extend -b and -c to -B and -C with optional α parameter

Reference: /n/atom/patch/applied2013/alphacrop
Date: Wed Jun 19 03:22:35 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/cmd/crop.c	Wed Jun 19 03:22:29 2013
+++ /sys/src/cmd/crop.c	Wed Jun 19 03:22:29 2013
@@ -16,7 +16,7 @@
 void
 usage(void)
 {
-	fprint(2, "usage: crop [-b rgb] [-c rgb] [-i ±inset | -r R | -x ±inset | -y ±inset] [-t tx ty] [imagefile]\n");
+	fprint(2, "usage: crop [-b rgb] [-B rgbα] [-c rgb] [-C rgbα] [-i ±inset | -r R | -x ±inset | -y ±inset] [-t tx ty] [imagefile]\n");
 	fprint(2, "\twhere R is a rectangle: minx miny maxx maxy\n");
 	fprint(2, "\twhere rgb is a color: red green blue\n");
 	exits("usage");
@@ -35,7 +35,7 @@
 }
 
 Rectangle
-crop(Memimage *m, ulong c)
+crop(Memimage *m, ulong c, ulong bg)
 {
 	Memimage *n;
 	int x, y, bpl, wpl;
@@ -52,6 +52,7 @@
 		n = allocmemimage(m->r, RGBA32);
 		if(n == nil)
 			sysfatal("can't allocate temporary image: %r");
+		memfillcolor(n, bg);
 		memimagedraw(n, n->r, m, m->r.min, nil, ZP, S);
 		m = n;
 	}
@@ -85,7 +86,7 @@
 void
 main(int argc, char *argv[])
 {
-	int fd, mode, red, green, blue;
+	int fd, mode, red, green, blue, α;
 	Rectangle r, rparam;
 	Point t;
 	Memimage *m, *new;
@@ -102,51 +103,55 @@
 
 	ARGBEGIN{
 	case 'b':
-		if(bg != 0)
-			usage();
-		red = getint(ARGF())&0xFF;
-		green = getint(ARGF())&0xFF;
-		blue = getint(ARGF())&0xFF;
-		bg = (red<<24)|(green<<16)|(blue<<8)|0xFF;
+	case 'B':
+		red = getint(EARGF(usage()))&0xFF;
+		green = getint(EARGF(usage()))&0xFF;
+		blue = getint(EARGF(usage()))&0xFF;
+		α = 0xff;
+		if(ARGC() == 'B')
+			α = getint(EARGF(usage()))&0xFF;
+		bg = red<<24 | green<<16 | blue<<8 | α;
 		break;
 	case 'c':
-		if(cropval != 0)
-			usage();
-		red = getint(ARGF())&0xFF;
-		green = getint(ARGF())&0xFF;
-		blue = getint(ARGF())&0xFF;
-		cropval = (red<<24)|(green<<16)|(blue<<8)|0xFF;
+	case 'C':
+		red = getint(EARGF(usage()))&0xFF;
+		green = getint(EARGF(usage()))&0xFF;
+		blue = getint(EARGF(usage()))&0xFF;
+		α = 0xff;
+		if(ARGC() == 'C')
+			α = getint(EARGF(usage()))&0xFF;
+		cropval = red<<24 | green<<16 | blue<<8 | α;
 		break;
 	case 'i':
 		if(mode != None)
 			usage();
 		mode = Inset;
-		rparam.min.x = getint(ARGF());
+		rparam.min.x = getint(EARGF(usage()));
 		break;
 	case 'x':
 		if(mode != None && mode != Insetxy)
 			usage();
 		mode = Insetxy;
-		rparam.min.x = getint(ARGF());
+		rparam.min.x = getint(EARGF(usage()));
 		break;
 	case 'y':
 		if(mode != None && mode != Insetxy)
 			usage();
 		mode = Insetxy;
-		rparam.min.y = getint(ARGF());
+		rparam.min.y = getint(EARGF(usage()));
 		break;
 	case 'r':
 		if(mode != None)
 			usage();
 		mode = Set;
-		rparam.min.x = getint(ARGF());
-		rparam.min.y = getint(ARGF());
-		rparam.max.x = getint(ARGF());
-		rparam.max.y = getint(ARGF());
+		rparam.min.x = getint(EARGF(usage()));
+		rparam.min.y = getint(EARGF(usage()));
+		rparam.max.x = getint(EARGF(usage()));
+		rparam.max.y = getint(EARGF(usage()));
 		break;
 	case 't':
-		t.x = getint(ARGF());
-		t.y = getint(ARGF());
+		t.x = getint(EARGF(usage()));
+		t.y = getint(EARGF(usage()));
 		break;
 	default:
 		usage();
@@ -172,7 +177,7 @@
 
 	r = m->r;
 	if(cropval != 0){
-		r = crop(m, cropval);
+		r = crop(m, cropval, bg);
 		m->clipr = r;
 	}
 
@@ -196,12 +201,8 @@
 	new = allocmemimage(r, m->chan);
 	if(new == nil)
 		sysfatal("can't allocate new image: %r");
-	if(bg != 0)
-		memfillcolor(new, bg);
-	else
-		memfillcolor(new, 0x000000FF);
-
-	memimagedraw(new, m->clipr, m, m->clipr.min, nil, ZP, S);
+	memfillcolor(new, bg);
+	memimagedraw(new, m->clipr, m, m->clipr.min, nil, ZP, SatopD);
 	dw = byteaddr(new, ZP) - byteaddr(new, t);
 	new->r = rectaddpt(new->r, t);
 	new->zero += dw;