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sixel: implement extract_data_table() #1378

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nick black 2021-02-28 06:33:43 -05:00 committed by Nick Black
parent 93da926e47
commit cb2e905ccf
1 changed files with 60 additions and 0 deletions
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60
src/lib/sixel.c
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@ -7,11 +7,20 @@ break_sixel_comps(unsigned char comps[static 3], uint32_t rgba){
comps[2] = ncpixel_b(rgba) * 100 / 255;
}
// first pass: extract up to 256 sixelspace colors over arbitrarily many sixels
// sixelspace is 0..100 corresponding to 0..255, lame =[
typedef struct colortable {
int colors;
int sixelcount;
unsigned char table[3 * 256];
} colortable;
// second pass: construct data for extracted colors over the sixels
typedef struct sixeltable {
const colortable* ctab;
unsigned char* data; // |colors|x|sixelcount|-byte arrays
} sixeltable;
// returns the index at which the provided color can be found, possibly
// inserting it into the table. returns -1 if the color is not in the
// table and the table is full.
@ -67,6 +76,40 @@ extract_color_table(ncplane* nc, const uint32_t* data, int placey, int placex,
return -1;
}
}
++ctab->sixelcount;
}
}
return 0;
}
static int
extract_data_table(ncplane* nc, const uint32_t* data, int placey, int placex,
int linesize, int begy, int begx, int leny, int lenx,
sixeltable* stab){
for(int c = 0 ; c < stab->ctab->colors ; ++c){
int dimy, dimx, x, y;
int pos = 0;
ncplane_dim_yx(nc, &dimy, &dimx);
int visy = begy;
for(y = placey ; visy < (begy + leny) && y < dimy ; ++y, visy += 6){
int visx = begx;
for(x = placex ; visx < (begx + lenx) && x < dimx ; ++x, visx += 1){
for(int sy = visy ; sy < dimy && sy < visy + 6 ; ++sy){
const uint32_t* rgb = (const uint32_t*)(data + (linesize * sy) + (visx * 4));
if(rgba_trans_p(ncpixel_a(*rgb))){
//fprintf(stderr, "transparent\n");
continue;
}
unsigned char comps[3];
break_sixel_comps(comps, *rgb);
//fprintf(stderr, "%d/%d/%d\n", comps[0], comps[1], comps[2]);
if(memcmp(comps, stab->ctab->table + c * 3, 3) == 0){
stab->data[c * stab->ctab->sixelcount + pos] |= (1u << (sy - visy));
}
}
//fprintf(stderr, "color %d pos %d: %u\n", c, pos, stab->data[c * stab->ctab->sixelcount + pos]);
++pos;
}
}
}
return 0;
@ -162,14 +205,31 @@ int sixel_blit(ncplane* nc, int placey, int placex, int linesize,
return -1;
}
ctab->colors = 0;
ctab->sixelcount = 0;
memset(ctab->table, 0xff, 3);
if(extract_color_table(nc, data, placey, placex, linesize,
begy, begx, leny, lenx, ctab)){
free(ctab);
return -1;
}
sixeltable stable = {
.ctab = ctab,
.data = malloc(ctab->colors * ctab->sixelcount),
};
if(stable.data == NULL){
free(ctab);
return -1;
}
memset(stable.data, 0, ctab->colors * ctab->sixelcount);
if(extract_data_table(nc, data, placey, placex, linesize,
begy, begx, leny, lenx, &stable)){
free(stable.data);
free(ctab);
return -1;
}
int r = sixel_blit_inner(nc, placey, placex, linesize, data,
begy, begx, leny, lenx, ctab);
free(stable.data);
free(ctab);
return r;
}