mtk: Add a Region type

Currently, we use cairo_region_t despite it being a thing wrapper around pixman_region_32
In order to push for a cairo-less and wayland only build in the future, replace
cairo_region_t with a thin wrapper that is almost a copy of the upstream cairo implementation

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3292>

src/tests/mtk/meson.build

@@ -6,4 +6,11 @@ test_cases += [
       'mtk/rectangle-tests.c',
     ],
   },
+  {
+    'name': 'mtk-region',
+    'suite': 'unit',
+    'sources': [
+      'mtk/region-tests.c',
+    ]
+  }
 ]

src/tests/mtk/region-tests.c

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2023 Bilal Elmoussaoui
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+#include "mtk/mtk.h"
+
+#include <glib.h>
+
+
+static void
+test_contains_point (void)
+{
+  g_autoptr (MtkRegion) r1 = NULL;
+
+  r1 = mtk_region_create_rectangle (mtk_rectangle_new (0, 0, 100, 100));
+
+  g_assert (!mtk_region_contains_point (r1, 200, 200));
+  g_assert (mtk_region_contains_point (r1, 50, 50));
+}
+
+/* A re-implementation of a pixman translation test */
+#define LARGE 32000
+static void
+test_translate (void)
+{
+  MtkRectangle rect = MTK_RECTANGLE_INIT (-LARGE, -LARGE, LARGE, LARGE);
+  g_autoptr (MtkRegion) r1, r2 = NULL;
+
+  r1 = mtk_region_create_rectangles (&rect, 1);
+  g_assert_cmpint (mtk_region_num_rectangles (r1), ==, 1);
+  r2 = mtk_region_create_rectangle (&rect);
+  g_assert_cmpint (mtk_region_num_rectangles (r2), ==, 1);
+
+  g_assert (mtk_region_equal (r1, r2));
+
+  mtk_region_translate (r1, -LARGE, LARGE);
+  mtk_region_translate (r1, LARGE, -LARGE);
+
+  g_assert (mtk_region_equal (r1, r2));
+}
+
+static void
+test_region (void)
+{
+  g_autoptr (MtkRegion) r1 = NULL;
+
+  r1 = mtk_region_create ();
+  g_assert (mtk_region_is_empty (r1));
+
+  MtkRectangle rect = MTK_RECTANGLE_INIT (5, 5, 20, 20);
+  mtk_region_union_rectangle (r1, &rect);
+
+  g_assert (!mtk_region_is_empty (r1));
+  MtkRectangle extents = mtk_region_get_extents (r1);
+  g_assert (mtk_rectangle_equal (&extents, &rect));
+
+  mtk_region_translate (r1, 15, 20);
+  extents = mtk_region_get_extents (r1);
+  g_assert_cmpint (extents.x, ==,  rect.x + 15);
+  g_assert_cmpint (extents.y, ==,  rect.y + 20);
+  g_assert_cmpint (extents.width, ==, rect.width);
+  g_assert_cmpint (extents.height, ==, rect.height);
+}
+
+int
+main (int    argc,
+      char **argv)
+{
+  g_test_init (&argc, &argv, NULL);
+
+  g_test_add_func ("/mtk/region/region", test_region);
+  g_test_add_func ("/mtk/region/contains-point", test_contains_point);
+  g_test_add_func ("/mtk/region/translate", test_translate);
+
+  return g_test_run ();
+}