From 236c7ad6259f2029a14115898dea41d72a641006 Mon Sep 17 00:00:00 2001
From: Liam Howatt <30486941+liamHowatt@users.noreply.github.com>
Date: Thu, 6 Feb 2025 07:28:01 -0500
Subject: [PATCH] fix(area): lv_area_diff remove overlap (#7696)

---
 src/misc/lv_area.c               |  8 ++--
 tests/src/test_cases/test_area.c | 69 ++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/src/misc/lv_area.c b/src/misc/lv_area.c
index 4410076d6..215002c16 100644
--- a/src/misc/lv_area.c
+++ b/src/misc/lv_area.c
@@ -130,7 +130,7 @@ int8_t lv_area_diff(lv_area_t res_p[], const lv_area_t * a1_p, const lv_area_t *
         n.x1 = a1_p->x1;
         n.y1 = a1_p->y1;
         n.x2 = a1_p->x2;
-        n.y2 = a1_p->y1 + th;
+        n.y2 = a1_p->y1 + th - 1;
         res_p[res_c++] = n;
     }
 
@@ -138,7 +138,7 @@ int8_t lv_area_diff(lv_area_t res_p[], const lv_area_t * a1_p, const lv_area_t *
     int32_t bh = a1_h - (a2_p->y2 - a1_p->y1);
     if(bh > 0 && a2_p->y2 < a1_p->y2) {
         n.x1 = a1_p->x1;
-        n.y1 = a2_p->y2;
+        n.y1 = a2_p->y2 + 1;
         n.x2 = a1_p->x2;
         n.y2 = a2_p->y2 + bh;
         res_p[res_c++] = n;
@@ -154,7 +154,7 @@ int8_t lv_area_diff(lv_area_t res_p[], const lv_area_t * a1_p, const lv_area_t *
     if(lw > 0 && sh > 0) {
         n.x1 = a1_p->x1;
         n.y1 = y1;
-        n.x2 = a1_p->x1 + lw;
+        n.x2 = a1_p->x1 + lw - 1;
         n.y2 = y1 + sh;
         res_p[res_c++] = n;
     }
@@ -162,7 +162,7 @@ int8_t lv_area_diff(lv_area_t res_p[], const lv_area_t * a1_p, const lv_area_t *
     /*Compute the right rectangle*/
     int32_t rw = a1_w - (a2_p->x2 - a1_p->x1);
     if(rw > 0) {
-        n.x1 = a2_p->x2;
+        n.x1 = a2_p->x2 + 1;
         n.y1 = y1;
         n.x2 = a2_p->x2 + rw;
         n.y2 = y1 + sh;
diff --git a/tests/src/test_cases/test_area.c b/tests/src/test_cases/test_area.c
index e683acc66..8d9542e5c 100644
--- a/tests/src/test_cases/test_area.c
+++ b/tests/src/test_cases/test_area.c
@@ -119,4 +119,73 @@ void test_pct(void)
     TEST_ASSERT_EQUAL_INT32(-PCT_MAX_VALUE, LV_COORD_GET_PCT(pct_coord));
 }
 
+void test_area_diff(void)
+{
+    lv_area_t expected[4] = {
+        {0,  0,  100, 29},  /* wide top rectangle */
+        {0,  91, 100, 100}, /* wide bottom rectangle */
+        {0,  30, 39,  90},  /* left rectangle */
+        {81, 30, 100, 90}   /* right rectangle */
+    };
+    lv_area_t outer = {0, 0, 100, 100};
+    lv_area_t remove = {40, 30, 80, 90};
+    lv_area_t actual[4];
+    lv_memset(actual, 0, sizeof(actual));
+
+    int8_t area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 4);
+
+    TEST_PRINTF("%d %d %d %d", actual[0].x1, actual[0].y1, actual[0].x2, actual[0].y2);
+    TEST_ASSERT_TRUE(lv_area_is_equal(&expected[0], &actual[0]));
+    TEST_PRINTF("%d %d %d %d", actual[1].x1, actual[1].y1, actual[1].x2, actual[1].y2);
+    TEST_ASSERT_TRUE(lv_area_is_equal(&expected[1], &actual[1]));
+    TEST_PRINTF("%d %d %d %d", actual[2].x1, actual[2].y1, actual[2].x2, actual[2].y2);
+    TEST_ASSERT_TRUE(lv_area_is_equal(&expected[2], &actual[2]));
+    TEST_PRINTF("%d %d %d %d", actual[3].x1, actual[3].y1, actual[3].x2, actual[3].y2);
+    TEST_ASSERT_TRUE(lv_area_is_equal(&expected[3], &actual[3]));
+
+
+    /* no left edge */
+    lv_area_set(&remove, 0, 10, 10, 20);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 3);
+
+    lv_area_set(&remove, 1, 10, 10, 20);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 4);
+
+    /* no right edge */
+    lv_area_set(&remove, 90, 10, 100, 20);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 3);
+
+    lv_area_set(&remove, 90, 10, 99, 20);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 4);
+
+    /* no top edge */
+    lv_area_set(&remove, 10, 0, 20, 20);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 3);
+
+    lv_area_set(&remove, 10, 1, 20, 20);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 4);
+
+    /* no bottom edge */
+    lv_area_set(&remove, 10, 90, 20, 100);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 3);
+
+    lv_area_set(&remove, 10, 90, 20, 99);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 4);
+
+
+    /* top and left edges missing */
+    lv_area_set(&remove, -50, -50, 50, 50);
+    area_count = lv_area_diff(actual, &outer, &remove);
+    TEST_ASSERT_EQUAL_INT8(area_count, 2);
+}
+
 #endif