/* * Usage: resample npixels [input] [B C] *	horizontally scales the input (default standard input) picture *	to be npixels wide.  B and C are parameters of the resampling kernel, *	which is (1-B)*ease + B*bspline + C*crisp. *	Default parameters are B=1/3, C=1/3 * * D. P. Mitchell  86/03/05. * Remangled td89.11.16 (removed Hitachi gamma-correction, tweaked for speed) */#include <u.h>#include <libc.h>#include <libg.h>#include <fb.h>#define MIN(X,Y) ((X) < (Y) ? (X) : (Y))#define HALFWIDTH 2.0#define	SCALE	4096	/* filter coefficients are scaled integers */typedef struct Filterprog {	short *coef;			/* Coefficients for this pixel */	short *ecoef;			/* End of coefficient list */	short decr;			/* how much to decrement (something) by */	struct Filterprog *next;	/* coefficients for next pixel */}Filterprog;float itox, jtox, xtoi, xtoj;int startprog;Filterprog *prog;int nchan;double B = 0.3333333333;double C = 0.3333333333;double bspline(double x){	if (x < 1.0)		return 0.5*x*x*x - x*x + 2.0/3.0;	else		return -x*x*x/6.0 + x*x - 2.0*x + 4.0/3.0;}double ease(double x){	if (x < 1.0)		return 2.0*x*x*x - 3.0*x*x + 1.0;	else		return 0.0;}double crisp(double x){	if (x < 1.0)		return -x*x*x + x*x;	else		return -x*x*x + 5.0*x*x - 8.0*x + 4.0;}double filter(double x){	if (x < 0.0) x = -x;	if (x >= 2.0) return 0.0;	return (1.0 -B)*ease(x) + B*bspline(x) + C*crisp(x);}static Filterprog *impulse_response(int j){	int start, stop, i, count;	float x, y;	Filterprog *fp;	fp = (Filterprog *)malloc(sizeof(Filterprog));	if(fp==0){	NoSpace:		fprint(2, "resample: no space\n");		exits("no space");	}	x = jtox*((float)j + 0.5);	start = floor(xtoi*(x - HALFWIDTH) - 0.5);	start++;	stop = floor(xtoi*(x + HALFWIDTH) - 0.5);	count=1+stop-start;	fp->coef = (short *)malloc(count * sizeof(short));	if(fp->coef==0) goto NoSpace;	fp->ecoef=fp->coef+count;	fp->decr = start*nchan;	fp->next = 0;	for (i = start; i <= stop; i++) {		y = itox*((float)i + 0.5);		fp->coef[i - start] = SCALE*filter(x - y) + 0.5;	}	return fp;}int gcd(int u, int v){	if (v > u)		return gcd(v, u);	else if (v == 0)		return u;	else		return gcd(v, u % v);}void compile_resampling_program(int m, int n){	int j, u, period;	Filterprog *temp, *fp, **fpp;	float x;	u = MIN(m, n);	itox = (float)u/(float)m;	jtox = (float)u/(float)n;	xtoi = 1.0/itox;	xtoj = 1.0/jtox;	period = n / gcd(m, n);	fpp = &fp;	for (j = 0; j < period + 1; j++) {		*fpp = impulse_response(j);		fpp = &(*fpp)->next;	}	startprog = fp->decr;	for (temp = fp, j = 0; j < period; j++) {		temp->decr = (temp->ecoef - temp->coef)*nchan - temp->next->decr + temp->decr;		if (j < period - 1)			temp = temp->next;	}	temp->next = fp;			/* circular */	prog = fp;}void resample(unsigned char input[], unsigned char *output, int m, int n){	static init = 0;	unsigned char *src;	short *coef, *ecoef;	int sig;	short temp;	Filterprog *fp;	if (init == 0) {		init = 1;		compile_resampling_program(m, n);	}	fp = prog;	src = input + startprog;	for (fp = prog; --n >= 0; fp = fp->next) {		coef=fp->coef;		ecoef= fp->ecoef;		sig=0;		while(coef!=ecoef){			sig += *src * *coef++;			src+=nchan;		}		if(m>n) sig=itox*(double)sig;		if(sig<0) *output=0;		else if(sig>=255*SCALE) *output=255;		else *output=sig/SCALE;		output+=nchan;		src -= fp->decr;	}}main(int argc, char *argv[]){	PICFILE *infile, *outfile;	int outwidth, n;	int i;	unsigned char *inrgba, *outrgba;	char *inname;	argc=getflags(argc, argv, "");	switch(argc){	default: usage("newwidth [picture] [B C]");	case 4:	B=atof(argv[2]);		C=atof(argv[3]);	case 2: inname="IN";		break;	case 5:	B=atof(argv[3]);		C=atof(argv[4]);	case 3: inname=argv[2];		break;	}	outwidth=atoi(argv[1]);	infile=picopen_r(inname);	if(infile==0){		perror(inname);		exits("open input");	}	nchan=PIC_NCHAN(infile);	inrgba=(unsigned char *)malloc((PIC_WIDTH(infile)+2000)*nchan);	if(inrgba==0){	NoSpace:		fprint(2, "%s: no space\n", argv[0]);		exits("no space");	}	memset(inrgba, 0, (PIC_WIDTH(infile)+2000)*nchan);	inrgba+=1000*nchan;	outrgba=(unsigned char *)malloc(outwidth * nchan);	if(outrgba==0) goto NoSpace;	outfile=picopen_w("OUT", infile->type,		0, 0, outwidth, PIC_HEIGHT(infile), infile->chan, argv, infile->cmap);	if(outfile==0){		perror(argv[0]);		exits("create output");	}	while(picread(infile, (char *)inrgba)){		for(n=0;n!=nchan;n++)			resample(inrgba+n, outrgba+n, PIC_WIDTH(infile), outwidth);		picwrite(outfile, (char *)outrgba);	}	exits("");}