fix(bar, slider): fix shadow drawing on short indicators

The issue is related to the case when the indicator is short but the main part (bg) clips it with a larger radius.
In this case this indicaotr might have a strange shape, like
 _
/ |
| |
\_|

We can't draw a shadow like this, so the indicator has to be et least a square,
to be sure it's not clipped to an ugly shape.

The previous code considered the bg radius to decide whether to draw shadow on short indicators or not.
However if the indicator's radius should be considered, becuse if its area at least a square
we can already draw shadows.

src/widgets/lv_bar.c

@@ -392,10 +392,6 @@ static void draw_indic(lv_event_t * e)
         return;
     }
 
-    lv_coord_t bg_radius = lv_obj_get_style_radius(obj, LV_PART_MAIN);
-    lv_coord_t short_side = LV_MIN(barw, barh);
-    if(bg_radius > short_side >> 1) bg_radius = short_side >> 1;
-
     lv_area_t indic_area;
     lv_area_copy(&indic_area, &bar->indic_area);
 
@@ -413,11 +409,19 @@ static void draw_indic(lv_event_t * e)
 
     lv_event_send(obj, LV_EVENT_DRAW_PART_BEGIN, &part_draw_dsc);
 
-    /*Draw only the shadow if the indicator is long enough.
+    lv_coord_t bg_radius = lv_obj_get_style_radius(obj, LV_PART_MAIN);
+    lv_coord_t short_side = LV_MIN(barw, barh);
+    if(bg_radius > short_side >> 1) bg_radius = short_side >> 1;
+
+    lv_coord_t indic_radius = draw_rect_dsc.radius;
+    short_side = LV_MIN(indicw, indich);
+    if(indic_radius > short_side >> 1) indic_radius = short_side >> 1;
+
+    /*Draw only the shadow and outline only if the indicator is long enough.
      *The radius of the bg and the indicator can make a strange shape where
      *it'd be very difficult to draw shadow.*/
-    if((hor && lv_area_get_width(&bar->indic_area) > bg_radius * 2) ||
-       (!hor && lv_area_get_height(&bar->indic_area) > bg_radius * 2)) {
+    if((hor && lv_area_get_width(&bar->indic_area) > indic_radius * 2) ||
+       (!hor && lv_area_get_height(&bar->indic_area) > indic_radius * 2)) {
         lv_opa_t bg_opa = draw_rect_dsc.bg_opa;
         lv_opa_t bg_img_opa = draw_rect_dsc.bg_img_opa;
         lv_opa_t border_opa = draw_rect_dsc.border_opa;