ndg/lib/lvgl/docs/libs/freetype.md

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

.. include:: ../../examples/libs/freetype/index.rst

Learn more

• FreeType tutorial
• LVGL's font interface

API

.. doxygenfile:: lv_freetype.h
  :project: lvgl