How to get coordinates

How-to
1

Description

how to get coordinates touchscreens and when you click mouse

What MCU/Processor/Board and compiler are you using?

PC

What LVGL version are you using?

v7

What do you want to achieve?

get coordinates

2

You can use a custom signal handler. The button matrix is a good example.

3

the example is certainly good, but I don’t understand how I get the coordinates, I just want to click anywhere on the screen and get x and y

4

You can create a fullscreen object and then use the method I linked to get the coordinates when you click on the screen.

5

ok, i`m create object like this

    lv_obj_t * obj1;
    obj1 = lv_obj_create(lv_scr_act(), NULL);
    lv_obj_set_size(obj1, 100, 50);
    lv_obj_set_event_cb(obj1, lv_signal);



lv_res_t lv_btnsignal(lv_obj_t * obj, lv_event_t event){
    lv_point_t p;
    if(event == LV_SIGNAL_PRESSING) {
//        uint16_t btn_pr = LV_BTNMATRIX_BTN_NONE;
        /*Search the pressed area*/
        lv_indev_t *indev = lv_indev_get_act();
        lv_indev_type_t indev_type = lv_indev_get_type(indev);
        if (indev_type == LV_INDEV_TYPE_ENCODER || indev_type == LV_INDEV_TYPE_KEYPAD) return LV_RES_OK;

        lv_indev_get_point(indev, &p);
    }
}

this is correctly? if not correctly, whats change?

6

That should be correct, but if you want to detect clicks on the whole screen you would need to make the object screen-sized.

7

I understand it…
ok, how print, function lv_indev_get_point there is nothing return

8

The coordinates are stored in p after you call that function.

9

yeeeeee))))
thanks))) i can apply to any object?

10

Yes, but keep in mind that if you use a custom signal handler on other objects, you will want to save the previous signal handler and call through to it, otherwise the object’s functionality will be lost.

1 Like
11

I understand it, thank you)

12

@embeddedt I have the same question but how to solve it in v8 of lvlg please? I cannot see such method on v8 in link you shared. Thanks.

13

OK figured it out by myself. Maybe it helps somebody:

    static void lv_custom_event(const lv_obj_class_t * class_p, lv_event_t * e)
{
    LV_UNUSED(class_p);

    lv_result_t res;

    lv_event_code_t code = lv_event_get_code(e);
    lv_obj_t * obj = lv_event_get_target(e);
    lv_buttonmatrix_t * btnm = (lv_buttonmatrix_t *)obj;
    lv_point_t p;

    if(code == LV_EVENT_PRESSED) {
        lv_indev_t * indev = lv_event_get_indev(e);

        lv_indev_type_t indev_type = lv_indev_get_type(lv_indev_active());
        if(indev_type == LV_INDEV_TYPE_POINTER || indev_type == LV_INDEV_TYPE_BUTTON) {
            /*Search the pressed area*/
            lv_indev_get_point(indev, &p);
            printf("X:%d, Y:%d\n", p.x, p.y);
        }
    }
}

    lv_obj_t * obj1;
    obj1 = lv_obj_create(lv_screen_active());
    lv_obj_set_size(obj1, 500, 300);
    lv_obj_add_event(obj1, lv_custom_event, 0, NULL);
14

Very helpful!