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/*
* Copyright 2012 Michael Drake <tlsa@netsurf-browser.org>
*
* This file is part of libnsfb, http://www.netsurf-browser.org/
* Licenced under the MIT License,
* http://www.opensource.org/licenses/mit-license.php
*
* This is the *internal* interface for the cursor.
*/
#ifndef PALETTE_H
#define PALETTE_H 1
#include <stdint.h>
#include <limits.h>
#include "libnsfb.h"
#include "libnsfb_plot.h"
enum nsfb_palette_type_e {
NSFB_PALETTE_EMPTY, /**< empty palette object */
NSFB_PALETTE_NSFB_8BPP, /**< libnsfb's own 8bpp palette */
NSFB_PALETTE_OTHER /**< any other palette */
};
struct nsfb_palette_s {
enum nsfb_palette_type_e type; /**< Palette type */
uint8_t last; /**< Last used palette index */
nsfb_colour_t data[256]; /**< Palette for index modes */
};
/** Create an empty palette object. */
bool nsfb_palette_new(struct nsfb_palette_s **palette);
/** Free a palette object. */
void nsfb_palette_free(struct nsfb_palette_s *palette);
/** Generate libnsfb 8bpp default palette. */
void nsfb_palette_generate_nsfb_8bpp(struct nsfb_palette_s *palette);
static inline uint8_t nsfb_palette_best_match(
const struct nsfb_palette_s *palette,
nsfb_colour_t c)
{
uint8_t best_col = 0;
nsfb_colour_t palent;
int col;
int dr, dg, db; /* delta red, green blue values */
int cur_distance;
int best_distance = INT_MAX;
switch (palette->type) {
case NSFB_PALETTE_NSFB_8BPP:
/* Index into colour cube part */
dr = ((( c & 0xFF) * 5) + 128) / 256;
dg = ((((c >> 8) & 0xFF) * 7) + 128) / 256;
db = ((((c >> 16) & 0xFF) * 4) + 128) / 256;
col = 40 * dr + 5 * dg + db;
palent = palette->data[col];
dr = ( c & 0xFF) - ( palent & 0xFF);
dg = ((c >> 8) & 0xFF) - ((palent >> 8 ) & 0xFF);
db = ((c >> 16) & 0xFF) - ((palent >> 16) & 0xFF);
cur_distance = (dr * dr) + (dg * dg) + (db * db);
best_col = col;
best_distance = cur_distance;
/* Index into grayscale part */
col = (( c & 0xFF) +
((c >> 8) & 0xFF) +
((c >> 16) & 0xFF) + (45 / 2)) / (15 * 3) - 1 + 240;
palent = palette->data[col];
dr = ( c & 0xFF) - ( palent & 0xFF);
dg = ((c >> 8) & 0xFF) - ((palent >> 8) & 0xFF);
db = ((c >> 16) & 0xFF) - ((palent >> 16) & 0xFF);
cur_distance = (dr * dr) + (dg * dg) + (db * db);
if (cur_distance < best_distance) {
best_distance = cur_distance;
best_col = col;
}
break;
case NSFB_PALETTE_OTHER:
/* Try all colours in palette */
for (col = 0; col <= palette->last; col++) {
palent = palette->data[col];
dr = ( c & 0xFF) - ( palent & 0xFF);
dg = ((c >> 8) & 0xFF) - ((palent >> 8) & 0xFF);
db = ((c >> 16) & 0xFF) - ((palent >> 16) & 0xFF);
cur_distance = (dr * dr) + (dg * dg) + (db * db);
if (cur_distance < best_distance) {
best_distance = cur_distance;
best_col = col;
}
}
break;
default:
break;
}
return best_col;
}
#endif /* PALETTE_H */
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