color: add function to create color curve from tf

When we create a parametric color profile (we still do not fully
support, but plan to), a struct weston_color_tf_info is created.

So add a new function weston_color_curve_from_tf_info() to create a
color curve given a transfer function.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>

libweston/color.c

@@ -189,6 +189,35 @@ weston_color_profile_params_to_str(struct weston_color_profile_params *params,
 	return str;
 }
 
+/**
+ * Initializes a struct weston_color_curve given a transfer function.
+ *
+ * \param curve The curve to initialize.
+ * \param tf_info The tf_info object.
+ * \param tf_params When the tf is parametric, this is required. Otherwise,
+ * this is ignored.
+ * \param tf_direction Determines if this inits a curve equivalent to the direct
+ * or the inverse of the tf.
+ */
+WL_EXPORT void
+weston_color_curve_from_tf_info(struct weston_color_curve *curve,
+				const struct weston_color_tf_info *tf_info,
+				const float tf_params[MAX_PARAMS_TF],
+				enum weston_tf_direction tf_direction)
+{
+	unsigned int i, j;
+
+	curve->type = WESTON_COLOR_CURVE_TYPE_ENUM;
+
+	curve->u.enumerated.tf = tf_info;
+	curve->u.enumerated.tf_direction = tf_direction;
+
+	for (j = 0; j < tf_info->count_parameters; j++) {
+		for (i = 0; i < 3; i++)
+			curve->u.enumerated.params[i][j] = tf_params[j];
+	}
+}
+
 /**
  * Given an enumerated color curve, returns an equivalent parametric curve.
  *

libweston/color.h

@@ -647,6 +647,12 @@ weston_color_curve_enum_get_parametric(struct weston_compositor *compositor,
 				       const struct weston_color_curve_enum *curve,
 				       struct weston_color_curve_parametric *out);
 
+void
+weston_color_curve_from_tf_info(struct weston_color_curve *curve,
+				const struct weston_color_tf_info *tf_info,
+				const float tf_params[MAX_PARAMS_TF],
+				enum weston_tf_direction tf_direction);
+
 struct weston_color_transform *
 weston_color_transform_ref(struct weston_color_transform *xform);