[#2497] Image preview proxy: implemented ffmpeg-based resizing, removed eimp & mogrify-based resizing.

1 files changed, 62 insertions, 0 deletions

diff --git a/lib/pleroma/helpers/media_helper.ex b/lib/pleroma/helpers/media_helper.ex
new file mode 100644
index 000000000..6d1f8ab22
--- /dev/null
+++ b/lib/pleroma/helpers/media_helper.ex
@@ -0,0 +1,62 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Helpers.MediaHelper do
+  @moduledoc """
+  Handles common media-related operations.
+  """
+
+  @ffmpeg_opts [{:sync, true}, {:stdout, true}]
+
+  def ffmpeg_resize_remote(uri, max_width, max_height) do
+    cmd = ~s"""
+    curl -L "#{uri}" |
+    ffmpeg -i pipe:0 -vf \
+      "scale='min(#{max_width},iw)':min'(#{max_height},ih)':force_original_aspect_ratio=decrease" \
+      -f image2 pipe:1 | \
+    cat
+    """
+
+    with {:ok, [stdout: stdout_list]} <- Exexec.run(cmd, @ffmpeg_opts) do
+      {:ok, Enum.join(stdout_list)}
+    end
+  end
+
+  @doc "Returns a temporary path for an URI"
+  def temporary_path_for(uri) do
+    name = Path.basename(uri)
+    random = rand_uniform(999_999)
+    Path.join(System.tmp_dir(), "#{random}-#{name}")
+  end
+
+  @doc "Stores binary content fetched from specified URL as a temporary file."
+  @spec store_as_temporary_file(String.t(), binary()) :: {:ok, String.t()} | {:error, atom()}
+  def store_as_temporary_file(url, body) do
+    path = temporary_path_for(url)
+    with :ok <- File.write(path, body), do: {:ok, path}
+  end
+
+  @doc "Modifies image file at specified path by resizing to specified limit dimensions."
+  @spec mogrify_resize_to_limit(String.t(), String.t()) :: :ok | any()
+  def mogrify_resize_to_limit(path, resize_dimensions) do
+    with %Mogrify.Image{} <-
+           path
+           |> Mogrify.open()
+           |> Mogrify.resize_to_limit(resize_dimensions)
+           |> Mogrify.save(in_place: true) do
+      :ok
+    end
+  end
+
+  defp rand_uniform(high) do
+    Code.ensure_loaded(:rand)
+
+    if function_exported?(:rand, :uniform, 1) do
+      :rand.uniform(high)
+    else
+      # Erlang/OTP < 19
+      apply(:crypto, :rand_uniform, [1, high])
+    end
+  end
+end