[gnome-color-manager] Calculate the profile whitepoint using the profile transform

[Richard Hughes <rhughes src gnome org>]

commit 873e8999ea3de3fdc1cac80c7bd7295eea929619
Author: Richard Hughes <richard hughsie com>
Date:   Fri Nov 23 09:48:01 2012 +0000

    Calculate the profile whitepoint using the profile transform
    
    For version 4 profiles, the whitepoint is set as D50 and a chromatic adaption
    matrix 'chad' is used to convert this to the target whitepoint.
    
    Using only cmsSigMediaWhitePointTag does not take chad into account, and so we
    display the wrong profile temperature. Using cmsFLAGS_NOOPTIMIZE means that the
    transform is cheap to set up and works for v2 and v4 profiles.

 src/gcm-profile.c |   91 ++++++++++++++++++++++++++++++++++++++--------------
 1 files changed, 66 insertions(+), 25 deletions(-)
---
diff --git a/src/gcm-profile.c b/src/gcm-profile.c
index 99182d4..f5d124d 100644
--- a/src/gcm-profile.c
+++ b/src/gcm-profile.c
@@ -616,6 +616,70 @@ out:
 }
 
 /**
+ * gcm_profile_calc_whitepoint:
+ **/
+static gboolean
+gcm_profile_calc_whitepoint (GcmProfile *profile)
+{
+	cmsBool bpc[2] = { FALSE, FALSE };
+	cmsCIExyY tmp;
+	cmsCIEXYZ whitepoint;
+	cmsFloat64Number adaption[2] = { 0, 0 };
+	cmsHPROFILE profiles[2];
+	cmsHTRANSFORM transform;
+	cmsUInt32Number intents[2] = { INTENT_ABSOLUTE_COLORIMETRIC,
+				       INTENT_ABSOLUTE_COLORIMETRIC };
+	gboolean ret;
+	gdouble temp_float;
+	guint8 data[3] = { 255, 255, 255 };
+	GcmProfilePrivate *priv = profile->priv;
+
+	/* do Lab to RGB transform to get primaries */
+	profiles[0] = priv->lcms_profile;
+	profiles[1] = cmsCreateXYZProfile ();
+	transform = cmsCreateExtendedTransform (NULL,
+						2,
+						profiles,
+						bpc,
+						intents,
+						adaption,
+						NULL, 0, /* gamut profile */
+						TYPE_RGB_8,
+						TYPE_XYZ_DBL,
+						cmsFLAGS_NOOPTIMIZE);
+	if (transform == NULL) {
+		ret = FALSE;
+		g_warning ("failed to setup RGB -> XYZ transform");
+		goto out;
+	}
+
+	/* Run white through the transform */
+	cmsDoTransform (transform, data, &whitepoint, 1);
+
+	/* convert to lcms xyY values */
+	cd_color_set_xyz (priv->white,
+			  whitepoint.X, whitepoint.Y, whitepoint.Z);
+	cmsXYZ2xyY (&tmp, &whitepoint);
+	g_debug ("whitepoint = %f,%f [%f]", tmp.x, tmp.y, tmp.Y);
+
+	/* get temperature */
+	ret = cmsTempFromWhitePoint (&temp_float, &tmp);
+	if (ret) {
+		/* round to nearest 100K */
+		priv->temperature = (((guint) temp_float) / 100) * 100;
+		g_debug ("color temperature = %i", priv->temperature);
+	} else {
+		priv->temperature = 0;
+	}
+out:
+	if (profiles[1] != NULL)
+		cmsCloseProfile (profiles[1]);
+	if (transform != NULL)
+		cmsDeleteTransform (transform);
+	return ret;
+}
+
+/**
  * gcm_profile_parse_data:
  * @profile: A valid #GcmProfile
  * @data: the data to parse
@@ -667,32 +731,9 @@ gcm_profile_parse_data (GcmProfile *profile, const guint8 *data, gsize length, G
 	}
 
 	/* get white point */
-	cie_xyz = cmsReadTag (priv->lcms_profile, cmsSigMediaWhitePointTag);
-	if (cie_xyz != NULL) {
-		cmsCIExyY xyY;
-		gdouble temp_float;
-		cd_color_set_xyz (priv->white,
-				   cie_xyz->X, cie_xyz->Y, cie_xyz->Z);
-
-		/* convert to lcms xyY values */
-		cmsXYZ2xyY (&xyY, cie_xyz);
-		g_debug ("whitepoint = %f,%f [%f]", xyY.x, xyY.y, xyY.Y);
-
-		/* get temperature */
-		ret = cmsTempFromWhitePoint (&temp_float, &xyY);
-		if (ret) {
-			/* round to nearest 100K */
-			priv->temperature = (((guint) temp_float) / 100) * 100;
-			g_debug ("color temperature = %i", priv->temperature);
-		} else {
-			priv->temperature = 0;
-			g_warning ("failed to get color temperature");
-		}
-	} else {
-		/* this is no big suprise, some profiles don't have these */
+	ret = gcm_profile_calc_whitepoint (profile);
+	if (!ret)
 		cd_color_clear_xyz (priv->white);
-		g_debug ("failed to get white point");
-	}
 
 	/* get the profile kind */
 	profile_class = cmsGetDeviceClass (priv->lcms_profile);