Message box (lv_msgbox)

Overview

The Message boxes act as pop-ups. They are built from a background container, a title, an optional close button, a text and optional buttons.

The text will be broken into multiple lines automatically and the height will be set automatically to include the text and the buttons.

The message box can be modal (blocking clicks on the rest of the screen) or not modal.

Parts and Styles

The message box is built from other widgets, so you can check these widgets' documentation for details.

Background: lv_obj
Close button: lv_btn
Title and text: lv_label
Buttons: lv_btnmatrix

Usage

Create a message box

lv_msgbox_create(parent, title, txt, btn_txts[], add_close_btn) creates a message box.

If parent is NULL the message box will be modal. title and txt are strings for the title and the text. btn_txts[] is an array with the buttons' text. E.g. const char * btn_txts[] = {"Ok", "Cancel", NULL}. add_close_btn can be true or false to add/don't add a close button.

Get the parts

The building blocks of the message box can be obtained using the following functions:

lv_obj_t * lv_msgbox_get_title(lv_obj_t * mbox);
lv_obj_t * lv_msgbox_get_close_btn(lv_obj_t * mbox);
lv_obj_t * lv_msgbox_get_text(lv_obj_t * mbox);
lv_obj_t * lv_msgbox_get_btns(lv_obj_t * mbox);

Close the message box

lv_msgbox_close(msgbox) closes (deletes) the message box.

Events

LV_EVENT_VALUE_CHANGED is sent by the buttons if one of them is clicked. LV_OBJ_FLAG_EVENT_BUBBLE is enabled on the buttons so you can add events to the message box itself. In the event handler, lv_event_get_target(e) will return the button matrix and lv_event_get_current_target(e) will return the message box. lv_msgbox_get_active_btn(msgbox) and lv_msgbox_get_active_btn_text(msgbox) can be used to get the index and text of the clicked button.

Learn more about Events.

Keys

Keys have effect on the close button and button matrix. You can add them manually to a group if required.

Learn more about Keys.

Example

Simple Message box

#include "../../lv_examples.h"
#if LV_USE_MSGBOX && LV_BUILD_EXAMPLES

static void event_cb(lv_event_t * e)
{
    lv_obj_t * obj = lv_event_get_target(e);
    LV_UNUSED(obj);
    LV_LOG_USER("Button %s clicked", lv_msgbox_get_active_button_text(obj));
}

void lv_example_msgbox_1(void)
{
    static const char * buttons[] = {"Apply", "Close", ""};

    lv_obj_t * mbox1 = lv_msgbox_create(NULL, "Hello", "This is a message box with two buttons.", buttons, true);
    lv_obj_add_event(mbox1, event_cb, LV_EVENT_VALUE_CHANGED, NULL);
    lv_obj_center(mbox1);
}

#endif

def event_cb(e):
    mbox = e.get_target_obj()
    print("Button %s clicked" % mbox.get_active_button_text())

buttons = ["Apply", "Close", ""]

mbox1 = lv.msgbox(lv.screen_active(), "Hello", "This is a message box with two buttons.", buttons, True)
mbox1.add_event(event_cb, lv.EVENT.VALUE_CHANGED, None)
mbox1.center()

API

lv_msgbox.h

lv_api_map.h