[babl] Oklab: disable only Oklch not Oklab

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

commit 3e5e4ed24fd8016159f56a5dd656be46f8360154
Author: Øyvind Kolås <pippin gimp org>
Date:   Fri Oct 29 03:34:36 2021 +0200

    Oklab: disable only Oklch not Oklab
    
    Oklab itself is enabled by default now for testing, but does not seem to
    produce correct values with the Oklab test vectors, even with manual
    attempt at converting the test vector (presumed) CIE XYZ D65 to CIE XYZ
    D50 before running the conversion.
    
    The failure to pass symmetry tests as mentioned in issue #63 seems to be
    limited to Oklch, Oklab itself is fine.

 extensions/oklab.c | 66 +++++++++++++++++++++++++++++++-----------------------
 1 file changed, 38 insertions(+), 28 deletions(-)
---
diff --git a/extensions/oklab.c b/extensions/oklab.c
index 6dab0a793..4add977b5 100644
--- a/extensions/oklab.c
+++ b/extensions/oklab.c
@@ -44,12 +44,14 @@ static void formats (void);
 
 int init (void);
 
+static int enable_lch = 0;
+ // the Oklch conversions are not fully symmetric,
+ // thus not allowing the tests to pass if we register
+ // the code
+
 int
 init (void)
 {
-  return 0; // the oklab conversions are not fully symmetric,
-            // thus not allowing the tests to pass if we register
-            // the code
   components ();
   models ();
   formats ();
@@ -84,15 +86,18 @@ models (void)
       babl_component ("Ok L"), babl_component ("Ok a"),
       babl_component ("Ok b"), babl_component ("A"), "alpha", NULL);
 
-  babl_model_new ("name", "Oklch", "doc",
-                  "Cylindrical representation of Oklab.",
-                  babl_component ("Ok L"), babl_component ("Ok C"),
-                  babl_component ("Ok H"), NULL);
+  if (enable_lch)
+  {
+    babl_model_new ("name", "Oklch", "doc",
+                    "Cylindrical representation of Oklab.",
+                    babl_component ("Ok L"), babl_component ("Ok C"),
+                    babl_component ("Ok H"), NULL);
 
-  babl_model_new (
-      "name", "OklchA", "doc", "Oklch color model with separate alpha.",
-      babl_component ("Ok L"), babl_component ("Ok C"),
-      babl_component ("Ok H"), babl_component ("A"), "alpha", NULL);
+    babl_model_new (
+        "name", "OklchA", "doc", "Oklch color model with separate alpha.",
+        babl_component ("Ok L"), babl_component ("Ok C"),
+        babl_component ("Ok H"), babl_component ("A"), "alpha", NULL);
+  }
 }
 
 static void
@@ -108,15 +113,6 @@ formats (void)
     NULL
   );
 
-  babl_format_new (
-    "name", "Oklch float",
-    babl_model ("Oklch"),
-    babl_type ("float"),
-    babl_component ("Ok L"),
-    babl_component ("Ok C"),
-    babl_component ("Ok H"),
-    NULL
-  );
 
   babl_format_new (
     "name", "Oklab alpha float",
@@ -129,6 +125,18 @@ formats (void)
     NULL
   );
 
+  if (enable_lch)
+  {
+  babl_format_new (
+    "name", "Oklch float",
+    babl_model ("Oklch"),
+    babl_type ("float"),
+    babl_component ("Ok L"),
+    babl_component ("Ok C"),
+    babl_component ("Ok H"),
+    NULL
+  );
+
   babl_format_new (
     "name", "Oklch alpha float",
     babl_model ("OklchA"),
@@ -139,6 +147,7 @@ formats (void)
     babl_component ("A"),
     NULL
   );
+  }
 }
 
 /* Convertion routine (space definition). */
@@ -323,12 +332,12 @@ constants (void)
   babl_matrix_mul_matrix (tmp, M1, M1);
 
   babl_matrix_invert (M1, inv_M1);
-  babl_matrix_to_float (inv_M1, inv_M1f);
   babl_matrix_invert (M2, inv_M2);
-  babl_matrix_to_float (inv_M2, inv_M2f);
 
   babl_matrix_to_float (M1, M1f);
   babl_matrix_to_float (M2, M2f);
+  babl_matrix_to_float (inv_M1, inv_M1f);
+  babl_matrix_to_float (inv_M2, inv_M2f);
 
   mat_ready = 1;
 }
@@ -809,6 +818,12 @@ conversions (void)
                        "linear", lab_to_rgba,
                        NULL);
 
+  _pair ("RGB float", "Oklab float", rgb_to_lab_float, lab_to_rgb_float);
+  _pair ("RGBA float", "Oklab alpha float", rgba_to_laba_float, laba_to_rgba_float);
+  _pair ("RGBA float", "Oklab float", rgba_to_lab_float, lab_to_rgba_float);
+
+  if (enable_lch)
+  {
   babl_conversion_new (babl_model("RGBA"),
                        babl_model("OklchA"),
                        "linear", rgba_to_lcha,
@@ -826,17 +841,12 @@ conversions (void)
                        babl_model("RGBA"),
                        "linear", lch_to_rgba,
                        NULL);
-
-
-  _pair ("RGB float", "Oklab float", rgb_to_lab_float, lab_to_rgb_float);
-  _pair ("RGBA float", "Oklab alpha float", rgba_to_laba_float, laba_to_rgba_float);
-  _pair ("RGBA float", "Oklab float", rgba_to_lab_float, lab_to_rgba_float);
-
   _pair ("RGBA float", "Oklch float", rgba_to_lch_float, lch_to_rgba_float);
   _pair ("RGB float", "Oklch float", rgb_to_lch_float, lch_to_rgb_float);
   _pair ("RGBA float", "Oklch alpha float", rgba_to_lcha_float, lcha_to_rgba_float);
   
   _pair ("Oklab float", "Oklch float", lab_to_lch_float, lch_to_lab_float);
   _pair ("Oklab alpha float", "Oklch alpha float", laba_to_lcha_float, lcha_to_laba_float);
+  }
   #undef _pair
 }