V853 LVGL app添加slider change调节屏幕亮度回调事件

[whycan]

diff --git a/demos/widgets/lv_demo_widgets.c b/demos/widgets/lv_demo_widgets.c
index 839b999c0..d2a6f4ac5 100644
--- a/demos/widgets/lv_demo_widgets.c
+++ b/demos/widgets/lv_demo_widgets.c
@@ -304,6 +304,8 @@ static void profile_create(lv_obj_t * parent)
     lv_obj_add_style(experience_label, &style_text_muted, 0);

     lv_obj_t * slider1 = lv_slider_create(panel3);
+    lv_slider_set_range(slider1, 0, 255);
+    lv_slider_set_value(slider1, 255, LV_ANIM_ON);
     lv_obj_set_width(slider1, LV_PCT(95));
     lv_obj_add_event_cb(slider1, slider_event_cb, LV_EVENT_ALL, NULL);
     lv_obj_refresh_ext_draw_size(slider1);
@@ -1275,14 +1277,24 @@ static void calendar_event_cb(lv_event_t * e)

 static void slider_event_cb(lv_event_t * e)
 {
+    char cmd[512];
     lv_event_code_t code = lv_event_get_code(e);
     lv_obj_t * obj = lv_event_get_target(e);
+    int32_t value = lv_slider_get_value(obj);

     if(code == LV_EVENT_REFR_EXT_DRAW_SIZE) {
         lv_coord_t * s = lv_event_get_param(e);
         *s = LV_MAX(*s, 60);
     }
+    else if(code == LV_EVENT_VALUE_CHANGED)
+    {
+       memset(cmd, sizeof(cmd), 0);
+       snprintf(cmd, sizeof(cmd)-1, "cd /sys/kernel/debug/dispdbg; echo lcd0 > name; echo setbl > command; echo %d > param; echo 1 > start\n", value);
+       system(cmd);
+       printf(cmd);
+    }
     else if(code == LV_EVENT_DRAW_PART_END) {
+
         lv_obj_draw_part_dsc_t * dsc = lv_event_get_param(e);
         if(dsc->part == LV_PART_KNOB && lv_obj_has_state(obj, LV_STATE_PRESSED)) {
             char buf[8];

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演示视频： https://www.bilibili.com/video/BV1ye411N7um/