OdfThumb

This gem extracts existing thumbnail files from OpenDocument files, i.e. files created with OpenOffice or LibreOffice.

It cannot be guaranteed, that such a file exists. Most desktop applications will create and update such a file, while converters, export tools and command line utilities might not.

According to Wikipedia, the thumbnail

should be a representation of the first page, first sheet, etc. of the document. The required size for the thumbnails is 128x128 pixel. In order to conform to the Thumbnail Managing Standard (TMS) at www.freedesktop.org, thumbnails must be saved as 8bit, non-interlaced PNG image with full alpha transparency.

Alternative approaches

If these properties do not meet your requirements, try creating a thumbnail by making use of LibreOffice's conversion capabilities. E.g. convert your document to a PNG and create a thumbnail based on that. The following command will create a PNG called Example.png based on the first page of a OpenDocument text file.

soffice --headless --convert-to png Example.odt

Installation

Add this line to your application's Gemfile:

gem 'odf_thumb'

And then execute:

$ bundle

Or install it yourself as:

$ gem install odf_thumb

Command line usage

OdfThumb comes with a command line tool

# Creates a path/to/source.png
odf_thumb path/to/source.odt

# Creates a path/to/target/thumb.png
odf_thumb path/to/source.odt -o path/to/target/thumb.png

# Exits with error code 1 if the given file did not contain a thumbnail file
odf_thumb other_file.txt
echo $? # => 1

API usage

doc = OdfThumb::Document.new("source.odt")

# Returns true if document contains thumbnail file
doc.has_thumb?

# Returns thumbnail as binary string, nil if has_thumb? == false
doc.thumbnail

# Write thumbnail to given path, does nothing if has_thumb? == false
doc.write_thumbnail_to("thumb.odt")

Development

After checking out the repo, run bundle install to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/schmidt/odf_thumb. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.