[gtk/path-work-rebased: 1023/1045] Add a test for tangents of degenerate curves

[Matthias Clasen <matthiasc src gnome org>]

commit 12dc97a6c63a970b7110e1240b24af21ff4e134f
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Dec 20 11:19:43 2020 -0500

    Add a test for tangents of degenerate curves
    
    The stroker relies on these to work.

 testsuite/gsk/curve-special-cases.c | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)
---
diff --git a/testsuite/gsk/curve-special-cases.c b/testsuite/gsk/curve-special-cases.c
index 820cb73d59..d8dd0274ba 100644
--- a/testsuite/gsk/curve-special-cases.c
+++ b/testsuite/gsk/curve-special-cases.c
@@ -87,7 +87,6 @@ test_curve_tangents (void)
   gsk_curve_get_end_tangent (&c, &t);
   g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
 
-
   graphene_point_init (&p[0], 0, 0);
   graphene_point_init (&p[1], 0, 100);
   gsk_curve_init (&c, gsk_pathop_encode (GSK_PATH_LINE, p));
@@ -120,6 +119,36 @@ test_curve_tangents (void)
   g_assert_true (graphene_vec2_near (&t, graphene_vec2_y_axis (), 0.0001));
 }
 
+static void
+test_curve_degenerate_tangents (void)
+{
+  GskCurve c;
+  graphene_point_t p[4];
+  graphene_vec2_t t;
+
+  graphene_point_init (&p[0], 0, 0);
+  graphene_point_init (&p[1], 0, 0);
+  graphene_point_init (&p[2], 100, 0);
+  graphene_point_init (&p[3], 100, 0);
+  gsk_curve_init (&c, gsk_pathop_encode (GSK_PATH_CURVE, p));
+
+  gsk_curve_get_start_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+  gsk_curve_get_end_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+
+  graphene_point_init (&p[0], 0, 0);
+  graphene_point_init (&p[1], 50, 0);
+  graphene_point_init (&p[2], 50, 0);
+  graphene_point_init (&p[3], 100, 0);
+  gsk_curve_init (&c, gsk_pathop_encode (GSK_PATH_CURVE, p));
+
+  gsk_curve_get_start_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+  gsk_curve_get_end_tangent (&c, &t);
+  g_assert_true (graphene_vec2_near (&t, graphene_vec2_x_axis (), 0.0001));
+}
+
 static void
 test_errant_intersection (void)
 {
@@ -258,7 +287,6 @@ test_line_intersection_parallel (void)
   g_assert_cmpfloat_with_epsilon (t1[1], 0.5, 0.001);
   g_assert_cmpfloat_with_epsilon (t2[0], 0.5, 0.001);
   g_assert_cmpfloat_with_epsilon (t2[1], 1, 0.001);
-
 }
 
 int
@@ -269,6 +297,7 @@ main (int   argc,
 
   g_test_add_func ("/curve/special/conic-segment", test_conic_segment);
   g_test_add_func ("/curve/special/tangents", test_curve_tangents);
+  g_test_add_func ("/curve/special/degenerate-tangents", test_curve_degenerate_tangents);
   g_test_add_func ("/curve/errant-intersection", test_errant_intersection);
   g_test_add_func ("/curve/errant-intersection2", test_errant_intersection2);
   g_test_add_func ("/curve/line-intersection-parallel", test_line_intersection_parallel);