yg = getPixel( top + j * (photoHeight + interval));
            g.drawLine(0,yg,xpixel,yg);
            y = yg + getPixel(photoHeight);
            g.drawLine(0,y,xpixel,y);
        }
        g.dispose();

        ImageIO.write(bi,"jpg",outFile);


    }
    /**
     * 计算像素数
     * 1毫米像素数=DPI/25.4
     * DPI可更改 暂设300
     */
    public static int getPixel(int mm){
        return (int) (300/25.4)*mm;
    }
}

 其中需要花时间理解的就是计算能排几张照片，以及绘图、绘线功能。

为了使照片和白色背景边缘距离>=2mm,pageWidth需要先减去interval。

int xNum = (pageWidth - interval) / (photoWidth + interval);  //横向放置个数
int yNum = (pageHeight - interval) / (photoHeight + interval);//纵向放置个数