docs/src/main-modules/fonts/font_manager.rst
.. _font_manager:
The font manager is a secondary encapsulation of the LVGL font engine, which facilitates the use and management of fonts for applications. The font management functions currently provided include:
.. _font_manager_usage:
Usage
Enable FreeType and Font Manager in lv_conf.h by setting the
:c:macro:LV_USE_FONT_MANAGER macros to non-zero
values, and configure :c:macro:LV_FONT_MANAGER_NAME_MAX_LEN to set the maximum
length of the font name.
Use :cpp:func:lv_font_manager_create to create a font manager, where the
:cpp:func:recycle_cache_size parameter is used to set the number of font recycling
caches, which can improve font creation efficiency.
Use :cpp:func:lv_font_manager_add_src_static to add a mapping between font names
and font resources to tell the font manager how to access the font resources.
Note that if the font resource description structure is not statically allocated
(for example, allocated from a local variable), use :cpp:func:lv_font_manager_add_src to add the resource.
This function will copy the contents of the structure itself.
Use :cpp:func:lv_font_manager_remove_src to remove the font resource mapping.
It should be noted that the src parameter must strictly correspond to class_p.
class_p will affect the way the font manager interprets src. If an incompatible parameter is passed, the program may fail.
For currently supported font classes, please refer to the example code.
.. code-block:: c
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_src_static(g_font_manager, "Lato-Regular", "./lvgl/examples/libs/freetype/Lato-Regular.ttf", &lv_freetype_font_class);
char path[] = "/path/to/myfont.ttf";
lv_font_manager_add_src(g_font_manager, "MyFont", path, &lv_freetype_font_class);
}
The parameters will be passed to the font creation function of the font backend,
such as :cpp:func:lv_freetype_font_create and :cpp:func:lv_tiny_ttf_create_file.
The font backend will select the supported parameters by itself and ignore the unsupported parameters.
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).
.. code-block:: c
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, LV_FONT_KERNING_NONE);
/* Handle error case */ if(g_font == NULL) { g_font = (lv_font_t *)LV_FONT_DEFAULT; }
/* 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!");
Use :cpp:func: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.
.. code-block:: c
/* Delete label and font */ lv_obj_delete(label); lv_font_manager_delete_font(g_font_manager, g_font); g_font = NULL;
Use :cpp:func: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 :cpp:func: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.
.. _font_manager_example:
Example
.. include:: /examples/others/font_manager/index.rst
.. _font_manager_api:
API