/* to HSV ... useful for compatibility with other packages

 *

 * 9/6/15

 *  - from LabS2Lab.c

 */

/*

  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

 */

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif /*HAVE_CONFIG_H*/

#include <glib/gi18n-lib.h>

#include <stdio.h>

#include <vips/vips.h>

#include "pcolour.h"

typedef VipsColourCode VipssRGB2HSV;

typedef VipsColourCodeClass VipssRGB2HSVClass;

G_DEFINE_TYPE(VipssRGB2HSV, vips_sRGB2HSV, VIPS_TYPE_COLOUR_CODE);

static void

vips_sRGB2HSV_line(VipsColour *colour, VipsPel *out, VipsPel **in, int width)

{

  unsigned char *p = (unsigned char *) in[0];

  unsigned char *q = (unsigned char *) out;

  int i;

  for (i = 0; i < width; i++) {

    unsigned char c_max;

    unsigned char c_min;

    float secondary_diff;

    float wrap_around_hue;

    if (p[1] < p[2]) {

      if (p[2] < p[0]) {

        /* Center red (at top).

         */

        c_max = p[0];

        c_min = p[1];

        secondary_diff = p[1] - p[2];

        wrap_around_hue = 255.0F;

      }

      else {

        /* Center blue.

         */

        c_max = p[2];

        c_min = VIPS_MIN(p[1], p[0]);

        secondary_diff = p[0] - p[1];

        wrap_around_hue = 170.0F;

      }

    }

    else {

      if (p[1] < p[0]) {

        /* Center red (at bottom)

         */

        c_max = p[0];

        c_min = p[2];

        secondary_diff = p[1] - p[2];

        wrap_around_hue = 0.0F;

      }

      else {

        /* Center green

         */

        c_max = p[1];

        c_min = VIPS_MIN(p[2], p[0]);

        secondary_diff = p[2] - p[0];

        wrap_around_hue = 85.0F;

      }

    }

    if (c_max == 0) {

      q[0] = 0;

      q[1] = 0;

      q[2] = 0;

    }

    else {

      unsigned char delta;

      q[2] = c_max;

      delta = c_max - c_min;

      if (delta == 0)

        q[0] = 0;

      else

        q[0] = 42.5 * (secondary_diff / (float) delta) +

          wrap_around_hue;

      q[1] = delta * 255.0 / (float) c_max;

    }

    p += 3;

    q += 3;

  }

}

static void

vips_sRGB2HSV_class_init(VipssRGB2HSVClass *class)

{

  VipsObjectClass *object_class = (VipsObjectClass *) class;

  VipsColourClass *colour_class = VIPS_COLOUR_CLASS(class);

  object_class->nickname = "sRGB2HSV";

  object_class->description = _("transform sRGB to HSV");

  colour_class->process_line = vips_sRGB2HSV_line;

}

static void

vips_sRGB2HSV_init(VipssRGB2HSV *sRGB2HSV)

{

  VipsColour *colour = VIPS_COLOUR(sRGB2HSV);

  VipsColourCode *code = VIPS_COLOUR_CODE(sRGB2HSV);

  colour->interpretation = VIPS_INTERPRETATION_HSV;

  colour->format = VIPS_FORMAT_UCHAR;

  colour->bands = 3;

  colour->input_bands = 3;

  code->input_coding = VIPS_CODING_NONE;

  code->input_format = VIPS_FORMAT_UCHAR;

  code->input_interpretation = VIPS_INTERPRETATION_sRGB;

}

/**

 * vips_sRGB2HSV: (method)

 * @in: input image

 * @out: (out): output image

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

 *

 * Convert to HSV.

 *

 * HSV is a crude polar coordinate system for RGB images. It is provided for

 * compatibility with other image processing systems. See [method@Image.Lab2LCh] for a

 * much better colour space.

 *

 * ::: seealso

 *     [method@Image.HSV2sRGB], [method@Image.Lab2LCh].

 *

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

 */

int

vips_sRGB2HSV(VipsImage *in, VipsImage **out, ...)

{

  va_list ap;

  int result;

  va_start(ap, out);

  result = vips_call_split("sRGB2HSV", ap, in, out);

  va_end(ap);

  return result;

}