/* Edge detector

 *

 * 12/4/23

 *  - from vips_sobel()

 */

/*

  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

 */

/*

#define DEBUG

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif /*HAVE_CONFIG_H*/

#include <glib/gi18n-lib.h>

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#include <vips/vips.h>

typedef struct _VipsEdge {

  VipsOperation parent_instance;

  VipsImage *in;

  VipsImage *out;

  VipsImage *mask;

  /* Need an image vector for start_many.

   */

  VipsImage *args[3];

} VipsEdge;

typedef VipsOperationClass VipsEdgeClass;

G_DEFINE_ABSTRACT_TYPE(VipsEdge, vips_edge, VIPS_TYPE_OPERATION);

static void

vips_edge_dispose(GObject *gobject)

{

  VipsEdge *edge = (VipsEdge *) gobject;

  VIPS_UNREF(edge->mask);

  G_OBJECT_CLASS(vips_edge_parent_class)->dispose(gobject);

}

static int

vips_edge_uchar_gen(VipsRegion *out_region,

  void *vseq, void *a, void *b, gboolean *stop)

{

  VipsRegion **in = (VipsRegion **) vseq;

  VipsRect *r = &out_region->valid;

  int sz = r->width * in[0]->im->Bands;

  int x, y;

  if (vips_reorder_prepare_many(out_region->im, in, r))

    return -1;

  for (y = 0; y < r->height; y++) {

    VipsPel *p1 = (VipsPel *restrict)

      VIPS_REGION_ADDR(in[0], r->left, r->top + y);

    VipsPel *p2 = (VipsPel *restrict)

      VIPS_REGION_ADDR(in[1], r->left, r->top + y);

    VipsPel *q = (VipsPel *restrict)

      VIPS_REGION_ADDR(out_region, r->left, r->top + y);

    for (x = 0; x < sz; x++) {

      int v1 = 2 * (p1[x] - 128);

      int v2 = 2 * (p2[x] - 128);

      /* Avoid the sqrt() for uchar.

       */

      int v = abs(v1) + abs(v2);

      q[x] = v > 255 ? 255 : v;

    }

  }

  return 0;

}

/* Fast uchar path.

 */

static int

vips_edge_build_uchar(VipsEdge *edge)

{

  VipsImage **t = (VipsImage **)

    vips_object_local_array(VIPS_OBJECT(edge), 20);

  g_info("vips_edge: uchar path");

  /* For uchar, use 128 as the zero and divide the result by 2 to

   * prevent overflow.

   */

  if (vips_copy(edge->mask, &t[1], NULL))

    return -1;

  vips_image_set_double(t[1], "offset", 128.0);

  vips_image_set_double(t[1], "scale", 2.0);

  if (vips_conv(edge->in, &t[3], t[1],

      "precision", VIPS_PRECISION_INTEGER,

      NULL))

    return -1;

  if (vips_rot90(t[1], &t[5], NULL) ||

    vips_conv(edge->in, &t[7], t[5],

      "precision", VIPS_PRECISION_INTEGER,

      NULL))

    return -1;

  g_object_set(edge, "out", vips_image_new(), NULL);

  edge->args[0] = t[3];

  edge->args[1] = t[7];

  edge->args[2] = NULL;

  if (vips_image_pipeline_array(edge->out,

      VIPS_DEMAND_STYLE_FATSTRIP, edge->args))

    return -1;

  if (vips_image_generate(edge->out,

      vips_start_many, vips_edge_uchar_gen, vips_stop_many,

      edge->args, NULL))

    return -1;

  return 0;

}

/* Accurate but slow path.

 */

static int

vips_edge_build_float(VipsEdge *edge)

{

  VipsImage **t = (VipsImage **)

    vips_object_local_array(VIPS_OBJECT(edge), 20);

  g_info("vips_edge: float path");

  if (vips_rot90(edge->mask, &t[0], NULL) ||

    vips_conv(edge->in, &t[1], edge->mask, NULL) ||

    vips_conv(edge->in, &t[2], t[0], NULL))

    return -1;

  if (vips_multiply(t[1], t[1], &t[3], NULL) ||

    vips_multiply(t[2], t[2], &t[4], NULL) ||

    vips_add(t[3], t[4], &t[5], NULL) ||

    vips_pow_const1(t[5], &t[6], 0.5, NULL) ||

    vips_cast_uchar(t[6], &t[7], NULL))

    return -1;

  g_object_set(edge, "out", vips_image_new(), NULL);

  if (vips_image_write(t[7], edge->out))

    return -1;

  return 0;

}

static int

vips_edge_build(VipsObject *object)

{

  VipsEdge *edge = (VipsEdge *) object;

  if (edge->in->BandFmt == VIPS_FORMAT_UCHAR) {

    if (vips_edge_build_uchar(edge))

      return -1;

  }

  else {

    if (vips_edge_build_float(edge))

      return -1;

  }

  return 0;

}

static void

vips_edge_class_init(VipsEdgeClass *class)

{

  GObjectClass *gobject_class = G_OBJECT_CLASS(class);

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  gobject_class->dispose = vips_edge_dispose;

  gobject_class->set_property = vips_object_set_property;

  gobject_class->get_property = vips_object_get_property;

  object_class->nickname = "edge";

  object_class->description = _("Edge detector");

  object_class->build = vips_edge_build;

  VIPS_ARG_IMAGE(class, "in", 1,

    _("Input"),

    _("Input image"),

    VIPS_ARGUMENT_REQUIRED_INPUT,

    G_STRUCT_OFFSET(VipsEdge, in));

  VIPS_ARG_IMAGE(class, "out", 2,

    _("Output"),

    _("Output image"),

    VIPS_ARGUMENT_REQUIRED_OUTPUT,

    G_STRUCT_OFFSET(VipsEdge, out));

}

static void

vips_edge_init(VipsEdge *edge)

{

}

typedef VipsEdge VipsSobel;

typedef VipsEdgeClass VipsSobelClass;

G_DEFINE_TYPE(VipsSobel, vips_sobel, vips_edge_get_type());

static int

vips_sobel_build(VipsObject *object)

{

  VipsEdge *edge = (VipsEdge *) object;

  edge->mask = vips_image_new_matrixv(3, 3,

    1.0, 2.0, 1.0,

    0.0, 0.0, 0.0,

    -1.0, -2.0, -1.0);

  return VIPS_OBJECT_CLASS(vips_sobel_parent_class)->build(object);

}

static void

vips_sobel_class_init(VipsSobelClass *class)

{

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  object_class->nickname = "sobel";

  object_class->description = _("Sobel edge detector");

  object_class->build = vips_sobel_build;

}

static void

vips_sobel_init(VipsEdge *sobel)

{

}

typedef VipsEdge VipsScharr;

typedef VipsEdgeClass VipsScharrClass;

G_DEFINE_TYPE(VipsScharr, vips_scharr, vips_edge_get_type());

static int

vips_scharr_build(VipsObject *object)

{

  VipsEdge *edge = (VipsEdge *) object;

  edge->mask = vips_image_new_matrixv(3, 3,

    -3.0, 0.0, 3.0,

    -10.0, 0.0, 10.0,

    -3.0, 0.0, 3.0);

  return VIPS_OBJECT_CLASS(vips_scharr_parent_class)->build(object);

}

static void

vips_scharr_class_init(VipsSobelClass *class)

{

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  object_class->nickname = "scharr";

  object_class->description = _("Scharr edge detector");

  object_class->build = vips_scharr_build;

}

static void

vips_scharr_init(VipsScharr *scharr)

{

}

typedef VipsEdge VipsPrewitt;

typedef VipsEdgeClass VipsPrewittClass;

G_DEFINE_TYPE(VipsPrewitt, vips_prewitt, vips_edge_get_type());

static int

vips_prewitt_build(VipsObject *object)

{

  VipsEdge *edge = (VipsEdge *) object;

  edge->mask = vips_image_new_matrixv(3, 3,

    -1.0, 0.0, 1.0,

    -1.0, 0.0, 1.0,

    -1.0, 0.0, 1.0);

  return VIPS_OBJECT_CLASS(vips_prewitt_parent_class)->build(object);

}

static void

vips_prewitt_class_init(VipsSobelClass *class)

{

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  object_class->nickname = "prewitt";

  object_class->description = _("Prewitt edge detector");

  object_class->build = vips_prewitt_build;

}

static void

vips_prewitt_init(VipsPrewitt *prewitt)

{

}

/**

 * vips_sobel: (method)

 * @in: input image

 * @out: (out): output image

 * @...: `NULL`-terminated list of optional named arguments

 *

 * Sobel edge detector.

 *

 * uchar images are computed using a fast, low-precision path. Cast to float

 * for a high-precision implementation.

 *

 * ::: seealso

 *     [method@Image.canny], [method@Image.sobel], [method@Image.prewitt],

 *     [method@Image.scharr].

 *

 * Returns: 0 on success, -1 on error.

 */

int

vips_sobel(VipsImage *in, VipsImage **out, ...)

{

  va_list ap;

  int result;

  va_start(ap, out);

  result = vips_call_split("sobel", ap, in, out);

  va_end(ap);

  return result;

}

/**

 * vips_scharr: (method)

 * @in: input image

 * @out: (out): output image

 * @...: `NULL`-terminated list of optional named arguments

 *

 * Scharr edge detector.

 *

 * uchar images are computed using a fast, low-precision path. Cast to float

 * for a high-precision implementation.

 *

 * ::: seealso

 *     [method@Image.canny], [method@Image.sobel], [method@Image.prewitt],

 *     [method@Image.scharr].

 *

 * Returns: 0 on success, -1 on error.

 */

int

vips_scharr(VipsImage *in, VipsImage **out, ...)

{

  va_list ap;

  int result;

  va_start(ap, out);

  result = vips_call_split("scharr", ap, in, out);

  va_end(ap);

  return result;

}

/**

 * vips_prewitt: (method)

 * @in: input image

 * @out: (out): output image

 * @...: `NULL`-terminated list of optional named arguments

 *

 * Prewitt edge detector.

 *

 * uchar images are computed using a fast, low-precision path. Cast to float

 * for a high-precision implementation.

 *

 * ::: seealso

 *     [method@Image.canny], [method@Image.sobel], [method@Image.prewitt],

 *     [method@Image.scharr].

 *

 * Returns: 0 on success, -1 on error.

 */

int

vips_prewitt(VipsImage *in, VipsImage **out, ...)

{

  va_list ap;

  int result;

  va_start(ap, out);

  result = vips_call_split("prewitt", ap, in, out);

  va_end(ap);

  return result;

}