/* Gaussian blur.

 *

 * 15/11/13

 *  - from vips_sharpen()

 * 19/11/14

 *  - change parameters to be more imagemagick-like

 * 21/9/20

 *  - allow sigma zero, meaning no blur

 *  - sigma < 0.2 is just copy

 */

/*

  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 _VipsGaussblur {

  VipsOperation parent_instance;

  VipsImage *in;

  VipsImage *out;

  gdouble sigma;

  gdouble min_ampl;

  VipsPrecision precision;

} VipsGaussblur;

typedef VipsOperationClass VipsGaussblurClass;

G_DEFINE_TYPE(VipsGaussblur, vips_gaussblur, VIPS_TYPE_OPERATION);

static int

vips_gaussblur_build(VipsObject *object)

{

  VipsGaussblur *gaussblur = (VipsGaussblur *) object;

  VipsImage **t = (VipsImage **) vips_object_local_array(object, 2);

  if (VIPS_OBJECT_CLASS(vips_gaussblur_parent_class)->build(object))

    return -1;

  /* vips_gaussmat() will make a 1x1 pixel mask for anything smaller than

   * this.

   */

  if (gaussblur->sigma < 0.2) {

    if (vips_copy(gaussblur->in, &t[1], NULL))

      return -1;

  }

  else {

    if (vips_gaussmat(&t[0],

        gaussblur->sigma, gaussblur->min_ampl,

        "separable", TRUE,

        "precision", gaussblur->precision,

        NULL))

      return -1;

#ifdef DEBUG

    printf("gaussblur: blurring with:\n");

    vips_matrixprint(t[0], NULL);

#endif /*DEBUG*/

    g_info("gaussblur mask width %d", t[0]->Xsize);

    if (vips_convsep(gaussblur->in, &t[1], t[0],

        "precision", gaussblur->precision,

        NULL))

      return -1;

  }

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

  if (vips_image_write(t[1], gaussblur->out))

    return -1;

  return 0;

}

static void

vips_gaussblur_class_init(VipsGaussblurClass *class)

{

  GObjectClass *gobject_class = G_OBJECT_CLASS(class);

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  VipsOperationClass *operation_class = VIPS_OPERATION_CLASS(class);

  gobject_class->set_property = vips_object_set_property;

  gobject_class->get_property = vips_object_get_property;

  object_class->nickname = "gaussblur";

  object_class->description = _("gaussian blur");

  object_class->build = vips_gaussblur_build;

  operation_class->flags = VIPS_OPERATION_SEQUENTIAL;

  VIPS_ARG_IMAGE(class, "in", 1,

    _("Input"),

    _("Input image"),

    VIPS_ARGUMENT_REQUIRED_INPUT,

    G_STRUCT_OFFSET(VipsGaussblur, in));

  VIPS_ARG_IMAGE(class, "out", 2,

    _("Output"),

    _("Output image"),

    VIPS_ARGUMENT_REQUIRED_OUTPUT,

    G_STRUCT_OFFSET(VipsGaussblur, out));

  VIPS_ARG_DOUBLE(class, "sigma", 3,

    _("Sigma"),

    _("Sigma of Gaussian"),

    VIPS_ARGUMENT_REQUIRED_INPUT,

    G_STRUCT_OFFSET(VipsGaussblur, sigma),

    0.0, 1000, 1.5);

  VIPS_ARG_DOUBLE(class, "min_ampl", 3,

    _("Minimum amplitude"),

    _("Minimum amplitude of Gaussian"),

    VIPS_ARGUMENT_OPTIONAL_INPUT,

    G_STRUCT_OFFSET(VipsGaussblur, min_ampl),

    0.001, 1.0, 0.2);

  VIPS_ARG_ENUM(class, "precision", 4,

    _("Precision"),

    _("Convolve with this precision"),

    VIPS_ARGUMENT_OPTIONAL_INPUT,

    G_STRUCT_OFFSET(VipsGaussblur, precision),

    VIPS_TYPE_PRECISION, VIPS_PRECISION_INTEGER);

}

static void

vips_gaussblur_init(VipsGaussblur *gaussblur)

{

  gaussblur->sigma = 1.5;

  gaussblur->min_ampl = 0.2;

  gaussblur->precision = VIPS_PRECISION_INTEGER;

}

/**

 * vips_gaussblur: (method)

 * @in: input image

 * @out: (out): output image

 * @sigma: how large a mask to use

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

 *

 * Optional arguments:

 *

 * * @precision: #VipsPrecision, precision for blur, default int

 * * @min_ampl: minimum amplitude, default 0.2

 *

 * This operator runs vips_gaussmat() and vips_convsep() for you on an image.

 * Set @min_ampl smaller to generate a larger, more accurate mask. Set @sigma

 * larger to make the blur more blurry.

 *

 * See also: vips_gaussmat(), vips_convsep().

 *

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

 */

int

vips_gaussblur(VipsImage *in, VipsImage **out, double sigma, ...)

{

  va_list ap;

  int result;

  va_start(ap, sigma);

  result = vips_call_split("gaussblur", ap, in, out, sigma);

  va_end(ap);

  return result;

}