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# frozen_string_literal: true
module ActiveStorage
# Extracts width and height in pixels from an image blob.
#
# If the image contains EXIF data indicating its angle is 90 or 270 degrees, its width and height are swapped for convenience.
#
# Example:
#
# ActiveStorage::Analyzer::ImageAnalyzer.new(blob).metadata
# # => { width: 4104, height: 2736 }
#
# This analyzer relies on the third-party {MiniMagick}[https://github.com/minimagick/minimagick] gem. MiniMagick requires
# the {ImageMagick}[http://www.imagemagick.org] system library.
class Analyzer::ImageAnalyzer < Analyzer
def self.accept?(blob)
blob.image?
end
def metadata
read_image do |image|
if rotated_image?(image)
{ width: image.height, height: image.width }
else
{ width: image.width, height: image.height }
end
end
rescue LoadError
logger.info "Skipping image analysis because the mini_magick gem isn't installed"
{}
end
private
def read_image
download_blob_to_tempfile do |file|
require "mini_magick"
yield MiniMagick::Image.new(file.path)
end
end
def rotated_image?(image)
%w[ RightTop LeftBottom ].include?(image["%[orientation]"])
end
end
end
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