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51 lines
2.4 KiB
Markdown
51 lines
2.4 KiB
Markdown
2 years ago
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# FreeType support
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Interface to [FreeType](https://www.freetype.org/) to generate font bitmaps run time.
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## Install FreeType
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- Download Freetype from [here](https://sourceforge.net/projects/freetype/files/)
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- `make`
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- `sudo make install`
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## Add FreeType to your project
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- Add include path: `/usr/include/freetype2` (for GCC: `-I/usr/include/freetype2 -L/usr/local/lib`)
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- Add library: `freetype` (for GCC: `-L/usr/local/lib -lfreetype`)
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## Usage
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Enable `LV_USE_FREETYPE` in `lv_conf.h`.
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To cache the glyphs from the opened fonts, set `LV_FREETYPE_CACHE_SIZE >= 0` and then use the following macros for detailed configuration:
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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.
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1. `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.
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1. `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.
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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.
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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.
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Font style supports bold and italic, you can use the following macros to set:
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1. `FT_FONT_STYLE_NORMAL`:default style.
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1. `FT_FONT_STYLE_ITALIC`:Italic style
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1. `FT_FONT_STYLE_BOLD`:bold style
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They can be combined.eg:`FT_FONT_STYLE_BOLD | FT_FONT_STYLE_ITALIC`.
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Note that, the FreeType extension doesn't use LVGL's file system.
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You can simply pass the path to the font as usual on your operating system or platform.
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## Example
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```eval_rst
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.. include:: ../../examples/libs/freetype/index.rst
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```
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## Learn more
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- FreeType [tutorial](https://www.freetype.org/freetype2/docs/tutorial/step1.html)
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- LVGL's [font interface](https://docs.lvgl.io/v7/en/html/overview/font.html#add-a-new-font-engine)
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## API
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```eval_rst
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.. doxygenfile:: lv_freetype.h
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:project: lvgl
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```
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