shithub: ifilter

ref: 0e8a14266851df16bcdf4ef9727dd22dc052e310
dir: /cfilter.c/

#include <u.h>
#include <libc.h>
#include <draw.h>
#include <memdraw.h>

#define MIN(x,y) ((x)<(y)?(x):(y))

typedef struct Filter Filter;

struct Filter
{
	const char *name;
	void (*filter)(uchar[3], float);
};

void
grayscale(uchar p[3], float)
{
	uchar v = 0.2126*p[2] + 0.7152*p[1] + 0.0722*p[0];
	p[0] = p[1] = p[2] = v;
}

void
sepia(uchar p[3], float)
{
	float r, g, b;

	r = 0.393*p[2] + 0.769*p[1] + 0.189*p[0];
	g = 0.349*p[2] + 0.686*p[1] + 0.168*p[0];
	b = 0.272*p[2] + 0.534*p[1] + 0.131*p[0];
	p[2] = MIN(r, 255);
	p[1] = MIN(g, 255);
	p[0] = MIN(b, 255);
}

void
invert(uchar p[3], float)
{
	p[0] = 255 - p[0];
	p[1] = 255 - p[1];
	p[2] = 255 - p[2];
}

void
shade(uchar p[3], float factor)
{
	p[0] = p[0] * (1 - factor);
	p[1] = p[1] * (1 - factor);
	p[2] = p[2] * (1 - factor);
}

void
tint(uchar p[3], float factor)
{
	p[0] = p[0] + (255.0 - p[0]) * factor;
	p[1] = p[1] + (255.0 - p[1]) * factor;
	p[2] = p[2] + (255.0 - p[2]) * factor;
}

void
usage(void)
{
	fprint(2, "usage: %s [-f factor] [grayscale|sepia|invert|shade|tint]\n", argv0);
	exits("usage");
}

static Filter filters[] = {
	{ "grayscale", grayscale },
	{ "sepia", sepia },
	{ "invert", invert },
	{ "shade", shade },
	{ "tint", tint },
};

void
main(int argc, char *argv[])
{
	Memimage *o, *i;
	int w, h, p, n;
	uchar *buf;
	Filter *f;
	float factor;

	f = nil;
	factor = 0.0;
	ARGBEGIN{
	case 'f':
		factor = (float)atof(EARGF(usage()));
		break;
	default:
		usage();
		break;
	}ARGEND;
	if(argc!=1)
		usage();
	for(n=0; n<nelem(filters); n++){
		if(strcmp(*argv, filters[n].name)==0){
			f = filters+n;
			break;
		}
	}
	if(f==nil)
		usage();
	if(factor<0.0 || factor>1.0){
		fprint(2, "factor should be between 0.0 and 1.0\n");
		exits("invalid factor");
	}
	if(memimageinit()<0)
		sysfatal("memimageinit: %r");
	o = readmemimage(0);
	if(o==nil)
		sysfatal("readmemimage: %r");
	i = allocmemimage(o->r, XRGB32);
	memimagedraw(i, i->r, o, o->r.min, nil, ZP, S);
	freememimage(o);
	w = Dx(i->r);
	h = Dy(i->r);
	n = 4*w*h*sizeof(uchar);
	buf = malloc(n);
	if(buf==nil)
		sysfatal("malloc: %r");
	if(unloadmemimage(i, i->r, buf, n)<0)
		sysfatal("unloadmemimage: %r");
	freememimage(i);
	for(p = 0; p < n; p+=4)
		f->filter(buf+p, factor);
	print("   x8r8g8b8 %11d %11d %11d %11d ", 0, 0, w, h);
	write(1, buf, n);
	exits(nil);
}