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QR Code Generator and Documentation

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QR Code Generator and Documentation

Table of Contents

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1. Overview

QR code generator with support for standard and ambiguous QR codes.

2. Configuration

(require 'qrencode)

(defgroup qr nil
  "QR code generation and analysis tools"
  :group 'tools)

(defcustom qr-base-urls 
  '("http://localhost:8080"
    "https://example.com")
  "Base URLs for QR code generation"
  :type '(repeat string)
  :group 'qr)

(defcustom qr-output-dir "/tmp/qr-diff"
  "Directory for QR code output files"
  :type 'directory
  :group 'qr)

(defun qr-ensure-output-dir ()
  "Ensure output directory exists"
  (unless (file-exists-p qr-output-dir)
    (make-directory qr-output-dir t)))

(defun qr-generate-url (base-url path)
  "Generate full URL for QR code"
  (concat base-url path))

(defun qr-encode-url-to-ascii (url)
  "Create ASCII QR code from URL"
  (qr-ensure-output-dir)
  (with-temp-buffer
    (call-process "qrencode" nil t nil 
                 "-t" "ASCII" 
                 "-o" "-"
                 url)
    (buffer-string)))

(provide 'qr-config)

3. Analysis

3.1. Test QR Codes

#!/bin/bash

set -euo pipefail

LOCAL_HOST="http://localhost:8080"
PATHS=("/1" "/2")
TMP_DIR="/tmp/qr-test"

test_local() {
    mkdir -p "$TMP_DIR"
    for path in "${PATHS[@]}"; do
        url="$LOCAL_HOST$path"
        outfile="$TMP_DIR/$(basename "$path").png"
        qrencode -o "$outfile" -s 10 "$url"
        qrencode -t ASCII -o - "$url" > "$TMP_DIR/$(basename "$path").txt"
    done
    
    compare "$TMP_DIR/1.png" "$TMP_DIR/2.png" "$TMP_DIR/diff.png"
    diff "$TMP_DIR/1.txt" "$TMP_DIR/2.txt" || true
}

test_local

4. Ambiguous QR Codes

The script supports generating ambiguous QR codes that encode two different URLs using a lenticular pattern.

4.1. String-based Implementation

#!/usr/bin/env python3

import qrcode

def generate_ambiguous_qr(host="example.com", paths=["/1", "/2"]):
    qr1 = qrcode.QRCode(version=1, box_size=1, border=4)
    qr2 = qrcode.QRCode(version=1, box_size=1, border=4)
    
    qr1.add_data(f"https://{host}{paths[0]}")
    qr2.add_data(f"https://{host}{paths[1]}")
    
    str1 = qr1.get_matrix()
    str2 = qr2.get_matrix()
    
    for i in range(len(str1)):
        for j in range(len(str1[0])):
            if str1[i][j] != str2[i][j]:
                str1[i][j] = "▚" if (i + j) % 2 else "▞"
    
    for row in str1:
        print("".join("█" if cell else " " for cell in row))

if __name__ == "__main__":
    hosts = ["localhost:8080", "example.com"]
    for host in hosts:
        print(f"\nAmbiguous QR for {host}:")
        generate_ambiguous_qr(host)

5. Development

5.1. Requirements

  • qrencode
  • imagemagick
  • python3, qrcode
  • emacs 25+

5.2. Installation

# macOS
brew install qrencode imagemagick
pip install qrcode

# Debian/Ubuntu
apt-get install qrencode imagemagick
pip install qrcode

5.3. Usage

  1. Load the configuration
  2. Generate QR codes with qr-encode-url-to-ascii
  3. Create ambiguous codes with generate_ambiguous_qr