Add SetMeta filter to store uploaded image sizes

lib/pleroma/upload/filter/set_meta.ex

@@ -0,0 +1,36 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Upload.Filter.SetMeta do
+  @moduledoc """
+  Extracts metadata about the upload, such as width/height
+  """
+  require Logger
+
+  @behaviour Pleroma.Upload.Filter
+
+  @spec filter(Pleroma.Upload.t()) ::
+          {:ok, :filtered, Pleroma.Upload.t()} | {:ok, :noop} | {:error, String.t()}
+  def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _} = upload) do
+    try do
+      image =
+        file
+        |> Mogrify.open()
+        |> Mogrify.verbose()
+
+      upload =
+        upload
+        |> Map.put(:width, image.width)
+        |> Map.put(:height, image.height)
+
+      {:ok, :filtered, upload}
+    rescue
+      e in ErlangError ->
+        Logger.warn("#{__MODULE__}: #{inspect(e)}")
+        {:ok, :noop}
+    end
+  end
+
+  def filter(_), do: {:ok, :noop}
+end