Sha256: ec4d4034975f5eaa85ac1be48e6cfa48f7ecde8d45fdce56270db4cf96d4409c
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Size: 1.85 KB
Versions: 2
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Contents
# frozen_string_literal: true require "active_storage/downloading" module ActiveStorage # This is an abstract base class for previewers, which generate images from blobs. See # ActiveStorage::Previewer::PDFPreviewer and ActiveStorage::Previewer::VideoPreviewer for examples of # concrete subclasses. class Previewer include Downloading attr_reader :blob # Implement this method in a concrete subclass. Have it return true when given a blob from which # the previewer can generate an image. def self.accept?(blob) false end def initialize(blob) @blob = blob end # Override this method in a concrete subclass. Have it yield an attachable preview image (i.e. # anything accepted by ActiveStorage::Attached::One#attach). def preview raise NotImplementedError end private # Executes a system command, capturing its binary output in a tempfile. Yields the tempfile. # # Use this method to shell out to a system library (e.g. mupdf or ffmpeg) for preview image # generation. The resulting tempfile can be used as the +:io+ value in an attachable Hash: # # def preview # download_blob_to_tempfile do |input| # draw "my-drawing-command", input.path, "--format", "png", "-" do |output| # yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png" # end # end # end # # The output tempfile is opened in the directory returned by ActiveStorage::Downloading#tempdir. def draw(*argv) # :doc: Tempfile.open("ActiveStorage", tempdir) do |file| capture(*argv, to: file) yield file end end def capture(*argv, to:) to.binmode IO.popen(argv) { |out| IO.copy_stream(out, to) } to.rewind end end end
Version data entries
2 entries across 2 versions & 1 rubygems
Version | Path |
---|---|
activestorage-5.2.0.beta2 | lib/active_storage/previewer.rb |
activestorage-5.2.0.beta1 | lib/active_storage/previewer.rb |