Comment définir un Event_cb

How-to
1

Hello, I am new to the lvgl library. I’ve been on a project for 4 months. But I was sick in the meantime. Currently I am in the finishing phase of my project. Here is a snippet of the code for my project. In this code, I have two windows: fen_one and fen_two. My first question is the following: I would like to display the window fen_deux if I click on the button “START A MEASUREMENT” of the window fen_un. Can you help me on this?

/**

  • @file main

*/

/*********************

  •  INCLUDES

*********************/
#include <stdlib.h>
#include <unistd.h>

#include “lvgl/lvgl.h”
#include “lv_drivers/win_drv.h”
#include “lv_examples/src/lv_demo_widgets/lv_demo_widgets.h”

#include <windows.h>

/*********************

  •  DEFINES

*********************/

/**********************

  •  TYPEDEFS

**********************/

/**********************

  • STATIC PROTOTYPES
    **********************/

static void hal_init(void);
static int tick_thread(void *data);

/**********************

  • STATIC VARIABLES
    **********************/

/**********************

  •  MACROS

**********************/

/**********************

  • GLOBAL FUNCTIONS
    ********************/
    #if WIN32
    int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR szCmdLine, int nCmdShow)
    #else
    int main(int argc, char     argv)
    #endif // WIN32
    {

static lv_obj_t * slider_label;

/*Initialize LittlevGL*/
lv_init();

/*Initialize the HAL for LittlevGL*/
hal_init();

/*Check the themes too*/
lv_disp_set_default(lv_windows_disp);



lv_obj_t * fen_un = lv_obj_create(lv_scr_act(), NULL);  //Création de la fenetre d'accueil
lv_obj_set_size(fen_un, 480, 320);              //Taille de l'écran


lv_obj_t * btn_1 = lv_btn_create(fen_un, NULL);         // Ajoute un bouton 1 à l'écran actuel
lv_obj_set_pos(btn_1, 50, 120);                         //Définit sa position
lv_obj_set_size(btn_1, 180, 30);                        //Définit sa taille
lv_obj_t * label_1 = lv_label_create(btn_1, NULL);      // Ajoute une étiquette au bouton
lv_label_set_text(label_1, "A PROPOS DU DISPOSITIF");   // Définit le texte de l'étiquette


lv_obj_t * btn_2 = lv_btn_create(fen_un, NULL);
lv_obj_set_pos(btn_2, 260, 120);
lv_obj_set_size(btn_2, 180, 30);
lv_obj_t * label_2 = lv_label_create(btn_2, NULL);
lv_label_set_text(label_2, "DEMARRER UNE MESURE");

lv_obj_t * fen_deux = lv_obj_create(NULL, NULL);
lv_obj_set_size(fen_deux, 480, 320);

lv_obj_t * btn_3 = lv_btn_create(fen_deux, NULL);
lv_obj_set_pos(btn_3, 150, 40);
lv_obj_set_size(btn_3, 180, 30);
lv_obj_t * label_3 = lv_label_create(btn_3, NULL);
lv_label_set_text(label_3, "PARAMETRES");


lv_obj_t * btn_5 = lv_btn_create(fen_deux, NULL);
lv_obj_set_pos(btn_5, 50, 100);
lv_obj_set_size(btn_5, 390, 30);
lv_obj_t * label_5 = lv_label_create(btn_5, NULL);
lv_label_set_text(label_5, "DEMARRER LE BALAYAGE");


    /* Create a slider in the center of the display */
lv_obj_t * slider = lv_slider_create(fen_deux, NULL);
lv_obj_set_width(slider, LV_DPI * 2);
lv_obj_align(slider, NULL, LV_ALIGN_CENTER, 0, 0);
//lv_obj_set_event_cb(slider, slider_event_cb);
lv_slider_set_range(slider, 0, 100);

/* Create a label below the slider */
slider_label = lv_label_create(fen_deux, NULL);
lv_label_set_text(slider_label, "PROGRESSION DE LA MESURE");
lv_obj_set_auto_realign(slider_label, true);
lv_obj_align(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);

lv_obj_t * btn_4 = lv_btn_create(fen_deux, NULL);
lv_obj_set_pos(btn_4, 50, 200);
lv_obj_set_size(btn_4, 180, 30);
lv_obj_t * label_4 = lv_label_create(btn_4, NULL);
lv_label_set_text(label_4, "GRANDEURS PHYSIQUES");


lv_obj_t * btn_7 = lv_btn_create(fen_deux, NULL);
lv_obj_set_pos(btn_7, 260, 200);
lv_obj_set_size(btn_7, 180, 30);
lv_obj_t * label_7 = lv_label_create(btn_7, NULL);
lv_label_set_text(label_7, "VOIR LES RESULTATS");

lv_obj_t * btn_6 = lv_btn_create(fen_deux, NULL);
lv_obj_set_pos(btn_6, 15, 260);
lv_obj_set_size(btn_6, 440, 30);
lv_obj_t * label_6 = lv_label_create(btn_6, NULL);
lv_label_set_text(label_6, "RETOUR");

lv_obj_t * fen_trois = lv_obj_create(NULL, NULL);
lv_obj_set_size(fen_trois, 480, 320);

lv_obj_t * tab = lv_tabview_create (fen_trois, NULL );
lv_obj_set_size (tab, LV_HOR_RES, LV_VER_RES);

lv_obj_t *  tab1= lv_tabview_add_tab (tab, " BALAYAGE " );



/*REMPLISSAGE DU TAB BALAYAGE*/


    /* Create the text area */

lv_obj_t * label1 = lv_label_create(tab1, NULL);
//lv_label_set_long_mode(label1, LV_LABEL_LONG_BREAK);
lv_obj_set_pos(label1, 15, 15);
lv_label_set_recolor(label1, true);
lv_label_set_align(label1, LV_LABEL_ALIGN_CENTER);
lv_label_set_text(label1, "#008000 DEMARRAGE#");
lv_obj_set_width(label1, 150);

lv_obj_t * label2 = lv_label_create(tab1, NULL);
//lv_label_set_long_mode(label1, LV_LABEL_LONG_BREAK);
lv_obj_set_pos(label2, 15, 55);
lv_label_set_recolor(label2, true);
lv_label_set_align(label1, LV_LABEL_ALIGN_CENTER);
lv_label_set_text(label2, "#008000 DELTA#");
lv_obj_set_width(label2, 150);



lv_obj_t * btn_13 = lv_btn_create(tab1, NULL);
lv_obj_set_pos(btn_13, 10, 220);
lv_obj_set_size(btn_13, 440, 20);
lv_obj_t * label_13 = lv_label_create(btn_13, NULL);
lv_label_set_text(label_13, "RETOUR");

lv_obj_t * ta_1 = lv_textarea_create(tab1, NULL);
lv_obj_set_pos(ta_1, 170, 10);
lv_obj_set_size(ta_1, 70, 1);
lv_textarea_set_accepted_chars(ta_1, "0123456789:");
lv_textarea_set_max_length(ta_1, 5);
lv_textarea_set_one_line(ta_1, true);
lv_textarea_set_text(ta_1, "");


lv_obj_t * ta_2 = lv_textarea_create(tab1, NULL);
lv_obj_set_pos(ta_2, 170, 50);
lv_obj_set_size(ta_2, 70, 1);
lv_textarea_set_accepted_chars(ta_2, "0123456789:");
lv_textarea_set_max_length(ta_2, 5);
lv_textarea_set_one_line(ta_2, true);
lv_textarea_set_text(ta_2, "");



lv_obj_t * fen_4 = lv_obj_create(tab1, NULL);
lv_obj_set_size(fen_4, 180, 190);
lv_obj_set_pos(fen_4,270, 10);


lv_obj_t * label6 = lv_label_create(fen_4, NULL);
lv_label_set_long_mode(label6, LV_LABEL_LONG_BREAK);
lv_obj_set_pos(label6, 10, 15);
lv_label_set_recolor(label6, true);
lv_label_set_align(label6, LV_LABEL_ALIGN_CENTER);
lv_label_set_text(label6, "#008000 DESCRIPTION DES#\n#008000     PARAMETRES##");
lv_obj_set_width(label6, 150);

lv_obj_t * btn_8 = lv_btn_create(fen_4, NULL);
lv_obj_set_pos(btn_8, 10, 50);
lv_obj_set_size(btn_8, 160, 15);
lv_obj_t * label_8 = lv_label_create(btn_8, NULL);
lv_label_set_text(label_8, "DEMARRAGE");

lv_obj_t * btn_9 = lv_btn_create(fen_4, NULL);
lv_obj_set_pos(btn_9, 10, 80);
lv_obj_set_size(btn_9, 160, 15);
lv_obj_t * label_9 = lv_label_create(btn_9, NULL);
lv_label_set_text(label_9, "DELTA");

#if WIN32
while(!lv_win_exit_flag) {
#else
while(1) {
#endif // WIN32
/* Periodically call the lv_task handler.
* It could be done in a timer interrupt or an OS task too.*/
lv_task_handler();
usleep(1000); /Just to let the system breath/
}
return 0;
}

/**********************

  • STATIC FUNCTIONS
    **********************/

/**

  • Initialize the Hardware Abstraction Layer (HAL) for the Littlev graphics library
    /
    static void hal_init(void)
    {
    #if !WIN32
    /     Add a display

    • Use the ‘monitor’ driver which creates window on PC’s monitor to simulate a display*/
      monitor_init();
      lv_disp_drv_t disp_drv;
      lv_disp_drv_init(&disp_drv); /Basic initialization/
      disp_drv.disp_flush = monitor_flush;
      disp_drv.disp_fill = monitor_fill;
      disp_drv.disp_map = monitor_map;
      lv_disp_drv_register(&disp_drv);

    /* Add the mouse (or touchpad) as input device

    • Use the ‘mouse’ driver which reads the PC’s mouse*/
      mouse_init();
      lv_indev_drv_t indev_drv;
      lv_indev_drv_init(&indev_drv); /Basic initialization/
      indev_drv.type = LV_INDEV_TYPE_POINTER;
      indev_drv.read = mouse_read; /This function will be called periodically (by the library) to get the mouse position and state/
      lv_indev_drv_register(&indev_drv);

    /* Tick init.

    • You have to call ‘lv_tick_handler()’ in every milliseconds
    • Create an SDL thread to do this*/
      SDL_CreateThread(tick_thread, “tick”, NULL);
      #else
      /* This sets up some timers to handle everything. /
      windrv_init();
      #endif
      }
      #if !WIN32
      /      *

  • A task to measure the elapsed time for LittlevGL

  • @param data unused

  • @return never return
    */
    static int tick_thread(void *data)
    {
    while(1) {
    lv_tick_inc(1);
    SDL_Delay(1); /Sleep for 1 millisecond/
    }

    return 0;
    }
    #endif

2

You can show/hide objects using lv_obj_set_hidden. By doing this you can make the window appear when your event handler is called.

If you are looking for an example of how to use events, take a look at this documentation page.

3

Bonjour pouvez vous être plus précis, je suis un novice en programmation

4

First, create the window like you are creating the rest of your objects. Then, call lv_obj_set_hidden(window, false).

Take a look at the example I provided. That shows how to hook up an event callback to a button. In that event callback, you could then show the window using lv_obj_set_hidden(window, true).

5

Bonjour, de quel exemple parlez vous ?

6

https://docs.lvgl.io/latest/en/html/overview/event.html#events

7

Hello, I tried what you suggested to me. I manage to display the second window but the objects in it are not displayed. In other words, when I click on the button, I get an empty window. I would like to know how to make the objects that are in the window appear.

8

Voici l’exemple que j’ai essayé

9

int main(int argc, char** argv)
{
/Initialize LittlevGL/
lv_init();

/*Initialize the HAL for LittlevGL*/
hal_init();

/*Check the themes too*/
lv_disp_set_default(lv_windows_disp);


lv_obj_t * fen = lv_obj_create(lv_scr_act(), NULL);
lv_obj_set_size(fen, 480, 320);

lv_obj_t * btn = lv_btn_create(fen, NULL);
lv_obj_set_pos(btn, 50, 130);
lv_obj_set_size(btn, 390, 30);
lv_obj_t * label = lv_label_create(btn, NULL);
lv_label_set_text(label, “DEMARRER LE BALAYAGE”);
lv_obj_set_event_cb(btn, event_handler); /Assign an event callback/

}
return 0;
}

static void event_handler(lv_obj_t *obj, lv_event_t event)
{

if(event == LV_EVENT_CLICKED){
lv_obj_t * fen_trois = lv_win_create(NULL, NULL);
lv_obj_set_size(fen_trois, 480, 320);

lv_obj_t * btn_13 = lv_btn_create(fen_trois, NULL);
lv_obj_set_pos(btn_13, 10, 220);
lv_obj_set_size(btn_13, 440, 20);
lv_obj_t * label_13 = lv_label_create(btn_13, NULL);
lv_label_set_text(label_13, “RETOUR”);

lv_group_t * g = lv_group_create();
lv_group_add_obj(g, fen_trois);
lv_group_add_obj(g, btn_13);

lv_obj_set_hidden(fen_trois, true);
lv_scr_load ( fen_trois );

}

}