1 /* A compressed font format based on run length encoding and dictionary
2  * compression.
3  */
4 
5 #ifndef _MF_RLEFONT_H_
6 #define _MF_RLEFONT_H_
7 
8 #include "mf_font.h"
9 
10 /* Versions of the RLE font format that are supported. */
11 #define MF_RLEFONT_VERSION_4_SUPPORTED 1
12 
13 /* Structure for a range of characters. This implements a sparse storage of
14  * character indices, so that you can e.g. pick a 100 characters in the middle
15  * of the UTF16 range and just store them. */
16 struct mf_rlefont_char_range_s
17 {
18     /* The number of the first character in this range. */
19     uint16_t first_char;
20 
21     /* The total count of characters in this range. */
22     uint16_t char_count;
23 
24     /* Lookup table with the start indices into glyph_data. */
25     uint16_t *glyph_offsets;
26     uint32_t glyph_offsets_size;
27     uint32_t glyph_offsets_fp_offset;
28 
29     /* The encoded glyph data for glyphs in this range. */
30     uint8_t *glyph_data;
31     uint32_t glyph_data_size;
32     uint32_t glyph_data_fp_offset;
33 };
34 
35 /* Structure for a single encoded font. */
36 struct mf_rlefont_s
37 {
38     struct mf_font_s font;
39 
40     /* Version of the font definition used. */
41     uint8_t version;
42 
43     /* Big array of the data for all the dictionary entries. */
44     uint8_t *dictionary_data;
45     uint32_t dictionary_data_size;
46     uint32_t dictionary_data_fp_offset;
47 
48     /* Lookup table with the start indices into dictionary_data.
49      * Contains N+1 entries, so that the length of the entry can
50      * be determined by subtracting from the next offset. */
51     uint16_t *dictionary_offsets;
52     uint32_t dictionary_offsets_size;
53     uint32_t dictionary_offsets_fp_offset;
54 
55     /* Number of dictionary entries using the RLE encoding.
56      * Entries starting at this index use the dictionary encoding. */
57     uint8_t rle_entry_count;
58 
59     /* Total number of dictionary entries.
60      * Entries after this are nonexistent. */
61     uint8_t dict_entry_count;
62 
63     /* Number of discontinuous character ranges */
64     uint8_t char_range_count;
65 
66     /* Array of the character ranges */
67     struct mf_rlefont_char_range_s *char_ranges;
68 };
69 
70 #ifdef MF_RLEFONT_INTERNALS
71 /* Internal functions, don't use these directly. */
72 MF_EXTERN uint8_t mf_rlefont_render_character(const struct mf_font_s *font,
73                                               int16_t x0, int16_t y0,
74                                               mf_char character,
75                                               mf_pixel_callback_t callback,
76                                               void *state);
77 
78 MF_EXTERN uint8_t mf_rlefont_character_width(const struct mf_font_s *font,
79                                              mf_char character);
80 #endif
81 
82 #endif
83