Hello
The lv_meter examples animates the indicator value automatically (with some anim functions).
But how can I set the position/value of the indicator/needle manually?
lv_meter_set_indicator_value(ui.screen_meter_1, 0, count);
does not work…
Thank you
This works for me from an MQTT push
lv_meter_set_indicator_value(DryerMeter, DryerIndic, level);
I think the problem is that 0 isnt an actual indicator…
yes, but how, where should this “DryerIndic” be defined?
Somewhere in a setup_scr_screen.c file I have the code see below.
Then in my main.c (loop) I try to set the position with the second code below - but this does not work…
I’m a beginner in C/C++, so it’s hard for me to define the right function, pointer, structure, class or whatever for this…
setup_scr_screen.c:
//add scale screen_meter_1_scale_1
lv_meter_scale_t *screen_meter_1_scale_1 = lv_meter_add_scale(ui->screen_meter_1);
lv_meter_set_scale_ticks(ui->screen_meter_1, screen_meter_1_scale_1, 41, 2, 10,
lv_color_make(0xff, 0x00, 0x00));
lv_meter_set_scale_major_ticks(ui->screen_meter_1, screen_meter_1_scale_1, 8, 5, 15,
lv_color_make(0xff, 0xff, 0x00), 10);
lv_meter_set_scale_range(ui->screen_meter_1, screen_meter_1_scale_1, 0, 100, 300, 90);
//add needle line for screen_meter_1_scale_1
lv_meter_indicator_t *screen_meter_1_scale_1_ndline_0;
screen_meter_1_scale_1_ndline_0 = lv_meter_add_needle_line(ui->screen_meter_1,
screen_meter_1_scale_1, 2, lv_color_make(0x00, 0x00, 0x00), -20);
lv_meter_set_indicator_value(ui->screen_meter_1, screen_meter_1_scale_1_ndline_0, 30);
main.c:
lv_meter_indicator_t *screen_meter_1_scale_1_ndline_0;
//screen_meter_1_scale_1_ndline_0 = lv_meter_add_needle_line(guider_ui.screen_meter_1, 0, 2, lv_color_make(0x00, 0x00, 0x00), -20);
lv_meter_set_indicator_value(guider_ui.screen_meter_1, screen_meter_1_scale_1_ndline_0, count);
lv_meter_scale_t *screen_meter_1_scale_1
and
lv_meter_indicator_t *screen_meter_1_scale_1_ndline_0
need to be global variables (in your h file)
Then you can call the update function with them.
screen_meter_1_scale_1 = lv_meter_add_scale(ui->screen_meter_1);
screen_meter_1_scale_1_ndline_0 = lv_meter_add_needle_line(ui->screen_meter_1, …
In your c files you dont need to declare them just use them as
Ok thank you, the needle moves now, with code below - but the previous drawn needle is not deleted? How to solve this? See picture below.
global in main.c:
lv_meter_indicator_t *screen_meter_1_scale_1_ndline_0;
lv_meter_scale_t *screen_meter_1_scale_1;
loop:
screen_meter_1_scale_1 = lv_meter_add_scale(guider_ui.screen_meter_1);
screen_meter_1_scale_1_ndline_0 = lv_meter_add_needle_line(guider_ui.screen_meter_1, screen_meter_1_scale_1, 2, lv_color_make(0x00, 0x00, 0x00), -20);
lv_meter_set_indicator_value(guider_ui.screen_meter_1, screen_meter_1_scale_1_ndline_0, count);
I dont think you want this in the loop:
screen_meter_1_scale_1 = lv_meter_add_scale(guider_ui.screen_meter_1);
screen_meter_1_scale_1_ndline_0 = lv_meter_add_needle_line(guider_ui.screen_meter_1, screen_meter_1_scale_1, 2, lv_color_make(0x00, 0x00, 0x00), -20);
As you are creating new needles on each loop. You want it in your initialization function.
Thank you very much. That did the job 
still one little strange thing, see picture below, this small black lines does not disappear:
Oh, thats really strange.
Do you have anything meter related other than this in your loop?
lv_meter_set_indicator_value(guider_ui.screen_meter_1, screen_meter_1_scale_1_ndline_0, count);
Strange. No other meter. It must be related to the three line code below.
If I comment out //screen_meter_1_scale_1 = lv_meter_add_scale(guider_ui.screen_meter_1);
these additional black ticks disappears, but of course also the needle…
at Init:
screen_meter_1_scale_1 = lv_meter_add_scale(guider_ui.screen_meter_1);
screen_meter_1_scale_1_ndline_0 = lv_meter_add_needle_line(guider_ui.screen_meter_1, screen_meter_1_scale_1, 2, lv_color_make(0x00, 0xFF, 0x00), -20);
in loop:
lv_meter_set_indicator_value(guider_ui.screen_meter_1, screen_meter_1_scale_1_ndline_0, count);