Class: FilePipeline::FileOperations::ExifRestoration

Inherits:
FileOperation
  • Object
show all
Includes:
ExifManipulable
Defined in:
lib/file_pipeline/file_operations/default_operations/exif_restoration.rb

Overview

A FileOperation that compares Exif Metadata in two files and copies tags missing in one from the other. Used to restore Exif tags that were not preserved during e.g. a file conversion.

Caveat: if this operation is applied to a file together with ExifRedaction, it should be applied before the latter, to avoid redacted tags being restored.

Instance Attribute Summary

Attributes inherited from FileOperation

#options

Instance Method Summary collapse

Methods included from ExifManipulable

#delete_tags, file_tags, #missing_exif_fields, #parse_exif_errors, parse_tag_error, #read_exif, strip_path, #write_exif

Methods inherited from FileOperation

#extension, #failure, #name, #results, #run, #success, #target, #target_extension

Constructor Details

#initialize(**opts) ⇒ ExifRestoration

:args: options

Returns a new instance.

Options

  • skip_tags - Exif tags to be ignored during restoration.

The ExifManipulable mixin defines a set of Exif tags that will always be ignored. These are tags relating to the file properties (e.g. filesize, MIME-type) that will have been altered by any prior operation, such as file format conversions.



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# File 'lib/file_pipeline/file_operations/default_operations/exif_restoration.rb', line 27

def initialize(**opts)
  defaults = { skip_tags: [] }
  super(opts, defaults)
  @options[:skip_tags] += ExifManipulable.file_tags
end

Instance Method Details

#captured_data_tag ⇒ Object

Returns the DROPPED_EXIF_DATA tag defined in CapturedDataTags.

This operation will capture any Exif tags and their values that could not be written to the file created by the operation.



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# File 'lib/file_pipeline/file_operations/default_operations/exif_restoration.rb', line 37

def captured_data_tag
  CapturedDataTags::DROPPED_EXIF_DATA
end

#operation(src_file, out_file, original) ⇒ Object

:args: src_file, out_file

Writes a new version of src_file to out_file with all writable Exif tags from original restored.

Will return any Exif tags that could not be written and their values from the original file as data.



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# File 'lib/file_pipeline/file_operations/default_operations/exif_restoration.rb', line 48

def operation(src_file, out_file, original)
  original_exif, src_file_exif = read_exif original, src_file
  values = missing_exif_fields(src_file_exif, original_exif)
  FileUtils.cp src_file, out_file
  write_exif out_file, values
end