[babl] babl: register gray and gray alpha shortcuts between spaces

[Øyvind "pippin" Kolås <ok src gnome org>]

commit 6a85f56af6dfd7796112b9d3fc5c69d56c76a316
Author: Øyvind Kolås <pippin gimp org>
Date:   Tue Aug 20 02:54:51 2019 +0200

    babl: register gray and gray alpha shortcuts between spaces
    
    The formats "Y float", "YA float" and "YaA float" between different RGB
    and gray spaces are all exactly the same. This registers memcpy shortcuts
    for these combinations for all spaces. This avoids temporarily expand
    into RGBA for many babl path fishes.

 babl/babl-space.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
---
diff --git a/babl/babl-space.c b/babl/babl-space.c
index c05796ca8..90c0a50f9 100644
--- a/babl/babl-space.c
+++ b/babl/babl-space.c
@@ -883,6 +883,27 @@ universal_rgb_converter (const Babl    *conversion,
 }
 
 
+static inline void
+universal_ya_converter (const Babl    *conversion,
+                        unsigned char *src_char,
+                        unsigned char *dst_char,
+                        long           samples,
+                        void          *data)
+{
+  memcpy (dst_char, src_char, samples * 4 * 2);
+}
+
+static inline void
+universal_y_converter (const Babl    *conversion,
+                       unsigned char *src_char,
+                       unsigned char *dst_char,
+                       long           samples,
+                       void          *data)
+{
+  memcpy (dst_char, src_char, samples * 4);
+}
+
+
 static inline void
 universal_nonlinear_rgb_u8_converter (const Babl    *conversion,
                                       unsigned char *src_char,
@@ -1268,6 +1289,22 @@ add_rgb_adapter (Babl *babl,
                     babl_format_with_space("RGB float", space),
                     "linear", universal_rgb_converter,
                     NULL));
+
+    prep_conversion(babl_conversion_new(
+                    babl_format_with_space("Y float", space),
+                    babl_format_with_space("Y float", babl),
+                    "linear", universal_y_converter,
+                    NULL));
+    prep_conversion(babl_conversion_new(
+                    babl_format_with_space("YaA float", babl),
+                    babl_format_with_space("YaA float", space),
+                    "linear", universal_ya_converter,
+                    NULL));
+    prep_conversion(babl_conversion_new(
+                    babl_format_with_space("YA float", babl),
+                    babl_format_with_space("YA float", space),
+                    "linear", universal_ya_converter,
+                    NULL));
   }
   return 0;
 }