colord: Add cd_spectrum_resample_to_size()

3 files changed, 65 insertions, 0 deletions

diff --git a/lib/colord/cd-spectrum.c b/lib/colord/cd-spectrum.c
index 59a72a9..9ee2a22 100644
--- a/lib/colord/cd-spectrum.c
+++ b/lib/colord/cd-spectrum.c
@@ -951,3 +951,34 @@ cd_spectrum_resample (CdSpectrum *spectrum,
 	cd_spectrum_set_end (sp, end);
 	return sp;
 }
+
+/**
+ * cd_spectrum_resample_to_size:
+ * @spectrum: a #CdSpectrum instance
+ * @size: the output spectrum size
+ *
+ * Resample a new spectrum with the desired number of points.
+ *
+ * Return value: a #CdSpectrum instance
+ *
+ * Since: 1.3.4
+ **/
+CdSpectrum *
+cd_spectrum_resample_to_size (CdSpectrum *spectrum, guint size)
+{
+	gdouble inc;
+	guint i;
+	CdSpectrum *sp;
+
+	sp = cd_spectrum_new ();
+	cd_spectrum_set_start (sp, spectrum->start);
+	cd_spectrum_set_end (sp, spectrum->end);
+
+	inc = (spectrum->end - spectrum->start) / (gdouble) (size - 1);
+	for (i = 0; i < size; i++) {
+		gdouble nm = spectrum->start + ((gdouble) i * inc);
+		gdouble tmp = cd_spectrum_get_value_for_nm (spectrum, nm);
+		cd_spectrum_add_value (sp, tmp);
+	}
+	return sp;
+}
diff --git a/lib/colord/cd-spectrum.h b/lib/colord/cd-spectrum.h
index 40a9bb5..83af8c1 100644
--- a/lib/colord/cd-spectrum.h
+++ b/lib/colord/cd-spectrum.h
@@ -108,6 +108,8 @@ CdSpectrum	*cd_spectrum_resample		(CdSpectrum		*spectrum,
 						 gdouble		 start,
 						 gdouble		 end,
 						 gdouble		 resolution);
+CdSpectrum	*cd_spectrum_resample_to_size	(CdSpectrum		*spectrum,
+						 guint			 size);
 
 G_DEFINE_AUTOPTR_CLEANUP_FUNC(CdSpectrum, cd_spectrum_free)
 
diff --git a/lib/colord/cd-test-private.c b/lib/colord/cd-test-private.c
index b9f10eb..c68991b 100644
--- a/lib/colord/cd-test-private.c
+++ b/lib/colord/cd-test-private.c
@@ -319,7 +319,9 @@ colord_spect_cx_func (void)
 {
 	gdouble tmp;
 	g_autoptr(CdSpectrum) sp = NULL;
+	g_autoptr(CdSpectrum) sp_linear = NULL;
 	g_autoptr(CdSpectrum) sp_resampled = NULL;
+	g_autoptr(CdSpectrum) sp_size = NULL;
 
 	/* create test spectrum */
 	sp = cd_spectrum_new ();
@@ -367,6 +369,36 @@ colord_spect_cx_func (void)
 	g_assert_cmpfloat (fabs (tmp - 1.998f), <, 0.001);
 	tmp = cd_spectrum_get_value_for_nm (sp_resampled, 300.f);
 	g_assert_cmpfloat (fabs (tmp - 2.498f), <, 0.001);
+
+	/* resample to a set number of points */
+	sp_linear = cd_spectrum_new ();
+	cd_spectrum_set_start (sp_linear, 100);
+	cd_spectrum_set_end (sp_linear, 200);
+	cd_spectrum_add_value (sp_linear, 1.f);
+	cd_spectrum_add_value (sp_linear, 2.f);
+	cd_spectrum_add_value (sp_linear, 3.f);
+
+	/* check values */
+	sp_size = cd_spectrum_resample_to_size (sp_linear, 4);
+	tmp = cd_spectrum_get_value (sp_size, 0);
+	g_assert_cmpfloat (fabs (tmp - 1.f), <, 0.001);
+	tmp = cd_spectrum_get_value (sp_size, 1);
+	g_assert_cmpfloat (fabs (tmp - 1.66f), <, 0.01);
+	tmp = cd_spectrum_get_value (sp_size, 2);
+	g_assert_cmpfloat (fabs (tmp - 2.33f), <, 0.01);
+	tmp = cd_spectrum_get_value (sp_size, 3);
+	g_assert_cmpfloat (fabs (tmp - 3.f), <, 0.001);
+
+	/* check spacing */
+	tmp = cd_spectrum_get_wavelength (sp_size, 0);
+	g_assert_cmpfloat (fabs (tmp - 100), <, 0.001);
+	tmp = cd_spectrum_get_wavelength (sp_size, 1);
+	g_assert_cmpfloat (fabs (tmp - 133.33f), <, 0.01);
+	tmp = cd_spectrum_get_wavelength (sp_size, 2);
+	g_assert_cmpfloat (fabs (tmp - 166.66), <, 0.01);
+	tmp = cd_spectrum_get_wavelength (sp_size, 3);
+	g_assert_cmpfloat (fabs (tmp - 200), <, 0.001);
+
 }
 
 static void