Elaphe

WARNING! trunk is broken for complete rewriting. For working version, grab 0.5.3 in /tags.

Elaphe is a python binding for the Barcode Writer In Pure PostScript (http://www.terryburton.co.uk/barcodewriter/). It is a thin-wrapper which employs Python Imaging Library as PostScript rendering interface.

Requirements

Python 2.5 or later (functional decorators, ternary operator, and

generator expressions are used).

If you want to render the generated barcode, Python Imaging Library

(http://www.pythonware.com/products/pil) is required under the condition that EpsImagePlugin is enabled (i.e. at least you must have Ghostscript is installed and callable from PIL).

Simple Usage

The following example:

  >>> from elaphe import barcode
  >>> barcode('qrcode',
  ...         'Hello Barcode Writer In Pure PostScript.',
  ...         options=dict(version=9, eclevel='M'), 
  ...         margin=10, data_mode='8bits'))   # Generates PIL.EpsImageFile instance
  <PIL.EpsImagePlugin.EpsImageFile instance at ...>
  >>> _.show()            # Show the image

should invoke default viewer which shows a QRcode symbol with 10px margin.

Remember, barcode() returns PIL image object.

Frequently Issued Problems

Trunk does not work

No problem, trunk is broken. Use /tags/0.5.3.

IOError: 32 Broken pipe

If you see, especially on Windows, something like:

File ".../PIL/EpsImagePlugin.py", line 72, in Ghostscript
    gs.write(s)
IOError: [Errno 32] Broken pipe

Make sure Ghostscript is installed as well as environment variable PATH is set.

Try following code on your enviroment:

# coding: utf-8                                                                 
from StringIO import StringIO
from PIL.EpsImagePlugin import EpsImageFile

src = """%!PS-Adobe 2.0                                                         
%%BoundingBox: 0 0 144 144                                                      
36 36 72 72 rectfill                                                            
/Courier findfont 12 scalefont setfont                                          
36 120 moveto (text) show                                                       
showpage                                                                        
"""

im = EpsImageFile(StringIO(src))
im.save('foo.png')

If PIL and Ghostscript are correctly installed, you will see square and text in 'foo.png'.

Plan

Elaphe will make use of reportlab.graphics.renderFooBar instead of bwipp/gs/PIL.