[+/-] : How to add watermark to images in java

The tool to adding watermark to images,recommended markImage () methods to create watermark image. You can use it in jsp, servlet, app.

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

/**
  * The tool to adding watermark to images,recommended markImage () methods to create watermark image.
  *
  *
  */
public class ImageWatermark
{
  private static final int OFFSET_X = 10;
  private static final int OFFSET_Y = 10;

  public static final int MARK_LEFT_TOP = 1;
  public static final int MARK_RIGHT_TOP = 2;
  public static final int MARK_CENTER = 3;
  public static final int MARK_LEFT_BOTTOM = 4;
  public static final int MARK_RIGHT_BOTTOM = 5;


  /**
   * add a text to an image. as a single color, the effect is rather poor.
   * @param srcImg
   * @param text
   * @param font
   * @param color
   * @param offset_x
   * @param offset_y
   */
  public static void markText(String srcImg,String text, Font font, Color color, int offset_x, int offset_y)
  {
    try
    {
      File _file = new File(srcImg);
      Image src = ImageIO.read(_file);
      int width = src.getWidth(null);
      int height = src.getHeight(null);
      BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
      Graphics g = image.createGraphics();
      g.drawImage(src, 0, 0, width, height, null);
//    g.setBackground(Color.white);
      g.setColor(color);
      g.setFont(font);

      g.drawString(text,  offset_x, height - font.getSize() / 2 - offset_y);
      g.dispose();

      FileOutputStream out = new FileOutputStream(srcImg);
      JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
      encoder.encode(image);
      out.close();
    } catch (Exception e)
    {
      e.printStackTrace();
    }
  }


  /**
   * A logo picture to picture and watermark, effective this way
   * one instance : http://www.mvgod.com/images/poster/NaNiYaChuanQi2XKaiSiBinWangZi-10285-12811-19978-13383/3.jpg
   * @param srcImg --
   *          source image
   * @param markImg --
   *          watermark logo image
   * @param alpha --
   *          alpha composite  0 - 1,　0 Full transparency, 1 Opaque
   * @param mark_position --
   *          Watermark position, the four corners and central respectively,
   *       and so constant that ImageWatermark.MARK_LEFT_TOP
   */
  public final static void markImage(String srcImg, String markImg, float alpha, int mark_position)
  {
    try
    {
      File _file = new File(srcImg);
      if(!_file.exists()) return;
      
      Image src = ImageIO.read(_file);
      int width = src.getWidth(null);
      int height = src.getHeight(null);
      BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
      Graphics2D g = image.createGraphics();
      g.drawImage(src, 0, 0, width, height, null);

      // watermark image file
      File markFile = new File(markImg);
      if(!markFile.exists()) return;
      
      Image mark_img = ImageIO.read(markFile);
      int mark_img_width = mark_img.getWidth(null);
      int mark_img_height = mark_img.getHeight(null);
      g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
      switch (mark_position)
      {
      case ImageWatermark.MARK_LEFT_TOP:
        g.drawImage(mark_img, OFFSET_X, OFFSET_Y, mark_img_width, mark_img_height, null);
        break;
      case ImageWatermark.MARK_LEFT_BOTTOM:
        g.drawImage(mark_img, OFFSET_X, (height - mark_img_height - OFFSET_Y), mark_img_width, mark_img_height, null);
        break;
      case ImageWatermark.MARK_CENTER:
        g.drawImage(mark_img, (width - mark_img_width - OFFSET_X) / 2, (height - mark_img_height - OFFSET_Y) / 2,
            mark_img_width, mark_img_height, null);
        break;
      case ImageWatermark.MARK_RIGHT_TOP:
        g.drawImage(mark_img, (width - mark_img_width - OFFSET_X), OFFSET_Y, mark_img_width, mark_img_height, null);
        break;
      case ImageWatermark.MARK_RIGHT_BOTTOM:
      default:
        g.drawImage(mark_img, (width - mark_img_width - OFFSET_X), (height - mark_img_height - OFFSET_Y),
            mark_img_width, mark_img_height, null);
      }

      g.dispose();
      FileOutputStream out = new FileOutputStream(srcImg);
      JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
      encoder.encode(image);
      out.close();
    } catch (Exception e)
    {
      e.printStackTrace();
    }
  }

  public static void markImage(String srcImg, String markImg, float alpha)
  {
    markImage(srcImg, markImg, alpha, ImageWatermark.MARK_RIGHT_BOTTOM);
  }

  public static void markImage( String srcImg, String markImg)
  {
    markImage(srcImg, markImg, 0.5f, ImageWatermark.MARK_RIGHT_BOTTOM);
  }

  public static void markImageRandomPos(String srcImg,String markImg,  float alpha)
  {
    int[] a =
    { ImageWatermark.MARK_LEFT_TOP, ImageWatermark.MARK_RIGHT_TOP, ImageWatermark.MARK_LEFT_TOP, ImageWatermark.MARK_LEFT_BOTTOM,
        ImageWatermark.MARK_RIGHT_BOTTOM, ImageWatermark.MARK_RIGHT_BOTTOM, ImageWatermark.MARK_CENTER };

    int i =  new Random().nextInt(a.length);
    markImage(srcImg, markImg, alpha, a[i]);
  }

  /**
   * Semi-transparent, random location imprint. 
   * With a slightly higher risk of lower right corner of the upper left corner, the central minimum risk.
   * @param srcImg
   * @param markImg
   */
  public static void markImageRandomPos(String srcImg,String markImg)
  {
    markImageRandomPos(srcImg, markImg, 0.5f);
  }
  
  public static void main(String[] args)
  {
   //test
    String src_path = "/home/mvgod/car.jpg";
    String markImg =  "/home/mvgod/logo.png"
    
    float alpha = 0.5f;

    String text = "MVGod.com";
    Font font =new Font("Arial", Font.BOLD, 30)
    ImageWatermark.markText(text, src_path, font, Color.gray, 5, 5);

    
    ImageWatermark.markImage( src_path, markImg, alpha, ImageWatermark.MARK_CENTER);
//    ImageWatermark.markImageRandomPos(src_path,markImg);
  }
}

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