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

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/Lato-Regular.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

MicroPython code  

 GitHub Simulator

#!/opt/bin/lv_micropython -i
import lvgl as lv
import display_driver
import fs_driver

info = lv.ft_info_t()
info.name ="./Lato-Regular.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

enum LV_FT_FONT_STYLE

Values:

enumerator FT_FONT_STYLE_NORMAL

enumerator FT_FONT_STYLE_ITALIC

enumerator FT_FONT_STYLE_BOLD

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

Public Members

const char *name

const void *mem

size_t mem_size

lv_font_t *font

uint16_t weight

uint16_t style