App:Library:LVGL:docs:3rd party libraries:FreeType support

https://docs.lvgl.io/8.2/libs/freetype.html

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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:

1. 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.
2. 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.
3. 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:

1. FT_FONT_STYLE_NORMAL:default style.
2. FT_FONT_STYLE_ITALIC:Italic style
3. FT_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

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Learn more

• FreeType tutorial
• LVGL's font interface

API

Enums

enum LV_FT_FONT_STYLE[1]

Values:

enumer[2]ator FT_FONT_STYLE_NORMAL[3]

enumerator FT_FONT_ST[4]YLE_ITALIC[5]

enumerator FT_FONT_ST[6]YLE_BOLD[7]

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

[12]

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.

struct lv_ft_info_t[17]

Public Members [18]

const char *name[19]

const [20]void *mem[21]

size_[22]t mem_size[23]

lv_fo[24]nt_t *font[25]

uint1[26]6_t weight[27]

uint1[28]6_t style

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