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# frozen_string_literal: true
module Tooling
module Image
# Determine the tolerance till when we run pngquant in a loop
TOLERANCE = 10000
def self.check_executables
unless system('pngquant --version', out: File::NULL)
warn(
'Error: pngquant executable was not detected in the system.',
'Download pngquant at https://pngquant.org/ and place the executable in /usr/local/bin'
)
abort
end
unless system('gm version', out: File::NULL)
warn(
'Error: gm executable was not detected in the system.',
'Please install imagemagick: brew install imagemagick or sudo apt install imagemagick'
)
abort
end
end
def self.compress_image(file, keep_original = false)
check_executables
compressed_file = "#{file}.compressed"
FileUtils.copy(file, compressed_file)
pngquant_file = PngQuantizator::Image.new(compressed_file)
# Run the image repeatedly through pngquant until
# the change in file size is within TOLERANCE
# or the loop count is above 1000
1000.times do
before = File.size(compressed_file)
pngquant_file.quantize!
after = File.size(compressed_file)
break if before - after <= TOLERANCE
end
savings = File.size(file) - File.size(compressed_file)
is_uncompressed = savings > TOLERANCE
if is_uncompressed && !keep_original
FileUtils.copy(compressed_file, file)
end
FileUtils.remove(compressed_file)
[is_uncompressed, savings]
end
end
end
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