Util: Add some basic geometry math

include/mgba-util/geometry.h

@@ -13,10 +13,13 @@ CXX_GUARD_START
 struct Rectangle {
     int x;
     int y;
-    unsigned width;
-    unsigned height;
+    int width;
+    int height;
 };
 
+void RectangleUnion(struct Rectangle* dst, const struct Rectangle* add);
+void RectangleCenter(const struct Rectangle* ref, struct Rectangle* rect);
+
 CXX_GUARD_END
 
 #endif

src/util/CMakeLists.txt

@@ -16,6 +16,7 @@ set(SOURCE_FILES
 	convolve.c
 	elf-read.c
 	export.c
+	geometry.c
 	patch.c
 	patch-fast.c
 	patch-ips.c
@@ -33,6 +34,7 @@ set(GUI_FILES
 	gui/menu.c)
 
 set(TEST_FILES
+	test/geometry.c
 	test/sfo.c
 	test/string-parser.c
 	test/string-utf8.c

src/util/geometry.c

@@ -0,0 +1,36 @@
+/* Copyright (c) 2013-2023 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include <mgba-util/geometry.h>
+
+void RectangleUnion(struct Rectangle* dst, const struct Rectangle* add) {
+	int x0 = dst->x;
+	int y0 = dst->y;
+	int x1 = dst->x + dst->width;
+	int y1 = dst->y + dst->height;
+
+	if (add->x < x0) {
+		x0 = add->x;
+	}
+	if (add->y < y0) {
+		y0 = add->y;
+	}
+	if (add->x + add->width > x1) {
+		x1 = add->x + add->width;
+	}
+	if (add->y + add->height > y1) {
+		y1 = add->y + add->height;
+	}
+
+	dst->x = x0;
+	dst->y = y0;
+	dst->width = x1 - x0;
+	dst->height = y1 - y0;
+}
+
+void RectangleCenter(const struct Rectangle* ref, struct Rectangle* rect) {
+	rect->x = ref->x + (ref->width - rect->width) / 2;
+	rect->y = ref->y + (ref->height - rect->height) / 2;
+}

src/util/test/geometry.c

@@ -0,0 +1,213 @@
+/* Copyright (c) 2013-2023 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include "util/test/suite.h"
+
+#include <mgba-util/geometry.h>
+
+M_TEST_DEFINE(unionRectOrigin) {
+	struct Rectangle a = {
+		.x = 0,
+		.y = 0,
+		.width = 1,
+		.height = 1
+	};
+	struct Rectangle b = {
+		.x = 1,
+		.y = 1,
+		.width = 1,
+		.height = 1
+	};
+	RectangleUnion(&a, &b);
+	assert_int_equal(a.x, 0);
+	assert_int_equal(a.y, 0);
+	assert_int_equal(a.width, 2);
+	assert_int_equal(a.height, 2);
+}
+
+M_TEST_DEFINE(unionRectOriginSwapped) {
+	struct Rectangle a = {
+		.x = 1,
+		.y = 1,
+		.width = 1,
+		.height = 1
+	};
+	struct Rectangle b = {
+		.x = 0,
+		.y = 0,
+		.width = 1,
+		.height = 1
+	};
+	RectangleUnion(&a, &b);
+	assert_int_equal(a.x, 0);
+	assert_int_equal(a.y, 0);
+	assert_int_equal(a.width, 2);
+	assert_int_equal(a.height, 2);
+}
+
+M_TEST_DEFINE(unionRectNonOrigin) {
+	struct Rectangle a = {
+		.x = 1,
+		.y = 1,
+		.width = 1,
+		.height = 1
+	};
+	struct Rectangle b = {
+		.x = 2,
+		.y = 2,
+		.width = 1,
+		.height = 1
+	};
+	RectangleUnion(&a, &b);
+	assert_int_equal(a.x, 1);
+	assert_int_equal(a.y, 1);
+	assert_int_equal(a.width, 2);
+	assert_int_equal(a.height, 2);
+}
+
+M_TEST_DEFINE(unionRectOverlapping) {
+	struct Rectangle a = {
+		.x = 0,
+		.y = 0,
+		.width = 2,
+		.height = 2
+	};
+	struct Rectangle b = {
+		.x = 1,
+		.y = 1,
+		.width = 2,
+		.height = 2
+	};
+	RectangleUnion(&a, &b);
+	assert_int_equal(a.x, 0);
+	assert_int_equal(a.y, 0);
+	assert_int_equal(a.width, 3);
+	assert_int_equal(a.height, 3);
+}
+
+M_TEST_DEFINE(unionRectSubRect) {
+	struct Rectangle a = {
+		.x = 0,
+		.y = 0,
+		.width = 3,
+		.height = 3
+	};
+	struct Rectangle b = {
+		.x = 1,
+		.y = 1,
+		.width = 1,
+		.height = 1
+	};
+	RectangleUnion(&a, &b);
+	assert_int_equal(a.x, 0);
+	assert_int_equal(a.y, 0);
+	assert_int_equal(a.width, 3);
+	assert_int_equal(a.height, 3);
+}
+
+M_TEST_DEFINE(unionRectNegativeOrigin) {
+	struct Rectangle a = {
+		.x = -1,
+		.y = -1,
+		.width = 1,
+		.height = 1
+	};
+	struct Rectangle b = {
+		.x = 0,
+		.y = 0,
+		.width = 1,
+		.height = 1
+	};
+	RectangleUnion(&a, &b);
+	assert_int_equal(a.x, -1);
+	assert_int_equal(a.y, -1);
+	assert_int_equal(a.width, 2);
+	assert_int_equal(a.height, 2);
+}
+
+M_TEST_DEFINE(centerRectBasic) {
+	struct Rectangle ref = {
+		.x = 0,
+		.y = 0,
+		.width = 4,
+		.height = 4
+	};
+	struct Rectangle a = {
+		.x = 0,
+		.y = 0,
+		.width = 2,
+		.height = 2
+	};
+	RectangleCenter(&ref, &a);
+	assert_int_equal(a.x, 1);
+	assert_int_equal(a.y, 1);
+}
+
+M_TEST_DEFINE(centerRectRoundDown) {
+	struct Rectangle ref = {
+		.x = 0,
+		.y = 0,
+		.width = 4,
+		.height = 4
+	};
+	struct Rectangle a = {
+		.x = 0,
+		.y = 0,
+		.width = 1,
+		.height = 1
+	};
+	RectangleCenter(&ref, &a);
+	assert_int_equal(a.x, 1);
+	assert_int_equal(a.y, 1);
+}
+
+M_TEST_DEFINE(centerRectRoundDown2) {
+	struct Rectangle ref = {
+		.x = 0,
+		.y = 0,
+		.width = 4,
+		.height = 4
+	};
+	struct Rectangle a = {
+		.x = 0,
+		.y = 0,
+		.width = 3,
+		.height = 2
+	};
+	RectangleCenter(&ref, &a);
+	assert_int_equal(a.x, 0);
+	assert_int_equal(a.y, 1);
+}
+
+M_TEST_DEFINE(centerRectOffset) {
+	struct Rectangle ref = {
+		.x = 1,
+		.y = 1,
+		.width = 4,
+		.height = 4
+	};
+	struct Rectangle a = {
+		.x = 0,
+		.y = 0,
+		.width = 2,
+		.height = 2
+	};
+	RectangleCenter(&ref, &a);
+	assert_int_equal(a.x, 2);
+	assert_int_equal(a.y, 2);
+}
+
+M_TEST_SUITE_DEFINE(Geometry,
+	cmocka_unit_test(unionRectOrigin),
+	cmocka_unit_test(unionRectOriginSwapped),
+	cmocka_unit_test(unionRectNonOrigin),
+	cmocka_unit_test(unionRectOverlapping),
+	cmocka_unit_test(unionRectSubRect),
+	cmocka_unit_test(unionRectNegativeOrigin),
+	cmocka_unit_test(centerRectBasic),
+	cmocka_unit_test(centerRectRoundDown),
+	cmocka_unit_test(centerRectRoundDown2),
+	cmocka_unit_test(centerRectOffset),
+)