/* hough transform for circles
 *
 * 7/3/14
 * 	- from hough_line.c
 * 2/1/18
 * 	- 20% speedup
 */

/*

	This file is part of VIPS.

	VIPS is free software; you can redistribute it and/or modify
	it under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation; either version 2 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	02110-1301  USA

 */

/*

	These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk

 */

/* Derived in part from David Young's Matlab circle detector:
 *
 * http://www.mathworks.com/matlabcentral/fileexchange/26978-hough-transform-for-circles
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>

#include <string.h>

#include <vips/vips.h>
#include <vips/internal.h>

#include "statistic.h"
#include "hough.h"

typedef struct _VipsHoughCircle {
	VipsHough parent_instance;

	int scale;
	int min_radius;
	int max_radius;

	int width;
	int height;
	int bands;

} VipsHoughCircle;

typedef VipsHoughClass VipsHoughCircleClass;

G_DEFINE_TYPE(VipsHoughCircle, vips_hough_circle, VIPS_TYPE_HOUGH);

/* Smaller circles have fewer pixels and therefore fewer votes. Scale bands by
 * the ratio of circumference, so all radii get equal weight.
 */
static void
vips_hough_circle_normalise(VipsHoughCircle *hough_circle)
{
	VipsHough *hough = (VipsHough *) hough_circle;

	int max_radius = hough_circle->max_radius;
	int min_radius = hough_circle->min_radius;
	int scale = hough_circle->scale;
	int bands = hough_circle->bands;
	int width = hough_circle->width;
	int height = hough_circle->height;

	double max_circumference = 2 * VIPS_PI * max_radius;

	int b;

	for (b = 0; b < bands; b++) {
		int radius = b * scale + min_radius;
		double circumference = 2 * VIPS_PI * radius;
		double ratio = max_circumference / circumference;
		size_t n_pels = (size_t) width * height * bands;

		size_t i;
		guint *q;

		q = b + (guint *) VIPS_IMAGE_ADDR(hough->out, 0, 0);
		for (i = 0; i < n_pels; i += bands)
			q[i] *= ratio;
	}
}

static int
vips_hough_circle_build(VipsObject *object)
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(object);
	VipsStatistic *statistic = (VipsStatistic *) object;
	VipsHoughCircle *hough_circle = (VipsHoughCircle *) object;
	int range = hough_circle->max_radius - hough_circle->min_radius;

	if (range <= 0) {
		vips_error(class->nickname,
			"%s", _("parameters out of range"));
		return -1;
	}

	hough_circle->width = statistic->in->Xsize / hough_circle->scale;
	hough_circle->height = statistic->in->Ysize / hough_circle->scale;
	hough_circle->bands = 1 + range / hough_circle->scale;

	if (VIPS_OBJECT_CLASS(vips_hough_circle_parent_class)->build(object))
		return -1;

	vips_hough_circle_normalise(hough_circle);

	return 0;
}

static int
vips_hough_circle_init_accumulator(VipsHough *hough, VipsImage *accumulator)
{
	VipsHoughCircle *hough_circle = (VipsHoughCircle *) hough;

	vips_image_init_fields(accumulator,
		hough_circle->width, hough_circle->height, hough_circle->bands,
		VIPS_FORMAT_UINT, VIPS_CODING_NONE,
		VIPS_INTERPRETATION_MATRIX,
		1.0, 1.0);

	return 0;
}

/* Vote endpoints, with clip.
 */
static void
vips_hough_circle_vote_endpoints_clip(VipsImage *image,
	int y, int x1, int x2, int quadrant, void *client)
{
	int r = *((int *) client);
	int b = image->Bands;

	if (y >= 0 &&
		y < image->Ysize) {
		guint *line = (guint *) VIPS_IMAGE_ADDR(image, 0, y) + r;

		if (x1 >= 0 &&
			x1 < image->Xsize)
			line[x1 * b] += 1;
		if (x2 >= 0 &&
			x2 < image->Xsize)
			line[x2 * b] += 1;
	}
}

/* Vote endpoints, no clip.
 */
static void
vips_hough_circle_vote_endpoints_noclip(VipsImage *image,
	int y, int x1, int x2, int quadrant, void *client)
{
	int r = *((int *) client);
	guint *line = (guint *) VIPS_IMAGE_ADDR(image, 0, y) + r;
	int b = image->Bands;

	line[x1 * b] += 1;
	line[x2 * b] += 1;
}

/* Cast votes for all possible circles passing through x, y.
 */
static void
vips_hough_circle_vote(VipsHough *hough, VipsImage *accumulator, int x, int y)
{
	VipsHoughCircle *hough_circle = (VipsHoughCircle *) hough;
	int min_radius = hough_circle->min_radius;
	int cx = x / hough_circle->scale;
	int cy = y / hough_circle->scale;

	int rb;

	g_assert(hough_circle->max_radius - min_radius >= 0);

	for (rb = 0; rb < hough_circle->bands; rb++) {
		/* r needs to be in scaled down image space.
		 */
		int r = rb + min_radius / hough_circle->scale;

		VipsDrawScanline draw_scanline;

		if (cx - r >= 0 &&
			cx + r < accumulator->Xsize &&
			cy - r >= 0 &&
			cy + r < accumulator->Ysize)
			draw_scanline = vips_hough_circle_vote_endpoints_noclip;
		else
			draw_scanline = vips_hough_circle_vote_endpoints_clip;

		vips__draw_circle_direct(accumulator,
			cx, cy, r, draw_scanline, &rb);
	}
}

static void
vips_hough_circle_class_init(VipsHoughClass *class)
{
	GObjectClass *gobject_class = (GObjectClass *) class;
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsHoughClass *hclass = (VipsHoughClass *) class;

	gobject_class->set_property = vips_object_set_property;
	gobject_class->get_property = vips_object_get_property;

	object_class->nickname = "hough_circle";
	object_class->description = _("find hough circle transform");
	object_class->build = vips_hough_circle_build;

	hclass->init_accumulator = vips_hough_circle_init_accumulator;
	hclass->vote = vips_hough_circle_vote;

	VIPS_ARG_INT(class, "scale", 119,
		_("Scale"),
		_("Scale down dimensions by this factor"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsHoughCircle, scale),
		1, 100000, 3);

	VIPS_ARG_INT(class, "min_radius", 120,
		_("Min radius"),
		_("Smallest radius to search for"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsHoughCircle, min_radius),
		1, 100000, 10);

	VIPS_ARG_INT(class, "max_radius", 121,
		_("Max radius"),
		_("Largest radius to search for"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsHoughCircle, max_radius),
		1, 100000, 20);
}

static void
vips_hough_circle_init(VipsHoughCircle *hough_circle)
{
	hough_circle->scale = 1;
	hough_circle->min_radius = 10;
	hough_circle->max_radius = 20;
}

/**
 * vips_hough_circle: (method)
 * @in: input image
 * @out: (out): output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * Optional arguments:
 *
 * * @scale: scale down dimensions by this much
 * * @min_radius: smallest radius to search for
 * * @max_radius: largest radius to search for
 *
 * Find the circular Hough transform of an image. @in must be one band, with
 * non-zero pixels for image edges. @out is three-band, with the third channel
 * representing the detected circle radius. The operation scales the number of
 * votes by circle circumference so circles of differing size are given equal
 * weight.
 *
 * The output pixel at (x, y, band) is the strength of the circle centred on
 * (x, y) and with radius (band).
 *
 * Use @max_radius and @min_radius to set the range of radii to search for.
 *
 * Use @scale to set how @in coordinates are scaled to @out coordinates. A
 * @scale of 3, for example, will make @out 1/3rd of the width and height of
 * @in, and reduce the number of radii tested (and hence the number of bands
 * int @out) by a factor of three as well.
 *
 * See also: vips_hough_line().
 *
 * Returns: 0 on success, -1 on error
 */
int
vips_hough_circle(VipsImage *in, VipsImage **out, ...)
{
	va_list ap;
	int result;

	va_start(ap, out);
	result = vips_call_split("hough_circle", ap, in, out);
	va_end(ap);

	return result;
}
