From f1f588fd5271c0b3bf09df002a83dbb57c42bae0 Mon Sep 17 00:00:00 2001
From: Ivan Tashkinov <ivantashkinov@gmail.com>
Date: Thu, 14 May 2020 20:18:31 +0300
Subject: [PATCH] [#2497] Added support for :eimp for image resizing.

---
 config/config.exs                             |  4 +-
 .../web/media_proxy/media_proxy_controller.ex | 64 +++++++++++++++----
 mix.exs                                       |  2 +-
 3 files changed, 56 insertions(+), 14 deletions(-)

diff --git a/config/config.exs b/config/config.exs
index 0f92b1ef9..e9403c7c8 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -393,7 +393,9 @@
 # Note: media preview proxy depends on media proxy to be enabled
 config :pleroma, :media_preview_proxy,
   enabled: false,
-  limit_dimensions: "400x200",
+  enable_eimp: true,
+  thumbnail_max_width: 400,
+  thumbnail_max_height: 200,
   proxy_opts: [
     head_request_max_read_duration: 5_000,
     max_read_duration: 10_000
diff --git a/lib/pleroma/web/media_proxy/media_proxy_controller.ex b/lib/pleroma/web/media_proxy/media_proxy_controller.ex
index 157365e08..8d8d073e9 100644
--- a/lib/pleroma/web/media_proxy/media_proxy_controller.ex
+++ b/lib/pleroma/web/media_proxy/media_proxy_controller.ex
@@ -62,24 +62,64 @@ defp handle_preview(conn, url) do
     end
   end
 
+  defp thumbnail_max_dimensions(params) do
+    config = Config.get([:media_preview_proxy], [])
+
+    thumbnail_max_width =
+      if w = params["thumbnail_max_width"] do
+        String.to_integer(w)
+      else
+        Keyword.fetch!(config, :thumbnail_max_width)
+      end
+
+    thumbnail_max_height =
+      if h = params["thumbnail_max_height"] do
+        String.to_integer(h)
+      else
+        Keyword.fetch!(config, :thumbnail_max_height)
+      end
+
+    {thumbnail_max_width, thumbnail_max_height}
+  end
+
+  defp thumbnail_binary(url, body, params) do
+    {thumbnail_max_width, thumbnail_max_height} = thumbnail_max_dimensions(params)
+
+    with true <- Config.get([:media_preview_proxy, :enable_eimp]),
+         {:ok, [type: image_type, width: source_width, height: source_height]} <-
+           :eimp.identify(body),
+         scale_factor <-
+           Enum.max([source_width / thumbnail_max_width, source_height / thumbnail_max_height]),
+         {:ok, thumbnail_binary} =
+           :eimp.convert(body, image_type, [
+             {:scale, {round(source_width / scale_factor), round(source_height / scale_factor)}}
+           ]) do
+      {:ok, thumbnail_binary}
+    else
+      _ ->
+        mogrify_dimensions = "#{thumbnail_max_width}x#{thumbnail_max_height}"
+
+        with {:ok, path} <- MogrifyHelper.store_as_temporary_file(url, body),
+             %Mogrify.Image{} <-
+               MogrifyHelper.in_place_resize_to_limit(path, mogrify_dimensions),
+             {:ok, thumbnail_binary} <- File.read(path),
+             _ <- File.rm(path) do
+          {:ok, thumbnail_binary}
+        else
+          _ -> :error
+        end
+    end
+  end
+
   defp handle_preview("image/" <> _ = content_type, %{params: params} = conn, url) do
-    with {:ok, %{status: status, body: body}} when status in 200..299 <-
+    with {:ok, %{status: status, body: image_contents}} when status in 200..299 <-
            url
            |> MediaProxy.url()
            |> Tesla.get(opts: [adapter: [timeout: preview_timeout()]]),
-         {:ok, path} <- MogrifyHelper.store_as_temporary_file(url, body),
-         resize_dimensions <-
-           Map.get(
-             params,
-             "limit_dimensions",
-             Config.get([:media_preview_proxy, :limit_dimensions])
-           ),
-         %Mogrify.Image{} <- MogrifyHelper.in_place_resize_to_limit(path, resize_dimensions),
-         {:ok, image_binary} <- File.read(path),
-         _ <- File.rm(path) do
+         {:ok, thumbnail_binary} <- thumbnail_binary(url, image_contents, params) do
       conn
       |> put_resp_header("content-type", content_type)
-      |> send_resp(200, image_binary)
+      |> send_resp(200, thumbnail_binary)
     else
       {_, %{status: _}} ->
         send_resp(conn, :failed_dependency, "Can't fetch the image.")
diff --git a/mix.exs b/mix.exs
index a9c4ad2e3..332febe48 100644
--- a/mix.exs
+++ b/mix.exs
@@ -139,7 +139,7 @@ defp deps do
        github: "ninenines/gun", ref: "e1a69b36b180a574c0ac314ced9613fdd52312cc", override: true},
       {:jason, "~> 1.0"},
       {:mogrify, "~> 0.6.1"},
-      {:eimp, ">= 0.0.0"},
+      {:eimp, "~> 1.0.14"},
       {:ex_aws, "~> 2.1"},
       {:ex_aws_s3, "~> 2.0"},
       {:sweet_xml, "~> 0.6.6"},