class ActiveStorage::Previewer

:doc:
The output tempfile is opened in the directory returned by ActiveStorage::Downloading#tempdir.

end
end
end
yield io: output, filename: "#{blob.filename.base}.png", content_type: "image/png"
draw "my-drawing-command", input.path, "--format", "png", "-" do |output|
download_blob_to_tempfile do |input|
def preview

generation. The resulting tempfile can be used as the +:io+ value in an attachable Hash:
Use this method to shell out to a system library (e.g. mupdf or ffmpeg) for preview image

Executes a system command, capturing its binary output in a tempfile. Yields the tempfile.

def draw(*argv) #:doc:
  ActiveSupport::Notifications.instrument("preview.active_storage") do
    open_tempfile_for_drawing do |file|
      capture(*argv, to: file)
      yield file
    end
  end
end