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image/histogram: display histograms in a single window and let the user select a region

i also fixed the warp transformations. i wrote the first
version in an outdated drawterm running an old version
of devdraw where memaffinewarp(2) used the dst->clipr as
the origin for the blitting. now it uses dst->r, and the
screen is a backed-store "view" of the actual screenimage
so internally, in devdraw, it refers to a Memimage with
its r equal to that of the entire display, and its r.min
always equal to ZP.

--- a/sys/man/1/image

+++ b/sys/man/1/image

@@ -114,8 +114,8 @@

 reads an image from a given

 .I file

 or stdin, opens a minimal visualizer in the current window, and

-generates a histogram for each of its channels in multiple,

-independent windows.

+generates a histogram for each of its channels in an independent

+window.

 .br

 When in the visualizer, use LMB to move the image around, scroll up/down or

 MMB to control zoom and RMB to open a menu with some extra options.

--- a/sys/src/cmd/image/histogram.c

+++ b/sys/src/cmd/image/histogram.c

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

 enum {

 	Hmargin	= 10,

 	Vmargin = 15,

+

+	DOrange	= 0xFFA500FF,

 };

 typedef struct Sampler Sampler;

@@ -29,11 +31,10 @@

 {

 	char	*title;

 	Image	*img;

-	Screen	*scr;

-	Image	*win;

 	uvlong	vals[256];

+	uvlong	avg;

+	uvlong	max;

 	ulong	col;

-	int	pid;

 };

 struct Slider

@@ -40,19 +41,24 @@

 {

 	Point2	p0;

 	Point2	p1;

-	int	left;

-	int	min;

-	int	max;

-	int	val;

+	Point2	kp;	/* knob position */

+	int	left;	/* or right */

+	int	min;	/* value at p0 */

+	int	max;	/* value at p1 */

+	int	val;	/* current value */

 };

 Histogram histos[4] = {

-	{ .title = "red",   .col = 0xCC0000FF },

-	{ .title = "green", .col = 0x00BB00FF },

-	{ .title = "blue",  .col = 0x0000CCFF },

 	{ .title = "alpha", .col = DBlack },

+	{ .title = "blue",  .col = 0x0000CCFF },

+	{ .title = "green", .col = 0x00BB00FF },

+	{ .title = "red",   .col = 0xCC0000FF },

 };

+Screen *histscr;

+Image *histwin;

+Point histspan;

+Channel *histrefc;

 Memimage *mimage;

 Image *image;

 char title[64];

@@ -60,6 +66,8 @@

 Matrix warpmat;

 Warp warp;

 int smoothen;

+Rectangle region;

+Image *regioncol;

 int

 sgn(double n)

@@ -251,8 +259,9 @@

 }

 void

-measureimage(Memimage *i)

+measureimage(Memimage *i, Rectangle sr)

 {

+	static int inited;

 	Histogram *h;

 	Image *brush;

 	Rectangle hr, dr, gr, r;

@@ -259,19 +268,34 @@

 	Sampler s;

 	Point sp;

 	ulong c;

-	int chan, ht, j;

-	uvlong vmax;

+	int ht, j;

+	if(inited)

+		for(h = histos; h < histos+nelem(histos); h++){

+			memset(h->vals, 0, sizeof(h->vals));

+			h->max = h->avg = 0;

+		}

+

 	initsampler(&s, i);

-	for(sp.y = i->r.min.y; sp.y < i->r.max.y; sp.y++)

-	for(sp.x = i->r.min.x; sp.x < i->r.max.x; sp.x++){

+	for(sp.y = sr.min.y; sp.y < sr.max.y; sp.y++)

+	for(sp.x = sr.min.x; sp.x < sr.max.x; sp.x++){

 		c = getpixel(&s, sp);

 		if(i->flags & Falpha)

 			c = clralpha(c);

-		for(chan = 4-1; chan >= 0; chan--)

-			histos[4-1-chan].vals[(c >> chan*8)&0xFF]++;

+		for(h = histos; h < histos+nelem(histos); h++){

+			if(++h->vals[c&0xFF] > h->max)

+				h->max = h->vals[c&0xFF];

+			h->avg += c&0xFF;

+			c >>= 8;

+		}

 	}

+	for(h = histos; h < histos+nelem(histos); h++){

+		if(h->max == 0)

+			h->max = 1;

+		h->avg /= Dx(sr)*Dy(sr);

+	}

+

 	brush = eallocimage(display, Rect(0,0,1,1), RGBA32, 1, DNofill);

 	hr = Rect(0, 0, Hmargin+256+Hmargin, 4+font->height+Vmargin+150+3+8+1+Vmargin);

 	dr = Rect(Hmargin, 4+font->height+Vmargin, hr.max.x-Hmargin, hr.max.y-Vmargin-1-8-3);

@@ -279,30 +303,42 @@

 	ht = Dy(dr);

 	for(h = histos; h < histos+nelem(histos); h++){

-		if(loadimage(brush, brush->r, (uchar*)&h->col, 4) < 0)

-			sysfatal("loadimage2: %r");

+		if(inited)

+			draw(h->img, dr, display->white, nil, ZP);

+		else{

+			h->img = eallocimage(display, hr, screen->chan, 0, DWhite);

+			string(h->img, addpt(hr.min, Pt(4, 4)), display->black, ZP, font, h->title);

+			border(h->img, dr, -1, display->black, ZP);

+		}

-		h->img = eallocimage(display, hr, screen->chan, 0, DWhite);

-		string(h->img, addpt(hr.min, Pt(4, 4)), display->black, ZP, font, h->title);

-		border(h->img, dr, -1, display->black, ZP);

-

-		for(vmax = j = 0; j < 256; j++)

-			if(h->vals[j] > vmax)

-				vmax = h->vals[j];

-

+		/* draw the columns */

+		if(fillcolor(brush, h->col) < 0)

+			sysfatal("fillcolor: %r");

 		r = dr;

 		r.max.x = r.min.x + 1;

 		for(j = 0; j < 256; j++){

 			r.min.y = r.max.y;

-			r.min.y -= h->vals[j]*ht / vmax;

+			r.min.y -= h->vals[j]*ht / h->max;

 			draw(h->img, r, brush, nil, ZP);

 			r.min.x = r.max.x++;

 		}

-		border(h->img, gr, -1, display->black, ZP);

-		drawgradient(h->img, gr, DBlack, DWhite);

+		/* draw the avg line */

+		r = dr;

+		r.min.x += h->avg;

+		r.max.x = r.min.x + 1;

+		if(fillcolor(brush, setalpha(DOrange, 0xBF)) < 0)

+			sysfatal("fillcolor: %r");

+		draw(h->img, r, brush, nil, ZP);

+

+		if(!inited){

+			border(h->img, gr, -1, display->black, ZP);

+			drawgradient(h->img, gr, DBlack, DWhite);

+		}

 	}

 	freeimage(brush);

+	if(!inited)

+		inited++;

 }

 int

@@ -356,37 +392,43 @@

 }

 void

-histredraw(Histogram *h)

+histredraw(void)

 {

-	draw(h->win, h->win->r, h->img, nil, ZP);

+	Histogram *h;

+	Point off;

+

+	off = histwin->r.min;

+	off.y += histspan.y;

+	for(h = histos; h < histos+nelem(histos); h++){

+		off.y -= Dy(h->img->r);

+		draw(histwin, rectaddpt(h->img->r, off), h->img, nil, ZP);

+	}

 	flushimage(display, 1);

 }

 void

-histresize(Histogram *h)

+histresize(void)

 {

 	lockdisplay(display);

-	if(gengetwindow(display, winname, &h->win, &h->scr, Refnone) < 0)

+	if(gengetwindow(display, winname, &histwin, &histscr, Refnone) < 0)

 		sysfatal("gengetwindow2: %r");

 	unlockdisplay(display);

-	if((Dx(h->win->r) != Dx(h->img->r)

-	||  Dy(h->win->r) != Dy(h->img->r)))

-		winresize(display, subpt(h->img->r.max, h->img->r.min));

-	histredraw(h);

+	if(Dx(histwin->r) != histspan.x

+	|| Dy(histwin->r) != histspan.y)

+		winresize(display, histspan);

+	histredraw();

 }

 void

-histmouse(Histogram *h, Mousectl *mc)

+histmouse(Mousectl *mc)

 {

-	static Mouse omtab[nelem(histos)];

-	Mouse *om;

+	static Mouse om;

-	om = &omtab[h-histos];

-	if((om->buttons & 4) && (mc->buttons & 4)){

-		line(h->win, om->xy, mc->xy, Enddisc, Enddisc, 1, display->black, ZP);

+	if((om.buttons & 4) && (mc->buttons & 4)){

+		line(histwin, om.xy, mc->xy, Enddisc, Enddisc, 1, display->black, ZP);

 		flushimage(display, 1);

 	}

-	*om = mc->Mouse;

+	om = mc->Mouse;

 }

 void

@@ -400,39 +442,37 @@

 }

 void

-histproc(void *arg)

+histproc(void *)

 {

-	Histogram *histo;

 	Mousectl *mc;

 	Keyboardctl *kc;

 	Rune r;

-	histo = arg;

-	histo->pid = getpid();

+	threadsetname("histograms");

-	threadsetname("%s", histo->title);

-

 	lockdisplay(display);	/* avoid races while attaching to new window */

 	newwindow(nil);

-	winsetlabel(display, "%s", histo->title);

-	winresize(display, subpt(histo->img->r.max, histo->img->r.min));

-	winmove(display, Pt(0, (Dy(histo->img->r)+2*Borderwidth)*(histo-histos)));

+	winsetlabel(display, "histograms");

+	histspan = Pt(Dx(histos[0].img->r), Dy(histos[0].img->r)*nelem(histos));

+	winresize(display, histspan);

+	winmove(display, ZP);

-	if(gengetwindow(display, winname, &histo->win, &histo->scr, Refnone) < 0)

+	if(gengetwindow(display, winname, &histwin, &histscr, Refnone) < 0)

 		sysfatal("gengetwindow: %r");

 	unlockdisplay(display);

-	if((mc = initmouse(nil, histo->win)) == nil)

+	if((mc = initmouse(nil, histwin)) == nil)

 		sysfatal("initmouse2: %r");

 	if((kc = initkeyboard(nil)) == nil)

 		sysfatal("initkeyboard2: %r");

-	histredraw(histo);

+	histredraw();

-	enum { MOUSE, RESIZE, KEY };

+	enum { MOUSE, RESIZE, KEY, REFRESH };

 	Alt a[] = {

 		{mc->c, &mc->Mouse, CHANRCV},

 		{mc->resizec, nil, CHANRCV},

 		{kc->c, &r, CHANRCV},

+		{histrefc, nil, CHANRCV},

 		{nil, nil, CHANEND}

 	};

 	for(;;)

@@ -439,17 +479,51 @@

 		switch(alt(a)){

 		default: sysfatal("alt interrupted");

 		case MOUSE:

-			histmouse(histo, mc);

+			histmouse(mc);

 			break;

 		case RESIZE:

-			histresize(histo);

+			histresize();

 			break;

 		case KEY:

 			histkey(r);

 			break;

+		case REFRESH:

+			histredraw();

+			break;

 		}

 }

+Rectangle

+xformrect(Rectangle r, Matrix m)

+{

+	Point2 p0, p1;

+

+	p0 = (Point2){r.min.x, r.min.y, 1};

+	p1 = (Point2){r.max.x, r.max.y, 1};

+	p0 = xform(p0, m);

+	p1 = xform(p1, m);

+	return Rect(p0.x+0.5, p0.y+0.5, p1.x+0.5, p1.y+0.5);

+}

+

+int

+getregion(Mousectl *mc)

+{

+	Matrix invwarpmat;

+

+	region = getrect(3, mc);

+	if(Dx(region)*Dy(region) <= 4){

+badregion:

+		region = ZR;

+		return 0;

+	}

+	memmove(invwarpmat, warpmat, sizeof(Matrix));

+	invm(invwarpmat);

+	region = xformrect(region, invwarpmat);

+	if(!rectclip(&region, rectsubpt(image->r, image->r.min)))

+		goto badregion;

+	return 1;

+}

+

 void

 redraw(void)

 {

@@ -457,6 +531,8 @@

 	draw(screen, screen->r, display->black, nil, ZP);

 	affinewarp(screen, screen->r, image, image->r.min, warp, smoothen);

+	if(!eqrect(region, ZR))

+		border(screen, xformrect(region, warpmat), -1, regioncol, ZP);

 	stringbg(screen, addpt(screen->r.min, titlep), display->white, ZP, font, title, display->black, ZP);

 	flushimage(display, 1);

 }

@@ -464,10 +540,16 @@

 void

 resize(void)

 {

+	Point dp;

+

+	dp = screen->r.min;

 	lockdisplay(display);

 	if(getwindow(display, Refnone) < 0)

 		fprint(2, "can't reattach to window\n");

 	unlockdisplay(display);

+	dp = subpt(screen->r.min, dp);

+	translate(warpmat, dp.x, dp.y);

+	mkwarp(warp, warpmat);

 	redraw();

 }

@@ -474,9 +556,11 @@

 static char *

 genrmbmenu(int idx)

 {

-	if(idx > 0)

-		return nil;

-	return smoothen? "sharpen": "smoothen";

+	switch(idx){

+	case 0: return smoothen? "sharpen": "smoothen";

+	case 1: return "select region";

+	default: return nil;

+	}

 }

 void

@@ -483,11 +567,23 @@

 rmb(Mousectl *mc)

 {

 	static Menu menu = { .gen = genrmbmenu };

+	static int therewas;	/* a region selected */

 	switch(menuhit(3, mc, &menu, _screen)){

 	case 0:

 		smoothen ^= 1;

 		break;

+	case 1:

+		if(getregion(mc)){

+			measureimage(mimage, rectaddpt(region, mimage->r.min));

+			therewas = 1;

+			nbsend(histrefc, nil);

+		}else if(therewas){

+			measureimage(mimage, mimage->r);

+			therewas = 0;

+			nbsend(histrefc, nil);

+		}

+		break;

 	}

 	redraw();

 }

@@ -510,7 +606,7 @@

 		tainted++;

 	}else if(mc->buttons & 2){

 		if((om.buttons & 2) == 0)

-			p = subpt(mc->xy, screen->r.min);

+			p = mc->xy;

 		switch(sgn(mc->xy.y - om.xy.y)){

 		case  1: goto zoomout;

 		case -1: goto zoomin;

@@ -518,7 +614,7 @@

 	}else if((om.buttons & 4) == 0 && (mc->buttons & 4))

 		rmb(mc);

 	if(mc->buttons & 8){

-		p = subpt(mc->xy, screen->r.min);

+		p = mc->xy;

 zoomin:

 		translate(warpmat, -p.x, -p.y);

 		scale(warpmat, Scrollzoomin);

@@ -525,7 +621,7 @@

 		translate(warpmat, p.x, p.y);

 		tainted++;

 	}else if(mc->buttons & 16){

-		p = subpt(mc->xy, screen->r.min);

+		p = mc->xy;

 zoomout:

 		translate(warpmat, -p.x, -p.y);

 		scale(warpmat, Scrollzoomout);

@@ -563,7 +659,7 @@

 	Keyboardctl *kc;

 	Rune r;

 	char cs[10];

-	int fd, i;

+	int fd;

 	fd = 0;

 	ARGBEGIN{

@@ -588,15 +684,17 @@

 	snprint(title, sizeof title, "%s %dx%d %s",

 		chantostr(cs, image->chan)? cs: "unknown", Dx(image->r), Dy(image->r),

 		argc > 0? argv[0]: "main");

+	regioncol = eallocimage(display, Rect(0,0,1,1), XRGB32, 1, DOrange);

 	identity(warpmat);

+	translate(warpmat, screen->r.min.x, screen->r.min.y);

 	mkwarp(warp, warpmat);

 	redraw();

-	measureimage(mimage);

-	unlockdisplay(display);

+	measureimage(mimage, mimage->r);

 	snprint(winname, sizeof winname, "%s/winname", display->windir);

-	for(i = 0; i < nelem(histos); i++)

-		proccreate(histproc, &histos[i], mainstacksize);

+	histrefc = chancreate(sizeof(void*), 1);

+	unlockdisplay(display);

+	proccreate(histproc, nil, mainstacksize);

 	enum { MOUSE, RESIZE, KEY };

 	Alt a[] = {

-- 

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