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/* Generic font type that supports fonts with multiple kinds of compression.
* Provides an interface for decoding and rendering single characters.
*/
#ifndef _MF_FONT_H_
#define _MF_FONT_H_
#include "mf_encoding.h"
/* Callback function that writes pixels to screen / buffer / whatever.
*
* x: X coordinate of the first pixel to write.
* y: Y coordinate of the first pixel to write.
* count: Number of pixels to fill (horizontally).
* alpha: The "opaqueness" of the pixels, 0 for background, 255 for text.
* state: Free variable that was passed to render_character().
*/
typedef void (*mf_pixel_callback_t) (int16_t x, int16_t y, uint8_t count,
uint8_t alpha, void *state);
/* General information about a font. */
struct mf_font_s
{
/* Full name of the font, comes from the original font file. */
char *full_name;
/* Short name of the font, comes from file name. */
char *short_name;
/* Width and height of the character bounding box. */
uint8_t width;
uint8_t height;
/* Minimum and maximum tracking width of characters. */
uint8_t min_x_advance;
uint8_t max_x_advance;
/* Location of the text baseline relative to character. */
int8_t baseline_x;
uint8_t baseline_y;
/* Line height of the font (vertical advance). */
uint8_t line_height;
/* Flags identifying various aspects of the font. */
uint8_t flags;
/* Fallback character to use for missing glyphs. */
mf_char fallback_character;
/* Function to get character width. Should return 0 if character is
* not found. */
uint8_t (*character_width)(const struct mf_font_s *font, mf_char character);
/* Function to render a character. Returns the character width or 0 if
* character is not found. */
uint8_t (*render_character)(const struct mf_font_s *font,
int16_t x0, int16_t y0,
mf_char character,
mf_pixel_callback_t callback,
void *state);
};
/* The flag definitions for the font.flags field. */
#define MF_FONT_FLAG_MONOSPACE 0x01
#define MF_FONT_FLAG_BW 0x02
/* Lookup structure for searching fonts by name. */
struct mf_font_list_s
{
const struct mf_font_list_s *next;
const struct mf_font_s *font;
};
/* Function to decode and render a single character.
*
* font: Pointer to the font definition.
* x0, y0: Upper left corner of the target area.
* character: The character code (unicode) to render.
* callback: Callback function to write out the pixels.
* state: Free variable for caller to use (can be NULL).
*
* Returns width of the character.
*/
MF_EXTERN uint8_t mf_render_character(const struct mf_font_s *font,
int16_t x0, int16_t y0,
mf_char character,
mf_pixel_callback_t callback,
void *state);
/* Function to get the width of a single character.
* This is not necessarily the bounding box of the character
* data, but rather the tracking width.
*
* font: Pointer to the font definition.
* character: The character code (unicode) to check width of.
*
* Returns width of the character in pixels.
*/
MF_EXTERN uint8_t mf_character_width(const struct mf_font_s *font,
mf_char character);
/* Count the amount of white space at the borders of a character.
*
* E.g. if the font->width and font->height are 10x20, but the character
* is only a thin line at the very left edge, this function will return
* (0, 0, 9, 0). If the character is fully whitespace, the function will
* return (10, 20, 0, 0).
*
* font: Pointer to the font definition.
* character: The character code (unicode) to check white space of.
* left: Number of empty rows at left edge. Can be NULL.
* top: Number of empty rows at top edge. Can be NULL.
* right: Number of empty rows at right edge. Can be NULL.
* bottom: Number of empty rows at bottom edge. Can be NULL.
*/
MF_EXTERN void mf_character_whitespace(const struct mf_font_s *font,
mf_char character,
uint8_t *left, uint8_t *top,
uint8_t *right, uint8_t *bottom);
/* Find a font based on name. The name can be either short name or full name.
* Note: You can pass MF_INCLUDED_FONTS to search among all the included .h
* files.
*
* name: Font name to search for.
* fonts: Pointer to the first font search entry.
*
* Returns a pointer to the font or NULL if not found.
*/
MF_EXTERN const struct mf_font_s *mf_find_font(const char *name);
/* Get the list of included fonts */
MF_EXTERN const struct mf_font_list_s *mf_get_font_list();
#endif
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