Tiny TTF font engine

Usage

Allow using TrueType fonts in LVGL.

Detailed introduction: https://github.com/nothings/stb

When enabled in lv_conf.h with LV_USE_TINY_TTF lv_tiny_ttf_create_data(data, data_size, font_size) can be used to create a TTF font instance at the specified line height. You can then use that font anywhere lv_font_t is accepted.

By default, the TTF or OTF file must be embedded as an array, either in a header, or loaded into RAM in order to function.

However, if LV_TINY_TTF_FILE_SUPPORT is enabled, lv_tiny_ttf_create_file(path, font_size) will also be available, allowing tiny_ttf to stream from a file. The file must remain open the entire time the font is being used.

After a font is created, you can change the font size in pixels by using lv_tiny_ttf_set_size(font, font_size).

By default, a font will use up to 4KB of cache to speed up rendering glyphs. This maximum can be changed by using lv_tiny_ttf_create_data_ex(data, data_size, font_size, cache_size) or lv_tiny_ttf_create_file_ex(path, font_size, cache_size) (when available). The cache size is indicated in bytes.

Example

Open a font with Tiny TTF from data array

C code  

 View on GitHub

#include "../../lv_examples.h"
#if LV_USE_TINY_TTF && LV_BUILD_EXAMPLES

/**
 * Load a font with Tiny_TTF
 */
void lv_example_tiny_ttf_1(void)
{
    extern const uint8_t ubuntu_font[];
    extern const int ubuntu_font_size;

    /*Create style with the new font*/
    static lv_style_t style;
    lv_style_init(&style);
    lv_font_t * font = lv_tiny_ttf_create_data(ubuntu_font, ubuntu_font_size, 30);
    lv_style_set_text_font(&style, 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_screen_active());
    lv_obj_add_style(label, &style, 0);
    lv_label_set_text(label, "Hello world\nI'm a font\ncreated\nwith Tiny TTF");
    lv_obj_center(label);
}
#endif

---

Load a font with Tiny_TTF from file

C code  

 View on GitHub

#include "../../lv_examples.h"
#if LV_USE_TINY_TTF && LV_TINY_TTF_FILE_SUPPORT && LV_BUILD_EXAMPLES

/**
 * Load a font with Tiny_TTF from file
 */
void lv_example_tiny_ttf_2(void)
{
    /*Create style with the new font*/
    static lv_style_t style;
    lv_style_init(&style);
    lv_font_t * font = lv_tiny_ttf_create_file("A:lvgl/examples/libs/tiny_ttf/Ubuntu-Medium.ttf", 30);
    lv_style_set_text_font(&style, 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_screen_active());
    lv_obj_add_style(label, &style, 0);
    lv_label_set_text(label, "Hello world\nI'm a font\ncreated\nwith Tiny TTF");
    lv_obj_center(label);
}
#endif

---

Change font size with Tiny_TTF

C code  

 View on GitHub

#include "../../lv_examples.h"
#if LV_USE_TINY_TTF && LV_BUILD_EXAMPLES && LV_USE_OBSERVER

static void font_size_observer_cb(lv_observer_t * observer, lv_subject_t * subject);

static lv_subject_t subject_font;

/**
 * Change font size with Tiny_TTF
 */
void lv_example_tiny_ttf_3(void)
{
    extern const uint8_t ubuntu_font[];
    extern const int ubuntu_font_size;

    lv_subject_init_int(&subject_font, 25);

    /*Create style with the new font*/
    static lv_style_t style;
    lv_style_init(&style);
    lv_font_t * font = lv_tiny_ttf_create_data(ubuntu_font, ubuntu_font_size, 25);
    lv_style_set_text_font(&style, font);
    lv_style_set_text_align(&style, LV_TEXT_ALIGN_CENTER);

    lv_obj_t * slider = lv_slider_create(lv_screen_active());
    lv_obj_center(slider);
    lv_slider_set_range(slider, 5, 50);
    lv_obj_align(slider, LV_ALIGN_BOTTOM_MID, 0, -50);
    lv_slider_bind_value(slider, &subject_font);

    lv_obj_t * slider_label = lv_label_create(lv_screen_active());
    lv_obj_align_to(slider_label, slider, LV_ALIGN_OUT_BOTTOM_MID, 0, 10);
    lv_label_bind_text(slider_label, &subject_font, "%d");

    /*Create a label with the new style*/
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_obj_add_style(label, &style, 0);
    lv_obj_set_size(label, LV_SIZE_CONTENT, LV_SIZE_CONTENT);
    lv_label_set_text(label, "Hello world!");
    lv_obj_center(label);

    lv_subject_add_observer(&subject_font, font_size_observer_cb, &style);
}

static void font_size_observer_cb(lv_observer_t * observer, lv_subject_t * subject)
{
    lv_style_t * style = observer->user_data;
    lv_style_value_t v;
    lv_style_get_prop(style, LV_STYLE_TEXT_FONT, &v);
    lv_font_t * font = (lv_font_t *) v.ptr;
    int32_t size = lv_subject_get_int(subject);

    lv_tiny_ttf_set_size(font, size);

    lv_obj_report_style_change(style);
}
#endif

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API

stb_rect_pack.h

stb_truetype_htcw.h