# GIMP - The GNU Image Manipulation Program
# Copyright (C) 1995 Spencer Kimball and Peter Mattis

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 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 General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

# "Perlized" from C source by Manish Singh <yosh@gimp.org>

sub drawable_brightness_contrast {
    $blurb = 'Modify brightness/contrast in the specified drawable.';

    $help = <<'HELP';
This procedures allows the brightness and contrast of the specified drawable to
be modified.  Both 'brightness' and 'contrast' parameters are defined between
-0.5 and 0.5.
HELP

    &std_pdb_misc;
    $date = '1997';
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'brightness', type => '-0.5 <= float <= 0.5',
	  desc => 'Brightness adjustment' },
	{ name => 'contrast', type => '-0.5 <= float <= 0.5',
	  desc => 'Contrast adjustment' }
    );

    %invoke = (
        headers => [ qw("operations/gimpbrightnesscontrastconfig.h") ],
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    {
      GObject *config = g_object_new (GIMP_TYPE_BRIGHTNESS_CONTRAST_CONFIG,
                                      "brightness", brightness,
                                      "contrast",   contrast,
                                      NULL);

      gimp_drawable_apply_operation_by_name (drawable, progress,
                                             C_("undo-type", "Brightness-Contrast"),
                                             "gimp:brightness-contrast",
                                             config);
      g_object_unref (config);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_color_balance {
    $blurb = 'Modify the color balance of the specified drawable.';

    $help = <<'HELP';
Modify the color balance of the specified drawable. There are three axis which
can be modified: cyan-red, magenta-green, and yellow-blue. Negative values
increase the amount of the former, positive values increase the amount of the
latter. Color balance can be controlled with the 'transfer_mode' setting, which
allows shadows, mid-tones, and highlights in an image to be affected
differently. The 'preserve-lum' parameter, if TRUE, ensures that the
luminosity of each pixel remains fixed.
HELP

    &std_pdb_misc;
    $date = '1997';
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'transfer_mode', type => 'enum GimpTransferMode',
	  desc => 'Transfer mode' },
	{ name => 'preserve_lum', type => 'boolean',
	  desc => 'Preserve luminosity values at each pixel' },
	{ name => 'cyan_red', type => '-100 <= float <= 100',
	  desc => 'Cyan-Red color balance' },
	{ name => 'magenta_green', type => '-100 <= float <= 100',
	  desc => 'Magenta-Green color balance' },
	{ name => 'yellow_blue', type => '-100 <= float <= 100',
	  desc => 'Yellow-Blue color balance' }
    );

    %invoke = (
	headers => [ qw("operations/gimpcolorbalanceconfig.h") ],
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error)  &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    {
      GObject *config = g_object_new (GIMP_TYPE_COLOR_BALANCE_CONFIG,
                                      "range",               transfer_mode,
                                      "preserve-luminosity", preserve_lum,
                                      NULL);

      g_object_set (config,
                    "cyan-red",      cyan_red      / 100.0,
                    "magenta-green", magenta_green / 100.0,
                    "yellow-blue",   yellow_blue   / 100.0,
                    NULL);

      gimp_drawable_apply_operation_by_name (drawable, progress,
                                             C_("undo-type", "Color Balance"),
                                             "gimp:color-balance",
                                             config);
      g_object_unref (config);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_colorize_hsl {
    $blurb = 'Render the drawable as a grayscale image seen through a colored glass.';

    $help = <<'HELP';
Desaturates the drawable, then tints it with the specified color. This tool is
only valid on RGB color images. It will not operate on grayscale drawables.
HELP

    &neo_pdb_misc('2004', '2.10');

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'hue', type => '0 <= float <= 360',
	  desc => 'Hue in degrees' },
	{ name => 'saturation', type => '0 <= float <= 100',
	  desc => 'Saturation in percent' },
	{ name => 'lightness', type => '-100 <= float <= 100',
	  desc => 'Lightness in percent' }
    );

    %invoke = (
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error) &&
      ! gimp_drawable_is_gray (drawable))
    {
      GeglNode *node =
        gegl_node_new_child (NULL,
                             "operation", "gimp:colorize",
                             "hue",        hue        / 360.0,
                             "saturation", saturation / 100.0,
                             "lightness",  lightness  / 100.0,
                             NULL);

      gimp_drawable_apply_operation (drawable, progress,
                                     C_("undo-type", "Colorize"),
                                     node);
      g_object_unref (node);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_curves_explicit {
    $blurb = 'Modifies the intensity curve(s) for specified drawable.';

    $help = <<'HELP';
Modifies the intensity mapping for one channel in the specified
drawable. The channel can be either an intensity component, or the
value. The 'values' parameter is an array of doubles which explicitly
defines how each pixel value in the drawable will be modified.  Use
the gimp_curves_spline() function to modify intensity levels with
Catmull Rom splines.
HELP

    &std_pdb_misc;
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'channel', type => 'enum GimpHistogramChannel',
	  desc => 'The channel to modify' },
	{ name => 'values', type => 'floatarray',
	  desc => 'The explicit curve',
	  array => { name => 'num_values', type => '256 <= int32 <= 2096',
		     desc => 'The number of values in the new curve' } }
    );

    %invoke = (
	headers => [ qw("operations/gimpcurvesconfig.h") ],
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error) &&
      (num_values >= 256) &&
      (num_values <= 4096) &&
      (gimp_drawable_has_alpha (drawable) || channel != GIMP_HISTOGRAM_ALPHA) &&
      (! gimp_drawable_is_gray (drawable) ||
       channel == GIMP_HISTOGRAM_VALUE || channel == GIMP_HISTOGRAM_ALPHA) &&
      channel != GIMP_HISTOGRAM_LUMINANCE)
    {
      GObject *config = gimp_curves_config_new_explicit (channel,
                                                         values,
                                                         num_values);

      gimp_drawable_apply_operation_by_name (drawable, progress,
                                             C_("undo-type", "Curves"),
                                             "gimp:curves",
                                             config);
      g_object_unref (config);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_curves_spline {
    $blurb = 'Modifies the intensity curve(s) for specified drawable.';

    $help = <<'HELP';
Modifies the intensity mapping for one channel in the specified
drawable. The channel can be either an intensity component, or the
value. The 'points' parameter is an array of doubles which define a
set of control points which describe a Catmull Rom spline which yields
the final intensity curve. Use the gimp_curves_explicit() function to
explicitly modify intensity levels.
HELP

    &std_pdb_misc;
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'channel', type => 'enum GimpHistogramChannel',
	  desc => 'The channel to modify' },
	{ name => 'points', type => 'floatarray',
	  desc => 'The spline control points: { cp1.x, cp1.y, cp2.x, cp2.y,
		   ... }',
	  array => { name => 'num_points', type => '4 <= int32 <= 2048',
		     desc => 'The number of values in the control point array' }
       }
    );

    %invoke = (
	headers => [ qw("operations/gimpcurvesconfig.h") ],
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error) &&
      ! (num_points & 1) &&
      (gimp_drawable_has_alpha (drawable) || channel != GIMP_HISTOGRAM_ALPHA) &&
      (! gimp_drawable_is_gray (drawable) ||
       channel == GIMP_HISTOGRAM_VALUE || channel == GIMP_HISTOGRAM_ALPHA) &&
      channel != GIMP_HISTOGRAM_LUMINANCE)
    {
      GObject *config = gimp_curves_config_new_spline (channel,
                                                       points,
                                                       num_points / 2);

      gimp_drawable_apply_operation_by_name (drawable, progress,
                                             C_("undo-type", "Curves"),
                                             "gimp:curves",
                                             config);
      g_object_unref (config);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_desaturate {
    $blurb = <<'BLURB';
Desaturate the contents of the specified drawable, with the specified formula.
BLURB

    $help = <<'HELP';
This procedure desaturates the contents of the specified drawable,
with the specified formula. This procedure only works on drawables of
type RGB color.
HELP

    $author = $copyright = 'Karine Delvare';
    $date = '2005';
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'desaturate_mode', type => 'enum GimpDesaturateMode',
	  desc => 'The formula to use to desaturate' }
    );

    %invoke = (
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error) &&
      gimp_drawable_is_rgb (drawable))
    {
      GeglNode *node =
        gegl_node_new_child (NULL,
                             "operation", "gimp:desaturate",
                             "mode",      desaturate_mode,
                             NULL);

      gimp_drawable_apply_operation (drawable, progress,
                                     C_("undo-type", "Desaturate"),
                                     node);
      g_object_unref (node);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_equalize {
    $blurb = 'Equalize the contents of the specified drawable.';

    $help = <<'HELP';
This procedure equalizes the contents of the specified drawable. Each
intensity channel is equalized independently. The equalized intensity
is given as inten' = (255 - inten). The 'mask_only' option specifies
whether to adjust only the area of the image within the selection
bounds, or the entire image based on the histogram of the selected
area. If there is no selection, the entire image is adjusted based on
the histogram for the entire image.
HELP

    &std_pdb_misc;
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'mask_only', type => 'boolean',
	  desc => 'Equalization option' }
    );

    %invoke = (
	headers => [ qw("core/gimpdrawable-equalize.h") ],
	code => <<'CODE'
{
  if (! gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                   GIMP_PDB_ITEM_CONTENT, error) ||
      ! gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    success = FALSE;

  if (success)
    gimp_drawable_equalize (drawable, mask_only);
}
CODE
    );
}

sub drawable_histogram {
    $blurb = <<'BLURB';
Returns information on the intensity histogram for the specified drawable.
BLURB

    $help = <<'HELP';

This tool makes it possible to gather information about the intensity
histogram of a drawable. A channel to examine is first specified. This
can be either value, red, green, or blue, depending on whether the
drawable is of type color or grayscale. Second, a range of intensities
are specified. The gimp_drawable_histogram() function returns
statistics based on the pixels in the drawable that fall under this
range of values. Mean, standard deviation, median, number of pixels,
and percentile are all returned.  Additionally, the total count of
pixels in the image is returned. Counts of pixels are weighted by any
associated alpha values and by the current selection mask. That is,
pixels that lie outside an active selection mask will not be
counted. Similarly, pixels with transparent alpha values will not be
counted. The returned mean, std_dev and median are in the range
(0..255) for 8-bit images or if the plug-in is not precision-aware,
and in the range (0.0..1.0) otherwise.

HELP

    &std_pdb_misc;
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'channel', type => 'enum GimpHistogramChannel',
	  desc => 'The channel to query' },
	{ name => 'start_range', type => '0.0 <= float <= 1.0',
	  desc => 'Start of the intensity measurement range' },
	{ name => 'end_range', type => '0.0 <= float <= 1.0',
	  desc => 'End of the intensity measurement range' }
    );

    @outargs = (
	{ name => 'mean', type => 'float', void_ret => 1,
	  desc => 'Mean intensity value' },
	{ name => 'std_dev',  type => 'float',
	  desc => 'Standard deviation of intensity values' },
	{ name => 'median',  type => 'float',
	  desc => 'Median intensity value' },
	{ name => 'pixels',  type => 'float',
	  desc => 'Alpha-weighted pixel count for entire image' },
	{ name => 'count',  type => 'float',
	  desc => 'Alpha-weighted pixel count for range' },
	{ name => 'percentile',  type => 'float',
	  desc => 'Percentile that range falls under' }
    );

    %invoke = (
	headers => [ qw("core/gimpdrawable-histogram.h"
                        "core/gimphistogram.h") ],
	code => <<'CODE'
{
  if (! gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL, 0, error) ||
      (! gimp_drawable_has_alpha (drawable) &&
       channel == GIMP_HISTOGRAM_ALPHA) ||
      (gimp_drawable_is_gray (drawable) &&
       channel != GIMP_HISTOGRAM_VALUE && channel != GIMP_HISTOGRAM_ALPHA))
    success = FALSE;

  if (success)
    {
      GimpHistogram *histogram;
      gint           n_bins;
      gint           start;
      gboolean       precision_enabled;
      gboolean       linear;
      gint           end;

      precision_enabled =
        gimp->plug_in_manager->current_plug_in &&
        gimp_plug_in_precision_enabled (gimp->plug_in_manager->current_plug_in);

      if (precision_enabled)
        linear = gimp_drawable_get_linear (drawable);
      else
        linear = FALSE;

      histogram = gimp_histogram_new (linear);
      gimp_drawable_calculate_histogram (drawable, histogram, FALSE);

      n_bins = gimp_histogram_n_bins (histogram);

      start = ROUND (start_range * (n_bins - 1));
      end   = ROUND (end_range   * (n_bins - 1));

      mean       = gimp_histogram_get_mean (histogram, channel,
		 			    start, end);
      std_dev    = gimp_histogram_get_std_dev (histogram, channel,
					       start, end);
      median     = gimp_histogram_get_median (histogram, channel,
					      start, end);
      pixels     = gimp_histogram_get_count (histogram, channel, 0, n_bins - 1);
      count      = gimp_histogram_get_count (histogram, channel,
                                             start, end);
      percentile = count / pixels;

      g_object_unref (histogram);

      if (n_bins == 256 || ! precision_enabled)
        {
          mean    *= 255;
          std_dev *= 255;
          median  *= 255;
        }
    }
}
CODE
    );
}

sub drawable_hue_saturation {
    $blurb = <<'BLURB';
Modify hue, lightness, and saturation in the specified drawable.
BLURB

    $help = <<'HELP';
This procedure allows the hue, lightness, and saturation in the specified
drawable to be modified. The 'hue-range' parameter provides the capability to
limit range of affected hues. The 'overlap' parameter provides blending into
neighboring hue channels when rendering.
HELP

    &std_pdb_misc;
    $since = '2.10';

    @inargs = (
        { name => 'drawable', type => 'drawable',
          desc => 'The drawable' },
        { name => 'hue_range', type => 'enum GimpHueRange',
          desc => 'Range of affected hues' },
        { name => 'hue_offset', type => '-180 <= float <= 180',
          desc => 'Hue offset in degrees' },
        { name => 'lightness', type => '-100 <= float <= 100',
          desc => 'Lightness modification' },
        { name => 'saturation', type => '-100 <= float <= 100',
          desc => 'Saturation modification' },
        { name => 'overlap', type => '0 <= float <= 100',
          desc => 'Overlap other hue channels' }
    );

    %invoke = (
        headers => [ qw("operations/gimphuesaturationconfig.h") ],
        code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    {
      GObject *config = g_object_new (GIMP_TYPE_HUE_SATURATION_CONFIG,
                                      "range", hue_range,
                                      NULL);

       g_object_set (config,
                     "hue",        hue_offset / 180.0,
                     "saturation", saturation / 100.0,
                     "lightness",  lightness  / 100.0,
                     "overlap",    overlap / 100.0,
                     NULL);

      gimp_drawable_apply_operation_by_name (drawable, progress,
                                             C_("undo-type", "Hue-Saturation"),
                                             "gimp:hue-saturation",
                                             config);
      g_object_unref (config);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_invert {
    $blurb = 'Invert the contents of the specified drawable.';

    $help = <<'HELP';
This procedure inverts the contents of the specified drawable. Each
intensity channel is inverted independently. The inverted intensity is
given as inten' = (255 - inten). If 'linear' is TRUE, the drawable is
inverted in linear space.
HELP

    &std_pdb_misc;
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'linear', type => 'boolean',
	  desc => 'Whether to invert in linear space' }
    );

    %invoke = (
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    {
      gimp_drawable_apply_operation_by_name (drawable, progress,
                                             C_("undo-type", "Invert"),
                                             linear ?
                                             "gegl:invert-linear" :
                                             "gegl:invert-gamma",
                                             NULL);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_levels {
    $blurb = 'Modifies intensity levels in the specified drawable.';

    $help = <<'HELP';
This tool allows intensity levels in the specified drawable to be remapped
according to a set of parameters. The low/high input levels specify an initial
mapping from the source intensities. The gamma value determines how intensities
between the low and high input intensities are interpolated. A gamma value of
1.0 results in a linear interpolation. Higher gamma values result in more
high-level intensities. Lower gamma values result in more low-level
intensities. The low/high output levels constrain the final intensity
mapping--that is, no final intensity will be lower than the low output level
and no final intensity will be higher than the high output level. This tool is
only valid on RGB color and grayscale images.
HELP

    &std_pdb_misc;
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'channel', type => 'enum GimpHistogramChannel',
	  desc => 'The channel to modify' },
	{ name => 'low_input', type => '0.0 <= float <= 1.0',
	  desc => "Intensity of lowest input" },
	{ name => 'high_input', type => '0.0 <= float <= 1.0',
	  desc => "Intensity of highest input" },
	{ name => 'clamp_input', type => 'boolean',
	  desc => 'Clamp input values before applying output levels' },
	{ name => 'gamma', type => '0.1 <= float <= 10',
	  desc => 'Gamma adjustment factor' },
	{ name => 'low_output', type => '0.0 <= float <= 1.0',
	  desc => "Intensity of lowest output" },
	{ name => 'high_output', type => '0.0 <= float <= 1.0',
	  desc => "Intensity of highest output" },
	{ name => 'clamp_output', type => 'boolean',
	  desc => 'Clamp final output values' },
    );

    %invoke = (
	headers => [ qw("operations/gimplevelsconfig.h") ],
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error) &&
      (gimp_drawable_has_alpha (drawable) || channel != GIMP_HISTOGRAM_ALPHA) &&
      (! gimp_drawable_is_gray (drawable) ||
       channel == GIMP_HISTOGRAM_VALUE || channel == GIMP_HISTOGRAM_ALPHA) &&
      channel != GIMP_HISTOGRAM_LUMINANCE)
    {
      GObject *config = g_object_new (GIMP_TYPE_LEVELS_CONFIG,
                                      "channel", channel,
                                      NULL);

      g_object_set (config,
                    "low-input",    low_input,
                    "high-input",   high_input,
                    "clamp-input",  clamp_input,
                    "gamma",        gamma,
                    "low-output",   low_output,
                    "high-output",  high_output,
                    "clamp-output", clamp_output,
                    NULL);

      gimp_drawable_apply_operation_by_name (drawable, progress,
                                             C_("undo-type", "Levels"),
                                             "gimp:levels",
                                             config);
      g_object_unref (config);
    }
  else
    success = TRUE;
}
CODE
    );
}

sub drawable_levels_stretch {
    $blurb = 'Automatically modifies intensity levels in the specified drawable.';

    $help = <<'HELP';
This procedure allows intensity levels in the specified drawable to be
remapped according to a set of guessed parameters. It is equivalent to
clicking the "Auto" button in the Levels tool.
HELP

    $author = $copyright = 'Joao S.O. Bueno, Shawn Willden';
    $date = '2003';
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' }
    );

    %invoke = (
        headers => [ qw("core/gimpdrawable-levels.h") ],
        code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    {
      gimp_drawable_levels_stretch (drawable, progress);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_posterize {
    $blurb = 'Posterize the specified drawable.';

    $help = <<'HELP';
This procedures reduces the number of shades allows in each intensity channel
to the specified 'levels' parameter.
HELP

    &std_pdb_misc;
    $date = '1997';
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'levels', type => '2 <= int32 <= 255',
	  desc => 'Levels of posterization' }
    );

    %invoke = (
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    {
      GeglNode *node =
        gegl_node_new_child (NULL,
                             "operation", "gimp:posterize",
                             "levels",    levels,
                             NULL);

      gimp_drawable_apply_operation (drawable, progress,
                                     C_("undo-type", "Posterize"),
                                     node);
      g_object_unref (node);
    }
  else
    success = FALSE;
}
CODE
    );
}

sub drawable_threshold {
    $blurb = 'Threshold the specified drawable.';

    $help = <<'HELP';
This procedures generates a threshold map of the specified
drawable. All pixels between the values of 'low_threshold' and
'high_threshold', on the scale of 'channel' are replaced with white,
and all other pixels with black.
HELP

    &std_pdb_misc;
    $date = '1997';
    $since = '2.10';

    @inargs = (
	{ name => 'drawable', type => 'drawable',
	  desc => 'The drawable' },
	{ name => 'channel', type => 'enum GimpHistogramChannel',
	  desc => 'The channel to base the threshold on' },
	{ name => 'low_threshold', type => '0.0 <= float <= 1.0',
	  desc => 'The low threshold value' },
	{ name => 'high_threshold', type => '0.0 <= float <= 1.0',
	  desc => 'The high threshold value' }
    );

    %invoke = (
	code => <<'CODE'
{
  if (gimp_pdb_item_is_attached (GIMP_ITEM (drawable), NULL,
                                 GIMP_PDB_ITEM_CONTENT, error) &&
      gimp_pdb_item_is_not_group (GIMP_ITEM (drawable), error))
    {
      GeglNode *node =
        gegl_node_new_child (NULL,
                             "operation", "gimp:threshold",
                             "channel",   channel,
                             "low",       low_threshold,
                             "high",      high_threshold,
                             NULL);

      gimp_drawable_apply_operation (drawable, progress,
                                     C_("undo-type", "Threshold"),
                                     node);
      g_object_unref (node);
    }
  else
    success = FALSE;
}
CODE
    );
}


@headers = qw("libgimpmath/gimpmath.h"
              "core/gimp.h"
              "core/gimpdrawable.h"
              "core/gimpdrawable-operation.h"
              "plug-in/gimpplugin.h"
              "plug-in/gimppluginmanager.h"
              "gimppdb-utils.h"
              "gimp-intl.h");

@procs = qw(drawable_brightness_contrast
            drawable_color_balance
            drawable_colorize_hsl
            drawable_curves_explicit
            drawable_curves_spline
            drawable_desaturate
            drawable_equalize
            drawable_histogram
            drawable_hue_saturation
            drawable_invert
            drawable_levels
            drawable_levels_stretch
            drawable_posterize
            drawable_threshold);

%exports = (app => [@procs], lib => [@procs]);

$desc = 'Color';
$doc_title = 'gimpdrawablecolor';
$doc_short_desc = "Functions for manipulating a drawable's color.";
$doc_long_desc = "Functions for manipulating a drawable's color, including curves and histograms.";

1;