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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Helpers.MediaHelper do
   6   @moduledoc """
   7   Handles common media-related operations.
   8   """
   9
  10   @ffmpeg_opts [{:sync, true}, {:stdout, true}]
  11
  12   def ffmpeg_resize_remote(uri, max_width, max_height) do
  13     cmd = ~s"""
  14     curl -L "#{uri}" |
  15     ffmpeg -i pipe:0 -vf \
  16       "scale='min(#{max_width},iw)':min'(#{max_height},ih)':force_original_aspect_ratio=decrease" \
  17       -f image2 pipe:1 | \
  18     cat
  19     """
  20
  21     with {:ok, [stdout: stdout_list]} <- Exexec.run(cmd, @ffmpeg_opts) do
  22       {:ok, Enum.join(stdout_list)}
  23     end
  24   end
  25
  26   @doc "Returns a temporary path for an URI"
  27   def temporary_path_for(uri) do
  28     name = Path.basename(uri)
  29     random = rand_uniform(999_999)
  30     Path.join(System.tmp_dir(), "#{random}-#{name}")
  31   end
  32
  33   @doc "Stores binary content fetched from specified URL as a temporary file."
  34   @spec store_as_temporary_file(String.t(), binary()) :: {:ok, String.t()} | {:error, atom()}
  35   def store_as_temporary_file(url, body) do
  36     path = temporary_path_for(url)
  37     with :ok <- File.write(path, body), do: {:ok, path}
  38   end
  39
  40   @doc "Modifies image file at specified path by resizing to specified limit dimensions."
  41   @spec mogrify_resize_to_limit(String.t(), String.t()) :: :ok | any()
  42   def mogrify_resize_to_limit(path, resize_dimensions) do
  43     with %Mogrify.Image{} <-
  44            path
  45            |> Mogrify.open()
  46            |> Mogrify.resize_to_limit(resize_dimensions)
  47            |> Mogrify.save(in_place: true) do
  48       :ok
  49     end
  50   end
  51
  52   defp rand_uniform(high) do
  53     Code.ensure_loaded(:rand)
  54
  55     if function_exported?(:rand, :uniform, 1) do
  56       :rand.uniform(high)
  57     else
  58       # Erlang/OTP < 19
  59       apply(:crypto, :rand_uniform, [1, high])
  60     end
  61   end
  62 end