Support blurhash

lib/pleroma/upload.ex

@@ -25,6 +25,7 @@ defmodule Pleroma.Upload do
   path as the temporary file is also tracked by `Plug.Upload{}` and automatically deleted once the request is over.
   * `:width` - width of the media in pixels
   * `:height` - height of the media in pixels
+  * `:blurhash` - string hash of the image encoded with the blurhash algorithm (https://blurha.sh/)
 
   Related behaviors:
 
@@ -58,9 +59,10 @@ defmodule Pleroma.Upload do
           content_type: String.t(),
           width: integer(),
           height: integer(),
+          blurhash: String.t(),
           path: String.t()
         }
-  defstruct [:id, :name, :tempfile, :content_type, :width, :height, :path]
+  defstruct [:id, :name, :tempfile, :content_type, :width, :height, :blurhash, :path]
 
   defp get_description(opts, upload) do
     case {opts[:description], Pleroma.Config.get([Pleroma.Upload, :default_description])} do
@@ -98,7 +100,8 @@ defmodule Pleroma.Upload do
            |> Maps.put_if_present("height", upload.height)
          ],
          "name" => description
-       }}
+       }
+       |> Maps.put_if_present("blurhash", upload.blurhash)}
     else
       {:description_limit, _} ->
         {:error, :description_too_long}

lib/pleroma/upload/filter/set_meta.ex

@@ -23,6 +23,7 @@ defmodule Pleroma.Upload.Filter.SetMeta do
         upload
         |> Map.put(:width, image.width)
         |> Map.put(:height, image.height)
+        |> Map.put(:blurhash, get_blurhash(file))
 
       {:ok, :filtered, upload}
     rescue
@@ -33,4 +34,12 @@ defmodule Pleroma.Upload.Filter.SetMeta do
   end
 
   def filter(_), do: {:ok, :noop}
+
+  defp get_blurhash(file) do
+    with {:ok, blurhash} <- :eblurhash.magick(file) do
+      blurhash
+    else
+      _ -> nil
+    end
+  end
 end

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -973,6 +973,7 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
         }
         |> Maps.put_if_present("width", url["width"])
         |> Maps.put_if_present("height", url["height"])
+        |> Maps.put_if_present("blurhash", data["blurhash"])
       end)
 
     Map.put(object, "attachment", attachments)