App:Library:LVGL:docs:3rd party libraries:FreeType support
https://docs.lvgl.io/8.2/libs/freetype.html
英文 | 自動翻訳 |
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FreeType support
Interface to FreeType to generate font bitmaps run time.
Install FreeType
- Download Freetype from here
make
sudo make install
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
https://docs.lvgl.io/8.2/libs/freetype.html#open-a-front-with-freetype
Learn more
- FreeType tutorial
- LVGL's font interface
API
Enums
- enum LV_FT_FONT_STYLE[1]
- Values:
Functions
- bool l[8]v_freetype_init(uint16_t max_faces, uint16_t max_sizes, uint32_t max_bytes)[9]
- init freetype library
- Parameters
-
- max_faces -- Maximum number of opene[10]d 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)[11]
- Destroy freetype library
- bool lv_ft_font_init(lv_ft_info_t *info)[13]
- Creates a font with info parameter s[14]pecified.
- 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)[15]
- Destroy a font that has been created[16].
- Parameters
- font -- pointer to font.