Button Matrix LV_VALUE_CHANGED on CLICK not working as intended

How-to
1

Description

I’m using a button matrix to create a scrollable (matrix height is set larger than screen resolution height) menu on one of my screens. I’ve set the control of all buttons in the button matrix to have LV_VALUE_CHANGED on CLICK instead of pressed, yet when I scroll through my menu my buttons are still being triggered.

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

I’m using a LPCxpresso54628 Development Board.

What LVGL version are you using?

Version 8.0.2

What do you want to achieve?

The buttons in my menu to not be triggered when scrolling through the menu, only when clicked.

What have you tried so far?

Using the provided function “lv_btnmatrix_set_btn_ctrl_all(my_matrix, LV_BTNMATRIX_CTRL_CLICK_TRIG | LV_BTNMATRIX_CTRL_NO_REPEAT)”

Code to reproduce

Below is a link to the micropython simulator using lvgl version 8.1, I reproduced the problem but with a simple numberpad. You can see that if you scroll around on the numberpad and then release (on a key) it’ll still trigger the event to add what key was press into the textarea.
https://sim.lvgl.io/v8.1/micropython/ports/javascript/index.html?script_direct=4ffd88de0342cfdd2ab8b5602ddb564e68dec0a5

For those that don’t like links, here’s the code from the micropython simulator:


# Initialize 

import display_driver
import lvgl as lv

########################################
# Create a button matrix as a numberpad
########################################

scr = lv.obj()
matrix_cont = lv.obj(scr)
matrix_cont.set_size(200, 320)
matrix_cont.set_pos(220, 0)


# Text area for testing

text = lv.textarea(scr)
text.set_size(220, 320)

# Styling for the textarea
text_style = lv.style_t()
text_style.init()
text_style.set_radius(0)
text_style.set_border_width(0)
text_style.set_text_color(lv.color_make(0x00, 0x00, 0x00))
text.add_style(text_style, 0)

# The numberpad button matrix

matrix_map = [
    "1","2","3"," ","\n",
    "4","5","6"," ","\n",
    "7","8","9"," ","\n",
    "<-","0",".","-",""]

matrix = lv.btnmatrix(matrix_cont)
matrix.set_size(200, 400)
matrix.set_pos(0,0)
matrix.set_map(matrix_map)
matrix.set_btn_ctrl(3, lv.btnmatrix.CTRL.HIDDEN)
matrix.set_btn_ctrl(7, lv.btnmatrix.CTRL.HIDDEN)
matrix.set_btn_ctrl(11, lv.btnmatrix.CTRL.HIDDEN)

# Styling for the button matrix
matrix_style = lv.style_t()
matrix_style.init()
matrix_style.set_radius(0)
matrix_style.set_bg_color(lv.color_make(0x40, 0x65, 0xFF))
matrix_style.set_border_width(0)
matrix_style.set_pad_left(0)
matrix_style.set_pad_right(0)
matrix_style.set_pad_top(0)
matrix_style.set_pad_bottom(0)
matrix_style.set_pad_row(0)
matrix_style.set_pad_column(0)

# Styling for the button matrix buttons
matrix_button_style = lv.style_t()
matrix_button_style.init()
matrix_button_style.set_radius(0)
matrix_button_style.set_bg_color(lv.color_make(0x40, 0x65, 0xFF))
matrix_button_style.set_border_width(1)
matrix_button_style.set_border_color(lv.color_make(0xFF, 0xFF, 0xFF))
matrix_button_style.set_text_color(lv.color_make(0xFF, 0xFF, 0xFF))

matrix.add_style(matrix_style, 0)
matrix.add_style(matrix_button_style, lv.PART.ITEMS)
# Comment out this line below to see how the event handler would process the numberpad
# Using lv.EVENT.VALUE_CHANGED on pressed instead of on clicked
matrix.set_btn_ctrl_all(lv.btnmatrix.CTRL.CLICK_TRIG|lv.btnmatrix.CTRL.NO_REPEAT)

# From documentation, LV_EVENT_CLICKED: Called on release if an object did not
# scroll (regardless of long press)

def event_handler(e):
    code = e.get_code()
    obj = e.get_target()

    if code == lv.EVENT.VALUE_CHANGED:
        btn_id = obj.get_selected_btn()
        text.add_text(obj.get_btn_text(btn_id))

matrix.add_event_cb(event_handler, lv.EVENT.ALL, None)
lv.scr_load(scr)
2

After a little bit of thinking I came up with a solution to my own problem. I’m not the largest fan of it, but it functions the way I would like it to. Unfortunately from what I can tell setting a button matrix to have the control flag LV_BTNMATRIX_CTRL_CLICK_TRIG, meant to send the event LV_EVENT_VALUE_CHANGED on CLICKED, behaves more like send the event LV_EVENT_VALUE_CHANGED on RELEASED.

To get around this I edited my event handler to become this:

trigger_guard = 0
btn_id = 0

def event_handler(e):
    code = e.get_code()
    obj = e.get_target()

    if code == lv.EVENT.PRESSED:
        global trigger_guard
        trigger_guard = 0

    if code == lv.EVENT.VALUE_CHANGED:
        global trigger_guard
        global btn_id
        trigger_guard = 1
        btn_id = obj.get_selected_btn()

    if code == lv.EVENT.CLICKED and trigger_guard:
        text.add_text(obj.get_btn_text(btn_id))

matrix.add_event_cb(event_handler, lv.EVENT.ALL, None)

I still wonder if the behaviour of the LV_BTNMATRIX_CTRL_CLICK_TRIG control flag could be changed to properly reflect what it’s saying it is doing in documentation.