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Provide an alternative PDF previewer based on Poppler

mutool is licensed under the Affero GPL, which has strict distribution requirements.

Poppler is licensed under the more liberal GPL, making it a good alternative for those who can't use mutool.
This commit is contained in:
Terence Lee 2018-02-05 19:33:35 -06:00 committed by George Claghorn
parent 060ed201e4
commit 0b717c2045
8 changed files with 104 additions and 35 deletions

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@ -24,6 +24,7 @@ addons:
- ffmpeg
- mupdf
- mupdf-tools
- poppler-utils
bundler_args: --without test --jobs 3 --retry 3
before_install:

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@ -21,10 +21,9 @@
#
# Outside of a Rails application, modify +ActiveStorage.previewers+ instead.
#
# The built-in previewers rely on third-party system libraries:
#
# * {ffmpeg}[https://www.ffmpeg.org]
# * {mupdf}[https://mupdf.com] (version 1.8 or newer)
# The built-in previewers rely on third-party system libraries. Specifically, the built-in video previewer requires
# {ffmpeg}[https://www.ffmpeg.org]. Two PDF previewers are provided: one requires {Poppler}[https://poppler.freedesktop.org],
# and the other requires {mupdf}[https://mupdf.com] (version 1.8 or newer). To preview PDFs, install either Poppler or mupdf.
#
# These libraries are not provided by Rails. You must install them yourself to use the built-in previewers. Before you
# install and use third-party software, make sure you understand the licensing implications of doing so.

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@ -3,7 +3,8 @@
require "rails"
require "active_storage"
require "active_storage/previewer/pdf_previewer"
require "active_storage/previewer/poppler_pdf_previewer"
require "active_storage/previewer/mupdf_previewer"
require "active_storage/previewer/video_previewer"
require "active_storage/analyzer/image_analyzer"
@ -14,7 +15,7 @@ module ActiveStorage
isolate_namespace ActiveStorage
config.active_storage = ActiveSupport::OrderedOptions.new
config.active_storage.previewers = [ ActiveStorage::Previewer::PDFPreviewer, ActiveStorage::Previewer::VideoPreviewer ]
config.active_storage.previewers = [ ActiveStorage::Previewer::PopplerPDFPreviewer, ActiveStorage::Previewer::MuPDFPreviewer, ActiveStorage::Previewer::VideoPreviewer ]
config.active_storage.analyzers = [ ActiveStorage::Analyzer::ImageAnalyzer, ActiveStorage::Analyzer::VideoAnalyzer ]
config.active_storage.paths = ActiveSupport::OrderedOptions.new

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@ -0,0 +1,36 @@
# frozen_string_literal: true
module ActiveStorage
class Previewer::MuPDFPreviewer < Previewer
class << self
def accept?(blob)
blob.content_type == "application/pdf" && mutool_exists?
end
def mutool_path
ActiveStorage.paths[:mutool] || "mutool"
end
def mutool_exists?
return @mutool_exists unless @mutool_exists.nil?
system mutool_path, out: File::NULL, err: File::NULL
@mutool_exists = $?.exitstatus == 1
end
end
def preview
download_blob_to_tempfile do |input|
draw_first_page_from input do |output|
yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png"
end
end
end
private
def draw_first_page_from(file, &block)
draw self.class.mutool_path, "draw", "-F", "png", "-o", "-", file.path, "1", &block
end
end
end

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@ -1,26 +0,0 @@
# frozen_string_literal: true
module ActiveStorage
class Previewer::PDFPreviewer < Previewer
def self.accept?(blob)
blob.content_type == "application/pdf"
end
def preview
download_blob_to_tempfile do |input|
draw_first_page_from input do |output|
yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png"
end
end
end
private
def draw_first_page_from(file, &block)
draw mutool_path, "draw", "-F", "png", "-o", "-", file.path, "1", &block
end
def mutool_path
ActiveStorage.paths[:mutool] || "mutool"
end
end
end

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@ -0,0 +1,35 @@
# frozen_string_literal: true
module ActiveStorage
class Previewer::PopplerPDFPreviewer < Previewer
class << self
def accept?(blob)
blob.content_type == "application/pdf" && pdftoppm_exists?
end
def pdftoppm_path
ActiveStorage.paths[:pdftoppm] || "pdftoppm"
end
def pdftoppm_exists?
return @pdftoppm_exists unless @pdftoppm_exists.nil?
@pdftoppm_exists = system(pdftoppm_path, "-v", out: File::NULL, err: File::NULL)
end
end
def preview
download_blob_to_tempfile do |input|
draw_first_page_from input do |output|
yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png"
end
end
end
private
def draw_first_page_from(file, &block)
# use 72 dpi to match thumbnail dimesions of the PDF
draw self.class.pdftoppm_path, "-singlefile", "-r", "72", "-png", file.path, &block
end
end
end

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@ -3,15 +3,15 @@
require "test_helper"
require "database/setup"
require "active_storage/previewer/pdf_previewer"
require "active_storage/previewer/mupdf_previewer"
class ActiveStorage::Previewer::PDFPreviewerTest < ActiveSupport::TestCase
class ActiveStorage::Previewer::MuPDFPreviewerTest < ActiveSupport::TestCase
setup do
@blob = create_file_blob(filename: "report.pdf", content_type: "application/pdf")
end
test "previewing a PDF document" do
ActiveStorage::Previewer::PDFPreviewer.new(@blob).preview do |attachable|
ActiveStorage::Previewer::MuPDFPreviewer.new(@blob).preview do |attachable|
assert_equal "image/png", attachable[:content_type]
assert_equal "report.png", attachable[:filename]

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@ -0,0 +1,23 @@
# frozen_string_literal: true
require "test_helper"
require "database/setup"
require "active_storage/previewer/poppler_pdf_previewer"
class ActiveStorage::Previewer::PopplerPDFPreviewerTest < ActiveSupport::TestCase
setup do
@blob = create_file_blob(filename: "report.pdf", content_type: "application/pdf")
end
test "previewing a PDF document" do
ActiveStorage::Previewer::PopplerPDFPreviewer.new(@blob).preview do |attachable|
assert_equal "image/png", attachable[:content_type]
assert_equal "report.png", attachable[:filename]
image = MiniMagick::Image.read(attachable[:io])
assert_equal 612, image.width
assert_equal 792, image.height
end
end
end