Basic Examples¶
Below are several basic examples. They include the application code that produces
the Widget Tree needed to make LVGL render the examples shown. Each example assumes
LVGL has undergone normal initialization, meaning that a lv_display_t
object
was created and therefore has an Active Screen.
A very simple hello world label¶
C code
View on GitHub#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_LABEL
/**
* Basic example to create a "Hello world" label
*/
void lv_example_get_started_1(void)
{
/*Change the active screen's background color*/
lv_obj_set_style_bg_color(lv_screen_active(), lv_color_hex(0x003a57), LV_PART_MAIN);
/*Create a white label, set its text and align it to the center*/
lv_obj_t * label = lv_label_create(lv_screen_active());
lv_label_set_text(label, "Hello world");
lv_obj_set_style_text_color(lv_screen_active(), lv_color_hex(0xffffff), LV_PART_MAIN);
lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
}
#endif
Create a slider and write its value on a label¶
C code
View on GitHub#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES && LV_USE_SLIDER
static lv_obj_t * label;
static void slider_event_cb(lv_event_t * e)
{
lv_obj_t * slider = lv_event_get_target_obj(e);
/*Refresh the text*/
lv_label_set_text_fmt(label, "%" LV_PRId32, lv_slider_get_value(slider));
lv_obj_align_to(label, slider, LV_ALIGN_OUT_TOP_MID, 0, -15); /*Align top of the slider*/
}
/**
* Create a slider and write its value on a label.
*/
void lv_example_get_started_4(void)
{
/*Create a slider in the center of the display*/
lv_obj_t * slider = lv_slider_create(lv_screen_active());
lv_obj_set_width(slider, 200); /*Set the width*/
lv_obj_center(slider); /*Align to the center of the parent (screen)*/
lv_obj_add_event_cb(slider, slider_event_cb, LV_EVENT_VALUE_CHANGED, NULL); /*Assign an event function*/
/*Create a label above the slider*/
label = lv_label_create(lv_screen_active());
lv_label_set_text(label, "0");
lv_obj_align_to(label, slider, LV_ALIGN_OUT_TOP_MID, 0, -15); /*Align top of the slider*/
}
#endif