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/* ppmtosix.c - read a portable pixmap and produce a color sixel file
**
** Copyright (C) 1991 by Rick Vinci.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation. This software is provided "as is" without express or
** implied warranty.
**
** "-7bit" option added August 2023 by Scott Pakin <scott+pbm@pakin.org>.
*/
#include "ppm.h"
#define MAXVAL 100
#define MAXCOLORS 256
/* Named escape sequences */
static struct {
const char * DCS; /* Device Control String */
const char * ST; /* String Terminator */
const char * CSI; /* Control String Introducer */
const char * ESC; /* Escape character */
} eseqs;
static pixel** pixels; /* stored ppm pixmap input */
static colorhash_table cht;
int margin;
static void
initEscapeSequences(const int nbits) {
if (nbits == 8) {
eseqs.DCS = "\220";
eseqs.ST = "\234";
eseqs.CSI = "\233";
eseqs.ESC = "\033";
} else if (nbits == 7) {
eseqs.DCS = "\033P";
eseqs.ST = "\033\\";
eseqs.CSI = "\033[";
eseqs.ESC = "\033";
} else
pm_error("internal error: bad bit count");
}
static void
writePackedImage(colorhash_table const cht,
int const rows,
int const cols) {
int rownum, colnum, b, repeat, thiscolor, nextcolor;
const char* sixel = "@ACGO_";
pixel* pP;
for (rownum = 0; rownum < rows; ++rownum) {
b = rownum % 6;
repeat = 1;
for (colnum = 0, pP = pixels[rownum]; colnum < cols; ++colnum, ++pP) {
thiscolor = ppm_lookupcolor(cht, pP);
if (colnum == cols -1) /* last pixel in row */
if (repeat == 1)
printf("#%d%c", thiscolor, sixel[b]);
else
printf("#%d!%d%c", thiscolor, repeat, sixel[b]);
else { /* not last pixel in row */
nextcolor = ppm_lookupcolor(cht, pP+1);
if (thiscolor == nextcolor)
++repeat;
else {
if (repeat == 1)
printf( "#%d%c", thiscolor, sixel[b] );
else {
printf( "#%d!%d%c", thiscolor, repeat, sixel[b] );
repeat = 1;
}
}
}
}
printf( "$\n" ); /* Carriage Return */
if (b == 5)
printf("-\n"); /* Line Feed (one sixel height) */
}
}
static void
writeHeader() {
if (margin == 1)
printf( "%s%d;%ds", eseqs.CSI, 14, 72 );
printf( "%s", eseqs.DCS ); /* start with Device Control String */
printf( "0;0;8q" ); /* Horizontal Grid Size at 1/90" and graphics On */
printf( "\"1;1\n" ); /* set aspect ratio 1:1 */
}
static void
writeColorMap(colorhist_vector const chv,
int const colors,
pixval const maxval) {
int colornum;
pixel p;
for (colornum = 0; colornum < colors ; ++colornum) {
p = chv[colornum].color;
if (maxval != MAXVAL)
PPM_DEPTH( p, p, maxval, MAXVAL );
printf( "#%d;2;%d;%d;%d", colornum,
(int) PPM_GETR(p), (int) PPM_GETG(p), (int) PPM_GETB(p));
}
printf( "\n" );
}
static void
writeRawImage(colorhash_table const cht,
int const rows,
int const cols) {
int rownum, colnum, b;
const char * sixel = "@ACGO_";
pixel * pP;
for (rownum = 0; rownum < rows; ++rownum) {
b = rownum % 6;
for (colnum = 0, pP = pixels[rownum]; colnum < cols; ++colnum, ++pP)
printf( "#%d%c", ppm_lookupcolor(cht, pP), sixel[b] );
printf("$\n"); /* Carriage Return */
if (b == 5)
printf("-\n"); /* Line Feed (one sixel height) */
}
}
static void
writeEnd() {
if (margin == 1)
printf ("%s%d;%ds", eseqs.CSI, 1, 80);
printf( "%s\n", eseqs.ST );
}
int
main(int argc, const char ** argv) {
FILE * ifp;
int argn, rows, cols, colors;
int raw;
int nbits;
pixval maxval;
colorhist_vector chv;
const char* const usage = "[-raw] [-margin] [ppmfile]";
pm_proginit(&argc, argv);
argn = 1;
raw = 0;
margin = 0;
nbits = 8;
/* Parse args. */
while ( argn < argc && argv[argn][0] == '-' && argv[argn][1] != '\0' )
{
if ( pm_keymatch( argv[argn], "-raw", 2 ) )
raw = 1;
else if ( pm_keymatch( argv[argn], "-margin", 2 ) )
margin = 1;
else if ( pm_keymatch( argv[argn], "-7bit", 2 ) )
nbits = 7;
else
pm_usage( usage );
++argn;
}
if ( argn < argc )
{
ifp = pm_openr( argv[argn] );
++argn;
}
else
ifp = stdin;
if ( argn != argc )
pm_usage( usage );
/* Read in the whole ppmfile. */
pixels = ppm_readppm(ifp, &cols, &rows, &maxval);
pm_close(ifp);
/* Print a warning if we could lose accuracy when rescaling colors. */
if (maxval > MAXVAL)
pm_message(
"maxval is not %d - automatically rescaling colors", MAXVAL);
/* Figure out the colormap. */
pm_message("computing colormap...");
chv = ppm_computecolorhist( pixels, cols, rows, MAXCOLORS, &colors );
if (chv == (colorhist_vector) 0)
pm_error( "too many colors - try doing a 'pnmquant %d'", MAXCOLORS );
pm_message( "%d colors found", colors );
/* Make a hash table for fast color lookup. */
cht = ppm_colorhisttocolorhash( chv, colors );
initEscapeSequences(nbits);
writeHeader();
writeColorMap(chv, colors, maxval);
if (raw == 1)
writeRawImage(cht, rows, cols);
else
writePackedImage(cht, rows, cols);
writeEnd();
/* If the program failed, it previously aborted with nonzero completion
code, via various function calls.
*/
return 0;
}
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