Kandinsky: KDRectUnion

Change-Id: Ib328275ab3a6fc6da9bc472dffe37c9948c727d5

kandinsky/test/rect.c

@@ -24,3 +24,59 @@ QUIZ_CASE(kandinsky_rect_intersect) {
   assert(c.width == 5);
   assert(c.height == 5);
 }
+
+QUIZ_CASE(kandinsky_rect_union) {
+  KDRect a = {
+    .x = -5, .y = -5,
+    .width = 10, .height = 10
+  };
+  KDRect b = {
+    .x = 0, .y = 0,
+    .width = 10, .height = 10
+  };
+
+  KDRect c = KDRectUnion(a,b);
+  assert(c.x == -5);
+  assert(c.y == -5);
+  assert(c.width == 15);
+  assert(c.height == 15);
+
+  c = KDRectUnion(a,b);
+  assert(c.x == -5);
+  assert(c.y == -5);
+  assert(c.width == 15);
+  assert(c.height == 15);
+}
+
+QUIZ_CASE(kandinsky_rect_empty_union) {
+  KDRect a = {
+    .x = 1, .y = 2,
+    .width = 3, .height = 4
+  };
+  KDRect b = {
+    .x = 5, .y = 6,
+    .width = 0, .height = 0
+  };
+  KDRect c = {
+    .x = -2, .y = -1,
+    .width = 0, .height = 1
+  };
+
+  KDRect t = KDRectUnion(a,b);
+  assert(t.x == a.x);
+  assert(t.y == a.y);
+  assert(t.width == a.width);
+  assert(t.height == a.height);
+
+  t = KDRectUnion(b,a);
+  assert(t.x == a.x);
+  assert(t.y == a.y);
+  assert(t.width == a.width);
+  assert(t.height == a.height);
+
+  t = KDRectUnion(a,c);
+  assert(t.x == a.x);
+  assert(t.y == c.y);
+  assert(t.width == a.width);
+  assert(t.height == 7);
+}