Back
Mar 4, 2011

Css sprite generation

I've created this small sprite to create css sprites. It glues images from directory directory into single file and generates corresponding css.

#!/usr/bin/python

import os
import os.path as p
import Image


css_inline_item_template = '''
%(selector)s {
    background: url(%(url)s) no-repeat -%(xpos)spx -%(ypos)spx;
    width: %(width)spx;
    height: %(height)spx;
}
'''

css_base_template = '''
%(base_selector)s {
    background-image: url(%(url)s);
    background-repeat: no-repeat;
}
'''

css_base_item_template = '''
%(selector)s {
    background-position: -%(xpos)spx -%(ypos)spx;
    width: %(width)spx;
    height: %(height)spx;
}
'''


def generate_sprite(images, margin=10):
    def _basename(path):
        return p.splitext(p.basename(path))[0]

    data = []

    master_height = max(*[i.size[1] for i in images])
    master_width = sum([i.size[0] for i in images]) + margin * (len(images) - 1)

    sprite = Image.new(
        mode='RGBA',
        size=(master_width, master_height),
        color=(0,0,0,0))  # fully transparent

    location = 0
    for image in images:
        if 'transparency' in image.info:
            raise Exception('Incorrect transparency mode: ' + image.filename)

        sprite.paste(image,(location, 0))
        data.append({
            'xpos': location,
            'ypos': 0,
            'dir': _basename(p.dirname(image.filename)),
            'file': _basename(image.filename),
            'width': image.size[0],
            'height': image.size[1],
        })
        location += image.size[0] + margin

    return sprite, data


def render_css(base_template, item_template, css_data, sprite_url, base_selector, selector):
    base_info = {
        'base_selector': base_selector,
        'url': sprite_url,
    }
    base_css = base_template % base_info

    items_css = '\n'.join([
        item_template % dict([('selector', selector % image_data)]
            + image_data.items()
            + base_info.items())
        for image_data in css_data])

    return base_css + items_css


def create_sprite_and_css(images_dir, css_output, sprite_output,
        selector='.%(file)s', base_selector='.sprite', url=None, inline=False):
    images = [Image.open(p.join(images_dir, filename))
                for filename in os.listdir(images_dir)
                if not filename.startswith('.')]

    sprite, css_data = generate_sprite(images)
    sprite.save(sprite_output)

    sprite_url = url or p.basename(sprite_output)
    if inline:
        css = render_css('', css_inline_item_template, css_data, sprite_url, base_selector, selector)
    else:
        css = render_css(css_base_template, css_base_item_template, css_data, sprite_url, base_selector, selector)

    css_file = open(css_output, 'w')
    css_file.write(css)
    css_file.close()


if __name__ == '__main__':
    from optparse import OptionParser

    usage = "usage: %prog [options] images_dir css_output sprite_output"
    parser = OptionParser(usage=usage)
    parser.add_option("-i", "--inline", action="store_true", dest="inline", default=False,
                      help="When set, image url will be put in css rule for every item.")
    parser.add_option("-s", "--selector", dest="selector", default='.%(file)s',
                      help="Selector template. You can use dir, file, width, height here.")
    parser.add_option("-S", "--base-selector", dest="base_selector", default='.sprite',
                      help="Base selector template for base css rule (when -i is not set).")
    parser.add_option("-u", "--url", dest="url", default='',
                      help="Css rule Image url template.")

    (options, args) = parser.parse_args()

    if len(args) < 3:
        print 'You must provide all 3 arguments.'
    else:
        images_dir, css_output, sprite_output = [p.realpath(arg) for arg in args]
        create_sprite_and_css(images_dir, css_output, sprite_output,
                selector=options.selector,
                base_selector=options.base_selector,
                inline=options.inline,
                url=options.url)

Update

This article is pretty old. Now it's better to use something integrated to your build process, like grunt or webassets.

Subscribe for the news and updates

More thoughts
Sep 21, 2020Technology
How to Optimize Django ORM Queries

Django ORM is a very abstract and flexible API. But if you do not know exactly how it works, you will likely end up with slow and heavy views, if you have not already. So, this article provides practical solutions to N+1 and high loading time issues. For clarity, I will create a simple view that demonstrates common ORM query problems and shows frequently used practices.

Jun 14, 2017Technology
How to Deploy a Django Application on Heroku?

In this article I'll show you how to deploy Django with Celery and Postgres to Heroku.

Jan 9, 2017Technology
How to Use GraphQL with Django

GraphQL is a very powerful library, which is not difficult to understand. GraphQL will help to write simple and clear REST API to suit every taste and meet any requirements.

Nov 21, 2016Technology
Crawling FTP server with Scrapy

Welcome all who are reading this article. I was given a task of creating a parser (spider) with the Scrapy library and parsing FTP server with data. The parser had to find lists of files on the server and handle each file separately depending on the requirement to the parser.

Oct 3, 2016Technology
How to include JQuery plugins in Angular 2 running via webpack

Learn more about how to include jquery plugins in angular 2 running via webpack. Our tutorial is perfect for Angular beginners.

Sep 22, 2016Technology
Angular Form Validation

In this article, we will describe some useful scripts and directives we use with angular form validation in our projects.