This question has been dealed a lot, but I cannot found a solution that’s working in LVGL.
I read the documentation but there is no example about how switching screens.
Here is what I want to do:
I have “screen_General”, and a list on it. Depending of the choice on the list, I want to change screens (screen_MotDePasse" for example for choice “Confort”). I found this topic https://forum.lvgl.io/t/how-to-switch-screens-correctly/12337/6 which seems to be a good solution and try to adapt it to me but it does not work.
For now, my code works until I choose “Confort” in the list which leads to nothong (or maybe it’s crashing). “Screen_General” is not deleted and “Screen_MotDePasse” is not loaded.
Welcome
you miss , delete object from self isnt good idea
if (strcmp(buf,"Confort")==0)
{
lv_obj_del(screen_General);
create_screen_2(0);
}
if you realy require del place it in create2. Plus best practice is create2 and load it as last cmd, not first. And after this load you can try del, but better is place del in unload callback…
Why do you use screen deletion?
I think that you can create all the screens during initialization, and when events occur, just switch between them using lv_scr_load(screen_x).
if you realy require del place it in create2. Plus best practice is create2 and load it as last cmd, not first.
OK, you suggest as “glory-man” said too to create all screens before and load them after ?
And after this load you can try del, but better is place del in unload callback…
I don’t understand what you mean here. Do you have an example ?
Why do you use screen deletion?
I think that you can create all the screens during initialization, and when events occur, just switch
Because for me, create a screen means put it in memory, which is not good. And when you load the fifth screen, it will save all other screen in memory (even if hidden), right ?
Morerover, as you can see, I have a keyboard for a password in create_screen_2 function. The keyboard has a callback for the button and textarea has a callback too when “OK” is pressed. How can I use create_screen_2 function without calling these callback ?
If you want to switch to another screen use lv_scr_load().
So create new screen. Use
to add LV_EVENT_SCREEN_UNLOADED event callback. And switch to new screen lv_scr_load(ui_Screen4). And when previous screen will be unloaded LV_EVENT_SCREEN_UNLOADED event occures for previous screen ui_Screen3. As result scr_unloaded_delete_cb() will call and delete previous screen.
Also: I need to create screens that are very similar. How can I adapt the init function to not create one function per screen. For example, is it possible to do that ?
Why do you say that ? What looks like contrary to you ?
I need to change to screens which are different.
But I need too to update some text (ans list) on same screens depending on choice made on screens. So the only way I find is to create a new screen and load it.
I have a list (Normal, Confort, etc) on the main screen. Depending on what I choose on list: I can have two behaviours.
1/ I need to load differents screens, then go back to the main screen
2/ I update some informations on the main screen
I also need to update informations on the main screen even if I don’t choose something (the state of a sensor has changed for example)
Below source code for what you asked and if needed my full source code in attachment.
void create_screen_1(byte etat_prgChauffe)
{
screen_General1 = lv_obj_create(NULL);
lv_obj_t * liste_Prg_Chauffe = lv_dropdown_create(screen_General1);
if (etat_prgChauffe == 1)
{
lv_dropdown_set_options(liste_Prg_Chauffe, "Normal\n"
"Prechauffe\n"
"Confort\n"
"Off");
}
//Some other code for the list here
lv_obj_align(liste_Prg_Chauffe, LV_ALIGN_CENTER, 85, -30);
//Some other code here to add elements to screen
}
lv_obj_t * create_screen_2(bool ErrorMDP)
{
lv_obj_t * screen_MotdePasse = lv_obj_create(NULL);
lv_obj_add_event_cb(screen_MotdePasse, scr_unloaded_delete_cb, LV_EVENT_SCREEN_UNLOADED, &screen_MotdePasse);
//Some other code here to add elements to screen
return screen_MotdePasse;
Switching 1:
static void choix_PrgChauffe(lv_event_t * e)
{
lv_event_code_t code = lv_event_get_code(e);
lv_obj_t * choix = ( lv_obj_t *) lv_event_get_target(e);
if(code == LV_EVENT_VALUE_CHANGED)
{
enterPrgChauffe = 1;
if (strcmp(buf,"Confort")==0)
{
screen_MotdePasse_Initial1 = create_screen_2(0);
lv_scr_load(screen_MotdePasse_Initial1);
//Screen switch fine from Screen_General1 to screen_MotdePasse_Initial1 here
}
Switching 2:
static void textarea_event_handler(lv_event_t * e)
{
lv_obj_t * ta = lv_event_get_target(e);
LV_UNUSED(ta);
char*texte = lv_textarea_get_text(ta);
LV_LOG_USER("Enter was pressed. The current text is: %s", texte);
if (strcmp(texte,"2785")==0)
{
lv_scr_load(screen_General1);
//Switch back to screen_General1 create seg fault
}
else
{
create_screen_3(1); // the aim is to use only create_screen2() then, and delete create_screen_3() function
lv_scr_load(screen_MotdePasse_Erreur);
//Switch to screen_MotdePasse_Erreur create seg fault too
}
static void textarea_event_handler(lv_event_t * e)
{
lv_obj_t * ta = lv_event_get_target(e);
LV_UNUSED(ta);
// char*texte = lv_textarea_get_text(ta);
// LV_LOG_USER("Enter was pressed. The current text is: %s", texte);
if (strcmp(texte,"2785")==0)
is segfault too? And from your no info about platform etc. nobody help
