Add vips_foreign_find_load_source & vips_foreign_find_save_target

c_src/vips_foreign.c

@@ -135,6 +135,71 @@ ERL_NIF_TERM nif_foreign_find_save(ErlNifEnv *env, int argc,
   return ret;
 }
 
+
+ERL_NIF_TERM nif_foreign_find_load_source(ErlNifEnv *env, int argc,
+                                          const ERL_NIF_TERM argv[]) {
+  ASSERT_ARGC(argc, 1);
+
+  ErlNifTime start;
+  ERL_NIF_TERM ret;
+  VipsSource *source;
+  const char *name;
+
+  start = enif_monotonic_time(ERL_NIF_USEC);
+
+  if (!erl_term_to_g_object(env, argv[0], (GObject **)&source)) {
+    ret = make_error(env, "Failed to get VipsSource");
+    goto exit;
+  }
+
+  name = vips_foreign_find_load_source(source);
+
+  if (!name) {
+    error("Failed to find the loader for the source. error: %s", vips_error_buffer());
+    vips_error_clear();
+    ret = make_error(env, "Failed to find loader for the source");
+    goto exit;
+  }
+
+  ret = make_ok(env, make_binary(env, name));
+
+exit:
+  notify_consumed_timeslice(env, start, enif_monotonic_time(ERL_NIF_USEC));
+  return ret;
+}
+
+ERL_NIF_TERM nif_foreign_find_save_target(ErlNifEnv *env, int argc,
+                                          const ERL_NIF_TERM argv[]) {
+  ASSERT_ARGC(argc, 1);
+
+  ErlNifTime start;
+  ERL_NIF_TERM ret;
+  char suffix[VIPS_PATH_MAX];
+  const char *name;
+
+  start = enif_monotonic_time(ERL_NIF_USEC);
+
+  if (!get_binary(env, argv[0], suffix, VIPS_PATH_MAX)) {
+    ret = make_error(env, "Failed to get suffix");
+    goto exit;
+  }
+
+  name = vips_foreign_find_save_target(suffix);
+
+  if (!name) {
+    error("Failed to find saver for the target. error: %s", vips_error_buffer());
+    vips_error_clear();
+    ret = make_error(env, "Failed to find saver for the target");
+    goto exit;
+  }
+
+  ret = make_ok(env, make_binary(env, name));
+
+exit:
+  notify_consumed_timeslice(env, start, enif_monotonic_time(ERL_NIF_USEC));
+  return ret;
+}
+
 ERL_NIF_TERM nif_foreign_get_suffixes(ErlNifEnv *env, int argc,
                                       const ERL_NIF_TERM argv[]) {
   ASSERT_ARGC(argc, 0);

c_src/vips_foreign.h

@@ -15,6 +15,12 @@ ERL_NIF_TERM nif_foreign_find_load(ErlNifEnv *env, int argc,
 ERL_NIF_TERM nif_foreign_find_save(ErlNifEnv *env, int argc,
                                    const ERL_NIF_TERM argv[]);
 
+ERL_NIF_TERM nif_foreign_find_load_source(ErlNifEnv *env, int argc,
+                                   const ERL_NIF_TERM argv[]);
+
+ERL_NIF_TERM nif_foreign_find_save_target(ErlNifEnv *env, int argc,
+                                   const ERL_NIF_TERM argv[]);
+
 ERL_NIF_TERM nif_foreign_get_suffixes(ErlNifEnv *env, int argc,
                                       const ERL_NIF_TERM argv[]);
 

c_src/vix.c

@@ -153,10 +153,12 @@ static ErlNifFunc nif_funcs[] = {
      0},
 
     /* VipsForeign */
-    {"nif_foreign_find_load", 1, nif_foreign_find_load, 0},
+    {"nif_foreign_find_load", 1, nif_foreign_find_load, ERL_NIF_DIRTY_JOB_IO_BOUND}, // it might read bytes form the file
     {"nif_foreign_find_save", 1, nif_foreign_find_save, 0},
     {"nif_foreign_find_load_buffer", 1, nif_foreign_find_load_buffer, 0},
     {"nif_foreign_find_save_buffer", 1, nif_foreign_find_save_buffer, 0},
+    {"nif_foreign_find_load_source", 1, nif_foreign_find_load_source, ERL_NIF_DIRTY_JOB_IO_BOUND}, // it might read bytes from source
+    {"nif_foreign_find_save_target", 1, nif_foreign_find_save_target, 0},
     {"nif_foreign_get_suffixes", 0, nif_foreign_get_suffixes, 0},
     {"nif_foreign_get_loader_suffixes", 0, nif_foreign_get_loader_suffixes, 0},
 

lib/vix/nif.ex

@@ -186,6 +186,12 @@ defmodule Vix.Nif do
   def nif_foreign_find_save(_filename),
     do: :erlang.nif_error(:nif_library_not_loaded)
 
+  def nif_foreign_find_load_source(_source),
+    do: :erlang.nif_error(:nif_library_not_loaded)
+
+  def nif_foreign_find_save_target(_suffix),
+    do: :erlang.nif_error(:nif_library_not_loaded)
+
   def nif_foreign_get_suffixes,
     do: :erlang.nif_error(:nif_library_not_loaded)
 

lib/vix/vips/foreign.ex

@@ -1,23 +1,46 @@
 defmodule Vix.Vips.Foreign do
-  alias Vix.Nif
   @moduledoc false
 
+  alias Vix.Nif
+
+  @type operation_name :: String.t()
+
+  @spec find_load_buffer(binary) :: {:ok, operation_name} | {:error, String.t()}
   def find_load_buffer(bin) do
     Nif.nif_foreign_find_load_buffer(bin)
   end
 
+  @spec find_save_buffer(String.t()) :: {:ok, operation_name} | {:error, String.t()}
   def find_save_buffer(suffix) do
     Nif.nif_foreign_find_save_buffer(suffix)
   end
 
+  @doc """
+  Returns Vips operation name which can load the passed file
+  """
+  @spec find_load(String.t()) :: {:ok, operation_name} | {:error, String.t()}
   def find_load(filename) do
     Nif.nif_foreign_find_load(filename)
   end
 
+  @doc """
+  Returns Vips operation name which can save an image to passed format
+  """
+  @spec find_save(String.t()) :: {:ok, operation_name} | {:error, String.t()}
   def find_save(filename) do
     Nif.nif_foreign_find_save(filename)
   end
 
+  @spec find_load_source(Vix.Vips.Source.t()) :: {:ok, operation_name} | {:error, String.t()}
+  def find_load_source(source) do
+    Nif.nif_foreign_find_load_source(source)
+  end
+
+  @spec find_save_target(String.t()) :: {:ok, operation_name} | {:error, String.t()}
+  def find_save_target(suffix) do
+    Nif.nif_foreign_find_save_target(suffix)
+  end
+
   def get_suffixes do
     with {:ok, suffixes} <- Nif.nif_foreign_get_suffixes() do
       {:ok, Enum.uniq(suffixes)}

test/vix/foreign_test.exs

@@ -20,4 +20,18 @@ defmodule Vix.Vips.ForeignTest do
   test "find_save" do
     assert {:ok, "VipsForeignSaveJpegFile"} = Foreign.find_save("puppies.jpg")
   end
+
+  test "find_load_source" do
+    bin = File.read!(img_path("puppies.jpg"))
+
+    assert {pipe, source} = Vix.SourcePipe.new()
+    assert :ok = Vix.SourcePipe.write(pipe, bin)
+    assert :ok = Vix.SourcePipe.stop(pipe)
+
+    assert {:ok, "VipsForeignLoadJpegSource"} = Foreign.find_load_source(source)
+  end
+
+  test "find_save_target" do
+    assert {:ok, "VipsForeignSaveJpegTarget"} = Foreign.find_save_target(".jpg")
+  end
 end