Images Gallery Generator Kata

Generate a set of static HTML files from an XML representation of EXIF data so users can browse large collections of images.

Add the gem to your Gemfile:

# Gemfile

gem 'images_gallery', '~> 1.0' # see semver.org

# Generate a gallery inside spec/tmp from the example source file
images_gallery generate spec/fixtures/works.xml spec/tmp

# Read usage intructions:
images_gallery help

# Open the images gallery automatically after it was generated
firefox $(images_gallery generate spec/fixtures/works.xml spec/tmp/)

# Run the test suite
rake

# Run the acceptance test suite only (can be seen as a demo)
rake features
# Visit spec/tmp/index.html to browse the sample images

The ImageGallery::Source relies on the LibXML SAX parser to extract the images described in the source XML file (e.g. works.xml). That parser is known to be fast and memory-thrifty.

This kata aims at writing a command-line tool to process large XML files which contain images metadata. Part of that metadata is relevant, and the images gallery should allow to preview a collection of thumbnails classified by camera make, model and ISO speed ratings.

Because the images collections can be really large, care has been taken to avoid loading the XML document in memory while parsing it.

Yet huges collections to review do also mean you probably don't want to review them without involving your team. That's to say the images gallery deployment is a key aspect of the task at hand, and keeping the files tree as simple as possible is a way to make the deployments as straightforward as possible. No external CSS, nor font, nor javascipts then.

The views/templates pattern makes the design extensible, this galleries generator is no CMS however! Priority has been given to simplify as much as possible the rendering engine task. Plain ERb should keep the HTML generation fast, while a basic partials system ensures that adding a few front-end features remains a pomodoro-sized task. (If more features would to be added, however, the views mechanics and the templates management should be refined - see the naviagtion links generation for example.)

The main user interface is the CLI, which was built with Thor as a way to make it both user-friendly and extensible. The CLI output was kept minimal, to make easy to insert the images_gallery program into any processing pipeline (since we are talking about large amount of data here, then we're probably also talking about processing pipelines).

That's pretty much all... a last word about those particularly numerous shared specs. I like to define the "public" API of the main classes this way in order to ensure I keep always at sight which methods I can depend on and which others could lead to tighter undesired coupling. These interfaces are kinds of consumer-driven contracts and keeping them apart helps to remember that.

Images Gallery Generator
Copyright (C) 2015 Gonzalo Bulnes Guilpain

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.