feat(refr): add reset function for FPS statistics (#2832)

* fix(Kconfig) remove duplicate LV_BUILD_EXAMPLES configuration

* feat(refr) add reset of FPS statistics

Co-authored-by: pengyiqiang <pengyiqiang@xiaomi.com>

src/core/lv_refr.c

@@ -321,8 +321,17 @@ void _lv_disp_refr_timer(lv_timer_t * tmr)
 }
 
 #if LV_USE_PERF_MONITOR
+void lv_refr_reset_fps_counter(void)
+{
+    fps_sum_all = 0;
+    fps_sum_cnt = 0;
+}
+
 uint32_t lv_refr_get_fps_avg(void)
 {
+    if(fps_sum_cnt == 0)
+        return 0;
+
     return fps_sum_all / fps_sum_cnt;
 }
 #endif

src/core/lv_refr.h

@@ -80,7 +80,12 @@ void _lv_refr_set_disp_refreshing(lv_disp_t * disp);
 
 #if LV_USE_PERF_MONITOR
 /**
- * Get the average FPS since start up
+ * Reset FPS counter
+ */
+void lv_refr_reset_fps_counter(void);
+
+/**
+ * Get the average FPS
  * @return the average FPS
  */
 uint32_t lv_refr_get_fps_avg(void);