FreeType support¶
Interface to FreeType to generate font bitmaps run time.
Add FreeType to your project¶
Add include path:
/usr/include/freetype2
(for GCC:-I/usr/include/freetype2 -L/usr/local/lib
)Add library:
freetype
(for GCC:-L/usr/local/lib -lfreetype
)
Usage¶
Enable LV_USE_FREETYPE
in lv_conf.h
.
To cache the glyphs from the opened fonts, set LV_FREETYPE_CACHE_SIZE >= 0
and then use the following macros for detailed configuration:
LV_FREETYPE_CACHE_SIZE
:maximum memory(bytes) used to cache font bitmap, outline, character maps, etc. 0 means use the system default value, less than 0 means disable cache. Note: that this value does not account for managed FT_Face and FT_Size objects.LV_FREETYPE_CACHE_FT_FACES
:maximum number of opened FT_Face objects managed by this cache instance.0 means use the system default value. Only useful when LV_FREETYPE_CACHE_SIZE >= 0.LV_FREETYPE_CACHE_FT_SIZES
:maximum number of opened FT_Size objects managed by this cache instance. 0 means use the system default value. Only useful when LV_FREETYPE_CACHE_SIZE >= 0.
When you are sure that all the used font sizes will not be greater than 256, you can enable LV_FREETYPE_SBIT_CACHE
, which is much more memory efficient for small bitmaps.
You can use lv_ft_font_init()
to create FreeType fonts. It returns true
to indicate success, at the same time, the font
member of lv_ft_info_t
will be filled with a pointer to an LVGL font, and you can use it like any LVGL font.
Font style supports bold and italic, you can use the following macros to set:
FT_FONT_STYLE_NORMAL
:default style.FT_FONT_STYLE_ITALIC
:Italic styleFT_FONT_STYLE_BOLD
:bold style
They can be combined.eg:FT_FONT_STYLE_BOLD | FT_FONT_STYLE_ITALIC
.
Note that, the FreeType extension doesn't use LVGL's file system. You can simply pass the path to the font as usual on your operating system or platform.
Example¶
Open a front with FreeType¶
C code
GitHub#include "../../lv_examples.h"
#if LV_BUILD_EXAMPLES
#if LV_USE_FREETYPE
/**
* Load a font with FreeType
*/
void lv_example_freetype_1(void)
{
/*Create a font*/
static lv_ft_info_t info;
/*FreeType uses C standard file system, so no driver letter is required.*/
info.name = "./lvgl/examples/libs/freetype/arial.ttf";
info.weight = 24;
info.style = FT_FONT_STYLE_NORMAL;
info.mem = NULL;
if(!lv_ft_font_init(&info)) {
LV_LOG_ERROR("create failed.");
}
/*Create style with the new font*/
static lv_style_t style;
lv_style_init(&style);
lv_style_set_text_font(&style, info.font);
lv_style_set_text_align(&style, LV_TEXT_ALIGN_CENTER);
/*Create a label with the new style*/
lv_obj_t * label = lv_label_create(lv_scr_act());
lv_obj_add_style(label, &style, 0);
lv_label_set_text(label, "Hello world\nI'm a font created with FreeType");
lv_obj_center(label);
}
#else
void lv_example_freetype_1(void)
{
/*TODO
*fallback for online examples*/
lv_obj_t * label = lv_label_create(lv_scr_act());
lv_label_set_text(label, "FreeType is not installed");
lv_obj_center(label);
}
#endif
#endif
#!/opt/bin/lv_micropython -i
import lvgl as lv
import display_driver
import fs_driver
info = lv.ft_info_t()
info.name ="./arial.ttf"
info.weight = 24
info.style = lv.FT_FONT_STYLE.NORMAL
info.font_init()
# Create style with the new font
style = lv.style_t()
style.init()
style.set_text_font(info.font)
style.set_text_align(lv.TEXT_ALIGN.CENTER)
# Create a label with the new style
label = lv.label(lv.scr_act())
label.add_style(style, 0)
label.set_text("Hello world\nI'm a font created with FreeType")
label.center()
Learn more¶
FreeType tutorial
LVGL's font interface
API¶
Enums
Functions
-
bool lv_freetype_init(uint16_t max_faces, uint16_t max_sizes, uint32_t max_bytes)¶
init freetype library
- Parameters
max_faces -- Maximum number of opened FT_Face objects managed by this cache instance. Use 0 for defaults.
max_sizes -- Maximum number of opened FT_Size objects managed by this cache instance. Use 0 for defaults.
max_bytes -- Maximum number of bytes to use for cached data nodes. Use 0 for defaults. Note that this value does not account for managed FT_Face and FT_Size objects.
- Returns
true on success, otherwise false.
-
void lv_freetype_destroy(void)¶
Destroy freetype library
-
bool lv_ft_font_init(lv_ft_info_t *info)¶
Creates a font with info parameter specified.
- Parameters
info -- See lv_ft_info_t for details. when success, lv_ft_info_t->font point to the font you created.
- Returns
true on success, otherwise false.
-
void lv_ft_font_destroy(lv_font_t *font)¶
Destroy a font that has been created.
- Parameters
font -- pointer to font.
-
struct lv_ft_info_t¶