FreeType support

Interface to FreeType to generate font bitmaps run time.

Add FreeType to your project

First, Download FreeType from here.

There are two ways to use FreeType: ### For UNIX For UNIX systems, it is recommended to use the way of compiling and installing libraries. - Enter the FreeType source code directory.

  • make

  • sudo make install

  • Add include path: /usr/include/freetype2 (for GCC: -I/usr/include/freetype2 -L/usr/local/lib)

  • Link library: freetype (for GCC: -L/usr/local/lib -lfreetype)

For Embedded Devices

For embedded devices, it is more recommended to use the FreeType configuration file provided by LVGL, which only includes the most commonly used functions, which is very meaningful for saving limited FLASH space.

  • Copy the FreeType source code to your project directory.

  • Refer to the following Makefile for configuration:

# FreeType custom configuration header file
CFLAGS += -DFT2_BUILD_LIBRARY
CFLAGS += -DFT_CONFIG_MODULES_H=<lvgl/src/libs/freetype/ftmodule.h>
CFLAGS += -DFT_CONFIG_OPTIONS_H=<lvgl/src/libs/freetype/ftoption.h>

# FreeType include path
CFLAGS += -Ifreetype/include

# FreeType C source file
FT_CSRCS += freetype/src/base/ftbase.c
FT_CSRCS += freetype/src/base/ftbitmap.c
FT_CSRCS += freetype/src/base/ftdebug.c
FT_CSRCS += freetype/src/base/ftglyph.c
FT_CSRCS += freetype/src/base/ftinit.c
FT_CSRCS += freetype/src/cache/ftcache.c
FT_CSRCS += freetype/src/gzip/ftgzip.c
FT_CSRCS += freetype/src/sfnt/sfnt.c
FT_CSRCS += freetype/src/smooth/smooth.c
FT_CSRCS += freetype/src/truetype/truetype.c
CSRCS += $(FT_CSRCS)

Usage

Enable LV_USE_FREETYPE in lv_conf.h.

Cache configuration:

  • LV_FREETYPE_CACHE_SIZE Maximum memory(Bytes) used to cache font bitmap, outline, character maps, etc. :Note: This value does not include the memory used by FT_Face and FT_Size objects

  • LV_FREETYPE_CACHE_FT_FACES: Maximum open number of FT_Face objects.

  • LV_FREETYPE_CACHE_FT_SIZES: Maximum open number of FT_Size objects.

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.

By default, 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.

If you want FreeType to use lvgl's memory allocation and file system interface, you can enable LV_FREETYPE_USE_LVGL_PORT in lv_conf.h, convenient for unified management.

The font style supports Italic and Bold fonts processed by software, and can be set with reference to the following values:

  • LV_FREETYPE_FONT_STYLE_NORMAL: Default style.

  • LV_FREETYPE_FONT_STYLE_ITALIC: Italic style.

  • LV_FREETYPE_FONT_STYLE_BOLD: Bold style.

They can be combined.eg: LV_FREETYPE_FONT_STYLE_BOLD | LV_FREETYPE_FONT_STYLE_ITALIC.

Use the lv_freetype_font_create() function to create a font. To delete a font, use lv_freetype_font_delete(). For more detailed usage, please refer to example code.

Example

Open a front with FreeType

C code  

 View on GitHub
#include "../../lv_examples.h"
#if LV_BUILD_EXAMPLES
#if LV_USE_FREETYPE

#if LV_FREETYPE_USE_LVGL_PORT
    #define PATH_PREFIX "A:"
#else
    #define PATH_PREFIX "./"
#endif

/**
 * Load a font with FreeType
 */
void lv_example_freetype_1(void)
{
    /*Create a font*/
    lv_font_t * font = lv_freetype_font_create(PATH_PREFIX "lvgl/examples/libs/freetype/Lato-Regular.ttf",
                                               24,
                                               LV_FREETYPE_FONT_STYLE_NORMAL);

    if(!font) {
        LV_LOG_ERROR("freetype font create failed.");
        return;
    }

    /*Create style with the new font*/
    static lv_style_t style;
    lv_style_init(&style);
    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 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_screen_active());
    lv_label_set_text(label, "FreeType is not installed");
    lv_obj_center(label);
}

#endif
#endif

MicroPython code  

 View on GitHub MicroPython Simulator
#!/opt/bin/lv_micropython -i
import lvgl as lv
import display_driver
import fs_driver

font = lv.freetype_font_create("./Lato-Regular.ttf", 24, lv.FREETYPE_FONT_STYLE.NORMAL)

# Create style with the new font
style = lv.style_t()
style.init()
style.set_text_font(font)
style.set_text_align(lv.TEXT_ALIGN.CENTER)

# Create a label with the new style
label = lv.label(lv.screen_active())
label.add_style(style, 0)
label.set_text("Hello world\nI'm a font created with FreeType")
label.center()

Learn more

API

ftoption.h

ftmodule.h