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quantize to ansi256, atrociously #4

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nick black 2019-12-15 20:53:10 -05:00
parent f9ac7a7737
commit 041e6438e3
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GPG Key ID: 5F43400C21CBFACC
2 changed files with 33 additions and 3 deletions
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2
src/demo/luigi.c
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@ -142,7 +142,7 @@ draw_luigi(struct ncplane* n, const char* sprite){
int luigi_demo(struct notcurses* nc){
struct ncplane* n = notcurses_stdplane(nc);
int averr = 0;
struct ncvisual* nv = ncplane_visual_open(n, "../tests/lamepatents.jpg", &averr);
struct ncvisual* nv = ncplane_visual_open(n, "../tests/megaman2.bmp", &averr);
if(nv == NULL){
return -1;
}

34
src/lib/notcurses.c
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@ -929,6 +929,27 @@ term_esc_rgb(FILE* out, int esc, unsigned r, unsigned g, unsigned b){
return 0;
}
// For our first attempt, O(1) uniform conversion from 8-bit r/g/b down to
// ~2.4-bit 6x6x6 ANSI cube + greyscale (assumed on entry; I know no way to
// even semi-portably recover the palette) proceeds via: map each 8-bit to
// a 5-bit target grey. if all 3 components match, select that grey.
// otherwise, c / 42.7 to map to 6 values. this never generates pure black
// nor white, though, lame...FIXME
static inline int
rgb_to_ansi256(unsigned r, unsigned g, unsigned b){
const unsigned GREYMASK = 0xf8;
r &= GREYMASK;
g &= GREYMASK;
b &= GREYMASK;
if(r == g && g == b){ // 5 MSBs match, return grey
return 216 + (r >> 3u);
}
r /= 43;
g /= 43;
b /= 43;
return r * 36 + g * 6 + b;
}
static int
term_bg_rgb8(notcurses* nc, FILE* out, unsigned r, unsigned g, unsigned b){
// We typically want to use tputs() and tiperm() to acquire and write the
@ -939,13 +960,16 @@ term_bg_rgb8(notcurses* nc, FILE* out, unsigned r, unsigned g, unsigned b){
if(nc->RGBflag){
return term_esc_rgb(out, 4, r, g, b);
}else{
if(nc->setaf == NULL){
if(nc->setab == NULL){
return -1;
}
// For 256-color indexed mode, start constructing a palette based off
// the inputs *if we can change the palette*. If more than 256 are used on
// a single screen, start... combining close ones? For 8-color mode, simple
// interpolation. I have no idea what to do for 88 colors. FIXME
if(nc->colors >= 256){
term_emit("setab", tiparm(nc->setab, rgb_to_ansi256(r, g, b)), out, false);
}
return -1;
}
return 0;
@ -964,6 +988,9 @@ term_fg_rgb8(notcurses* nc, FILE* out, unsigned r, unsigned g, unsigned b){
if(nc->setaf == NULL){
return -1;
}
if(nc->colors >= 256){
term_emit("setaf", tiparm(nc->setaf, rgb_to_ansi256(r, g, b)), out, false);
}
// For 256-color indexed mode, start constructing a palette based off
// the inputs *if we can change the palette*. If more than 256 are used on
// a single screen, start... combining close ones? For 8-color mode, simple
@ -1246,7 +1273,10 @@ blocking_write(int fd, const char* buf, size_t buflen){
}
// determine the best palette for the current frame, and write the necessary
// escape sequences to 'out'.
// escape sequences to 'out'. for now, we just assume the ANSI palettes. at
// 256 colors, this is the 16 normal ones, 6x6x6 color cubes, and 32 greys.
// it's probably better to sample the darker regions rather than cover so much
// chroma, but whatever....FIXME
static int
prep_optimized_palette(notcurses* nc, FILE* out __attribute__ ((unused))){
if(nc->RGBflag){