File content as of revision 0:10c4b83c458d:

//#pragma -O0
#include "mbed.h"
#include "lvgl/lvgl.h"
#include "lv_port_disp.h"
#include "lv_port_indev.h"
#include "demo.h" //Comment/uncomment will switch between LittlevGL demo and Hello word example

#define LVGL_TICK 5                             //Time tick value for lvgl in ms (1-10msa)
#define TICKER_TIME 0.001 * LVGL_TICK           //modified to miliseconds
#define WAIT_TIME 1000 * LVGL_TICK              //modified to microseconds

Ticker ticker;                                  //Ticker for lvgl                    

//Callback function for lvgl timing.
void lv_ticker_func(){
    
    lv_tick_inc(LVGL_TICK); 
    //Call lv_tick_inc(x) every x milliseconds in a Timer or Task (x should be between 1 and 10). 
    //It is required for the internal timing of LittlevGL.
    lv_task_handler(); 
    //Call lv_task_handler() periodically every few milliseconds. 
    //It will redraw the screen if required, handle input devices etc.
}

//lvgl button object event handler
void event_handler(lv_obj_t * obj, lv_event_t event){ 
    if(event == LV_EVENT_CLICKED) {
        printf("Clicked\n");
    }
    else if(event == LV_EVENT_VALUE_CHANGED) {
        printf("Toggled\n");
    }
} 

int main()
{
    printf("LittlevGL GUI-"); 
    lv_init();                                  //Initialize the LittlevGL
    lv_port_disp_init();                        //Initialize diplay 
    lv_port_indev_init();                       //Initialize touchpad
    ticker.attach(callback(&lv_ticker_func),TICKER_TIME); //Attach callback to ticker
    
#ifndef DEMO_H
    printf("Hello word\n");
    lv_obj_t * label_h = lv_label_create(lv_scr_act(), NULL);
    static lv_style_t st;
    lv_style_copy( &st, &lv_style_plain );
    st.text.font = &lv_font_roboto_28;
    lv_obj_set_style( label_h, &st );
    lv_obj_set_size(label_h, 50, 30);
    lv_label_set_recolor(label_h, true);
    lv_label_set_text(label_h, "#ff0000 Hello word#");
    lv_obj_align(label_h, NULL, LV_ALIGN_IN_TOP_MID, 0, 0);
    
    lv_obj_t * label;
    lv_obj_t * btn1 = lv_btn_create(lv_scr_act(), NULL);
    lv_obj_set_event_cb(btn1, event_handler);
    lv_obj_align(btn1, NULL, LV_ALIGN_CENTER, 0, -40);
    label = lv_label_create(btn1, NULL);
    lv_label_set_text(label, "Button");
    lv_obj_t *btn2 = lv_btn_create(lv_scr_act(), NULL);
    lv_obj_set_event_cb(btn2, event_handler);
    lv_obj_align(btn2, NULL, LV_ALIGN_CENTER, 0, 40);
    lv_btn_set_toggle(btn2, true);
    lv_btn_toggle(btn2);
    lv_btn_set_fit2(btn2, LV_FIT_NONE, LV_FIT_TIGHT);
    label = lv_label_create(btn2, NULL);
    lv_label_set_text(label, "Toggled");
#else   
    printf("Demo\n");
    demo_create(); // Demo from lv_examples
#endif   

    while(1) {
        //something   
        //wait_us(WAIT_TIME);
    }
}