[gimp] libgimpcolor: add gimp_color_profile_is_gray()

[Michael Natterer <mitch src gnome org>]

commit 4780471c5f71f54f8cdf5d2f75059619019cba4a
Author: Michael Natterer <mitch gimp org>
Date:   Sun Dec 13 14:33:51 2015 +0100

    libgimpcolor: add gimp_color_profile_is_gray()
    
    and improve gimp_color_profile_is_linear() to return TRUE for linear
    gray matrix profiles.

 libgimpcolor/gimpcolor.def      |    1 +
 libgimpcolor/gimpcolorprofile.c |   84 ++++++++++++++++++++++++++------------
 libgimpcolor/gimpcolorprofile.h |    4 +-
 3 files changed, 61 insertions(+), 28 deletions(-)
---
diff --git a/libgimpcolor/gimpcolor.def b/libgimpcolor/gimpcolor.def
index 70f3168..9f4dc8c 100644
--- a/libgimpcolor/gimpcolor.def
+++ b/libgimpcolor/gimpcolor.def
@@ -37,6 +37,7 @@ EXPORTS
        gimp_color_profile_get_type
        gimp_color_profile_is_cmyk
        gimp_color_profile_is_equal
+       gimp_color_profile_is_gray
        gimp_color_profile_is_linear
        gimp_color_profile_is_rgb
        gimp_color_profile_new_adobe_rgb
diff --git a/libgimpcolor/gimpcolorprofile.c b/libgimpcolor/gimpcolorprofile.c
index 3159497..fd8b4fe 100644
--- a/libgimpcolor/gimpcolorprofile.c
+++ b/libgimpcolor/gimpcolorprofile.c
@@ -634,6 +634,40 @@ gimp_color_profile_is_rgb (GimpColorProfile *profile)
   return (cmsGetColorSpace (profile->priv->lcms_profile) == cmsSigRgbData);
 }
 
+/**
+ * gimp_color_profile_is_gray:
+ * @profile: a #GimpColorProfile
+ *
+ * Return value: %TRUE if the profile's color space is grayscale, %FALSE
+ * otherwise.
+ *
+ * Since: 2.10
+ **/
+gboolean
+gimp_color_profile_is_gray (GimpColorProfile *profile)
+{
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), FALSE);
+
+  return (cmsGetColorSpace (profile->priv->lcms_profile) == cmsSigGrayData);
+}
+
+/**
+ * gimp_color_profile_is_cmyk:
+ * @profile: a #GimpColorProfile
+ *
+ * Return value: %TRUE if the profile's color space is CMYK, %FALSE
+ * otherwise.
+ *
+ * Since: 2.10
+ **/
+gboolean
+gimp_color_profile_is_cmyk (GimpColorProfile *profile)
+{
+  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), FALSE);
+
+  return (cmsGetColorSpace (profile->priv->lcms_profile) == cmsSigCmykData);
+}
+
 
 /**
  * gimp_color_profile_is_linear:
@@ -651,7 +685,7 @@ gimp_color_profile_is_rgb (GimpColorProfile *profile)
 gboolean
 gimp_color_profile_is_linear (GimpColorProfile *profile)
 {
-  cmsHPROFILE prof;
+  cmsHPROFILE   prof;
   cmsToneCurve *curve;
 
   g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), FALSE);
@@ -667,38 +701,34 @@ gimp_color_profile_is_linear (GimpColorProfile *profile)
   if (cmsIsCLUT (prof, INTENT_PERCEPTUAL, LCMS_USED_AS_OUTPUT))
     return FALSE;
 
-  curve = cmsReadTag(prof, cmsSigRedTRCTag);
-  if (curve == NULL || ! cmsIsToneCurveLinear (curve))
-    return FALSE;
+  if (gimp_color_profile_is_rgb (profile))
+    {
+      curve = cmsReadTag(prof, cmsSigRedTRCTag);
+      if (curve == NULL || ! cmsIsToneCurveLinear (curve))
+        return FALSE;
 
-  curve = cmsReadTag (prof, cmsSigGreenTRCTag);
-  if (curve == NULL || ! cmsIsToneCurveLinear (curve))
-    return FALSE;
+      curve = cmsReadTag (prof, cmsSigGreenTRCTag);
+      if (curve == NULL || ! cmsIsToneCurveLinear (curve))
+        return FALSE;
 
-  curve = cmsReadTag (prof, cmsSigBlueTRCTag);
-  if (curve == NULL || ! cmsIsToneCurveLinear (curve))
-    return FALSE;
+      curve = cmsReadTag (prof, cmsSigBlueTRCTag);
+      if (curve == NULL || ! cmsIsToneCurveLinear (curve))
+        return FALSE;
+    }
+  else if (gimp_color_profile_is_gray (profile))
+    {
+      curve = cmsReadTag(prof, cmsSigGrayTRCTag);
+      if (curve == NULL || ! cmsIsToneCurveLinear (curve))
+        return FALSE;
+    }
+  else
+    {
+      return FALSE;
+    }
 
   return TRUE;
 }
 
-/**
- * gimp_color_profile_is_cmyk:
- * @profile: a #GimpColorProfile
- *
- * Return value: %TRUE if the profile's color space is CMYK, %FALSE
- * otherwise.
- *
- * Since: 2.10
- **/
-gboolean
-gimp_color_profile_is_cmyk (GimpColorProfile *profile)
-{
-  g_return_val_if_fail (GIMP_IS_COLOR_PROFILE (profile), FALSE);
-
-  return (cmsGetColorSpace (profile->priv->lcms_profile) == cmsSigCmykData);
-}
-
 static void
 gimp_color_profile_set_tag (cmsHPROFILE      profile,
                             cmsTagSignature  sig,
diff --git a/libgimpcolor/gimpcolorprofile.h b/libgimpcolor/gimpcolorprofile.h
index b184e7d..ec3b22d 100644
--- a/libgimpcolor/gimpcolorprofile.h
+++ b/libgimpcolor/gimpcolorprofile.h
@@ -99,9 +99,11 @@ gboolean           gimp_color_profile_is_equal              (GimpColorProfile  *
                                                              GimpColorProfile  *profile2);
 
 gboolean           gimp_color_profile_is_rgb                (GimpColorProfile  *profile);
-gboolean           gimp_color_profile_is_linear             (GimpColorProfile  *profile);
+gboolean           gimp_color_profile_is_gray               (GimpColorProfile  *profile);
 gboolean           gimp_color_profile_is_cmyk               (GimpColorProfile  *profile);
 
+gboolean           gimp_color_profile_is_linear             (GimpColorProfile  *profile);
+
 const Babl       * gimp_color_profile_get_format            (const Babl        *format,
                                                              guint32           *lcms_format);