gsk: Add (private) gsk_rounded_rect_intersection()

The idea is that for a rectangle intersection, each corner of the
result is either entirely part of one original rectangle or it is
an intersection point.

By detecting those 2 cases and treating them differently, we can
simplify the code to compare rounded rectangles.

1 files changed, 140 insertions, 0 deletions

diff --git a/testsuite/gsk/rounded-rect.c b/testsuite/gsk/rounded-rect.c
index 5a72928257..552bed49d9 100644
--- a/testsuite/gsk/rounded-rect.c
+++ b/testsuite/gsk/rounded-rect.c
@@ -241,6 +241,145 @@ test_intersect_with_rect (void)
     }
 }
 
+static void
+test_intersect (void)
+{
+  struct {
+    GskRoundedRect a;
+    GskRoundedRect b;
+    GskRoundedRectIntersection result;
+    GskRoundedRect expected;
+  } test[] = {
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 0),
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(50, 50, 100, 100, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT_UNIFORM(50, 50, 50, 50, 20, 0, 20, 0),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(50, 0, 100, 100, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT(50, 0, 50, 100, 20),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(0, 50, 100, 100, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT(0, 50, 100, 50, 20),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(-50, -50, 100, 100, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 50, 50, 20, 0, 20, 0),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(0, -50, 100, 100, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT(0, 0, 100, 50, 20),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(-50, 0, 100, 100, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT(0, 0, 50, 100, 20),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(10, 10, 80, 80, 20),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT(10, 10, 80, 80, 20),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 20),
+      ROUNDED_RECT_INIT(10, 10, 80, 80, 10),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT(10, 10, 80, 80, 10),
+    },
+    {
+      ROUNDED_RECT_INIT(0, 0, 100, 100, 40),
+      ROUNDED_RECT_INIT(10, 10, 80, 80, 0),
+      GSK_INTERSECTION_NOT_REPRESENTABLE,
+    },
+    {
+      ROUNDED_RECT_INIT(10, 10, 100, 100, 40),
+      ROUNDED_RECT_INIT(30, 0, 40, 40, 0),
+      GSK_INTERSECTION_NOT_REPRESENTABLE,
+    },
+    {
+      ROUNDED_RECT_INIT(10, 10, 100, 100, 40),
+      ROUNDED_RECT_INIT(0, 0, 100, 20, 0),
+      GSK_INTERSECTION_NOT_REPRESENTABLE,
+    },
+    {
+      ROUNDED_RECT_INIT_UNIFORM(647, 18, 133, 35, 5, 0, 0, 5),
+      ROUNDED_RECT_INIT_UNIFORM(14, 12, 1666, 889, 8, 8, 0, 0),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT_UNIFORM(647, 18, 133, 35, 5, 0, 0, 5),
+    },
+    {
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 100, 100, 100, 0, 0, 0),
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 100, 100, 0, 0, 100, 0),
+      GSK_INTERSECTION_NONEMPTY,
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 100, 100, 100, 0, 100, 0),
+    },
+    {
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 100, 100, 100, 0, 0, 0),
+      ROUNDED_RECT_INIT_UNIFORM(-20, -20, 100, 100, 0, 0, 100, 0),
+      GSK_INTERSECTION_NOT_REPRESENTABLE,
+    },
+    {
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 50, 50, 0, 0, 50, 0),
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 20, 20, 20, 0, 0, 0),
+      GSK_INTERSECTION_NOT_REPRESENTABLE, /* FIXME: should be empty */
+    },
+    {
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 50, 50, 0, 0, 50, 0),
+      ROUNDED_RECT_INIT_UNIFORM(0, 0, 21, 21, 21, 0, 0, 0),
+      GSK_INTERSECTION_NOT_REPRESENTABLE,
+    },
+  };
+  gsize i;
+
+  for (i = 0; i < G_N_ELEMENTS (test); i++)
+    {
+      GskRoundedRect out;
+      GskRoundedRectIntersection res;
+
+      if (g_test_verbose ())
+        g_test_message ("intersection test %zu", i);
+
+      memset (&out, 0, sizeof (GskRoundedRect));
+
+      res = gsk_rounded_rect_intersection (&test[i].a, &test[i].b, &out);
+      g_assert_cmpint (res, ==, test[i].result);
+      if (res == GSK_INTERSECTION_NONEMPTY)
+        {
+          if (!gsk_rounded_rect_equal (&out, &test[i].expected))
+            {
+              char *a = gsk_rounded_rect_to_string (&test[i].a);
+              char *b = gsk_rounded_rect_to_string (&test[i].b);
+              char *expected = gsk_rounded_rect_to_string (&test[i].expected);
+              char *result = gsk_rounded_rect_to_string (&out);
+              g_test_message ("     A = %s\n"
+                              "     B = %s\n"
+                              "expected %s\n"
+                              "     got %s\n",
+                              a, b, expected, result);
+            }
+          g_assert_true (gsk_rounded_rect_equal (&out, &test[i].expected));
+        }
+    }
+}
+
 int
 main (int   argc,
       char *argv[])
@@ -253,6 +392,7 @@ main (int   argc,
   g_test_add_func ("/rounded-rect/is-circular", test_is_circular);
   g_test_add_func ("/rounded-rect/to-float", test_to_float);
   g_test_add_func ("/rounded-rect/intersect-with-rect", test_intersect_with_rect);
+  g_test_add_func ("/rounded-rect/intersect", test_intersect);
 
   return g_test_run ();
 }