shithub: ifilter

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add a simple pixelation filter

--- a/README

+++ b/README

@@ -24,6 +24,10 @@

 -----

 blur implements blurring algorithms.

+Usage: blur [-s size] [box|pixelate]

+

 Available filters are:

 - box: 3x3 box blur

+- pixelate: a simple pixelation filter using `-s` argument as pixel size

+

--- a/blur.c

+++ b/blur.c

@@ -4,6 +4,7 @@

 #include <memdraw.h>

 typedef struct Filter Filter;

+int size;

 struct Filter

 {

@@ -11,8 +12,6 @@

 	uchar* (*filter)(uchar *data, int w, int h, int depth);

 };

-enum { R, G, B };

-

 uchar*

 box(uchar *data, int w, int h, int depth)

 {

@@ -43,15 +42,43 @@

 	return out;

 }

+uchar*

+pixelate(uchar *data, int w, int h, int depth)

+{

+	uchar *out;

+	int x, y, i, ox, oy, oi;

+

+	if(size < 0)

+		sysfatal("pixelate filter needs a size argument");

+	out = malloc(depth*w*h*sizeof(uchar));

+	if(out == nil)

+		return nil;

+	for(y = 0; y < h; y += size){

+		for(x = 0; x < w; x += size){

+			i = (x + w * y) * depth;

+			for(oy = y; oy < y+size; oy++){

+				for(ox = x; ox < x+size; ox++){

+					oi = (ox + w * oy) * depth;

+					out[oi + 0] = data[i + 0];

+					out[oi + 1] = data[i + 1];

+					out[oi + 2] = data[i + 2];

+				}

+			}

+		}

+	}

+	return out;

+}

+

 void

 usage(void)

 {

-	fprint(2, "usage: %s [box]\n", argv0);

+	fprint(2, "usage: %s [-s size] [box|pixelate]\n", argv0);

 	exits("usage");

 }

 static Filter filters[] = {

 	{ "box", box },

+	{ "pixelate", pixelate },

 };

 void

@@ -62,8 +89,12 @@

 	uchar *buf, *out;

 	Filter *f;

+	size = -1;

 	f = nil;

 	ARGBEGIN{

+	case 's':

+		size = atoi(EARGF(usage()));

+		break;

 	default:

 		usage();

 		break;