This is a simple qrcode builder that is build ontop of the awesome ZXing library for barcode generation: https://github.com/zxing/zxing

QRCodeBuilder

Requirements

• JDK 25
• Maven 3.9+

Build

mvn package

This also produces a runnable demo:

java -jar target/qrbuilder-0.1.jar

Usage

The builder is very simple to use, as the following example will shows.

Create a QRCode with dimensions 250*250, a image overlay and some data:

package org.skrymer.qrbuilder;

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

import static org.skrymer.qrbuilder.decorator.ImageOverlay.*;

public class Main {
  static final float TRANSPARENCY = 0.25f;
  static final float OVERLAY_RATIO = 1f;
  static final int WIDTH = 250;
  static final int HEIGHT = 250;

  public static void main(String[] args) {
    QRCode.ZXingBuilder.build(builder ->
        builder.withSize(WIDTH, HEIGHT)
              .and()
            .withData("The answer is 42")
              .and()
            .withColor(Color.green.darker())
              .and()
            .withDecorator(addImageOverlay(readImage("/images/skull_bw.png"), TRANSPARENCY, OVERLAY_RATIO))
              .and()
            .verify(true)

    ).toFile("./qrCode.png", "PNG");
  }

  static BufferedImage readImage(String resource) {
    try (InputStream in = Main.class.getResourceAsStream(resource)) {
      return ImageIO.read(in);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
  }
}

The following qrCode is then generated:

Decorators

The builder uses the decorators to decorate(obviously) the generated QRCode.

Decorators currently available:

• ImageOverlay

The qrcode colour is not a decorator - set it on the builder with withColor(Color), which colours the code as it is rendered rather than repainting it afterwards.

Sizing

withSize(width, height) is required, and the size you ask for is the size you get. A payload that needs more modules than the requested size can hold throws InvalidSizeException naming the minimum, rather than quietly returning a larger image than you asked for.

You can create new Decorators by implementing the Decorator interface