Unsharp Mask with PIL and PythonMagick

**A Magick PIL** I used to do my image conversions with ImageMagick and system calls back in my PHP days. With Django PIL is the obvious choice for most image stuff, but frustrated by the lack of a proper unsharp mask function for PIL I found some code in the bits and pieces of documentation for PythonMagick. (yes I know, Kevin Cabazon wrote PIL_usm, but I could not get it to work, probably due to my inexperience. Anyway, this code makes it easy to convert back and forth from PIL to PythonMagick (maybe not such a good idea on a memory tight high loaded production server, but no problem on my private server (Pentium-M @ 1.8 Ghz with 1 GB Mem.) **usage:** usm takes a PIL image object. Radius and sigma is in pixels, amount 1 compares to 100% in photoshop, threshold 0.004 ~ (1/256) compares to 1 in photoshop: I'm using r=1,s=0.5,a=0.8,t=0.016 for roughly 800x600 images created from 3000x2000 (6MP) images. Experiment for your own preferences.

• image
• pil
• sharpen
• thumbnails
• pythonmagick
• usm

Sun 11 Jul 2010 Read More

Image resize on demand

** Image on demand view ** I often post photos on photography fora. Most fora want you to place a link to a photo somewhere on the net, but different fora have different rules. Some fora want you to stick to a maximum of 800 pixels wide, some 700 pixel and some even strange values like 639 pixels. My own site uses 600 pixels so I end up resizing images all the time. Since I keep my originals with my gallery as well (hidden for public viewing) resizing on the fly would be a nice asset. I'm using my previous snippet to apply a slight unsharp mask for better web display of my photos. ** usage ** This snippet takes the url to my photo application which is a simple link using the pk of my photo table and adds 'width'.jpg to the end (some fora check if the link is an image based on extenstion) The view takes the width requested and creates the resized image from the original full size image or takes it from the cache for display on demand. To prevent a dozen directories I use a setting to specify which widths are allowed, providing room for several versions of the same image. Any improvements are appreciated since I'm still rather inexperienced in Python and Django.

• image
• pil
• resize
• pythonmagick

Sun 11 Jul 2010 Read More

FTP storage backend

Simple FTP storage class. See description at the beginning of the snippet.

• storage
• ftp

Sun 11 Jul 2010 Read More

Null Field Admin Filter

This patch adds a new admin Filter, for Filtering nullable fields. It adds 3 possible choices: 'All' (no filter), 'Null' (it applies field__isnull=True filter), and 'With Value' (it filters null values). This patch is interesting when you have a Integer or String fields and you want to filter wether a value is set or not. In other case, it would show too many filtering options. Remember this is a patch and you must modify a django file in `django/contrib/admin/filterspecs.py`

• filter
• admin
• null

Sun 11 Jul 2010 Read More

Lazy options on ModelForm fields - like setting a ModelChoiceField queryset from the view

Example view code: lazy_field_options = { 'field_name_that_is_m2m': { 'queryset': YourRelatedModel.objects.filter(groups=request.user.groups.all()), }, 'field_name_that_is_fk': { 'queryset': YourOtherRelatedModel.objects.filter(slug=request_slug), }, } modelform = YourModelForm(jpic_field_options=lazy_field_options) # after the modelform has called for parent __init__, it will set # options for each field if possible.

• hack
• form
• queryset
• modelchoicefield
• modelform
• modelmultiplechoicefield

Sun 11 Jul 2010 Read More

UnicodeReprMixIn

Add's updated and created fields to a model if mixed in. Example that uses the name as the representation: class Company(models.Model, UnicodeReprMixIn): """ A representation of a comic book company. """ name = models.CharField(max_length=255) slug = models.SlugField() logo = models.ImageField(upload_to=os.path.join('upload', 'company_logos')) url = models.URLField(verify_exists=True) _unicode = "name"

• model
• unicode
• orm
• mixin
• __unicode__

Sun 11 Jul 2010 Read More

Media Wiki With mwlib

### Simple wiki with MediaWiki and Markdown Support Once you install the mwlib you can use mwit to convert Mediawiki markup to HTML. I am include the model that uses it to hopefully provide a good example. I maintain a version and only one copy of each wiki entry in the main table and archive replaced markup into another table, you will need to create the archive model or remove that section of code. The line ending changes in mwit are so that it will work with IE.

• markup
• markdown
• mediawiki
• wiki
• archive

Sun 11 Jul 2010 Read More

Play nice with ModelAdmin mixins

There are several nice ModelAdmin subclasses that provide useful functionality (such as django-batchadmin, django-reversion, and others), but unfortunately a ModelAdmin can really only subclass one at a time, making them mutually exclusive. This snippet aims to make mixing these classes in as easy as possible -- you can inherit your model admin from it, add a tuple of mixins, and it will dynamically change the inheritance tree to match. This isn't guaranteed to work with all ModelAdmins, but so long as the mixins play nice with django modeladmin they *should* work.

• mixin
• modeladmin

Sun 11 Jul 2010 Read More

ifinlist template tag

I recently had to write a custom template tag which checks to see if a value exists in a list variable from within a Django template. This was my first ever attempt at writing a template tag so any feedback would be appreciated.

• template-tag
• if-in-list
• if-value-in-list

Sun 11 Jul 2010 Read More

iter_fetchmany

When executing custom sql, the temptation is to use fetchall or fetchone, since the API for fetchmany is a bit awkward. (fetchall makes all records resident in client memory at once; fetchone takes a network round-trip to the DB for each record.) This snippet, hoisted from django.db.models.sql.query.results_iter, presents a nice, simple iterator over multiple fetchmany calls which hits a sweet spot of minimizing memory and network usage.

• sql
• db
• db-api
• fetchmany

Sun 11 Jul 2010 Read More

simple app using RestViews

Inspired by [Eric Florenzano's](http://www.eflorenzano.com/) post about [writing simple and very fast pure-WSGI applications](http://www.eflorenzano.com/blog/post/writing-blazing-fast-infinitely-scalable-pure-wsgi/). Using [RestView](http://www.djangosnippets.org/snippets/1071/) approach. More about it on [my blog](http://my.opera.com/kubiku/blog/2009/01/16/bare-wsgi-vs-python-frameworks-django-chapter)

• rest

Sun 11 Jul 2010 Read More

Dynamic growing model

This model is designed for my webshop. The Client-object is very 'stretch-able' by defining more fields to the client. These extra fields ares stored in the ClientConfig-object. Be sure to create a new Client-instance first and SAVE it! Without a client.id the ClientConfig won't work.

• django
• dynamic
• model
• example
• client

Sun 11 Jul 2010 Read More

Load Windows ICO files

PIL IcoImagePlugin is twelve year old and it can't handle recent Windows ICO files. Here is a function that handles all ICO versions and preserve transparency. Usage: # Load biggest icon from file image = load_icon('icon.ico') # Save third icon as PNG load_icon('icon.ico', 2).save('icon.png')

• image
• pil
• ico

Sun 11 Jul 2010 Read More

Severity codes in user messages

This is the code for a template tag. Put this code in your template to render your messages: {% for message in messages %} {% render_user_message message %} {% endfor %} When you're adding a message to the user's message set, follow these rules: If you want a message to appear as an error, append "0001" to the end of it. To appear as a notice, append "0002" to it. To appear as a happy message, appear "0000" to it. If no code is present, it will default to displaying as an error. This makes use of the classes "error", "notice", and "success", so you need to define these in your CSS. For help with custom template tags, see [the Django docs](http://docs.djangoproject.com/en/dev/howto/custom-template-tags/)

• user
• message

Sun 11 Jul 2010 Read More

Formalchemy hack for newforms-based form validation

Very simple proof-of-concept that uses the django.forms library (newforms) for validation, and formalchemy for saving the model instance using sqlalchemy. it can be used like this (pseudo-code): if form.is_valid(): form.save(session=Session, app_label='Contact') Feel free to improve the concept. Ideally, either use formalchemy or django.forms but not both like this example. ;-)

• newforms
• hack
• formalchemy
• notmm
• sqlalchemy

Sun 11 Jul 2010 Read More