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|
# frozen_string_literal: true
module Paperclip
class LazyThumbnail < Paperclip::Processor
ALLOWED_FIELDS = %w(
width
height
bands
format
coding
interpretation
icc-profile-data
page-height
n-pages
loop
delay
).freeze
class PixelGeometryParser
def self.parse(current_geometry, pixels)
width = Math.sqrt(pixels * (current_geometry.width.to_f / current_geometry.height)).round.to_i
height = Math.sqrt(pixels * (current_geometry.height.to_f / current_geometry.width)).round.to_i
Paperclip::Geometry.new(width, height)
end
end
def initialize(file, options = {}, attachment = nil)
super
@crop = options[:geometry].to_s[-1, 1] == '#'
@current_geometry = options.fetch(:file_geometry_parser, Geometry).from_file(@file)
@target_geometry = options[:pixels] ? PixelGeometryParser.parse(@current_geometry, options[:pixels]) : options.fetch(:string_geometry_parser, Geometry).parse(options[:geometry].to_s)
@format = options[:format]
@current_format = File.extname(@file.path)
@basename = File.basename(@file.path, @current_format)
correct_current_format!
correct_target_geometry!
end
def make
return File.open(@file.path) unless needs_convert?
dst = TempfileFactory.new.generate([@basename, @format ? ".#{@format}" : @current_format].join)
transformed_image.write_to_file(dst.path, **save_options)
dst
end
private
def correct_target_geometry!
min_side = [@current_geometry.width, @current_geometry.height].min.to_i
@target_geometry = Paperclip::Geometry.new(min_side, min_side) if @target_geometry&.square? && min_side < @target_geometry.width
end
def correct_current_format!
# If the attachment was uploaded through a base64 payload, the tempfile
# will not have a file extension. It could also have the wrong file extension,
# depending on what the uploaded file was named. We correct for this in the final
# file name, which is however not yet physically in place on the temp file, so we
# need to use it here. Mind that this only reliably works if this processor is
# the first in line and we're working with the original, unmodified file.
@current_format = File.extname(attachment.instance_read(:file_name))
end
def transformed_image
# libvips has some optimizations for resizing an image on load. If we don't need to
# resize the image, we have to load it a different way.
if @target_geometry.nil?
return Vips::Image.new_from_file(preserve_animation? ? "#{@file.path}[n=-1]" : @file.path, access: :sequential).copy.mutate do |mutable|
(mutable.get_fields - ALLOWED_FIELDS).each do |field|
mutable.remove!(field)
end
end
end
# libvips thumbnail operation does not work correctly on animated GIFs. If we need to
# preserve the animation, we have to load all the frames and then manually crop
# them to then reassemble.
if preserve_animation?
original_image = Vips::Image.new_from_file("#{@file.path}[n=-1]", access: :sequential)
n_pages = original_image.get('n-pages')
# The loaded image has each frame stacked on top of each other, therefore we must
# account for this when giving the resizing constraint, otherwise the width will
# always end up smaller than we want.
resized_image = original_image.thumbnail_image(@target_geometry.width, height: @target_geometry.height * n_pages, size: :down).mutate do |mutable|
(mutable.get_fields - ALLOWED_FIELDS).each do |field|
mutable.remove!(field)
end
end
# If we don't need to crop the image, then we're already done. Otherwise,
# we need to manually crop each frame of the animation and reassemble them.
return resized_image unless @crop
page_height = resized_image.get('page-height')
frames = (0...n_pages).map do |i|
resized_image.crop(0, i * page_height, @target_geometry.width, @target_geometry.height)
end
Vips::Image.arrayjoin(frames, across: 1).copy.mutate do |mutable|
mutable.set!('page-height', @target_geometry.height)
end
else
Vips::Image.thumbnail(@file.path, @target_geometry.width, height: @target_geometry.height, **thumbnail_options).mutate do |mutable|
(mutable.get_fields - ALLOWED_FIELDS).each do |field|
mutable.remove!(field)
end
end
end
end
def thumbnail_options
@crop ? { crop: :centre } : { size: :down }
end
def save_options
case @format
when 'jpg'
{ Q: 90, interlace: true }
else
{}
end
end
def preserve_animation?
@format == 'gif' || (@format.blank? && @current_format == '.gif')
end
def needs_convert?
needs_different_geometry? || needs_different_format? || needs_metadata_stripping?
end
def needs_different_geometry?
(options[:geometry] && @current_geometry.width != @target_geometry.width && @current_geometry.height != @target_geometry.height) ||
(options[:pixels] && @current_geometry.width * @current_geometry.height > options[:pixels])
end
def needs_different_format?
@format.present? && @current_format != ".#{@format}"
end
def needs_metadata_stripping?
@attachment.instance.respond_to?(:local?) && @attachment.instance.local?
end
end
end
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