[gimp] libgimpcolor: add gimp_color_transform_can_gegl_copy()

[Michael Natterer <mitch src gnome org>]

commit ca349f88cd09c1cca2a5808847b0f2ba04f444c8
Author: Michael Natterer <mitch gimp org>
Date:   Thu May 26 23:11:24 2016 +0200

    libgimpcolor: add gimp_color_transform_can_gegl_copy()
    
    Which takes two profiles and returns TRUE if converting between
    them works correctly without a GimpColorTransform. Use it in
    gimp_color_transform_new() to return a NULL transform if none
    is needed. Took the code from gimp-gegl-loops.c.

 app/gegl/gimp-gegl-loops.c        |   44 ----------------------------
 libgimpcolor/gimpcolor.def        |    1 +
 libgimpcolor/gimpcolortransform.c |   58 ++++++++++++++++++++++++++++++++++++-
 libgimpcolor/gimpcolortransform.h |    3 ++
 4 files changed, 61 insertions(+), 45 deletions(-)
---
diff --git a/app/gegl/gimp-gegl-loops.c b/app/gegl/gimp-gegl-loops.c
index 9275e4c..2110bc4 100644
--- a/app/gegl/gimp-gegl-loops.c
+++ b/app/gegl/gimp-gegl-loops.c
@@ -661,42 +661,6 @@ gimp_gegl_index_to_mask (GeglBuffer          *indexed_buffer,
     }
 }
 
-static gboolean
-gimp_color_profile_can_gegl_copy (GimpColorProfile *src_profile,
-                                  GimpColorProfile *dest_profile)
-{
-  static GimpColorProfile *srgb_profile        = NULL;
-  static GimpColorProfile *srgb_linear_profile = NULL;
-  static GimpColorProfile *gray_profile        = NULL;
-  static GimpColorProfile *gray_linear_profile = NULL;
-
-  if (gimp_color_profile_is_equal (src_profile, dest_profile))
-    return TRUE;
-
-  if (! srgb_profile)
-    {
-      srgb_profile        = gimp_color_profile_new_rgb_srgb ();
-      srgb_linear_profile = gimp_color_profile_new_rgb_srgb_linear ();
-      gray_profile        = gimp_color_profile_new_d65_gray_srgb_trc ();
-      gray_linear_profile = gimp_color_profile_new_d65_gray_linear ();
-    }
-
-  if ((gimp_color_profile_is_equal (src_profile, srgb_profile)        ||
-       gimp_color_profile_is_equal (src_profile, srgb_linear_profile) ||
-       gimp_color_profile_is_equal (src_profile, gray_profile)        ||
-       gimp_color_profile_is_equal (src_profile, gray_linear_profile))
-      &&
-      (gimp_color_profile_is_equal (dest_profile, srgb_profile)        ||
-       gimp_color_profile_is_equal (dest_profile, srgb_linear_profile) ||
-       gimp_color_profile_is_equal (dest_profile, gray_profile)        ||
-       gimp_color_profile_is_equal (dest_profile, gray_linear_profile)))
-    {
-      return TRUE;
-    }
-
-  return FALSE;
-}
-
 void
 gimp_gegl_convert_color_profile (GeglBuffer               *src_buffer,
                                  const GeglRectangle      *src_rect,
@@ -716,13 +680,6 @@ gimp_gegl_convert_color_profile (GeglBuffer               *src_buffer,
   src_format  = gegl_buffer_get_format (src_buffer);
   dest_format = gegl_buffer_get_format (dest_buffer);
 
-  if (gimp_color_profile_can_gegl_copy (src_profile, dest_profile))
-    {
-      gegl_buffer_copy (src_buffer,  src_rect, GEGL_ABYSS_NONE,
-                        dest_buffer, dest_rect);
-      return;
-    }
-
   if (bpc)
     flags |= GIMP_COLOR_TRANSFORM_FLAGS_BLACK_POINT_COMPENSATION;
 
@@ -745,7 +702,6 @@ gimp_gegl_convert_color_profile (GeglBuffer               *src_buffer,
     }
   else
     {
-      /* FIXME: no idea if this ever happens */
       gegl_buffer_copy (src_buffer,  src_rect, GEGL_ABYSS_NONE,
                         dest_buffer, dest_rect);
 
diff --git a/libgimpcolor/gimpcolor.def b/libgimpcolor/gimpcolor.def
index 24ab7f8..9c7cf94 100644
--- a/libgimpcolor/gimpcolor.def
+++ b/libgimpcolor/gimpcolor.def
@@ -52,6 +52,7 @@ EXPORTS
        gimp_color_profile_new_rgb_srgb_linear
        gimp_color_profile_new_srgb_trc_from_color_profile
        gimp_color_profile_save_to_file
+       gimp_color_transform_can_gegl_copy
        gimp_color_transform_get_type
        gimp_color_transform_new
        gimp_color_transform_new_proofing
diff --git a/libgimpcolor/gimpcolortransform.c b/libgimpcolor/gimpcolortransform.c
index 310e5f4..6d81075 100644
--- a/libgimpcolor/gimpcolortransform.c
+++ b/libgimpcolor/gimpcolortransform.c
@@ -155,7 +155,8 @@ gimp_color_transform_finalize (GObject *object)
  *
  * This function creates an color transform.
  *
- * Return value: the #GimpColorTransform, or %NULL.
+ * Return value: the #GimpColorTransform, or %NULL if no transform is needed
+ *               to convert between pixels of @src_profile and @dest_profile.
  *
  * Since: 2.10
  **/
@@ -179,6 +180,9 @@ gimp_color_transform_new (GimpColorProfile         *src_profile,
   g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (dest_profile), NULL);
   g_return_val_if_fail (dest_format != NULL, NULL);
 
+  if (gimp_color_transform_can_gegl_copy (src_profile, dest_profile))
+    return NULL;
+
   transform = g_object_new (GIMP_TYPE_COLOR_TRANSFORM, NULL);
 
   priv = transform->priv;
@@ -415,3 +419,55 @@ gimp_color_transform_process_buffer (GimpColorTransform  *transform,
   g_signal_emit (transform, gimp_color_transform_signals[PROGRESS], 0,
                  1.0);
 }
+
+/**
+ * gimp_color_transform_can_gegl_copy:
+ * @src_format:  src profile
+ * @dest_format: dest profile
+ *
+ * This function checks if a GimpColorTransform is needed at all.
+ *
+ * Return value: %TRUE if pixels can be correctly converted between
+ *               @src_profile and @dest_profile by simply using
+ *               gegl_buffer_copy(), babl_process() or similar.
+ *
+ * Since: 2.10
+ **/
+gboolean
+gimp_color_transform_can_gegl_copy (GimpColorProfile *src_profile,
+                                    GimpColorProfile *dest_profile)
+{
+  static GimpColorProfile *srgb_profile        = NULL;
+  static GimpColorProfile *srgb_linear_profile = NULL;
+  static GimpColorProfile *gray_profile        = NULL;
+  static GimpColorProfile *gray_linear_profile = NULL;
+
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (src_profile), FALSE);
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (dest_profile), FALSE);
+
+  if (gimp_color_profile_is_equal (src_profile, dest_profile))
+    return TRUE;
+
+  if (! srgb_profile)
+    {
+      srgb_profile        = gimp_color_profile_new_rgb_srgb ();
+      srgb_linear_profile = gimp_color_profile_new_rgb_srgb_linear ();
+      gray_profile        = gimp_color_profile_new_d65_gray_srgb_trc ();
+      gray_linear_profile = gimp_color_profile_new_d65_gray_linear ();
+    }
+
+  if ((gimp_color_profile_is_equal (src_profile, srgb_profile)        ||
+       gimp_color_profile_is_equal (src_profile, srgb_linear_profile) ||
+       gimp_color_profile_is_equal (src_profile, gray_profile)        ||
+       gimp_color_profile_is_equal (src_profile, gray_linear_profile))
+      &&
+      (gimp_color_profile_is_equal (dest_profile, srgb_profile)        ||
+       gimp_color_profile_is_equal (dest_profile, srgb_linear_profile) ||
+       gimp_color_profile_is_equal (dest_profile, gray_profile)        ||
+       gimp_color_profile_is_equal (dest_profile, gray_linear_profile)))
+    {
+      return TRUE;
+    }
+
+  return FALSE;
+}
diff --git a/libgimpcolor/gimpcolortransform.h b/libgimpcolor/gimpcolortransform.h
index cb6bee0..aaa9d76 100644
--- a/libgimpcolor/gimpcolortransform.h
+++ b/libgimpcolor/gimpcolortransform.h
@@ -106,6 +106,9 @@ void    gimp_color_transform_process_buffer   (GimpColorTransform       *transfo
                                                GeglBuffer               *dest_buffer,
                                                const GeglRectangle      *dest_rect);
 
+gboolean gimp_color_transform_can_gegl_copy   (GimpColorProfile         *src_profile,
+                                               GimpColorProfile         *dest_profile);
+
 
 G_END_DECLS