/*
* This file is subject to the terms of the GFX License. If a copy of
* the license was not distributed with this file, you can obtain one at:
*
* http://ugfx.org/license.html
*/
#include "mf_rlefont.h"
#ifndef MF_NO_COMPILE
/* Number of reserved codes before the dictionary entries. */
#define DICT_START 24
/* Special reference to mean "fill with zeros to the end of the glyph" */
#define REF_FILLZEROS 16
/* RLE codes */
#define RLE_CODEMASK 0xC0
#define RLE_VALMASK 0x3F
#define RLE_ZEROS 0x00
#define RLE_64ZEROS 0x40
#define RLE_ONES 0x80
#define RLE_SHADE 0xC0
/* Dictionary "fill entries" for encoding bits directly. */
#define DICT_START7BIT 4
#define DICT_START6BIT 132
#define DICT_START5BIT 196
#define DICT_START4BIT 228
#define DICT_START3BIT 244
#define DICT_START2BIT 252
/* Find a pointer to the glyph matching a given character by searching
* through the character ranges. If the character is not found, return
* pointer to the default glyph.
*/
static const uint8_t *find_glyph(const struct mf_rlefont_s *font,
uint16_t character)
{
unsigned i, index;
const struct mf_rlefont_char_range_s *range;
for (i = 0; i < font->char_range_count; i++)
{
range = &font->char_ranges[i];
index = character - range->first_char;
if (character >= range->first_char && index < range->char_count)
{
uint16_t offset = range->glyph_offsets[index];
return &range->glyph_data[offset];
}
}
return 0;
}
/* Structure to keep track of coordinates of the next pixel to be written,
* and also the bounds of the character. */
struct renderstate_r
{
int16_t x_begin;
int16_t x_end;
int16_t x;
int16_t y;
int16_t y_end;
mf_pixel_callback_t callback;
void *state;
};
/* Call the callback to write one pixel to screen, and advance to next
* pixel position. */
static void write_pixels(struct renderstate_r *rstate, uint16_t count,
uint8_t alpha)
{
uint8_t rowlen;
/* Write row-by-row if the run spans multiple rows. */
while (rstate->x + count >= rstate->x_end)
{
rowlen = rstate->x_end - rstate->x;
rstate->callback(rstate->x, rstate->y, rowlen, alpha, rstate->state);
count -= rowlen;
rstate->x = rstate->x_begin;
rstate->y++;
}
/* Write the remaining part */
if (count)
{
rstate->callback(rstate->x, rstate->y, count, alpha, rstate->state);
rstate->x += count;
}
}
/* Skip the given number of pixels (0 alpha) */
static void skip_pixels(struct renderstate_r *rstate, uint16_t count)
{
rstate->x += count;
while (rstate->x >= rstate->x_end)
{
rstate->x -= rstate->x_end - rstate->x_begin;
rstate->y++;
}
}
/* Decode and write out a RLE-encoded dictionary entry. */
static void write_rle_dictentry(const struct mf_rlefont_s *font,
struct renderstate_r *rstate,
uint8_t index)
{
uint16_t offset = font->dictionary_offsets[index];
uint16_t length = font->dictionary_offsets[index + 1] - offset;
uint16_t i;
for (i = 0; i < length; i++)
{
uint8_t code = font->dictionary_data[offset + i];
if ((code & RLE_CODEMASK) == RLE_ZEROS)
{
skip_pixels(rstate, code & RLE_VALMASK);
}
else if ((code & RLE_CODEMASK) == RLE_64ZEROS)
{
skip_pixels(rstate, ((code & RLE_VALMASK) + 1) * 64);
}
else if ((code & RLE_CODEMASK) == RLE_ONES)
{
write_pixels(rstate, (code & RLE_VALMASK) + 1, 255);
}
else if ((code & RLE_CODEMASK) == RLE_SHADE)
{
uint8_t count, alpha;
count = ((code & RLE_VALMASK) >> 4) + 1;
alpha = ((code & RLE_VALMASK) & 0xF) * 0x11;
write_pixels(rstate, count, alpha);
}
}
}
/* Get bit count for the "fill entries" */
static uint8_t fillentry_bitcount(uint8_t index)
{
if (index >= DICT_START2BIT)
return 2;
else if (index >= DICT_START3BIT)
return 3;
else if (index >= DICT_START4BIT)
return 4;
else if (index >= DICT_START5BIT)
return 5;
else if (index >= DICT_START6BIT)
return 6;
else
return 7;
}
/* Decode and write out a direct binary codeword */
static void write_bin_codeword(const struct mf_rlefont_s *font,
struct renderstate_r *rstate,
uint8_t code)
{
uint8_t bitcount = fillentry_bitcount(code);
uint8_t byte = code - DICT_START7BIT;
uint8_t runlen = 0;
(void) font;
while (bitcount--)
{
if (byte & 1)
{
runlen++;
}
else
{
if (runlen)
{
write_pixels(rstate, runlen, 255);
runlen = 0;
}
skip_pixels(rstate, 1);
}
byte >>= 1;
}
if (runlen)
write_pixels(rstate, runlen, 255);
}
/* Decode and write out a reference codeword */
static void write_ref_codeword(const struct mf_rlefont_s *font,
struct renderstate_r *rstate,
uint8_t code)
{
if (code <= 15)
{
write_pixels(rstate, 1, 0x11 * code);
}
else if (code == REF_FILLZEROS)
{
/* Fill with zeroes to end */
rstate->y = rstate->y_end;
}
else if (code < DICT_START)
{
/* Reserved */
}
else if (code < DICT_START + font->rle_entry_count)
{
write_rle_dictentry(font, rstate, code - DICT_START);
}
else
{
write_bin_codeword(font, rstate, code);
}
}
/* Decode and write out a reference encoded dictionary entry. */
static void write_ref_dictentry(const struct mf_rlefont_s *font,
struct renderstate_r *rstate,
uint8_t index)
{
uint16_t offset = font->dictionary_offsets[index];
uint16_t length = font->dictionary_offsets[index + 1] - offset;
uint16_t i;
for (i = 0; i < length; i++)
{
uint8_t code = font->dictionary_data[offset + i];
write_ref_codeword(font, rstate, code);
}
}
/* Decode and write out an arbitrary glyph codeword */
static void write_glyph_codeword(const struct mf_rlefont_s *font,
struct renderstate_r *rstate,
uint8_t code)
{
if (code >= DICT_START + font->rle_entry_count &&
code < DICT_START + font->dict_entry_count)
{
write_ref_dictentry(font, rstate, code - DICT_START);
}
else
{
write_ref_codeword(font, rstate, code);
}
}
uint8_t mf_rlefont_render_character(const struct mf_font_s *font,
int16_t x0, int16_t y0,
uint16_t character,
mf_pixel_callback_t callback,
void *state)
{
const uint8_t *p;
uint8_t width;
struct renderstate_r rstate;
rstate.x_begin = x0;
rstate.x_end = x0 + font->width;
rstate.x = x0;
rstate.y = y0;
rstate.y_end = y0 + font->height;
rstate.callback = callback;
rstate.state = state;
p = find_glyph((struct mf_rlefont_s*)font, character);
if (!p)
return 0;
width = *p++;
while (rstate.y < rstate.y_end)
{
write_glyph_codeword((struct mf_rlefont_s*)font, &rstate, *p++);
}
return width;
}
uint8_t mf_rlefont_character_width(const struct mf_font_s *font,
uint16_t character)
{
const uint8_t *p;
p = find_glyph((struct mf_rlefont_s*)font, character);
if (!p)
return 0;
return *p;
}
#endif //MF_NO_COMPILE