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return if Rails.env.production?
require 'png_quantizator'
require 'parallel'
# The amount of variance (in bytes) allowed in
# file size when testing for compression size
TOLERANCE = 10000
namespace :pngquant do
# Returns an array of all images eligible for compression
def doc_images
Dir.glob('doc/**/*.png', File::FNM_CASEFOLD)
end
# Runs pngquant on an image and optionally
# writes the result to disk
def compress_image(file, overwrite_original)
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
loop 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 && overwrite_original
FileUtils.copy(compressed_file, file)
end
FileUtils.remove(compressed_file)
[is_uncompressed, savings]
end
# Ensures pngquant is available and prints an error if not
def check_executable
unless system('pngquant --version', out: File::NULL)
warn(
'Error: pngquant executable was not detected in the system.'.color(:red),
'Download pngquant at https://pngquant.org/ and place the executable in /usr/local/bin'.color(:green)
)
abort
end
end
desc 'GitLab | Pngquant | Compress all documentation PNG images using pngquant'
task :compress do
check_executable
files = doc_images
puts "Compressing #{files.size} PNG files in doc/**"
Parallel.each(files) do |file|
was_uncompressed, savings = compress_image(file, true)
if was_uncompressed
puts "#{file} was reduced by #{savings} bytes"
end
end
end
desc 'GitLab | Pngquant | Checks that all documentation PNG images have been compressed with pngquant'
task :lint do
check_executable
files = doc_images
puts "Checking #{files.size} PNG files in doc/**"
uncompressed_files = Parallel.map(files) do |file|
is_uncompressed, _ = compress_image(file, false)
if is_uncompressed
puts "Uncompressed file detected: ".color(:red) + file
file
end
end.compact
if uncompressed_files.empty?
puts "All documentation images are optimally compressed!".color(:green)
else
warn(
"The #{uncompressed_files.size} image(s) above have not been optimally compressed using pngquant.".color(:red),
'Please run "bin/rake pngquant:compress" and commit the result.'
)
abort
end
end
end
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