fix(flex): LV_FLEX_ALIGN_SPACE_BETWEEN align single item left (#5915)

src/layouts/flex/lv_flex.c

@@ -472,7 +472,6 @@ static void place_content(lv_flex_align_t place, int32_t max_size, int32_t conte
 {
     if(item_cnt <= 1) {
         switch(place) {
-            case LV_FLEX_ALIGN_SPACE_BETWEEN:
             case LV_FLEX_ALIGN_SPACE_AROUND:
             case LV_FLEX_ALIGN_SPACE_EVENLY:
                 place = LV_FLEX_ALIGN_CENTER;
@@ -492,7 +491,7 @@ static void place_content(lv_flex_align_t place, int32_t max_size, int32_t conte
             *start_pos += max_size - content_size;
             break;
         case LV_FLEX_ALIGN_SPACE_BETWEEN:
-            *gap = (int32_t)(max_size - content_size) / (int32_t)(item_cnt - 1);
+            if(item_cnt > 1) *gap = (int32_t)(max_size - content_size) / (int32_t)(item_cnt - 1);
             break;
         case LV_FLEX_ALIGN_SPACE_AROUND:
             *gap += (int32_t)(max_size - content_size) / (int32_t)(item_cnt);

tests/src/test_cases/test_align_flex.c

@@ -0,0 +1,80 @@
+#if LV_BUILD_TEST
+#include "../lvgl.h"
+
+#include "unity/unity.h"
+
+static lv_obj_t * active_screen = NULL;
+
+void setUp(void)
+{
+    active_screen = lv_screen_active();
+}
+
+void tearDown(void)
+{
+    lv_obj_clean(active_screen);
+}
+
+static void simple_style(lv_obj_t * obj)
+{
+    lv_obj_set_style_radius(obj, 0, LV_PART_MAIN);
+    lv_obj_set_scrollbar_mode(obj, LV_SCROLLBAR_MODE_OFF);
+    lv_obj_set_style_border_width(obj, 0, LV_PART_MAIN);
+    lv_obj_set_style_pad_all(obj, 0, LV_PART_MAIN);
+    lv_obj_set_style_margin_all(obj, 0, LV_PART_MAIN);
+    lv_obj_set_style_outline_pad(obj, 0, LV_PART_MAIN);
+    lv_obj_set_style_outline_width(obj, 0, LV_PART_MAIN);
+}
+
+static lv_obj_t * create_row(lv_flex_align_t main_place, int n_children)
+{
+    lv_obj_t * row = lv_obj_create(lv_screen_active());
+    lv_obj_set_size(row, LV_PCT(100), LV_PCT(100));
+    lv_obj_set_flex_flow(row, LV_FLEX_FLOW_ROW);
+    lv_obj_set_flex_align(row, main_place, LV_FLEX_ALIGN_CENTER, LV_FLEX_ALIGN_CENTER);
+    simple_style(row);
+    for(int i = 0; i < n_children; i++) {
+        lv_obj_t * child = lv_obj_create(row);
+        lv_obj_set_size(child, 40, 40);
+        lv_obj_set_style_bg_color(child, lv_palette_main(LV_PALETTE_BLUE), 0);
+        simple_style(child);
+    }
+    return row;
+}
+
+void test_align(void)
+{
+    create_row(LV_FLEX_ALIGN_CENTER, 1);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_center1.png");
+    lv_obj_clean(active_screen);
+
+    create_row(LV_FLEX_ALIGN_CENTER, 2);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_center2.png");
+    lv_obj_clean(active_screen);
+
+    create_row(LV_FLEX_ALIGN_SPACE_EVENLY, 1);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_space_evenly1.png");
+    lv_obj_clean(active_screen);
+
+    create_row(LV_FLEX_ALIGN_SPACE_EVENLY, 2);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_space_evenly2.png");
+    lv_obj_clean(active_screen);
+
+    create_row(LV_FLEX_ALIGN_SPACE_AROUND, 1);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_space_around1.png");
+    lv_obj_clean(active_screen);
+
+    create_row(LV_FLEX_ALIGN_SPACE_AROUND, 2);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_space_around2.png");
+    lv_obj_clean(active_screen);
+
+    create_row(LV_FLEX_ALIGN_SPACE_BETWEEN, 1);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_space_between1.png");
+    lv_obj_clean(active_screen);
+
+    create_row(LV_FLEX_ALIGN_SPACE_BETWEEN, 2);
+    TEST_ASSERT_EQUAL_SCREENSHOT("align_flex_space_between2.png");
+    lv_obj_clean(active_screen);
+}
+
+#endif