testsuite: Add a test for the conic that got us segment()

testsuite/gsk/curve-special-cases.c

@@ -0,0 +1,83 @@
+/*
+ * Copyright © 2020 Benjamin Otte
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#include <gtk/gtk.h>
+
+#include "gsk/gskcurveprivate.h"
+
+static gboolean
+measure_segment (const graphene_point_t *from,
+                 const graphene_point_t *to,
+                 float                   from_t,
+                 float                   to_t,
+                 gpointer                data)
+{
+  float *length = data;
+
+  *length += graphene_point_distance (from, to, NULL, NULL);
+
+  return TRUE;
+}
+
+static float
+measure_length (const GskCurve *curve)
+{
+  float result = 0;
+
+  gsk_curve_decompose (curve, 0.5, measure_segment, &result);
+
+  return result;
+}
+
+/* This is a pretty nasty conic that makes it obvious that split()
+ * does not respect the progress values, so split() twice  with
+ * scaled factor won't work.
+ */
+static void
+test_conic_segment (void)
+{
+  GskCurve c, s, e, m;
+  graphene_point_t pts[4] = {
+    GRAPHENE_POINT_INIT (-1856.131591796875, 46.217609405517578125),
+    GRAPHENE_POINT_INIT (-1555.9866943359375, 966.0810546875),
+    GRAPHENE_POINT_INIT (98.94945526123046875, 0),
+    GRAPHENE_POINT_INIT (-1471.33154296875, 526.701171875)
+  };
+  float start = 0.02222645096480846405029296875;
+  float end = 0.982032716274261474609375;
+
+  gsk_curve_init (&c, gsk_pathop_encode (GSK_PATH_CONIC, pts));
+
+  gsk_curve_split (&c, start, &s, NULL);
+  gsk_curve_segment (&c, start, end, &m);
+  gsk_curve_split (&c, end, NULL, &e);
+
+  g_assert_cmpfloat_with_epsilon (measure_length (&c), measure_length (&s) + measure_length (&m) + measure_length (&e), 0.03125);
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  gtk_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/curve/special/conic-segment", test_conic_segment);
+
+  return g_test_run ();
+}

testsuite/gsk/meson.build

@@ -356,6 +356,7 @@ endforeach
 
 tests = [
   ['curve', ['../../gsk/gskcurve.c'], ['-DGTK_COMPILATION']],
+  ['curve-special-cases', ['../../gsk/gskcurve.c'], ['-DGTK_COMPILATION']],
   ['path'],
   ['path-special-cases'],
   ['transform'],