FreeType support（FreeType 支持）

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Interface to FreeType library to generate font bitmap at run time.

Detailed introduction: https://www.freetype.org

FreeType 库的接口，用于生成字体位图运行时。

详细介绍：https://www.freetype.org

Add FreeType to your project（将 FreeType 添加到你的项目）

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First, Download FreeType from here.

There are two ways to use FreeType:

首先，从这里下载 FreeType。

有两种方法可以使用 FreeType：

For UNIX（对于 UNIX）

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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)

对于UNIX系统，建议使用编译和安装库的方式。

进入 FreeType 源码目录
make
sudo make install
添加包含路径： /usr/include/freetype2 (对于 GCC： -I/usr/include/freetype2 -L/usr/local/lib)
链接库： freetype (对于 GCC： -L/usr/local/lib -lfreetype)

For Embedded Devices（对于嵌入式设备）

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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)

对于嵌入式设备，更建议使用 FreeType LVGL 提供的配置文件，其中仅包含最常用函数，对于节省有限非常有意义 FLASH空间。

将 FreeType 源代码复制到项目目录。
有关配置，请参阅以下内容： Makefile

# 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（用法）

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Enable LV_USE_FREETYPE in lv_conf.h.

Cache configuration:

LV_FREETYPE_CACHE_FT_GLYPH_CNT Maximum number of cached glyphs., etc.

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.

The FreeType extension also supports colored bitmap glyphs such as emojis. Note that only bitmaps are supported at this time. Colored vector graphics cannot be rendered. An example on how to draw a colored bitmap glyph is shown below.

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.

在 lv_conf.h 中启用 LV_USE_FREETYPE。

缓存配置：

LV_FREETYPE_CACHE_FT_GLYPH_CNT 最大缓存的字形数量，等等。

默认情况下，FreeType 扩展不使用 LVGL 的文件系统。您可以像平常一样传递字体的路径，具体取决于您的操作系统或平台。

如果您希望 FreeType 使用 LVGL 的内存分配和文件系统接口，可以在 lv_conf.h 中启用 LV_FREETYPE_USE_LVGL_PORT，以便统一管理。

字体样式支持软件处理的斜体和粗体字体，并可以通过以下值进行设置：

它们可以组合使用。例如：LV_FREETYPE_FONT_STYLE_BOLD | LV_FREETYPE_FONT_STYLE_ITALIC。

FreeType 扩展还支持彩色位图字形（例如表情符号）。请注意，目前仅支持位图，不支持彩色矢量图形渲染。下面是如何绘制彩色位图字形的示例。

使用 lv_freetype_font_create() 函数来创建字体。要删除字体，使用 lv_freetype_font_delete()。更多详细用法，请参见示例代码。 .. _freetype_example:

Example

Open a front with FreeType

#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",
                                               LV_FREETYPE_FONT_RENDER_MODE_BITMAP,
                                               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

Use a bitmap font to draw Emojis using FreeType

#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_2(void)
{
    /*Create a font*/
    lv_font_t * font = lv_freetype_font_create(PATH_PREFIX "lvgl/examples/libs/freetype/Lato-Regular.ttf",
                                               LV_FREETYPE_FONT_RENDER_MODE_BITMAP,
                                               24,
                                               LV_FREETYPE_FONT_STYLE_NORMAL);

    /* this font is created from a downscaled NotoColorEmoji to 34x32px
     * Subset containing only a single emoji was created using fonttools:
     * Command: fonttools subset NotoColorEmoji.ttf --text=😀 */
    lv_font_t * font_emoji = lv_freetype_font_create(PATH_PREFIX "lvgl/examples/libs/freetype/NotoColorEmoji-32.subset.ttf",
                                                     LV_FREETYPE_FONT_RENDER_MODE_BITMAP,
                                                     24,
                                                     LV_FREETYPE_FONT_STYLE_NORMAL);

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

    font->fallback = font_emoji;

    /*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_2(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

Learn more（了解更多信息）

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FreeType`tutorial <https://www.freetype.org/freetype2/docs/tutorial/step1.html>`__
LVGL's Add a new font（添加新的字体）

FreeType 教程
LVGL的 Add a new font（添加新的字体）

API

ftoption.h

ftmodule.h

lv_font_manager_utils.h

lv_types.h

lv_freetype.h