Image font (imgfont)

Draw image in label or span obj with imgfont. This is often used to display Unicode emoji icons in text. Supported image formats: determined by LVGL image decoder.

Usage

Enable LV_USE_IMGFONT in lv_conf.h.

To create a new imgfont use lv_imgfont_create(height, path_cb).

height used to indicate the size of a imgfont. path_cb Used to get the image path of the specified unicode.

Use lv_imgfont_destroy(imgfont) to destroy a imgfont that is no longer used.

Example

Use emojis in a text.

C code  

 GitHub
#include "../../lv_examples.h"
#include <stdio.h>

#if LV_BUILD_EXAMPLES
#if LV_USE_IMGFONT

LV_IMG_DECLARE(emoji_F617)
static bool get_imgfont_path(const lv_font_t * font, void * img_src,
                             uint16_t len, uint32_t unicode, uint32_t unicode_next,
                             void * user_data)
{
    LV_UNUSED(font);
    LV_UNUSED(unicode_next);
    LV_UNUSED(user_data);
    LV_ASSERT_NULL(img_src);

    if(unicode < 0xF000) return false;

    if(unicode == 0xF617) {
        memcpy(img_src, &emoji_F617, sizeof(lv_img_dsc_t));
    }
    else {
        char * path = (char *)img_src;
#if LV_USE_FFMPEG
        snprintf(path, len, "%s/%04X.%s", "lvgl/examples/assets/emoji", unicode, "png");
#elif LV_USE_PNG
        snprintf(path, len, "%s/%04X.%s", "A:lvgl/examples/assets/emoji", unicode, "png");
#endif
        path[len - 1] = '\0';
    }

    return true;
}

/**
 * draw img in label or span obj
 */
void lv_example_imgfont_1(void)
{
    lv_font_t * imgfont = lv_imgfont_create(80, get_imgfont_path, NULL);
    if(imgfont == NULL) {
        LV_LOG_ERROR("imgfont init error");
    }

    imgfont->fallback = LV_FONT_DEFAULT;

    lv_obj_t * label1 = lv_label_create(lv_scr_act());
    lv_label_set_text(label1, "12\uF600\uF617AB");
    lv_obj_set_style_text_font(label1, imgfont, LV_PART_MAIN);
    lv_obj_center(label1);
}
#else

void lv_example_imgfont_1(void)
{
    lv_obj_t * label = lv_label_create(lv_scr_act());
    lv_label_set_text(label, "imgfont is not installed");
    lv_obj_center(label);
}

#endif
#endif

MicroPython code  

 GitHub Simulator
import fs_driver
import sys

# set LV_USE_FFMPEG to True if it is enabled in lv_conf.h
LV_USE_FFMPEG = True
LV_FONT_DEFAULT = lv.font_montserrat_14

fs_drv = lv.fs_drv_t()
fs_driver.fs_register(fs_drv, 'A')

# get the directory in which the script is running
try:
    script_path = __file__[:__file__.rfind('/')] if __file__.find('/') >= 0 else '.'
except NameError: 
    script_path = ''
    
def get_imgfont_path(font, img_src, length, unicode, unicode_next,user_data) :
    if unicode < 0xf600:
        return
    if LV_USE_FFMPEG:
        path = bytes(script_path + "/../../assets/emoji/{:04X}.png".format(unicode) + "\0","ascii")
    else:
        path = bytes("A:"+ script_path + "/../../assets/emoji/{:04X}.png".format(unicode) + "\0","ascii")
    # print("image path: ",path)
    img_src.__dereference__(length)[0:len(path)] = path
    return True

#
# draw img in label or span obj
#
imgfont = lv.imgfont_create(80, get_imgfont_path, None)
if imgfont == None:
    print("imgfont init error")

imgfont.fallback = LV_FONT_DEFAULT

label1 = lv.label(lv.scr_act())
label1.set_text("12\uF600\uF617AB")
label1.set_style_text_font(imgfont, lv.PART.MAIN)
label1.center()

API

Typedefs

typedef bool (*lv_get_imgfont_path_cb_t)(const lv_font_t *font, void *img_src, uint16_t len, uint32_t unicode, uint32_t unicode_next, void *user_data)

Functions

lv_font_t *lv_imgfont_create(uint16_t height, lv_get_imgfont_path_cb_t path_cb, void *user_data)

Creates a image font with info parameter specified.

Parameters
  • height -- font size

  • path_cb -- a function to get the image path name of character.

Returns

pointer to the new imgfont or NULL if create error.

void lv_imgfont_destroy(lv_font_t *font)

Destroy a image font that has been created.

Parameters

font -- pointer to image font handle.