# xmp - Extensible Metadata Platform (XMP) parser

XMP provides an object oriented interface to [XMP data](http://en.wikipedia.org/wiki/Extensible_Metadata_Platform). XMP data can be found in PDF, JPEG, GIF, PNG, and many other formats.

## Supported Formats

Format    | File extension  | Additional dependency
----------|-----------------|-----------------------
JPEG      | .jpeg, .jpg     | [exifr/jpeg](https://github.com/remvee/exifr)
TIFF      | .tiff, .tif     | [exifr/tiff](https://github.com/remvee/exifr)
XMP Files | .xmp, .xml      | none

## Usage

``` ruby
require 'xmp'
xmp = XMP.new('example.jpg')
xmp.dc.subject # => ["something interesting"]

xmp.namespaces.each do |namespace|
  xmp[namespace].attributes.each do |attribute|
    puts "#{namespace}.#{attribute}: #{xmp[namespace][attribute].inspect}"
  end
end
```

`XMP.new` accepts:
* Paths to files (it will choose based on file extension)
* File objects (it will choose based on file extension)
* Nokogiri documents or XML strings

Attributes can be accessed in the following ways:

``` ruby
# assuming an XMP entry AttributeName within the NamespaceName namespace, these are all equivalent
xmp['NamespaceName']['AttributeName']
xmp.namespace_name.attribute_name
xmp.NamespaceName.AttributeName

# you can also mix them
xmp.namespace_name['AttributeName']

# or convert the data to an actual hash
xmp.to_h # => { 'NamespaceName' => { … }, … }
```

## Installation

``` shell
$ gem install xmp
$ gem install exifr # optional, for jpeg/tiff support
```

Or you can add it to your Gemfile:

``` ruby
gem 'xmp',   '~> 1.0'
gem 'exifr', '~> 1.3'
```

## Requirements
* Ruby 2 (supported on >= 2.6, though xmp may work on earlier versions) or Ruby 3
* nokogiri (>= 1.10). The xmp gem depends on this gem. It will be installed automatically.
  * On Ruby 2.6, nokogiri 1.13.10 will be installed; nokogiri >= 1.14 require Ruby 2.7.
  * On Ruby 2.7, nokogiri 1.15.5 will be installed; nokogiri >= 1.16 require Ruby 3.
  * See https://nokogiri.org/CHANGELOG.html for nokogiri support for older or newer Ruby versions.
* exifr (>= 1.3). This gem is optional. If you need it, add it to your Gemfile.

## Development

Fork it at https://github.com/amberbit/xmp

``` shell
$ bundle install # install development dependencies
$ rake spec      # run specs
```

## License
[Ruby's license.](https://www.ruby-lang.org/en/about/license.txt)

Copyright (c) 2011 Wojciech Piekutowski, AmberBit (<http://amberbit.com>) and contributors.