Font Manager

Font Manager is a secondary encapsulation of FreeType support, which provides facilities for high-level applications to manage and use vector fonts. Currently provided font-management functions includes:

Font resource reference counting (reduces repeated creation of font resources).
Font resource concatenation (font fallback).
Font resource recycling mechanism (buffers recently deleted font resources to reduce the time overhead of repeated creation).

Usage

Enable FreeType and Font Manager in lv_conf.h by setting the LV_USE_FREETYPE and LV_USE_FONT_MANAGER macros to non-zero values, and configure LV_FONT_MANAGER_NAME_MAX_LEN to set the maximum length of the font name.

Initialize Font Manager

Use lv_font_manager_create() to create a font manager, where the recycle_cache_size() parameter is used to set the number of font recycling caches, which can improve font creation efficiency.

Use lv_font_manager_add_path_static() to add a mapping between the font file path and the custom font name, so that the application can access the font resources more conveniently. It should be noted that if the file path is not static (assigned from a local variable), use lv_font_manager_add_path() to add the path. This function will make its own copy of the string.

Use lv_font_manager_remove_path() to remove the font path mapping.

static lv_font_manager_t * g_font_manager = NULL;

void font_manager_init(void)
{
   /* Create font manager, with 8 fonts recycling buffers */
   g_font_manager = lv_font_manager_create(8);

   /* Add font path mapping to font manager */
   lv_font_manager_add_path_static(g_font_manager, "Lato-Regular", "./lvgl/examples/libs/freetype/Lato-Regular.ttf");
   lv_font_manager_add_path_static(g_font_manager, "MyFont", "./path/to/myfont.ttf");
}

Create Font from Font Manager

Use lv_font_manager_create_font() to create a font. The parameters are basically the same as lv_freetype_font_create().

The font_family parameter can be filled with the names of multiple fonts (separated by ,) to achieve font concatenation (when the corresponding glyph is not found in a font file, it will automatically search from the next concatenated font).

static lv_font_t * g_font = NULL;

/* Create font from font manager */
lv_font_t * g_font = lv_font_manager_create_font(g_font_manager,
                                                 "Lato-Regular,MyFont",
                                                 LV_FREETYPE_FONT_RENDER_MODE_BITMAP,
                                                 24,
                                                 LV_FREETYPE_FONT_STYLE_NORMAL);

/* Create label with the font */
lv_obj_t * label = lv_label_create(lv_screen_active());
lv_obj_set_style_text_font(label, g_font, 0);
lv_label_set_text(label, "Hello World!");

Delete Font

Use lv_font_manager_delete_font() to delete the font when it is no longer needed. The font manager will mark the font resource as a recyclable font so that it has the possibility of being more quickly created next time.

Note that you need to delete any Widgets that used the font first, and then delete the font to avoid accessing wild pointers.

/* Delete label and font */
lv_obj_delete(label);
lv_font_manager_delete_font(g_font_manager, g_font);
g_font = NULL;

Delete Font Manager

Use lv_font_manager_delete() to destroy the entire font manager. It should be noted that before destruction, it is necessary to ensure that the application has deleted all fonts using lv_font_manager_delete_font(). The font manager will check the reference status of all allocated fonts. If there are still fonts being referenced, the font manager will fail to be destroyed and the function will return false.

Example

Font manager example

#include "../../lv_examples.h"
#if LV_USE_FREETYPE && LV_USE_FONT_MANAGER && LV_BUILD_EXAMPLES

#if LV_FREETYPE_USE_LVGL_PORT
    #define PATH_PREFIX "A:"
#else
    #define PATH_PREFIX "./"
#endif

static lv_font_manager_t * g_font_manager = NULL;

void lv_example_font_manager_1(void)
{
    /* Create font manager, with 8 fonts recycling buffers */
    g_font_manager = lv_font_manager_create(8);

    /* Add font path mapping to font manager */
    lv_font_manager_add_path_static(g_font_manager,
                                    "Lato-Regular",
                                    PATH_PREFIX "lvgl/examples/libs/freetype/Lato-Regular.ttf");

    /* Create font from font manager */
    lv_font_t * font = lv_font_manager_create_font(g_font_manager,
                                                   "Lato-Regular",
                                                   LV_FREETYPE_FONT_RENDER_MODE_BITMAP,
                                                   24,
                                                   LV_FREETYPE_FONT_STYLE_NORMAL);

    if(!font) {
        LV_LOG_ERROR("Could not create font");
        return;
    }

    /* Create label with the font */
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_obj_set_style_text_font(label, font, 0);
    lv_label_set_text(label, "Hello Font Manager!");
    lv_obj_center(label);
}

#else

void lv_example_font_manager_1(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_label_set_text(label, "FreeType or font_manager is not enabled");
    lv_obj_center(label);
}

#endif

API

lv_font_manager_recycle.h

lv_font_manager.h