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ui-library-playground/Core/Inc/graphics/fonts/lvgl/lvgl.h
Dylan Smith 73005fc56b WIP
2026-01-12 14:40:36 -05:00

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/**
* I want to use bitmap fonts generated with lv_font_conv.
* This generates a .h bitmap font header from a .TTF file, but it's
* designed to be used with the full LVGL library.
* This compatibility layer is here so that we can drop
* a font .h file into the project and use it without modification.
*
* This layer includes a lot of code from lv_font_fmt_txt.h to define how
* a bitmapped font is expressed.
*
* See:
* - https://github.com/lvgl/lv_font_conv
* - https://github.com/lvgl/lvgl/blob/master/src/font/lv_font.h
* - https://github.com/lvgl/lvgl/blob/master/src/font/fmt_txt/lv_font_fmt_txt.h
*
* - Dylan
*/
#ifndef LVGL_H
#define LVGL_H
#include "stdint.h"
#include "stdbool.h"
#ifndef NULL
#define NULL 0
#endif
/******************************************* */
/* Dummy defines for LVGL font compatibility */
#ifndef LV_ATTRIBUTE_LARGE_CONST
#define LV_ATTRIBUTE_LARGE_CONST
#endif
#ifndef LV_FONT_SUBPX_NONE
#define LV_FONT_SUBPX_NONE 0
#endif
#ifndef LVGL_VERSION_MAJOR
#define LVGL_VERSION_MAJOR 7
#define LV_VERSION_CHECK(X,Y,Z) 0
#endif
/******************** */
/* Struct Definitions */
typedef struct _lv_font_t lv_font_t;
typedef struct _lv_font_fmt_txt_glyph_dsc_t lv_font_fmt_txt_glyph_dsc_t;
typedef struct _lv_draw_buf_t lv_draw_buf_t;
struct _lv_font_t {
bool (*get_glyph_dsc)(const lv_font_t * font, lv_font_fmt_txt_glyph_dsc_t * dsc_out, uint32_t unicode_letter); /* Function pointer for glyph descriptor */
const void * (*get_glyph_bitmap)(lv_font_fmt_txt_glyph_dsc_t * g_dsc, lv_draw_buf_t * draw_buf); /* Function pointer for glyph bitmap */
uint16_t line_height; /* The maximum line height required by the font */
int16_t base_line; /* Baseline measured from the bottom of the line */
uint8_t subpx; /* Subpixel rendering type */
int16_t underline_position; /* Underline position */
int16_t underline_thickness; /* Underline thickness */
const void * dsc; /* The custom font data. Will be accessed by `get_glyph_bitmap/dsc` */
const void * fallback; /* Fallback font (if any) */
void * user_data; /* Custom user data */
};
/** A simple mapping of kern values from pairs*/
typedef struct {
/*To get a kern value of two code points:
1. Get the `glyph_id_left` and `glyph_id_right` from `lv_font_fmt_txt_cmap_t
2. for(i = 0; i < pair_cnt * 2; i += 2)
if(glyph_ids[i] == glyph_id_left &&
glyph_ids[i+1] == glyph_id_right)
return values[i / 2];
*/
const void * glyph_ids;
const int8_t * values;
uint32_t pair_cnt : 30;
uint32_t glyph_ids_size : 2; /**< 0: `glyph_ids` is stored as `uint8_t`; 1: as `uint16_t` */
} lv_font_fmt_txt_kern_pair_t;
/** This describes a glyph.*/
struct _lv_font_fmt_txt_glyph_dsc_t {
#if LV_FONT_FMT_TXT_LARGE == 0
uint32_t bitmap_index : 20; /**< Start index of the bitmap. A font can be max 1 MB.*/
uint32_t adv_w : 12; /**< Draw the next glyph after this width. 8.4 format (real_value * 16 is stored).*/
uint8_t box_w; /**< Width of the glyph's bounding box*/
uint8_t box_h; /**< Height of the glyph's bounding box*/
int8_t ofs_x; /**< x offset of the bounding box*/
int8_t ofs_y; /**< y offset of the bounding box. Measured from the top of the line*/
#else
uint32_t bitmap_index; /**< Start index of the bitmap. A font can be max 4 GB.*/
uint32_t adv_w; /**< Draw the next glyph after this width. 28.4 format (real_value * 16 is stored).*/
uint16_t box_w; /**< Width of the glyph's bounding box*/
uint16_t box_h; /**< Height of the glyph's bounding box*/
int16_t ofs_x; /**< x offset of the bounding box*/
int16_t ofs_y; /**< y offset of the bounding box. Measured from the top of the line*/
#endif
};
/** Format of font character map.*/
typedef enum {
LV_FONT_FMT_TXT_CMAP_FORMAT0_FULL,
LV_FONT_FMT_TXT_CMAP_SPARSE_FULL,
LV_FONT_FMT_TXT_CMAP_FORMAT0_TINY,
LV_FONT_FMT_TXT_CMAP_SPARSE_TINY,
} lv_font_fmt_txt_cmap_type_t;
/**
* Map codepoints to a `glyph_dsc`s
* Several formats are supported to optimize memory usage
* See https://github.com/lvgl/lv_font_conv/blob/master/doc/font_spec.md
*/
typedef struct {
/** First Unicode character for this range*/
uint32_t range_start;
/** Number of Unicode characters related to this range.
* Last Unicode character = range_start + range_length - 1*/
uint16_t range_length;
/** First glyph ID (array index of `glyph_dsc`) for this range*/
uint16_t glyph_id_start;
/*
According the specification there are 4 formats:
https://github.com/lvgl/lv_font_conv/blob/master/doc/font_spec.md
For simplicity introduce "relative code point":
rcp = codepoint - range_start
and a search function:
search a "value" in an "array" and returns the index of "value".
Format 0 tiny
unicode_list == NULL && glyph_id_ofs_list == NULL
glyph_id = glyph_id_start + rcp
Format 0 full
unicode_list == NULL && glyph_id_ofs_list != NULL
glyph_id = glyph_id_start + glyph_id_ofs_list[rcp]
Sparse tiny
unicode_list != NULL && glyph_id_ofs_list == NULL
glyph_id = glyph_id_start + search(unicode_list, rcp)
Sparse full
unicode_list != NULL && glyph_id_ofs_list != NULL
glyph_id = glyph_id_start + glyph_id_ofs_list[search(unicode_list, rcp)]
*/
const uint16_t * unicode_list;
/** if(type == LV_FONT_FMT_TXT_CMAP_FORMAT0_...) it's `uint8_t *`
* if(type == LV_FONT_FMT_TXT_CMAP_SPARSE_...) it's `uint16_t *`
*/
const void * glyph_id_ofs_list;
/** Length of `unicode_list` and/or `glyph_id_ofs_list`*/
uint16_t list_length;
/** Type of this character map*/
lv_font_fmt_txt_cmap_type_t type;
} lv_font_fmt_txt_cmap_t;
/** Bitmap formats*/
typedef enum {
LV_FONT_FMT_TXT_PLAIN = 0,
LV_FONT_FMT_TXT_COMPRESSED = 1,
LV_FONT_FMT_TXT_COMPRESSED_NO_PREFILTER = 2,
} lv_font_fmt_txt_bitmap_format_t;
/** Describe store for additional data for fonts */
typedef struct {
/** The bitmaps of all glyphs */
const uint8_t * glyph_bitmap;
/** Describe the glyphs */
const lv_font_fmt_txt_glyph_dsc_t * glyph_dsc;
/** Map the glyphs to Unicode characters.
*Array of `lv_font_cmap_fmt_txt_t` variables */
const lv_font_fmt_txt_cmap_t * cmaps;
/**
* Store kerning values.
* Can be `lv_font_fmt_txt_kern_pair_t * or `lv_font_kern_classes_fmt_txt_t *`
* depending on `kern_classes`
*/
const void * kern_dsc;
/** Scale kern values in 12.4 format */
uint16_t kern_scale;
/** Number of cmap tables */
uint16_t cmap_num : 9;
/** Bit per pixel: 1, 2, 3, 4, 8 */
uint16_t bpp : 4;
/** Type of `kern_dsc` */
uint16_t kern_classes : 1;
/**
* storage format of the bitmap
* from `lv_font_fmt_txt_bitmap_format_t`
*/
uint16_t bitmap_format : 2;
/**
* Bytes to which each line is padded.
* 0: means no align and padding
* 1: e.g. with bpp=4 lines are aligned to 1 byte, so there can be a 4 bits of padding
* 4, 8, 16, 32, 64: each line is padded to the given byte boundaries
*/
uint8_t stride;
} lv_font_fmt_txt_dsc_t;
struct _lv_draw_buf_t {
uint32_t data_size; /**< Total buf size in bytes */
uint8_t * data;
};
/**********************
* GLOBAL PROTOTYPES
**********************/
/**
* Used as `get_glyph_bitmap` callback in lvgl's native font format if the font is uncompressed.
* @param g_dsc the glyph descriptor including which font to use, which supply the glyph_index and format.
* @param draw_buf a draw buffer that can be used to store the bitmap of the glyph, it's OK not to use it.
* @return pointer to an A8 bitmap (not necessarily bitmap_out) or NULL if `unicode_letter` not found
*/
const void * lv_font_get_bitmap_fmt_txt(lv_font_fmt_txt_glyph_dsc_t * g_dsc, lv_draw_buf_t * draw_buf);
/**
* Used as `get_glyph_dsc` callback in lvgl's native font format if the font is uncompressed.
* @param font pointer to font
* @param dsc_out store the result descriptor here
* @param unicode_letter a UNICODE letter code
* @return true: descriptor is successfully loaded into `dsc_out`.
* false: the letter was not found, no data is loaded to `dsc_out`
*/
bool lv_font_get_glyph_dsc_fmt_txt(const lv_font_t * font, lv_font_fmt_txt_glyph_dsc_t * dsc_out, uint32_t unicode_letter);
#endif
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