https://github.com/ruediger/qrencode-el

QRCode encoder for Emacs in pure elisp
https://github.com/ruediger/qrencode-el

elisp emacs lisp qrcode qrcode-generator

Last synced: 6 months ago
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QRCode encoder for Emacs in pure elisp

• Host: GitHub
• URL: https://github.com/ruediger/qrencode-el
• Owner: ruediger
• License: gpl-3.0
• Created: 2021-09-01T13:02:33.000Z (almost 5 years ago)
• Default Branch: main
• Last Pushed: 2024-01-04T22:46:12.000Z (over 2 years ago)
• Last Synced: 2024-01-05T00:27:27.669Z (over 2 years ago)
• Topics: elisp, emacs, lisp, qrcode, qrcode-generator
• Language: Emacs Lisp
• Homepage:
• Size: 106 KB
• Stars: 26
• Watchers: 4
• Forks: 4
• Open Issues: 1
• Metadata Files:
  • Readme: README.org
  • License: LICENSE.md

Awesome Lists containing this project

README

          
* QREncode EL

  QR Code encoder written in pure Emacs Lisp.

  For example the self-link (https://github.com/ruediger/qrencode-el)

  below was generated using this code:

  [[file:qr-self.png]]

** Usage

  This package provides two user facing interactive functions, that

  will encode text into a QR Code and show it in a separate buffer.

  * =qrencode-region= :: Shows the current selection as a QR Code.

  * =qrencode-url-at-point= :: Encode URL at point as QR Code.

  Some customizations are provided using =M-x customize-group RET

  qrencode RET=.

  QR Codes are rendered as Unicode text, but there is an option to

  export them as bitmap (NetPBM format).  There are also some public

  elisp library functions to generate QR Codes for use in other elisp

  code.

*** Converting different bitmaps

  This package only supports exporting to NetPBM format due to the

  simplicity of the format.  If PNG or other bitmap formats are

  desired this can be achieved by using

  =qrencode-post-export-functions= to run a conversion after the

  export.  For example using =convert(1)= from [[https://www.imagemagick.org/script/convert.php][ImageMagick]]:

#+BEGIN_SRC emacs-lisp

  (add-hook 'qrencode-post-export-functions

          #'(lambda (filename)

              (call-process "convert" nil nil nil

                            filename

                            (file-name-with-extension filename "png"))))

#+END_SRC

** Installation

  [[https://melpa.org/#/qrencode][file:https://melpa.org/packages/qrencode-badge.svg]]

  [[https://stable.melpa.org/#/qrencode][file:https://stable.melpa.org/packages/qrencode-badge.svg]]

  QREncode is available via [[https://melpa.org/#/qrencode][MELPA]] and [[https://github.com/dimitri/el-get/blob/master/recipes/qrencode.rcp][el-get]].

** Background

   [[file:https://github.com/ruediger/qrencode-el/actions/workflows/test.yml/badge.svg]]

  The code is written in pure Emacs Lisp on GNU Emacs 27.  It should

  be backwards compatible to GNU Emacs 25.1 and potentially even

  earlier with =seq= and =cl-lib= compat libraries.

  There are unit tests and an integration test using [[https://zbar.sf.net][zbar.sf.net]]

  (Debian/Ubuntu package =zbar-tools=) to verify that generated QR

  Codes can be decoded.  https://qrlogo.kaarposoft.dk/qrdecode.html is

  another good way to test the generated codes, since the decoder

  supports debug output.

  The encoder is written for the ISO/IEC 18004:2015 standard.  It only

  supports regular QR Codes (Model 2) and byte encoding (#11).  I

  believe this is sufficient for use-cases in GNU Emacs.  The word "QR

  Code" is registered trademark of DENSO WAVE INCORPORATED in Japan

  and other countries.