colorzones.c

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/*
    This file is part of darktable,
    Copyright (C) 2010 Bruce Guenter.
    Copyright (C) 2010-2012 Henrik Andersson.
    Copyright (C) 2010-2014, 2016 johannes hanika.
    Copyright (C) 2010-2012, 2019 Pascal de Bruijn.
    Copyright (C) 2011 Antony Dovgal.
    Copyright (C) 2011 Brian Teague.
    Copyright (C) 2011 Jochen Schroeder.
    Copyright (C) 2011 Robert Bieber.
    Copyright (C) 2011-2016, 2018-2019 Tobias Ellinghaus.
    Copyright (C) 2012 Richard Wonka.
    Copyright (C) 2012-2016, 2019 Ulrich Pegelow.
    Copyright (C) 2013 Dennis Gnad.
    Copyright (C) 2013, 2018-2022 Pascal Obry.
    Copyright (C) 2013-2016, 2019 Roman Lebedev.
    Copyright (C) 2013 Simon Spannagel.
    Copyright (C) 2013 Thomas Pryds.
    Copyright (C) 2014, 2019 parafin.
    Copyright (C) 2015 Pedro Côrte-Real.
    Copyright (C) 2017-2018, 2020-2021 Dan Torop.
    Copyright (C) 2017, 2019-2020 Heiko Bauke.
    Copyright (C) 2018-2020, 2022-2026 Aurélien PIERRE.
    Copyright (C) 2018-2019 Edgardo Hoszowski.
    Copyright (C) 2018 Matthieu Moy.
    Copyright (C) 2018 Maurizio Paglia.
    Copyright (C) 2018 rawfiner.
    Copyright (C) 2019 Andreas Schneider.
    Copyright (C) 2019-2022 Diederik Ter Rahe.
    Copyright (C) 2019 Diederik ter Rahe.
    Copyright (C) 2019 emeikei.
    Copyright (C) 2019 Jacques Le Clerc.
    Copyright (C) 2020, 2022 Aldric Renaudin.
    Copyright (C) 2020-2021 Chris Elston.
    Copyright (C) 2020 Hubert Kowalski.
    Copyright (C) 2020-2021 Marco.
    Copyright (C) 2020 msdm.
    Copyright (C) 2020-2021 Ralf Brown.
    Copyright (C) 2021 lhietal.
    Copyright (C) 2021 Marco Carrarini.
    Copyright (C) 2021 Martin Straeten.
    Copyright (C) 2022 Hanno Schwalm.
    Copyright (C) 2022 Martin Bařinka.
    Copyright (C) 2022 Philipp Lutz.
    
    darktable 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.
    
    darktable 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 darktable.  If not, see <http://www.gnu.org/licenses/>.
*/
 
#ifdef HAVE_CONFIG_H
#include "common/darktable.h"
#include "gui/gdkkeys.h"
#include "config.h"
#endif
 
#include "bauhaus/bauhaus.h"
#include "common/iop_profile.h"
#include "common/colorspaces_inline_conversions.h"
#include "common/imagebuf.h"
#include "common/math.h"
#include "control/control.h"
#include "develop/imageop.h"
#include "develop/imageop_gui.h"
#include "dtgtk/drawingarea.h"
 
#include "gui/color_picker_proxy.h"
#include "gui/gtk.h"
#include "gui/draw.h"
#include "gui/presets.h"
#include "libs/colorpicker.h"
#include "libs/lib.h"
 
DT_MODULE_INTROSPECTION(5, dt_iop_colorzones_params_t)
 
#define DT_IOP_COLORZONES_INSET DT_PIXEL_APPLY_DPI(5)
#define DT_IOP_COLORZONES_CURVE_INFL .3f
#define DT_IOP_COLORZONES_RES 256
#define DT_IOP_COLORZONES_LUT_RES 0x10000
 
#define DT_IOP_COLORZONES_BANDS 8
 
#define DT_IOP_COLORZONES_MAXNODES 20
#define DT_IOP_COLORZONES_DEFAULT_STEP (0.001f)
 
#define DT_IOP_COLORZONES_MIN_X_DISTANCE 0.0025f
 
typedef enum dt_iop_colorzones_modes_t
{
  DT_IOP_COLORZONES_MODE_SMOOTH = 0, // $DESCRIPTION: "smooth"
  DT_IOP_COLORZONES_MODE_STRONG = 1  // $DESCRIPTION: "strong"
} dt_iop_colorzones_modes_t;
 
typedef enum dt_iop_colorzones_splines_version_t
{
  DT_IOP_COLORZONES_SPLINES_V1 = 0,
  DT_IOP_COLORZONES_SPLINES_V2 = 1
} dt_iop_colorzones_splines_version_t;
 
typedef enum dt_iop_colorzones_channel_t
{
  DT_IOP_COLORZONES_L = 0, // $DESCRIPTION: "lightness"
  DT_IOP_COLORZONES_C = 1, // $DESCRIPTION: "saturation"
  DT_IOP_COLORZONES_h = 2, // $DESCRIPTION: "hue"
  DT_IOP_COLORZONES_MAX_CHANNELS = 3
} dt_iop_colorzones_channel_t;
 
typedef struct dt_iop_colorzones_node_t
{
  float x;
  float y;
} dt_iop_colorzones_node_t;
 
typedef struct dt_iop_colorzones_params_t
{
  dt_iop_colorzones_channel_t channel; // $DEFAULT: DT_IOP_COLORZONES_h $DESCRIPTION: "select by"
  // three curves (L, C, h) with max number of nodes
  dt_iop_colorzones_node_t curve[DT_IOP_COLORZONES_MAX_CHANNELS][DT_IOP_COLORZONES_MAXNODES];
  int curve_num_nodes[DT_IOP_COLORZONES_MAX_CHANNELS]; // number of nodes per curve
  int curve_type[DT_IOP_COLORZONES_MAX_CHANNELS];      // CUBIC_SPLINE, CATMULL_ROM, MONOTONE_HERMITE
  float strength;  // $MIN: -200.0 $MAX: 200.0 $DEFAULT: 0.0 $DESCRIPTION: "mix"
  dt_iop_colorzones_modes_t mode; // $MIN: 0 $MAX: 1 $DEFAULT: DT_IOP_COLORZONES_MODE_SMOOTH $DESCRIPTION: "process mode"
  int splines_version;
} dt_iop_colorzones_params_t;
 
typedef struct dt_iop_colorzones_gui_data_t
{
  dt_draw_curve_t *minmax_curve[DT_IOP_COLORZONES_MAX_CHANNELS]; // curve for gui to draw
  int minmax_curve_nodes[DT_IOP_COLORZONES_MAX_CHANNELS];
  int minmax_curve_type[DT_IOP_COLORZONES_MAX_CHANNELS];
  GtkBox *hbox;
  GtkDrawingArea *area;
  GtkWidget *bottom_area;
  GtkNotebook *channel_tabs;
  GtkWidget *select_by;
  GtkWidget *strength;
  GtkWidget *interpolator; // curve type
  GtkWidget *mode;
  GtkWidget *bt_showmask;
  double mouse_x, mouse_y;
  float mouse_radius;
  int selected;
  int dragging;
  int x_move;
  GtkWidget *colorpicker;
  GtkWidget *colorpicker_set_values;
  GtkWidget *chk_edit_by_area;
  dt_iop_colorzones_channel_t channel;
  float draw_ys[DT_IOP_COLORZONES_MAX_CHANNELS][DT_IOP_COLORZONES_RES];
  float draw_min_ys[DT_IOP_COLORZONES_RES];
  float draw_max_ys[DT_IOP_COLORZONES_RES];
  float zoom_factor;
  float offset_x, offset_y;
  int edit_by_area;
  gboolean display_mask;
} dt_iop_colorzones_gui_data_t;
 
typedef struct dt_iop_colorzones_data_t
{
  dt_draw_curve_t *curve[DT_IOP_COLORZONES_MAX_CHANNELS];
  int curve_nodes[DT_IOP_COLORZONES_MAX_CHANNELS]; // number of nodes
  int curve_type[DT_IOP_COLORZONES_MAX_CHANNELS];  // curve style (e.g. CUBIC_SPLINE)
  dt_iop_colorzones_channel_t channel;
  float lut[3][DT_IOP_COLORZONES_LUT_RES];
  int mode;
} dt_iop_colorzones_data_t;
 
typedef struct dt_iop_colorzones_global_data_t
{
  int kernel_colorzones;
  int kernel_colorzones_v3;
} dt_iop_colorzones_global_data_t;
 
 
const char *name()
{
  return _("color _zones");
}
 
const char **description(struct dt_iop_module_t *self)
{
  return dt_iop_set_description(self, _("selectively shift hues, saturation and brightness of pixels"),
                                      _("creative"),
                                      _("linear or non-linear, Lab, display-referred"),
                                      _("non-linear, Lab"),
                                      _("non-linear, Lab, display-referred"));
}
 
int flags()
{
  return IOP_FLAGS_INCLUDE_IN_STYLES | IOP_FLAGS_SUPPORTS_BLENDING | IOP_FLAGS_ALLOW_TILING | IOP_FLAGS_DEPRECATED;
}
 
int default_group()
{
  return IOP_GROUP_COLOR;
}
 
int default_colorspace(dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece)
{
  return IOP_CS_LAB;
}
 
int legacy_params(dt_iop_module_t *self, const void *const old_params, const int old_version, void *new_params,
                  const int new_version)
{
#define DT_IOP_COLORZONES1_BANDS 6
 
  if(old_version == 1 && new_version == 5)
  {
    typedef struct dt_iop_colorzones_params1_t
    {
      int32_t channel;
      float equalizer_x[3][DT_IOP_COLORZONES1_BANDS], equalizer_y[3][DT_IOP_COLORZONES1_BANDS];
    } dt_iop_colorzones_params1_t;
 
    const dt_iop_colorzones_params1_t *old = old_params;
    dt_iop_colorzones_params_t *new = new_params;
 
    new->channel = old->channel;
 
    // keep first point
    for(int i = 0; i < 3; i++)
    {
      new->curve[i][0].x = old->equalizer_x[i][0];
      new->curve[i][0].y = old->equalizer_y[i][0];
    }
 
    for(int i = 0; i < 3; i++)
      for(int k = 0; k < 6; k++)
      {
        //  first+1 and last-1 are set to just after and before the first and last point
        if(k == 0)
          new->curve[i][k + 1].x = old->equalizer_x[i][k] + 0.001f;
        else if(k == 5)
          new->curve[i][k + 1].x = old->equalizer_x[i][k] - 0.001f;
        else
          new->curve[i][k + 1].x = old->equalizer_x[i][k];
        new->curve[i][k + 1].y = old->equalizer_y[i][k];
      }
 
    // keep last point
    for(int i = 0; i < 3; i++)
    {
      new->curve[i][7].x = old->equalizer_x[i][5];
      new->curve[i][7].y = old->equalizer_y[i][5];
    }
    for(int c = 0; c < 3; c++)
    {
      new->curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS;
      new->curve_type[c] = CATMULL_ROM;
    }
    new->strength = 0.0f;
    new->mode = DT_IOP_COLORZONES_MODE_SMOOTH;
    new->splines_version = DT_IOP_COLORZONES_SPLINES_V1;
    return 0;
  }
  if(old_version == 2 && new_version == 5)
  {
    typedef struct dt_iop_colorzones_params2_t
    {
      int32_t channel;
      float equalizer_x[3][DT_IOP_COLORZONES_BANDS], equalizer_y[3][DT_IOP_COLORZONES_BANDS];
    } dt_iop_colorzones_params2_t;
 
    const dt_iop_colorzones_params2_t *old = old_params;
    dt_iop_colorzones_params_t *new = new_params;
    new->channel = old->channel;
 
    for(int b = 0; b < DT_IOP_COLORZONES_BANDS; b++)
      for(int c = 0; c < 3; c++)
      {
        new->curve[c][b].x = old->equalizer_x[c][b];
        new->curve[c][b].y = old->equalizer_y[c][b];
      }
    for(int c = 0; c < 3; c++)
    {
      new->curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS;
      new->curve_type[c] = CATMULL_ROM;
    }
    new->strength = 0.0f;
    new->mode = DT_IOP_COLORZONES_MODE_SMOOTH;
    new->splines_version = DT_IOP_COLORZONES_SPLINES_V1;
    return 0;
  }
  if(old_version == 3 && new_version == 5)
  {
    typedef struct dt_iop_colorzones_params3_t
    {
      int32_t channel;
      float equalizer_x[3][DT_IOP_COLORZONES_BANDS], equalizer_y[3][DT_IOP_COLORZONES_BANDS];
      float strength;
    } dt_iop_colorzones_params3_t;
 
    const dt_iop_colorzones_params3_t *old = old_params;
    dt_iop_colorzones_params_t *new = new_params;
    new->channel = old->channel;
 
    for(int b = 0; b < DT_IOP_COLORZONES_BANDS; b++)
    {
      for(int c = 0; c < 3; c++)
      {
        new->curve[c][b].x = old->equalizer_x[c][b];
        new->curve[c][b].y = old->equalizer_y[c][b];
      }
    }
    for(int c = 0; c < 3; c++)
    {
      new->curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS;
      new->curve_type[c] = CATMULL_ROM;
    }
    new->strength = old->strength;
    new->mode = DT_IOP_COLORZONES_MODE_SMOOTH;
    new->splines_version = DT_IOP_COLORZONES_SPLINES_V1;
    return 0;
  }
  if(old_version == 4 && new_version == 5)
  {
    typedef struct dt_iop_colorzones_params4_t
    {
      int32_t channel;
      dt_iop_colorzones_node_t curve[DT_IOP_COLORZONES_MAX_CHANNELS][DT_IOP_COLORZONES_MAXNODES];
      int curve_num_nodes[DT_IOP_COLORZONES_MAX_CHANNELS];
      int curve_type[DT_IOP_COLORZONES_MAX_CHANNELS];
      float strength;
      int mode;
    } dt_iop_colorzones_params4_t;
 
    const dt_iop_colorzones_params4_t *old = old_params;
    dt_iop_colorzones_params_t *new = new_params;
    new->channel = old->channel;
 
    for(int i = 0; i < DT_IOP_COLORZONES_MAXNODES; i++)
    {
      for(int c = 0; c < DT_IOP_COLORZONES_MAX_CHANNELS; c++)
      {
        new->curve[c][i].x = old->curve[c][i].x;
        new->curve[c][i].y = old->curve[c][i].y;
      }
    }
    for(int c = 0; c < DT_IOP_COLORZONES_MAX_CHANNELS; c++)
    {
      new->curve_num_nodes[c] = old->curve_num_nodes[c];
      new->curve_type[c] = old->curve_type[c];
    }
    new->strength = old->strength;
    new->mode = old->mode;
    new->splines_version = DT_IOP_COLORZONES_SPLINES_V1;
    return 0;
  }
#undef DT_IOP_COLORZONES1_BANDS
 
  return 1;
}
 
static float _curve_to_mouse(const float x, const float zoom_factor, const float offset)
{
  return (x - offset) * zoom_factor;
}
 
static float _mouse_to_curve(const float x, const float zoom_factor, const float offset)
{
  return (x / zoom_factor) + offset;
}
 
// fills in new parameters based on mouse position (in 0,1)
static void dt_iop_colorzones_get_params(dt_iop_colorzones_params_t *p, dt_iop_colorzones_gui_data_t *c,
                                         const int ch, const double mouse_x, const double mouse_y,
                                         const float radius)
{
  const int bands = p->curve_num_nodes[ch];
 
  const float lin_mouse_x = _mouse_to_curve(mouse_x, c->zoom_factor, c->offset_x);
  const float lin_mouse_y = _mouse_to_curve(mouse_y, c->zoom_factor, c->offset_y);
 
  const float rad = radius / c->zoom_factor;
 
  if(p->channel == DT_IOP_COLORZONES_h && p->splines_version == DT_IOP_COLORZONES_SPLINES_V1)
  {
    // periodic boundary
    for(int k = 1; k < bands - 1; k++)
    {
      const float f = expf(-(lin_mouse_x - p->curve[ch][k].x) * (lin_mouse_x - p->curve[ch][k].x) / (rad * rad));
      p->curve[ch][k].y = (1.f - f) * p->curve[ch][k].y + f * lin_mouse_y;
    }
    const int m = bands - 1;
    const float mind = fminf((lin_mouse_x - p->curve[ch][0].x) * (lin_mouse_x - p->curve[ch][0].x),
                             (lin_mouse_x - p->curve[ch][m].x) * (lin_mouse_x - p->curve[ch][m].x));
    const float f = expf(-mind / (rad * rad));
    p->curve[ch][0].y = (1.f - f) * p->curve[ch][0].y + f * lin_mouse_y;
    p->curve[ch][m].y = (1.f - f) * p->curve[ch][m].y + f * lin_mouse_y;
  }
  else
  {
    for(int k = 0; k < bands; k++)
    {
      const float f = expf(-(lin_mouse_x - p->curve[ch][k].x) * (lin_mouse_x - p->curve[ch][k].x) / (rad * rad));
      p->curve[ch][k].y = (1.f - f) * p->curve[ch][k].y + f * lin_mouse_y;
    }
  }
}
 
static inline __attribute__((always_inline)) float lookup(const float *lut, const float i)
{
  const int bin0 = MIN(0xffff, MAX(0, (int)(DT_IOP_COLORZONES_LUT_RES * i)));
  const int bin1 = MIN(0xffff, MAX(0, (int)(DT_IOP_COLORZONES_LUT_RES * i) + 1));
  const float f = DT_IOP_COLORZONES_LUT_RES * i - bin0;
  return lut[bin1] * f + lut[bin0] * (1.f - f);
}
 
static inline float strength(float value, float strength)
{
  return value + (value - 0.5f) * (strength / 100.0f);
}
 
__DT_CLONE_TARGETS__
void process_display(struct dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece,
                     const void *const ivoid, void *const ovoid, const dt_iop_roi_t *const roi_in,
                     const dt_iop_roi_t *const roi_out)
{
  dt_iop_colorzones_data_t *d = (dt_iop_colorzones_data_t *)(piece->data);
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  const int ch = piece->dsc_in.channels;
  const float normalize_C = 1.f / (128.0f * sqrtf(2.f));
 
  const dt_iop_colorzones_channel_t display_channel = g->channel;
 
  dt_iop_image_copy_by_size(ovoid, ivoid, roi_out->width, roi_out->height, ch);
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < (size_t)roi_out->width * roi_out->height; k++)
  {
    float *in = (float *)ivoid + ch * k;
    float *out = (float *)ovoid + ch * k;
 
    dt_aligned_pixel_t LCh;
 
    dt_Lab_2_LCH(in, LCh);
 
    float select = 0.0f;
    switch(d->channel)
    {
      case DT_IOP_COLORZONES_L:
        select = LCh[0] * 0.01f;
        break;
      case DT_IOP_COLORZONES_C:
        select = LCh[1] * normalize_C;
        break;
      case DT_IOP_COLORZONES_h:
      default:
        select = LCh[2];
        break;
    }
    select = CLAMP(select, 0.f, 1.f);
 
    out[3] = fabsf(lookup(d->lut[display_channel], select) - .5f) * 4.f;
    out[3] = CLAMP(out[3], 0.f, 1.f);
  }
 
  pipe->mask_display = DT_DEV_PIXELPIPE_DISPLAY_MASK;
  pipe->bypass_blendif = 1;
}
 
__DT_CLONE_TARGETS__
void process_v1(struct dt_iop_module_t *self, const dt_dev_pixelpipe_iop_t *piece, const void *const ivoid,
                void *const ovoid, const dt_iop_roi_t *const roi_in, const dt_iop_roi_t *const roi_out)
{
  dt_iop_colorzones_data_t *d = (dt_iop_colorzones_data_t *)(piece->data);
 
  const int ch = piece->dsc_in.channels;
  const float normalize_C = 1.f / (128.0f * sqrtf(2.f));
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < (size_t)roi_out->width * roi_out->height; k++)
  {
    float *in = (float *)ivoid + ch * k;
    float *out = (float *)ovoid + ch * k;
 
    dt_aligned_pixel_t LCh;
 
    dt_Lab_2_LCH(in, LCh);
 
    float select = 0.0f;
    switch(d->channel)
    {
      case DT_IOP_COLORZONES_L:
        select = LCh[0] * 0.01f;
        break;
      case DT_IOP_COLORZONES_C:
        select = LCh[1] * normalize_C;
        break;
      case DT_IOP_COLORZONES_h:
      default:
        select = LCh[2];
        break;
    }
    select = CLAMP(select, 0.f, 1.f);
 
    LCh[0] *= powf(2.0f, 4.0f * (lookup(d->lut[0], select) - .5f));
    LCh[1] *= 2.f * lookup(d->lut[1], select);
    LCh[2] += lookup(d->lut[2], select) - .5f;
 
    dt_LCH_2_Lab(LCh, out);
 
    out[3] = in[3];
  }
}
 
__DT_CLONE_TARGETS__
void process_v3(struct dt_iop_module_t *self, const dt_dev_pixelpipe_iop_t *piece, const void *const ivoid,
                void *const ovoid, const dt_iop_roi_t *const roi_in, const dt_iop_roi_t *const roi_out)
{
  dt_iop_colorzones_data_t *d = (dt_iop_colorzones_data_t *)(piece->data);
  const int ch = piece->dsc_in.channels;
  __OMP_PARALLEL_FOR__()
  for(size_t k = 0; k < (size_t)roi_out->width * roi_out->height; k++)
  {
    float *in = (float *)ivoid + ch * k;
    float *out = (float *)ovoid + ch * k;
    const float a = in[1], b = in[2];
    const float h = fmodf(atan2f(b, a) + 2.0f * DT_M_PI_F, 2.0f * DT_M_PI_F) / (2.0f * DT_M_PI_F);
    const float C = sqrtf(b * b + a * a);
    float select = 0.0f;
    float blend = 0.0f;
    switch(d->channel)
    {
      case DT_IOP_COLORZONES_L:
        select = fminf(1.0f, in[0] / 100.0f);
        break;
      case DT_IOP_COLORZONES_C:
        select = fminf(1.0f, C / 128.0f);
        break;
      default:
      case DT_IOP_COLORZONES_h:
        select = h;
        blend = powf(1.0f - C / 128.0f, 2.0f);
        break;
    }
    const float Lm = (blend * .5f + (1.0f - blend) * lookup(d->lut[0], select)) - .5f;
    const float hm = (blend * .5f + (1.0f - blend) * lookup(d->lut[2], select)) - .5f;
    blend *= blend; // saturation isn't as prone to artifacts:
    // const float Cm = 2.0 * (blend*.5f + (1.0f-blend)*lookup(d->lut[1], select));
    const float Cm = 2.0f * lookup(d->lut[1], select);
    const float L = in[0] * powf(2.0f, 4.0f * Lm);
    out[0] = L;
    out[1] = cosf(2.0f * DT_M_PI_F * (h + hm)) * Cm * C;
    out[2] = sinf(2.0f * DT_M_PI_F * (h + hm)) * Cm * C;
    out[3] = in[3];
  }
}
 
int process(struct dt_iop_module_t *self, const dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece, const void *const ivoid,
             void *const ovoid)
{
  const dt_iop_roi_t *const roi_in = &piece->roi_in;
  const dt_iop_roi_t *const roi_out = &piece->roi_out;
  dt_iop_colorzones_data_t *d = (dt_iop_colorzones_data_t *)(piece->data);
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  // display selection if requested
  if(pipe->type == DT_DEV_PIXELPIPE_FULL && !IS_NULL_PTR(g) && g->display_mask && self->dev->gui_attached
     && (self == self->dev->gui_module) && (pipe == self->dev->pipe))
    process_display(self, (dt_dev_pixelpipe_t *)pipe, piece, ivoid, ovoid, roi_in, roi_out);
  else if(d->mode == DT_IOP_COLORZONES_MODE_SMOOTH)
    process_v3(self, piece, ivoid, ovoid, roi_in, roi_out);
  else
    process_v1(self, piece, ivoid, ovoid, roi_in, roi_out);
  return 0;
}
 
#ifdef HAVE_OPENCL
int process_cl(struct dt_iop_module_t *self, const dt_dev_pixelpipe_t *pipe, const dt_dev_pixelpipe_iop_t *piece, cl_mem dev_in, cl_mem dev_out)
{
  const dt_iop_roi_t *const roi_in = &piece->roi_in;
  dt_iop_colorzones_data_t *d = (dt_iop_colorzones_data_t *)piece->data;
  dt_iop_colorzones_global_data_t *gd = (dt_iop_colorzones_global_data_t *)self->global_data;
  cl_mem dev_L, dev_a, dev_b = NULL;
  cl_int err = -999;
 
  const int devid = pipe->devid;
  const int width = roi_in->width;
  const int height = roi_in->height;
  const int kernel_colorzones
      = (d->mode == DT_IOP_COLORZONES_MODE_SMOOTH) ? gd->kernel_colorzones_v3 : gd->kernel_colorzones;
 
  size_t sizes[] = { ROUNDUPDWD(width, devid), ROUNDUPDHT(height, devid), 1 };
  dev_L = dt_opencl_copy_host_to_device(devid, d->lut[0], 256, 256, sizeof(float));
  dev_a = dt_opencl_copy_host_to_device(devid, d->lut[1], 256, 256, sizeof(float));
  dev_b = dt_opencl_copy_host_to_device(devid, d->lut[2], 256, 256, sizeof(float));
  if(IS_NULL_PTR(dev_L) || IS_NULL_PTR(dev_a) || IS_NULL_PTR(dev_b)) goto error;
 
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 0, sizeof(cl_mem), &dev_in);
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 1, sizeof(cl_mem), &dev_out);
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 2, sizeof(int), &width);
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 3, sizeof(int), &height);
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 4, sizeof(int), &d->channel);
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 5, sizeof(cl_mem), &dev_L);
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 6, sizeof(cl_mem), &dev_a);
  dt_opencl_set_kernel_arg(devid, kernel_colorzones, 7, sizeof(cl_mem), &dev_b);
  err = dt_opencl_enqueue_kernel_2d(devid, kernel_colorzones, sizes);
 
  if(err != CL_SUCCESS) goto error;
  dt_opencl_release_mem_object(dev_L);
  dt_opencl_release_mem_object(dev_a);
  dt_opencl_release_mem_object(dev_b);
  return TRUE;
 
error:
  dt_opencl_release_mem_object(dev_L);
  dt_opencl_release_mem_object(dev_a);
  dt_opencl_release_mem_object(dev_b);
  dt_print(DT_DEBUG_OPENCL, "[opencl_colorzones] couldn't enqueue kernel! %d\n", err);
  return FALSE;
}
#endif
 
void init_presets(dt_iop_module_so_t *self)
{
  dt_iop_colorzones_params_t p = { 0 };
  const int version = 5;
 
  p.strength = 0.f;
  p.mode = DT_IOP_COLORZONES_MODE_SMOOTH;
  p.splines_version = DT_IOP_COLORZONES_SPLINES_V2;
 
  dt_database_start_transaction(darktable.db);
 
  // red black white
  p.channel = DT_IOP_COLORZONES_h;
  for(int k = 0; k < DT_IOP_COLORZONES_BANDS - 1; k++)
  {
    p.curve[DT_IOP_COLORZONES_L][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_C][k].y = .0f;
    p.curve[DT_IOP_COLORZONES_h][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_L][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_C][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_h][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
  }
  p.curve[DT_IOP_COLORZONES_C][0].y = p.curve[DT_IOP_COLORZONES_C][DT_IOP_COLORZONES_BANDS - 1].y = 0.65f;
  p.curve[DT_IOP_COLORZONES_C][1].x = 3.f / 16.f;
  p.curve[DT_IOP_COLORZONES_C][3].x = 0.50f;
  p.curve[DT_IOP_COLORZONES_C][4].x = 0.51f;
  p.curve[DT_IOP_COLORZONES_C][6].x = 15.f / 16.f;
  for(int c = 0; c < 3; c++)
  {
    p.curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS - 1;
    p.curve_type[c] = CATMULL_ROM;
  }
  dt_gui_presets_add_generic(_("red black white"), self->op,
                             version, &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  // black white and skin tones
  p.channel = DT_IOP_COLORZONES_h;
  for(int k = 0; k < DT_IOP_COLORZONES_BANDS - 1; k++)
  {
    p.curve[DT_IOP_COLORZONES_L][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_C][k].y = .0f;
    p.curve[DT_IOP_COLORZONES_h][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_L][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_C][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_h][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
  }
  p.curve[DT_IOP_COLORZONES_C][0].y = 0.5f;
  p.curve[DT_IOP_COLORZONES_C][2].x = 0.25f;
  p.curve[DT_IOP_COLORZONES_C][1].x = 0.16f;
  p.curve[DT_IOP_COLORZONES_C][1].y = 0.3f;
  for(int c = 0; c < 3; c++)
  {
    p.curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS - 1;
    p.curve_type[c] = CATMULL_ROM;
  }
  dt_gui_presets_add_generic(_("black white and skin tones"), self->op,
                             version, &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  // polarizing filter
  p.channel = DT_IOP_COLORZONES_C;
  for(int k = 0; k < DT_IOP_COLORZONES_BANDS; k++)
  {
    p.curve[DT_IOP_COLORZONES_L][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_C][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_h][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_L][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_C][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_h][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
  }
  for(int k = 3; k < DT_IOP_COLORZONES_BANDS; k++)
    p.curve[DT_IOP_COLORZONES_C][k].y += (k - 2.5f) / (DT_IOP_COLORZONES_BANDS - 2.0f) * 0.25f;
  for(int k = 4; k < DT_IOP_COLORZONES_BANDS; k++)
    p.curve[DT_IOP_COLORZONES_L][k].y -= (k - 3.5f) / (DT_IOP_COLORZONES_BANDS - 3.0f) * 0.35f;
  for(int c = 0; c < 3; c++)
  {
    p.curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS;
    p.curve_type[c] = CATMULL_ROM;
  }
  dt_gui_presets_add_generic(_("polarizing filter"), self->op,
                             version, &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  // natural skin tone
  p.channel = DT_IOP_COLORZONES_h;
  for(int k = 0; k < DT_IOP_COLORZONES_BANDS - 1; k++)
  {
    p.curve[DT_IOP_COLORZONES_L][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_C][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_h][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_L][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_C][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_h][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
  }
  p.curve[DT_IOP_COLORZONES_C][1].y = .45f;
  p.curve[DT_IOP_COLORZONES_h][1].y = .55f;
  for(int c = 0; c < 3; c++)
  {
    p.curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS - 1;
    p.curve_type[c] = CATMULL_ROM;
  }
  dt_gui_presets_add_generic(_("natural skin tones"), self->op,
                             version, &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  // black and white film
  p.channel = DT_IOP_COLORZONES_h;
  for(int k = 0; k < DT_IOP_COLORZONES_BANDS - 1; k++)
  {
    p.curve[DT_IOP_COLORZONES_C][k].y = .0f;
    p.curve[DT_IOP_COLORZONES_h][k].y = .5f;
    p.curve[DT_IOP_COLORZONES_C][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
    p.curve[DT_IOP_COLORZONES_h][k].x = k / (DT_IOP_COLORZONES_BANDS - 1.f);
  }
  p.curve[DT_IOP_COLORZONES_L][0].x = 0.000000f;
  p.curve[DT_IOP_COLORZONES_L][0].y = 0.613040f;
  p.curve[DT_IOP_COLORZONES_L][1].x = 0.010000f;
  p.curve[DT_IOP_COLORZONES_L][1].y = 0.613040f;
  p.curve[DT_IOP_COLORZONES_L][2].x = 0.245283f;
  p.curve[DT_IOP_COLORZONES_L][2].y = 0.447962f;
  p.curve[DT_IOP_COLORZONES_L][3].x = 0.498113f;
  p.curve[DT_IOP_COLORZONES_L][3].y = 0.529201f;
  p.curve[DT_IOP_COLORZONES_L][4].x = 0.641509f;
  p.curve[DT_IOP_COLORZONES_L][4].y = 0.664967f;
  p.curve[DT_IOP_COLORZONES_L][5].x = 0.879245f;
  p.curve[DT_IOP_COLORZONES_L][5].y = 0.777294f;
  p.curve[DT_IOP_COLORZONES_L][6].x = 0.990000f;
  p.curve[DT_IOP_COLORZONES_L][6].y = 0.613040f;
  for(int c = 0; c < 3; c++)
  {
    p.curve_num_nodes[c] = DT_IOP_COLORZONES_BANDS - 1;
    p.curve_type[c] = CATMULL_ROM;
  }
  dt_gui_presets_add_generic(_("black & white film"), self->op,
                             version, &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  // neutral preset with just a set of nodes uniformly distributed along the hue axis
  const int colorzones_bands_hsl = 8;
  p.channel = DT_IOP_COLORZONES_h;
  for(int k = 0; k < colorzones_bands_hsl; k++)
  {
    p.curve[DT_IOP_COLORZONES_L][k].x = (float)k / colorzones_bands_hsl;
    p.curve[DT_IOP_COLORZONES_L][k].y = 0.5f;
    p.curve[DT_IOP_COLORZONES_C][k].x = (float)k / colorzones_bands_hsl;
    p.curve[DT_IOP_COLORZONES_C][k].y = 0.5f;
    p.curve[DT_IOP_COLORZONES_h][k].x = (float)k / colorzones_bands_hsl;
    p.curve[DT_IOP_COLORZONES_h][k].y = 0.5f;
  }
  for(int c = 0; c < 3; c++)
  {
    p.curve_num_nodes[c] = colorzones_bands_hsl;
    p.curve_type[c] = MONOTONE_HERMITE;
  }
  dt_gui_presets_add_generic(_("HSL base setting"), self->op,
                             version, &p, sizeof(p), 1, DEVELOP_BLEND_CS_RGB_DISPLAY);
 
  dt_database_release_transaction(darktable.db);
}
 
static void _reset_display_selection(dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  if(c)
  {
    if(c->display_mask)
    {
      c->display_mask = FALSE;
      dt_dev_pixelpipe_update_history_main(self->dev);
    }
    if(gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(c->bt_showmask)))
    {
      dt_gui_freeze_begin();
      gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(c->bt_showmask), FALSE);
      dt_gui_freeze_end();
    }
  }
}
 
static void _reset_nodes(dt_iop_colorzones_params_t *p, const int ch, const _Bool touch_edges)
{
  for(int k = 0; k < p->curve_num_nodes[ch]; k++)
  {
    if(touch_edges)
      p->curve[ch][k].x = (float)k / (float)(p->curve_num_nodes[ch] - 1);
    else
      p->curve[ch][k].x = ((float)k + 0.5f) / (float)p->curve_num_nodes[ch];
    p->curve[ch][k].y = 0.5f;
  }
}
 
static void _reset_parameters(dt_iop_colorzones_params_t *p, const int channel, const int splines_version)
{
  for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++)
  {
    p->curve_num_nodes[ch] = 2;
    p->curve_type[ch] = CATMULL_ROM; // CUBIC_SPLINE, MONOTONE_HERMITE
    _reset_nodes(p, ch, channel != DT_IOP_COLORZONES_h);
  }
  p->strength = 0.0f;
  p->channel = channel;
  p->mode = DT_IOP_COLORZONES_MODE_SMOOTH;
  p->splines_version = splines_version;
}
 
static int _select_base_display_color(dt_iop_module_t *self, float *picked_color, float *picker_min,
                                      float *picker_max)
{
  const int select_by_picker = !(self->request_color_pick != DT_REQUEST_COLORPICK_MODULE
                                 || self->picked_color_max[0] < 0.0f || self->picked_color[0] == 0.0f);
  if(!select_by_picker)
  {
    dt_aligned_pixel_t rgb = { 0.0f, 0.3f, 0.7f };
    dt_aligned_pixel_t xyz;
    dt_aligned_pixel_t lab;
    dt_sRGB_to_XYZ(rgb, xyz);
    dt_XYZ_to_Lab(xyz, lab);
    dt_Lab_2_LCH(lab, picked_color);
 
    picker_max[0] = picker_min[0] = picked_color[0];
    picker_max[1] = picker_min[1] = picked_color[1];
    picker_max[2] = picker_min[2] = picked_color[2];
  }
  else
  {
    for(int k = 0; k < 3; k++)
    {
      picked_color[k] = self->picked_color[k];
      picker_min[k] = self->picked_color_min[k];
      picker_max[k] = self->picked_color_max[k];
    }
  }
  return select_by_picker;
}
 
static void _draw_color_picker(dt_iop_module_t *self, cairo_t *cr, dt_iop_colorzones_params_t *p,
                               dt_iop_colorzones_gui_data_t *c, const int width, const int height,
                               const float *const picker_color, const float *const picker_min,
                               const float *const picker_max)
{
  if(self->request_color_pick == DT_REQUEST_COLORPICK_MODULE &&
     ( gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(c->colorpicker)) ||
       gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(c->colorpicker_set_values)) ))
  {
    // the global live samples ...
    GSList *samples = darktable.develop->color_picker.samples;
    if(samples)
    {
      const dt_iop_order_iccprofile_info_t *const display_profile
          = dt_ioppr_get_pipe_output_profile_info(self->dev->pipe);
      const dt_iop_order_iccprofile_info_t *const work_profile
          = dt_ioppr_get_iop_work_profile_info(self, self->dev->iop);
      dt_aligned_pixel_t pick_mean, pick_min, pick_max;
      int converted_cst;
 
      if(!IS_NULL_PTR(work_profile) && !IS_NULL_PTR(display_profile))
      {
        dt_colorpicker_sample_t *sample = NULL;
        for(; samples; samples = g_slist_next(samples))
        {
          sample = samples->data;
 
          float picked_i = -1.0f;
          float picked_min_i = -1.0f;
          float picked_max_i = -1.0f;
 
          // this functions need a 4c image
          for(int k = 0; k < 3; k++)
          {
            pick_mean[k] = sample->scope[DT_LIB_COLORPICKER_STATISTIC_MEAN][k];
            pick_min[k] = sample->scope[DT_LIB_COLORPICKER_STATISTIC_MIN][k];
            pick_max[k] = sample->scope[DT_LIB_COLORPICKER_STATISTIC_MAX][k];
          }
          pick_mean[3] = pick_min[3] = pick_max[3] = 1.f;
 
          dt_ioppr_transform_image_colorspace_rgb(pick_mean, pick_mean, 1, 1, display_profile, work_profile,
                                                  "color zones");
          dt_ioppr_transform_image_colorspace_rgb(pick_min, pick_min, 1, 1, display_profile, work_profile,
                                                  "color zones");
          dt_ioppr_transform_image_colorspace_rgb(pick_max, pick_max, 1, 1, display_profile, work_profile,
                                                  "color zones");
 
          dt_ioppr_transform_image_colorspace(self, pick_mean, pick_mean, 1, 1, IOP_CS_RGB, IOP_CS_LAB,
                                              &converted_cst, work_profile);
          dt_ioppr_transform_image_colorspace(self, pick_min, pick_min, 1, 1, IOP_CS_RGB, IOP_CS_LAB,
                                              &converted_cst, work_profile);
          dt_ioppr_transform_image_colorspace(self, pick_max, pick_max, 1, 1, IOP_CS_RGB, IOP_CS_LAB,
                                              &converted_cst, work_profile);
 
          dt_Lab_2_LCH(pick_mean, pick_mean);
          dt_Lab_2_LCH(pick_min, pick_min);
          dt_Lab_2_LCH(pick_max, pick_max);
 
          switch(p->channel)
          {
            // select by channel, abscissa:
            case DT_IOP_COLORZONES_L:
              picked_i = pick_mean[0] / 100.0f;
              picked_min_i = pick_min[0] / 100.0f;
              picked_max_i = pick_max[0] / 100.0f;
              break;
            case DT_IOP_COLORZONES_C:
              picked_i = pick_mean[1] / (128.0f * sqrtf(2.f));
              picked_min_i = pick_min[1] / (128.0f * sqrtf(2.f));
              picked_max_i = pick_max[1] / (128.0f * sqrtf(2.f));
              break;
            default: // case DT_IOP_COLORZONES_h:
              picked_i = pick_mean[2];
              picked_min_i = pick_min[2];
              picked_max_i = pick_max[2];
              break;
          }
 
          // Convert abcissa to log coordinates if needed
          picked_i = _curve_to_mouse(picked_i, c->zoom_factor, c->offset_x);
          picked_min_i = _curve_to_mouse(picked_min_i, c->zoom_factor, c->offset_x);
          picked_max_i = _curve_to_mouse(picked_max_i, c->zoom_factor, c->offset_x);
 
          cairo_set_source_rgba(cr, 0.5, 0.7, 0.5, 0.15);
          cairo_rectangle(cr, width * picked_min_i, 0, width * fmax(picked_max_i - picked_min_i, 0.0f), height);
          cairo_fill(cr);
          cairo_set_source_rgba(cr, 0.5, 0.7, 0.5, 0.5);
          cairo_move_to(cr, width * picked_i, 0);
          cairo_line_to(cr, width * picked_i, height);
          cairo_stroke(cr);
        }
      }
    }
  }
 
  if(self->request_color_pick == DT_REQUEST_COLORPICK_MODULE &&
     ( gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(c->colorpicker)) ||
       gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(c->colorpicker_set_values)) ))
  {
    // draw marker for currently selected color:
    float picked_i = -1.0f;
    float picked_min_i = -1.0f;
    float picked_max_i = -1.0f;
    switch(p->channel)
    {
      // select by channel, abscissa:
      case DT_IOP_COLORZONES_L:
        picked_i = picker_color[0] / 100.0f;
        picked_min_i = picker_min[0] / 100.0f;
        picked_max_i = picker_max[0] / 100.0f;
        break;
      case DT_IOP_COLORZONES_C:
        picked_i = picker_color[1] / (128.0f * sqrtf(2.f));
        picked_min_i = picker_min[1] / (128.0f * sqrtf(2.f));
        picked_max_i = picker_max[1] / (128.0f * sqrtf(2.f));
        break;
      default: // case DT_IOP_COLORZONES_h:
        picked_i = picker_color[2];
        picked_min_i = picker_min[2];
        picked_max_i = picker_max[2];
        break;
    }
 
    picked_i = _curve_to_mouse(picked_i, c->zoom_factor, c->offset_x);
    picked_min_i = _curve_to_mouse(picked_min_i, c->zoom_factor, c->offset_x);
    picked_max_i = _curve_to_mouse(picked_max_i, c->zoom_factor, c->offset_x);
 
    cairo_save(cr);
 
    cairo_set_source_rgba(cr, 1.0, 1.0, 1.0, 0.25);
    cairo_rectangle(cr, width * picked_min_i, 0, width * fmax(picked_max_i - picked_min_i, 0.0), height);
    cairo_fill(cr);
 
    cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
    cairo_set_operator(cr, CAIRO_OPERATOR_XOR);
    cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(2.));
    cairo_move_to(cr, width * picked_i, 0.0);
    cairo_line_to(cr, width * picked_i, height);
    cairo_stroke(cr);
 
    cairo_restore(cr);
  }
}
 
// graph x resulolution
#define DT_COLORZONES_CELLSI 64
// graph y resulolution
#define DT_COLORZONES_CELLSJ 36
 
#define COLORZONES_DRAW_BACKGROUD_BOX                                                                             \
  dt_aligned_pixel_t Lab;                                                                                         \
  dt_LCH_2_Lab(LCh, Lab);                                                                                         \
  const float L0 = Lab[0];                                                                                        \
  /* gamut mapping magic from iop/exposure.c: */                                                                  \
  const float Lwhite = 100.0f, Lclip = 20.0f;                                                                     \
  const float Lcap = fminf(100.0f, Lab[0]);                                                                       \
  const float clip                                                                                                \
      = 1.0f                                                                                                      \
        - (Lcap - L0) * (1.0f / 100.0f) * fminf(Lwhite - Lclip, fmaxf(0.0f, Lab[0] - Lclip)) / (Lwhite - Lclip);  \
  const float clip2 = clip * clip * clip;                                                                         \
  Lab[1] *= Lab[0] / L0 * clip2;                                                                                  \
  Lab[2] *= Lab[0] / L0 * clip2;                                                                                  \
                                                                                                                  \
  dt_aligned_pixel_t xyz;                                                                                         \
  dt_aligned_pixel_t rgb;                                                                                         \
  dt_Lab_to_XYZ(Lab, xyz);                                                                                        \
  dt_XYZ_to_sRGB(xyz, rgb);                                                                                       \
                                                                                                                  \
  cairo_set_source_rgb(cr, rgb[0], rgb[1], rgb[2]);
 
static void _draw_background(cairo_t *cr, dt_iop_colorzones_params_t *p, dt_iop_colorzones_gui_data_t *c,
                             const int select_by_picker, const int width, const int height,
                             const float *picked_color)
{
  const float bg_sat_factor = dt_conf_get_float("plugins/darkroom/colorzones/bg_sat_factor");
  const float normalize_C = (128.f * bg_sat_factor * sqrtf(2.f));
 
  const int cellsi = DT_COLORZONES_CELLSI;
  const int cellsj = DT_COLORZONES_CELLSJ;
 
  for(int j = 0; j < cellsj; j++)
  {
    for(int i = 0; i < cellsi; i++)
    {
      dt_aligned_pixel_t LCh = { 0 };
 
      const float jj = _mouse_to_curve(1.0f - ((float)j - .5f) / (float)(cellsj - 1), c->zoom_factor, c->offset_y);
      const float jjh
          = _mouse_to_curve(1.0f - (((float)j / (float)(cellsj - 1))), c->zoom_factor, c->offset_y) + .5f;
      const float ii = _mouse_to_curve(((float)i + .5f) / (float)(cellsi - 1), c->zoom_factor, c->offset_x);
      const float iih = _mouse_to_curve((float)i / (float)(cellsi - 1), c->zoom_factor, c->offset_x);
 
      // select by channel, abscissa:
      switch(p->channel)
      {
        // select by channel, abscissa:
        case DT_IOP_COLORZONES_L:
          LCh[0] = 100.0f * ii;
          LCh[1] = normalize_C * .5f;
          LCh[2] = picked_color[2];
          break;
        case DT_IOP_COLORZONES_C:
          LCh[0] = 50.0f;
          LCh[1] = picked_color[1] * 2.f * bg_sat_factor * ii;
          LCh[2] = picked_color[2];
          break;
        default: // DT_IOP_COLORZONES_h
          LCh[0] = 50.0f;
          LCh[1] = normalize_C * .5f;
          LCh[2] = iih;
          break;
      }
      // channel to be altered:
      switch(c->channel)
      {
        // select by channel, abscissa:
        case DT_IOP_COLORZONES_L:
          if(p->channel == DT_IOP_COLORZONES_L)
            LCh[0] *= jj;
          else
            LCh[0] += -50.0f + 100.0f * jj;
          break;
        case DT_IOP_COLORZONES_C:
          LCh[1] *= 2.f * jj;
          break;
        default: // DT_IOP_COLORZONES_h
          LCh[2] += jjh;
          break;
      }
 
      COLORZONES_DRAW_BACKGROUD_BOX
 
      cairo_rectangle(cr, width * i / (float)cellsi, height * j / (float)cellsj, width / (float)cellsi,
                      height / (float)cellsj);
      cairo_fill(cr);
    }
  }
}
 
static gboolean _area_draw_callback(GtkWidget *widget, cairo_t *crf, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_iop_colorzones_params_t p = *(dt_iop_colorzones_params_t *)self->params;
 
  if(p.splines_version == DT_IOP_COLORZONES_SPLINES_V1)
  {
    for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++)
    {
      if(c->minmax_curve_type[ch] != p.curve_type[ch] || c->minmax_curve_nodes[ch] != p.curve_num_nodes[ch])
      {
        dt_draw_curve_destroy(c->minmax_curve[ch]);
        c->minmax_curve[ch] = dt_draw_curve_new(0.0f, 1.0f, p.curve_type[ch]);
        c->minmax_curve_nodes[ch] = p.curve_num_nodes[ch];
        c->minmax_curve_type[ch] = p.curve_type[ch];
 
        if(p.channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_add_point(c->minmax_curve[ch], p.curve[ch][p.curve_num_nodes[ch] - 2].x - 1.0f,
                                  p.curve[ch][p.curve_num_nodes[ch] - 2].y);
        else
          dt_draw_curve_add_point(c->minmax_curve[ch], p.curve[ch][p.curve_num_nodes[ch] - 2].x - 1.0f,
                                  p.curve[ch][0].y);
        for(int k = 0; k < p.curve_num_nodes[ch]; k++)
          dt_draw_curve_add_point(c->minmax_curve[ch], p.curve[ch][k].x, p.curve[ch][k].y);
        if(p.channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_add_point(c->minmax_curve[ch], p.curve[ch][1].x + 1.0f, p.curve[ch][1].y);
        else
          dt_draw_curve_add_point(c->minmax_curve[ch], p.curve[ch][1].x + 1.0f,
                                  p.curve[ch][p.curve_num_nodes[ch] - 1].y);
      }
      else
      {
        if(p.channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_set_point(c->minmax_curve[ch], 0, p.curve[ch][p.curve_num_nodes[ch] - 2].x - 1.0f,
                                  p.curve[ch][p.curve_num_nodes[ch] - 2].y);
        else
          dt_draw_curve_set_point(c->minmax_curve[ch], 0, p.curve[ch][p.curve_num_nodes[ch] - 2].x - 1.0f,
                                  p.curve[ch][0].y);
        for(int k = 0; k < p.curve_num_nodes[ch]; k++)
          dt_draw_curve_set_point(c->minmax_curve[ch], k + 1, p.curve[ch][k].x, p.curve[ch][k].y);
        if(p.channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_set_point(c->minmax_curve[ch], p.curve_num_nodes[ch] + 1, p.curve[ch][1].x + 1.0f,
                                  p.curve[ch][1].y);
        else
          dt_draw_curve_set_point(c->minmax_curve[ch], p.curve_num_nodes[ch] + 1, p.curve[ch][1].x + 1.0f,
                                  p.curve[ch][p.curve_num_nodes[ch] - 1].y);
      }
      dt_draw_curve_calc_values(c->minmax_curve[ch], 0.0f, 1.0f, DT_IOP_COLORZONES_RES, NULL, c->draw_ys[ch]);
    }
  }
  else
  {
    for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++)
    {
      if(c->minmax_curve_type[ch] != p.curve_type[ch] || c->minmax_curve_nodes[ch] != p.curve_num_nodes[ch]
         || c->minmax_curve[ch]->c.m_numAnchors != p.curve_num_nodes[ch])
      {
        dt_draw_curve_destroy(c->minmax_curve[ch]);
        c->minmax_curve[ch] = dt_draw_curve_new(0.f, 1.f, p.curve_type[ch]);
        c->minmax_curve_nodes[ch] = p.curve_num_nodes[ch];
        c->minmax_curve_type[ch] = p.curve_type[ch];
 
        for(int k = 0; k < p.curve_num_nodes[ch]; k++)
          dt_draw_curve_add_point(c->minmax_curve[ch], p.curve[ch][k].x, p.curve[ch][k].y);
      }
      else
      {
        for(int k = 0; k < p.curve_num_nodes[ch]; k++)
          dt_draw_curve_set_point(c->minmax_curve[ch], k, p.curve[ch][k].x, p.curve[ch][k].y);
      }
      dt_draw_curve_calc_values_V2(c->minmax_curve[ch], 0.f, 1.f, DT_IOP_COLORZONES_RES, NULL, c->draw_ys[ch],
                                   p.channel == DT_IOP_COLORZONES_h);
    }
  }
 
  const int ch = (int)c->channel;
 
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  const int inset = DT_IOP_COLORZONES_INSET;
  int width = allocation.width, height = allocation.height;
  cairo_surface_t *cst = dt_cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
  cairo_t *cr = cairo_create(cst);
 
  // clear bg, match color of the notebook tabs:
  GdkRGBA color;
  GtkStyleContext *context = gtk_widget_get_style_context(widget);
  gboolean color_found = gtk_style_context_lookup_color(context, "graph_overlay", &color);
  if(!color_found)
  {
    color.red = 1.0;
    color.green = 0.0;
    color.blue = 0.0;
    color.alpha = 1.0;
  }
  gdk_cairo_set_source_rgba(cr, &color);
  cairo_paint(cr);
 
  cairo_translate(cr, inset, inset);
  width -= 2 * inset;
  height -= 2 * inset;
 
  cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.0));
  cairo_set_source_rgb(cr, .1, .1, .1);
  cairo_rectangle(cr, 0, 0, width, height);
  cairo_stroke(cr);
 
  cairo_set_source_rgb(cr, .3, .3, .3);
  cairo_rectangle(cr, 0, 0, width, height);
  cairo_fill(cr);
 
  // if color picker is active we use it as base color
  // otherwise we use a light blue
  // we will work on LCh
  dt_aligned_pixel_t picked_color, picker_min, picker_max;
  const int select_by_picker = _select_base_display_color(self, picked_color, picker_min, picker_max);
 
  cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE);
 
  _draw_background(cr, &p, c, select_by_picker, width, height, picked_color);
 
  cairo_set_antialias(cr, CAIRO_ANTIALIAS_DEFAULT);
 
  // draw histogram in background
  // only if module is enabled
  if(self->enabled)
  {
    // only if no color picker
    if(self->request_color_pick != DT_REQUEST_COLORPICK_MODULE)
    {
      const int ch_hist = p.channel;
      const uint32_t *hist = self->histogram;
      const gboolean is_linear = FALSE;
      const float hist_max = is_linear ? self->histogram_max[ch_hist]
                                       : logf(1.0f + self->histogram_max[ch_hist]);
      if(!IS_NULL_PTR(hist) && hist_max > 0.0f)
      {
        cairo_save(cr);
        cairo_translate(cr, 0, height);
        cairo_scale(cr, width / 255.0, -(height - DT_PIXEL_APPLY_DPI(5)) / hist_max);
 
        cairo_set_source_rgba(cr, .2, .2, .2, 0.5);
        dt_draw_histogram_8_zoomed(cr, hist, 4, ch_hist, c->zoom_factor, c->offset_x * 255.f,
                                   c->offset_y * hist_max, is_linear);
 
        cairo_restore(cr);
      }
    }
 
    _draw_color_picker(self, cr, &p, c, width, height, picked_color, picker_min, picker_max);
  }
 
  if(c->edit_by_area)
  {
    // draw x positions
    cairo_set_source_rgb(cr, 0.6, 0.6, 0.6);
    cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.));
    const float arrw = DT_PIXEL_APPLY_DPI(7.0f);
    for(int k = 0; k < p.curve_num_nodes[ch]; k++)
    {
      const float x = _curve_to_mouse(p.curve[ch][k].x, c->zoom_factor, c->offset_x);
 
      cairo_move_to(cr, width * x, height + inset - DT_PIXEL_APPLY_DPI(1));
      cairo_rel_line_to(cr, -arrw * .5f, 0);
      cairo_rel_line_to(cr, arrw * .5f, -arrw);
      cairo_rel_line_to(cr, arrw * .5f, arrw);
      cairo_close_path(cr);
      if(c->x_move == k)
        cairo_fill(cr);
      else
        cairo_stroke(cr);
    }
  }
 
  cairo_translate(cr, 0, height);
  
  // draw curves, selected last.
  cairo_set_operator(cr, CAIRO_OPERATOR_OVER);
  cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(2.));
  for(int i = 0; i < DT_IOP_COLORZONES_MAX_CHANNELS; i++)
  {
    const int ch_inv = ((int)c->channel + i + 1) % 3;
 
    if(i == 2)
      cairo_set_source_rgba(cr, .7, .7, .7, 1.0);
    else
      cairo_set_source_rgba(cr, .7, .7, .7, 0.3);
 
    cairo_move_to(cr, 0, -height * _curve_to_mouse(c->draw_ys[ch_inv][0], c->zoom_factor, c->offset_y));
    for(int k = 1; k < DT_IOP_COLORZONES_RES; k++)
    {
      const float xx = (float)k / (float)(DT_IOP_COLORZONES_RES - 1);
      const float yy = c->draw_ys[ch_inv][k];
 
      const float x = _curve_to_mouse(xx, c->zoom_factor, c->offset_x),
                  y = _curve_to_mouse(yy, c->zoom_factor, c->offset_y);
 
      cairo_line_to(cr, x * width, -height * y);
    }
 
    cairo_stroke(cr);
  }
 
  // draw dots on knots
  cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.));
  cairo_set_source_rgb(cr, 0.6, 0.6, 0.6);
  cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.));
  for(int k = 0; k < p.curve_num_nodes[ch]; k++)
  {
    const float x = _curve_to_mouse(p.curve[ch][k].x, c->zoom_factor, c->offset_x),
                y = _curve_to_mouse(p.curve[ch][k].y, c->zoom_factor, c->offset_y);
    cairo_arc(cr, width * x, -height * y, DT_PIXEL_APPLY_DPI(3.0), 0.0, 2.0 * M_PI);
    cairo_stroke(cr);
  }
 
  // draw min/max, if selected
  if(c->edit_by_area && (c->mouse_y > 0 || c->dragging))
  {
    const int bands = p.curve_num_nodes[ch];
 
    p = *(dt_iop_colorzones_params_t *)self->params;
    dt_iop_colorzones_get_params(&p, c, c->channel, c->mouse_x, 1., c->mouse_radius);
    if(p.splines_version == DT_IOP_COLORZONES_SPLINES_V1)
    {
      if(p.channel == DT_IOP_COLORZONES_h)
        dt_draw_curve_set_point(c->minmax_curve[ch], 0, p.curve[ch][bands - 2].x - 1.f, p.curve[ch][bands - 2].y);
      else
        dt_draw_curve_set_point(c->minmax_curve[ch], 0, p.curve[ch][bands - 2].x - 1.f, p.curve[ch][0].y);
      for(int k = 0; k < bands; k++)
        dt_draw_curve_set_point(c->minmax_curve[ch], k + 1, p.curve[ch][k].x, p.curve[ch][k].y);
      if(p.channel == DT_IOP_COLORZONES_h)
        dt_draw_curve_set_point(c->minmax_curve[ch], bands + 1, p.curve[ch][1].x + 1.f, p.curve[ch][1].y);
      else
        dt_draw_curve_set_point(c->minmax_curve[ch], bands + 1, p.curve[ch][1].x + 1.f, p.curve[ch][bands - 1].y);
      dt_draw_curve_calc_values(c->minmax_curve[ch], 0.f, 1.f, DT_IOP_COLORZONES_RES, NULL, c->draw_min_ys);
    }
    else
    {
      for(int k = 0; k < bands; k++)
        dt_draw_curve_set_point(c->minmax_curve[ch], k, p.curve[ch][k].x, p.curve[ch][k].y);
      dt_draw_curve_calc_values_V2(c->minmax_curve[ch], 0.f, 1.f, DT_IOP_COLORZONES_RES, NULL, c->draw_min_ys,
                                   p.channel == DT_IOP_COLORZONES_h);
    }
 
    p = *(dt_iop_colorzones_params_t *)self->params;
    dt_iop_colorzones_get_params(&p, c, c->channel, c->mouse_x, .0, c->mouse_radius);
    if(p.splines_version == DT_IOP_COLORZONES_SPLINES_V1)
    {
      if(p.channel == DT_IOP_COLORZONES_h)
        dt_draw_curve_set_point(c->minmax_curve[ch], 0, p.curve[ch][bands - 2].x - 1.f, p.curve[ch][bands - 2].y);
      else
        dt_draw_curve_set_point(c->minmax_curve[ch], 0, p.curve[ch][bands - 2].x - 1.f, p.curve[ch][0].y);
      for(int k = 0; k < bands; k++)
        dt_draw_curve_set_point(c->minmax_curve[ch], k + 1, p.curve[ch][k].x, p.curve[ch][k].y);
      if(p.channel == DT_IOP_COLORZONES_h)
        dt_draw_curve_set_point(c->minmax_curve[ch], bands + 1, p.curve[ch][1].x + 1.f, p.curve[ch][1].y);
      else
        dt_draw_curve_set_point(c->minmax_curve[ch], bands + 1, p.curve[ch][1].x + 1.f, p.curve[ch][bands - 1].y);
      dt_draw_curve_calc_values(c->minmax_curve[ch], 0.f, 1.f, DT_IOP_COLORZONES_RES, NULL, c->draw_max_ys);
    }
    else
    {
      for(int k = 0; k < bands; k++)
        dt_draw_curve_set_point(c->minmax_curve[ch], k, p.curve[ch][k].x, p.curve[ch][k].y);
      dt_draw_curve_calc_values_V2(c->minmax_curve[ch], 0.f, 1.f, DT_IOP_COLORZONES_RES, NULL, c->draw_max_ys,
                                   p.channel == DT_IOP_COLORZONES_h);
    }
 
    // restore params values
    p = *(dt_iop_colorzones_params_t *)self->params;
 
    // draw min/max curves:
    cairo_set_source_rgba(cr, .7, .7, .7, .6);
    cairo_move_to(cr, 0, -height * _curve_to_mouse(c->draw_min_ys[0], c->zoom_factor, c->offset_y));
 
    for(int k = 1; k < DT_IOP_COLORZONES_RES; k++)
    {
      const float xx = (float)k / (float)(DT_IOP_COLORZONES_RES - 1);
      const float yy = c->draw_min_ys[k];
 
      const float x = _curve_to_mouse(xx, c->zoom_factor, c->offset_x),
                  y = _curve_to_mouse(yy, c->zoom_factor, c->offset_y);
 
      cairo_line_to(cr, x * width, -height * y);
    }
 
    for(int k = DT_IOP_COLORZONES_RES - 1; k >= 0; k--)
    {
      const float xx = (float)k / (float)(DT_IOP_COLORZONES_RES - 1);
      const float yy = c->draw_max_ys[k];
 
      const float x = _curve_to_mouse(xx, c->zoom_factor, c->offset_x),
                  y = _curve_to_mouse(yy, c->zoom_factor, c->offset_y);
 
      cairo_line_to(cr, x * width, -height * y);
    }
 
    cairo_close_path(cr);
    cairo_fill(cr);
 
    // draw mouse focus circle
    cairo_set_source_rgba(cr, .9, .9, .9, .5);
 
    const int k = DT_IOP_COLORZONES_RES * _mouse_to_curve(c->mouse_x, c->zoom_factor, c->offset_x);
    const float x = c->mouse_x, y = _curve_to_mouse(c->draw_ys[ch][k], c->zoom_factor, c->offset_y);
 
    cairo_arc(cr, x * width, -height * y, c->mouse_radius * width, 0, 2. * DT_M_PI);
    cairo_stroke(cr);
  }
  else
  {
    // draw selected cursor
    cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.));
 
    if(c->selected >= 0)
    {
      cairo_set_source_rgb(cr, .9, .9, .9);
      const float x = _curve_to_mouse(p.curve[c->channel][c->selected].x, c->zoom_factor, c->offset_x),
                  y = _curve_to_mouse(p.curve[c->channel][c->selected].y, c->zoom_factor, c->offset_y);
 
      cairo_arc(cr, x * width, -y * height, DT_PIXEL_APPLY_DPI(4), 0, 2. * M_PI);
      cairo_stroke(cr);
    }
  }
 
  cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
 
  cairo_destroy(cr);
  cairo_set_source_surface(crf, cst, 0, 0);
  cairo_paint(crf);
  cairo_surface_destroy(cst);
  return TRUE;
}
 
static gboolean _bottom_area_draw_callback(GtkWidget *widget, cairo_t *crf, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_iop_colorzones_params_t p = *(dt_iop_colorzones_params_t *)self->params;
 
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  const int inset = DT_IOP_COLORZONES_INSET;
  int width = allocation.width, height = allocation.height;
  cairo_surface_t *cst = dt_cairo_image_surface_create(CAIRO_FORMAT_ARGB32, width, height);
  cairo_t *cr = cairo_create(cst);
  // clear bg, match color of the notebook tabs:
  GdkRGBA color;
  GtkStyleContext *context = gtk_widget_get_style_context(widget);
  gboolean color_found = gtk_style_context_lookup_color(context, "graph_overlay", &color);
  if(!color_found)
  {
    color.red = 1.0;
    color.green = 0.0;
    color.blue = 0.0;
    color.alpha = 1.0;
  }
  gdk_cairo_set_source_rgba(cr, &color);
  cairo_paint(cr);
 
  cairo_translate(cr, inset, inset);
  width -= 2 * inset;
  height -= 2 * inset;
 
  cairo_set_line_width(cr, DT_PIXEL_APPLY_DPI(1.0));
  cairo_set_source_rgb(cr, .1, .1, .1);
  cairo_rectangle(cr, 0, 0, width, height);
  cairo_stroke(cr);
 
  cairo_set_source_rgb(cr, .3, .3, .3);
  cairo_rectangle(cr, 0, 0, width, height);
  cairo_fill(cr);
 
  // if color picker is active we use it as base color
  // otherwise we use a light blue
  // we will work on LCh
  dt_aligned_pixel_t picked_color, picker_min, picker_max;
  _select_base_display_color(self, picked_color, picker_min, picker_max);
  const float normalize_C = (128.f * sqrtf(2.f));
 
  cairo_set_antialias(cr, CAIRO_ANTIALIAS_NONE);
 
  const int cellsi = DT_COLORZONES_CELLSI;
 
  for(int i = 0; i < cellsi; i++)
  {
    const float ii = _mouse_to_curve(((float)i + .5f) / (float)(cellsi - 1), c->zoom_factor, c->offset_x);
    const float iih = _mouse_to_curve((float)i / (float)(cellsi - 1), c->zoom_factor, c->offset_x);
 
    dt_aligned_pixel_t LCh;
 
    switch(p.channel)
    {
      // select by channel, abscissa:
      case DT_IOP_COLORZONES_L:
        LCh[0] = 100.0f * ii;
        LCh[1] = normalize_C * .5f;
        LCh[2] = picked_color[2];
        break;
      case DT_IOP_COLORZONES_C:
        LCh[0] = 50.0f;
        LCh[1] = picked_color[1] * 2.f * ii;
        LCh[2] = picked_color[2];
        break;
      default: // DT_IOP_COLORZONES_h
        LCh[0] = 50.0f;
        LCh[1] = normalize_C * .5f;
        LCh[2] = iih;
        break;
    }
 
    COLORZONES_DRAW_BACKGROUD_BOX
 
    cairo_rectangle(cr, width * i / (float)cellsi, 0, width / (float)cellsi, height);
    cairo_fill(cr);
  }
 
  cairo_set_antialias(cr, CAIRO_ANTIALIAS_DEFAULT);
 
  if(self->enabled)
  {
    _draw_color_picker(self, cr, &p, c, width, height, picked_color, picker_min, picker_max);
  }
 
  cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
 
  cairo_destroy(cr);
  cairo_set_source_surface(crf, cst, 0, 0);
  cairo_paint(crf);
  cairo_surface_destroy(cst);
  return TRUE;
}
 
#undef COLORZONES_DRAW_BACKGROUD_BOX
#undef DT_COLORZONES_CELLSI
#undef DT_COLORZONES_CELLSJ
 
static gboolean _bottom_area_button_press_callback(GtkWidget *widget, GdkEventButton *event, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  if(event->button == 1 && event->type == GDK_2BUTTON_PRESS)
  {
    // reset zoom level
    c->zoom_factor = 1.f;
    c->offset_x = c->offset_y = 0.f;
 
    gtk_widget_queue_draw(self->widget);
 
    return TRUE;
  }
 
  return FALSE;
}
 
static gboolean _sanity_check(const float x, const int selected, const int nodes,
                              const dt_iop_colorzones_node_t *curve)
{
  gboolean point_valid = TRUE;
 
  // check if it is not too close to other node
  const float min_dist = DT_IOP_COLORZONES_MIN_X_DISTANCE; // in curve coordinates
  if((selected > 0 && x - curve[selected - 1].x <= min_dist)
     || (selected < nodes - 1 && curve[selected + 1].x - x <= min_dist))
    point_valid = FALSE;
 
  // for all points, x coordinate of point must be strictly larger than
  // the x coordinate of the previous point
  if((selected > 0 && (curve[selected - 1].x >= x)) || (selected < nodes - 1 && (curve[selected + 1].x <= x)))
  {
    point_valid = FALSE;
  }
 
  return point_valid;
}
 
static gboolean _move_point_internal(dt_iop_module_t *self, GtkWidget *widget, int node, float dx, float dy, guint state)
{
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  int ch = c->channel;
  dt_iop_colorzones_node_t *curve = p->curve[ch];
 
  if(p->splines_version == DT_IOP_COLORZONES_SPLINES_V1)
    // do not move the first or last nodes on the x-axis
    if(node == 0 || node == p->curve_num_nodes[ch] - 1) dx = 0.f;
 
  float new_x = CLAMP(curve[node].x + dx, 0.0f, 1.0f);
  const float new_y = CLAMP(curve[node].y + dy, 0.0f, 1.0f);
 
  if(_sanity_check(new_x, node, p->curve_num_nodes[ch], p->curve[ch]))
  {
    if(p->splines_version == DT_IOP_COLORZONES_SPLINES_V1)
    {
      curve[node].x = new_x;
      curve[node].y = new_y;
 
      if(p->channel == DT_IOP_COLORZONES_h && (node == 0 || node == p->curve_num_nodes[ch] - 1))
      {
        if(node == 0)
        {
          curve[p->curve_num_nodes[ch] - 1].x = 1.f - curve[node].x;
          curve[p->curve_num_nodes[ch] - 1].y = curve[node].y;
        }
        else
        {
          curve[0].x = 1.f - curve[node].x;
          curve[0].y = curve[node].y;
        }
      }
    }
    else
    {
      if(p->channel == DT_IOP_COLORZONES_h && (node == 0 || node == p->curve_num_nodes[ch] - 1))
      {
        if(node == 0)
        {
          if(new_x + 1.f - curve[p->curve_num_nodes[ch] - 1].x < DT_IOP_COLORZONES_MIN_X_DISTANCE)
            new_x = curve[p->curve_num_nodes[ch] - 1].x + DT_IOP_COLORZONES_MIN_X_DISTANCE - 1.f;
        }
        else
        {
          if(curve[0].x + 1.f - new_x < DT_IOP_COLORZONES_MIN_X_DISTANCE)
            new_x = curve[0].x + 1.f - DT_IOP_COLORZONES_MIN_X_DISTANCE;
        }
      }
      curve[node].x = new_x;
      curve[node].y = new_y;
    }
 
    dt_gui_throttle_queue(self, dt_iop_throttled_history_update, self);
  }
 
  gtk_widget_queue_draw(widget);
 
  return TRUE;
}
 
static void _delete_node(dt_iop_module_t *self, dt_iop_colorzones_node_t *curve, int *nodes, int node, gboolean zero)
{
  if(zero)
  {
    curve[node].y = 0.5f;
  }
  else
  {
    //  for p->splines_version == DT_IOP_COLORZONES_SPLINES_V1 condition nodes > 1 always true
    if(*nodes > 1)
    {
      for(int k = node; k < *nodes - 1; k++)
      {
        curve[k].x = curve[k + 1].x;
        curve[k].y = curve[k + 1].y;
      }
      curve[*nodes - 1].x = curve[*nodes - 1].y = 0;
      (*nodes)--;
    }
    else
    {
      curve[0].x = 0.5f;
      curve[0].y = 0.5f;
    }
  }
 
  dt_iop_color_picker_reset(self, TRUE);
  gtk_widget_queue_draw(self->widget);
  dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
}
 
static inline int _add_node(dt_iop_colorzones_node_t *curve, int *nodes, float x, float y)
{
  int selected = -1;
  if(curve[0].x > x)
    selected = 0;
  else
  {
    for(int k = 1; k < *nodes; k++)
    {
      if(curve[k].x > x)
      {
        selected = k;
        break;
      }
    }
  }
  if(selected == -1) selected = *nodes;
 
  // check if it is not too close to other node
  const float min_dist = DT_IOP_COLORZONES_MIN_X_DISTANCE; // in curve coordinates
  if((selected > 0 && x - curve[selected - 1].x <= min_dist)
     || (selected < *nodes && curve[selected].x - x <= min_dist))
    selected = -2;
 
  if(selected >= 0)
  {
    for(int i = *nodes; i > selected; i--)
    {
      curve[i].x = curve[i - 1].x;
      curve[i].y = curve[i - 1].y;
    }
    // found a new point
    curve[selected].x = x;
    curve[selected].y = y;
    (*nodes)++;
  }
  return selected;
}
 
static gboolean _area_scrolled_callback(GtkWidget *widget, GdkEventScroll *event, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
 
  int delta_y;
 
  // (the graph height is now adjusted with the drag grip on its bottom edge, not Ctrl+Scroll)
 
  if(c->selected < 0 && !c->edit_by_area) return TRUE;
 
  if(dt_gui_get_scroll_unit_delta(event, &delta_y))
  {
    dt_iop_color_picker_reset(self, TRUE);
 
    if(c->edit_by_area)
    {
      const int bands = p->curve_num_nodes[c->channel];
      c->mouse_radius = CLAMP(c->mouse_radius * (1.0 + 0.1 * delta_y), 0.2 / bands, 1.0);
      gtk_widget_queue_draw(widget);
    }
    else
    {
      delta_y *= -DT_IOP_COLORZONES_DEFAULT_STEP;
      return _move_point_internal(self, widget, c->selected, 0.f, delta_y, event->state);
    }
  }
 
  return TRUE;
}
 
static gboolean _area_motion_notify_callback(GtkWidget *widget, GdkEventMotion *event, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
 
  const int inset = DT_IOP_COLORZONES_INSET;
 
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
 
  const int height = allocation.height - 2 * inset;
  const int width = allocation.width - 2 * inset;
 
  const int ch = c->channel;
  const int nodes = p->curve_num_nodes[ch];
  dt_iop_colorzones_node_t *curve = p->curve[ch];
 
  const double old_m_x = c->mouse_x;
  const double old_m_y = fabs(c->mouse_y);
 
  c->mouse_x = CLAMP(event->x - inset, 0, width) / (float)width;
  c->mouse_y = 1.0 - CLAMP(event->y - inset, 0, height) / (float)height;
 
  // move a node
  if(event->state & GDK_BUTTON1_MASK)
  {
    if(c->edit_by_area)
    {
      if(c->dragging && c->x_move >= 0)
        c->selected = c->x_move;
      else
        c->selected = -1;
    }
 
    // got a vertex selected:
    if(c->selected >= 0)
    {
      // this is used to translate mause position in zoom_factor to make this behavior unified with linear scale.
      const float translate_mouse_x = old_m_x - _curve_to_mouse(curve[c->selected].x, c->zoom_factor, c->offset_x);
      const float translate_mouse_y = old_m_y - _curve_to_mouse(curve[c->selected].y, c->zoom_factor, c->offset_y);
      // dx & dy are in linear coordinates
      const float dx = _mouse_to_curve(c->mouse_x - translate_mouse_x, c->zoom_factor, c->offset_x)
                       - _mouse_to_curve(old_m_x - translate_mouse_x, c->zoom_factor, c->offset_x);
      const float dy = _mouse_to_curve(c->mouse_y - translate_mouse_y, c->zoom_factor, c->offset_y)
                       - _mouse_to_curve(old_m_y - translate_mouse_y, c->zoom_factor, c->offset_y);
 
      dt_iop_color_picker_reset(self, TRUE);
      return _move_point_internal(self, widget, c->selected, dx, dy, event->state);
    }
  }
 
  if(c->edit_by_area)
  {
    if(c->dragging)
    {
      if(c->x_move < 0)
      {
        dt_iop_colorzones_get_params(p, c, c->channel, c->mouse_x, c->mouse_y, c->mouse_radius);
        dt_iop_color_picker_reset(self, TRUE);
        dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
      }
    }
    else if(event->y > height)
    {
      c->x_move = 0;
      const int bands = p->curve_num_nodes[c->channel];
      const float mouse_x = _mouse_to_curve(c->mouse_x, c->zoom_factor, c->offset_x);
      float dist = fabsf(p->curve[c->channel][0].x - mouse_x);
      for(int k = 1; k < bands; k++)
      {
        const float d2 = fabsf(p->curve[c->channel][k].x - mouse_x);
        if(d2 < dist)
        {
          c->x_move = k;
          dist = d2;
        }
      }
    }
    else
    {
      c->x_move = -1;
    }
  }
  else
  {
    if(event->state & GDK_BUTTON1_MASK)
    {
      if(nodes < DT_IOP_COLORZONES_MAXNODES && c->selected == -1)
      {
        const float linx = _mouse_to_curve(c->mouse_x, c->zoom_factor, c->offset_x),
                    liny = _mouse_to_curve(c->mouse_y, c->zoom_factor, c->offset_y);
 
        // no vertex was close, create a new one!
        c->selected = _add_node(curve, &p->curve_num_nodes[ch], linx, liny);
 
        dt_iop_color_picker_reset(self, TRUE);
        dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
      }
    }
    else
    {
      const float mx = c->mouse_x;
      const float my = c->mouse_y;
 
      // minimum area around the node to select it:
      float min = .04f * .04f; // comparing against square
      int nearest = -1;
      for(int k = 0; k < nodes; k++)
      {
        float dist = (my - _curve_to_mouse(curve[k].y, c->zoom_factor, c->offset_y))
                         * (my - _curve_to_mouse(curve[k].y, c->zoom_factor, c->offset_y))
                     + (mx - _curve_to_mouse(curve[k].x, c->zoom_factor, c->offset_x))
                           * (mx - _curve_to_mouse(curve[k].x, c->zoom_factor, c->offset_x));
        if(dist < min)
        {
          min = dist;
          nearest = k;
        }
      }
      c->selected = nearest;
    }
    if(c->selected >= 0) gtk_widget_grab_focus(widget);
  }
 
  gtk_widget_queue_draw(widget);
  return TRUE;
}
 
static gboolean _area_button_press_callback(GtkWidget *widget, GdkEventButton *event, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
  dt_iop_colorzones_params_t *d = (dt_iop_colorzones_params_t *)self->default_params;
 
  int ch = c->channel;
  int nodes = p->curve_num_nodes[ch];
  dt_iop_colorzones_node_t *curve = p->curve[ch];
 
  if(event->button == 1)
  {
    if(c->edit_by_area && event->type != GDK_2BUTTON_PRESS && !dt_modifier_is(event->state, GDK_CONTROL_MASK))
    {
      c->dragging = 1;
      return TRUE;
    }
    else if(event->type == GDK_BUTTON_PRESS && dt_modifier_is(event->state, GDK_CONTROL_MASK)
            && nodes < DT_IOP_COLORZONES_MAXNODES && (c->selected == -1 || c->edit_by_area))
    {
      // if we are not on a node -> add a new node at the current x of the pointer and y of the curve at that x
      const int inset = DT_IOP_COLORZONES_INSET;
      GtkAllocation allocation;
      gtk_widget_get_allocation(widget, &allocation);
      const int height = allocation.height - 2 * inset;
      const int width = allocation.width - 2 * inset;
 
      c->mouse_x = CLAMP(event->x - inset, 0, width) / (float)width;
      c->mouse_y = 1.0 - CLAMP(event->y - inset, 0, height) / (float)height;
 
      const float mx = _mouse_to_curve(c->mouse_x, c->zoom_factor, c->offset_x);
 
      // don't add a node too close to others in x direction, it can crash dt
      int selected = -1;
      if(curve[0].x > mx)
        selected = 0;
      else
      {
        for(int k = 1; k < nodes; k++)
        {
          if(curve[k].x > mx)
          {
            selected = k;
            break;
          }
        }
      }
      if(selected == -1) selected = nodes;
 
      // evaluate the curve at the current x position
      const float y = dt_draw_curve_calc_value(c->minmax_curve[ch], mx);
 
      if(y >= 0.0f && y <= 1.0f) // never add something outside the viewport, you couldn't change it afterwards
      {
        // create a new node
        selected = _add_node(curve, &p->curve_num_nodes[ch], mx, y);
 
        // maybe set the new one as being selected
        const float min = .04f * .04f; // comparing against square
 
        for(int k = 0; k < nodes; k++)
        {
          const float other_y = _curve_to_mouse(curve[k].y, c->zoom_factor, c->offset_y);
          const float dist = (y - other_y) * (y - other_y);
          if(dist < min) c->selected = selected;
        }
 
        dt_iop_color_picker_reset(self, TRUE);
        dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
        gtk_widget_queue_draw(self->widget);
      }
 
      return TRUE;
    }
    else if(event->type == GDK_2BUTTON_PRESS)
    {
      // reset current curve
      p->curve_num_nodes[ch] = d->curve_num_nodes[ch];
      p->curve_type[ch] = d->curve_type[ch];
      _reset_nodes(p, c->channel,
                   p->splines_version == DT_IOP_COLORZONES_SPLINES_V1 || p->channel != DT_IOP_COLORZONES_h);
 
      c->selected = -2; // avoid motion notify re-inserting immediately.
      dt_bauhaus_combobox_set(c->interpolator, p->curve_type[ch]);
 
      dt_iop_color_picker_reset(self, TRUE);
      dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
      gtk_widget_queue_draw(self->widget);
 
      return TRUE;
    }
  }
  else if(event->button == 3 && c->selected >= 0)
  {
    if((c->selected == 0 || c->selected == nodes - 1) && p->splines_version == DT_IOP_COLORZONES_SPLINES_V1)
    {
      if(p->channel == DT_IOP_COLORZONES_h)
      {
        curve[0].y = 0.5f;
        curve[0].x = 0.f;
        curve[nodes - 1].y = 0.5f;
        curve[nodes - 1].x = 1.f;
      }
      else
      {
        const float reset_value = c->selected == 0 ? 0.f : 1.f;
        curve[c->selected].y = 0.5f;
        curve[c->selected].x = reset_value;
      }
 
      dt_iop_color_picker_reset(self, TRUE);
      gtk_widget_queue_draw(self->widget);
      dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
      return TRUE;
    }
 
    // right click deletes the node, ctrl+right click reset the node to y-zero
    _delete_node(self, curve, &p->curve_num_nodes[ch], c->selected, dt_modifier_is(event->state, GDK_CONTROL_MASK));
    c->selected = -2; // avoid re-insertion of that point immediately after this
 
    return TRUE;
  }
 
  return FALSE;
}
 
static gboolean _area_button_release_callback(GtkWidget *widget, GdkEventButton *event, gpointer user_data)
{
  if(event->button == 1)
  {
    dt_iop_module_t *self = (dt_iop_module_t *)user_data;
    dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
    c->dragging = 0;
    return TRUE;
  }
  return FALSE;
}
 
static gboolean _area_enter_notify_callback(GtkWidget *widget, GdkEventCrossing *event, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  c->mouse_y = fabs(c->mouse_y);
  gtk_widget_queue_draw(widget);
  return TRUE;
}
 
static gboolean _area_leave_notify_callback(GtkWidget *widget, GdkEventCrossing *event, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  // for fluxbox
  c->mouse_y = -fabs(c->mouse_y);
  gtk_widget_queue_draw(widget);
  return TRUE;
}
 
static gboolean _area_resized_callback(GtkWidget *widget, GdkEvent *event, gpointer user_data)
{
  GtkRequisition r;
  GtkAllocation allocation;
  gtk_widget_get_allocation(widget, &allocation);
  r.width = allocation.width;
  r.height = allocation.width;
  gtk_widget_get_preferred_size(widget, &r, NULL);
  return TRUE;
}
 
static gboolean _area_key_press_callback(GtkWidget *widget, GdkEventKey *event, dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  if(c->selected < 0) return FALSE;
 
  guint key = dt_keys_mainpad_alternatives(event->keyval);
  int handled = 0;
  float dx = 0.0f, dy = 0.0f;
  if(key == GDK_KEY_Up)
  {
    handled = 1;
    dy = DT_IOP_COLORZONES_DEFAULT_STEP;
  }
  else if(key == GDK_KEY_Down)
  {
    handled = 1;
    dy = -DT_IOP_COLORZONES_DEFAULT_STEP;
  }
  else if(key == GDK_KEY_Right)
  {
    handled = 1;
    dx = DT_IOP_COLORZONES_DEFAULT_STEP;
  }
  else if(key == GDK_KEY_Left)
  {
    handled = 1;
    dx = -DT_IOP_COLORZONES_DEFAULT_STEP;
  }
 
  if(!handled) return FALSE;
 
  dt_iop_color_picker_reset(self, TRUE);
  return _move_point_internal(self, widget, c->selected, dx, dy, event->state);
}
 
static void _channel_tabs_switch_callback(GtkNotebook *notebook, GtkWidget *page, guint page_num,
                                          dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
 
  c->channel = (dt_iop_colorzones_channel_t)page_num;
 
  dt_gui_freeze_begin();
 
  dt_bauhaus_combobox_set(c->interpolator, p->curve_type[c->channel]);
 
  dt_gui_freeze_end();
 
  if(c->display_mask)
    dt_dev_pixelpipe_update_history_main(self->dev);
  gtk_widget_queue_draw(self->widget);
}
 
 
void gui_changed(dt_iop_module_t *self, GtkWidget *w, void *previous)
{
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  if(w == g->select_by)
  {
    _reset_parameters(p, p->channel, p->splines_version);
    if(g->display_mask) _reset_display_selection(self);
    gtk_widget_queue_draw(GTK_WIDGET(g->area));
    gtk_widget_queue_draw(GTK_WIDGET(g->bottom_area));
  }
}
 
static void _interpolator_callback(GtkWidget *widget, dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  const int combo = dt_bauhaus_combobox_get(widget);
 
  if(combo == 0)
    p->curve_type[g->channel] = CUBIC_SPLINE;
  else if(combo == 1)
    p->curve_type[g->channel] = CATMULL_ROM;
  else if(combo == 2)
    p->curve_type[g->channel] = MONOTONE_HERMITE;
 
  dt_iop_color_picker_reset(self, TRUE);
  dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
  gtk_widget_queue_draw(GTK_WIDGET(g->area));
}
 
static void _edit_by_area_callback(GtkWidget *widget, dt_iop_module_t *self)
{
  if(dt_gui_widgets_suppressed()) return;
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  g->edit_by_area = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(widget));
 
  gtk_widget_queue_draw(GTK_WIDGET(g->area));
}
 
static void _display_mask_callback(GtkToggleButton *togglebutton, dt_iop_module_t *module)
{
  if(dt_gui_widgets_suppressed()) return;
 
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)module->gui_data;
 
  // if blend module is displaying mask do not display it here
  if(module->request_mask_display && !g->display_mask)
  {
    dt_control_log(_("cannot display masks when the blending mask is displayed"));
 
    dt_gui_freeze_begin();
    gtk_toggle_button_set_active(togglebutton, FALSE);
    dt_gui_freeze_end();
    return;
  }
 
  g->display_mask = gtk_toggle_button_get_active(togglebutton);
 
  if(module->off) gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(module->off), 1);
  dt_iop_request_focus(module);
  dt_dev_pixelpipe_update_history_main(module->dev);
}
 
void color_picker_apply(dt_iop_module_t *self, GtkWidget *picker, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  if(picker == g->colorpicker_set_values)
  {
    dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
    dt_iop_colorzones_params_t *d = (dt_iop_colorzones_params_t *)self->default_params;
 
    const int ch_curve = g->channel;
    const int ch_val = p->channel;
    dt_iop_colorzones_node_t *curve = p->curve[ch_curve];
 
    // reset current curve
    p->curve_num_nodes[ch_curve] = d->curve_num_nodes[ch_curve];
    p->curve_type[ch_curve] = d->curve_type[ch_curve];
    for(int k = 0; k < DT_IOP_COLORZONES_MAXNODES; k++)
    {
      curve[k].x = d->curve[ch_curve][k].x;
      curve[k].y = d->curve[ch_curve][k].y;
    }
 
    const GdkModifierType state = dt_key_modifier_state();
    int picker_set_upper_lower; // flat=0, lower=-1, upper=1
    if(dt_modifier_is(state, GDK_CONTROL_MASK))
      picker_set_upper_lower = 1;
    else if(dt_modifier_is(state, GDK_SHIFT_MASK))
      picker_set_upper_lower = -1;
    else
      picker_set_upper_lower = 0;
 
    // now add 5 nodes: feather, min, center, max, feather
    const float feather = 0.02f;
    const float increment = 0.1f * picker_set_upper_lower;
    float x = 0.f;
 
    if(ch_val == DT_IOP_COLORZONES_L)
      x = self->picked_color_min[0] / 100.f;
    else if(ch_val == DT_IOP_COLORZONES_C)
      x = self->picked_color_min[1] / (128.f * sqrtf(2.f));
    else if(ch_val == DT_IOP_COLORZONES_h)
      x = self->picked_color_min[2];
    x -= feather;
    if(x > 0.f && x < 1.f) _add_node(curve, &p->curve_num_nodes[ch_curve], x, .5f);
 
    if(ch_val == DT_IOP_COLORZONES_L)
      x = self->picked_color_min[0] / 100.f;
    else if(ch_val == DT_IOP_COLORZONES_C)
      x = self->picked_color_min[1] / (128.f * sqrtf(2.f));
    else if(ch_val == DT_IOP_COLORZONES_h)
      x = self->picked_color_min[2];
    if(x > 0.f && x < 1.f) _add_node(curve, &p->curve_num_nodes[ch_curve], x, .5f + increment);
 
    if(ch_val == DT_IOP_COLORZONES_L)
      x = self->picked_color[0] / 100.f;
    else if(ch_val == DT_IOP_COLORZONES_C)
      x = self->picked_color[1] / (128.f * sqrtf(2.f));
    else if(ch_val == DT_IOP_COLORZONES_h)
      x = self->picked_color[2];
    if(x > 0.f && x < 1.f) _add_node(curve, &p->curve_num_nodes[ch_curve], x, .5f + 2.f * increment);
 
    if(ch_val == DT_IOP_COLORZONES_L)
      x = self->picked_color_max[0] / 100.f;
    else if(ch_val == DT_IOP_COLORZONES_C)
      x = self->picked_color_max[1] / (128.f * sqrtf(2.f));
    else if(ch_val == DT_IOP_COLORZONES_h)
      x = self->picked_color_max[2];
    if(x > 0.f && x < 1.f) _add_node(curve, &p->curve_num_nodes[ch_curve], x, .5f + increment);
 
    if(ch_val == DT_IOP_COLORZONES_L)
      x = self->picked_color_max[0] / 100.f;
    else if(ch_val == DT_IOP_COLORZONES_C)
      x = self->picked_color_max[1] / (128.f * sqrtf(2.f));
    else if(ch_val == DT_IOP_COLORZONES_h)
      x = self->picked_color_max[2];
    x += feather;
    if(x > 0.f && x < 1.f) _add_node(curve, &p->curve_num_nodes[ch_curve], x, .5f);
 
    dt_dev_add_history_item(darktable.develop, self, TRUE, TRUE);
  }
 
  dt_control_queue_redraw_widget(self->widget);
}
 
void gui_reset(struct dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  dt_iop_color_picker_reset(self, TRUE);
 
  c->zoom_factor = 1.f;
  _reset_display_selection(self);
}
 
void gui_focus(struct dt_iop_module_t *self, gboolean in)
{
  if(!in)
  {
    _reset_display_selection(self);
  }
}
 
void gui_init(struct dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = IOP_GUI_ALLOC(colorzones);
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->default_params;
 
  self->histogram_cst = IOP_CS_LCH;
 
  c->channel = dt_conf_get_int("plugins/darkroom/colorzones/gui_channel");
  for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++)
  {
    c->minmax_curve[ch] = dt_draw_curve_new(0.f, 1.f, p->curve_type[ch]);
    c->minmax_curve_nodes[ch] = p->curve_num_nodes[ch];
    c->minmax_curve_type[ch] = p->curve_type[ch];
 
    for(int k = 0; k < p->curve_num_nodes[ch]; k++)
      dt_draw_curve_add_point(c->minmax_curve[ch], p->curve[ch][k].x, p->curve[ch][k].y);
  }
 
  c->mouse_x = c->mouse_y = -1.0;
  c->selected = -1;
  c->offset_x = c->offset_y = 0.f;
  c->zoom_factor = 1.f;
  c->x_move = -1;
  c->mouse_radius = 1.f / DT_IOP_COLORZONES_BANDS;
  c->dragging = 0;
  c->edit_by_area = 0;
  c->display_mask = FALSE;
  self->timeout_handle = 0;
 
  self->widget = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
 
  // tabs
  GtkWidget *hbox = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, DT_GUI_BOX_SPACING);
  GtkWidget *vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
  gtk_box_pack_start(GTK_BOX(vbox), hbox, FALSE, FALSE, 0);
 
  c->channel_tabs = dt_ui_notebook_new();
 
  dt_ui_notebook_page(c->channel_tabs, N_("lightness"), NULL);
  dt_ui_notebook_page(c->channel_tabs, N_("saturation"), NULL);
  dt_ui_notebook_page(c->channel_tabs, N_("hue"), NULL);
 
  gtk_widget_show(gtk_notebook_get_nth_page(c->channel_tabs, c->channel));
  gtk_notebook_set_current_page(c->channel_tabs, c->channel);
  g_signal_connect(G_OBJECT(c->channel_tabs), "switch_page", G_CALLBACK(_channel_tabs_switch_callback), self);
  /* The picker samples for the *currently selected* channel (c->channel), read at apply
     time. Leaving it active across a tab switch would apply a sample picked for one
     channel to whichever channel is now selected once the async sample lands. */
  dt_ui_notebook_set_picker_owner(c->channel_tabs, self);
  gtk_box_pack_start(GTK_BOX(hbox), GTK_WIDGET(c->channel_tabs), TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(hbox), gtk_label_new("   "), FALSE, FALSE, 0);
 
  // color pickers
  c->colorpicker = dt_color_picker_new_with_cst(self, DT_COLOR_PICKER_POINT_AREA, hbox, IOP_CS_LCH);
  gtk_widget_set_tooltip_text(c->colorpicker, _("pick GUI color from image\nctrl+click or right-click to select an area"));
  c->colorpicker_set_values = dt_color_picker_new_with_cst(self, DT_COLOR_PICKER_AREA, hbox, IOP_CS_LCH);
  dtgtk_togglebutton_set_paint(DTGTK_TOGGLEBUTTON(c->colorpicker_set_values),
                               dtgtk_cairo_paint_colorpicker, CPF_ALTER, NULL);
 
  gtk_widget_set_size_request(c->colorpicker_set_values, DT_PIXEL_APPLY_DPI(14), DT_PIXEL_APPLY_DPI(14));
  gtk_widget_set_tooltip_text(c->colorpicker_set_values, _("create a curve based on an area from the image\n"
                                                           "drag to create a flat curve\n"
                                                           "ctrl+drag to create a positive curve\n"
                                                           "shift+drag to create a negative curve"));
 
  // the nice graph
  c->area = GTK_DRAWING_AREA(gtk_drawing_area_new());
  gtk_widget_set_hexpand(GTK_WIDGET(c->area), TRUE);
 
  gtk_box_pack_start(GTK_BOX(vbox),
                     dt_ui_resizable_drawing_area(GTK_WIDGET(c->area),
                                                  "plugins/darkroom/colorzones/graphheight", 280, 100),
                     FALSE, FALSE, 0);
 
  GtkWidget *dabox = gtk_box_new(GTK_ORIENTATION_VERTICAL, DT_GUI_BOX_SPACING);
  gtk_widget_set_name(GTK_WIDGET(dabox), "iop-bottom-bar");
  c->bottom_area = gtk_drawing_area_new();
  gtk_box_pack_start(GTK_BOX(dabox), GTK_WIDGET(c->bottom_area), TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(vbox), GTK_WIDGET(dabox), TRUE, TRUE, 0);
  gtk_box_pack_start(GTK_BOX(self->widget), GTK_WIDGET(vbox), TRUE, TRUE, 0);
 
  GtkWidget *hbox_select_by = gtk_box_new(GTK_ORIENTATION_HORIZONTAL, DT_GUI_BOX_SPACING);
 
  // edit by area
  gchar *label = N_("edit by area");
  c->chk_edit_by_area = gtk_check_button_new_with_label(_(label));
  gtk_label_set_ellipsize(GTK_LABEL(gtk_bin_get_child(GTK_BIN(c->chk_edit_by_area))), PANGO_ELLIPSIZE_START);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(c->chk_edit_by_area), c->edit_by_area);
  gtk_widget_set_tooltip_text(c->chk_edit_by_area, _("edit the curve nodes by area"));
  gtk_box_pack_start(GTK_BOX(hbox_select_by), c->chk_edit_by_area, TRUE, TRUE, 0);
  g_signal_connect(G_OBJECT(c->chk_edit_by_area), "toggled", G_CALLBACK(_edit_by_area_callback), self);
 
  // display selection
  c->bt_showmask = dtgtk_togglebutton_new(dtgtk_cairo_paint_showmask, 0, NULL);
 
  gtk_widget_set_tooltip_text(c->bt_showmask, _("display selection"));
  g_signal_connect(G_OBJECT(c->bt_showmask), "toggled", G_CALLBACK(_display_mask_callback), self);
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(c->bt_showmask), FALSE);
  gtk_box_pack_end(GTK_BOX(hbox_select_by), c->bt_showmask, FALSE, FALSE, 0);
 
  gtk_box_pack_start(GTK_BOX(self->widget), hbox_select_by, TRUE, TRUE, 0);
 
  // select by which dimension
  c->select_by = dt_bauhaus_combobox_from_params(self, "channel");
  dt_bauhaus_combobox_remove_at(c->select_by, DT_IOP_COLORZONES_MAX_CHANNELS);
  gtk_widget_set_tooltip_text(c->select_by, _("choose selection criterion, will be the abscissa in the graph"));
 
  c->mode = dt_bauhaus_combobox_from_params(self, "mode");
  gtk_widget_set_tooltip_text(c->mode, _("choose between a smoother or stronger effect"));
 
  c->strength = dt_bauhaus_slider_from_params(self, "strength");
  dt_bauhaus_slider_set_format(c->strength, "%");
  gtk_widget_set_tooltip_text(c->strength, _("make effect stronger or weaker"));
 
  gtk_widget_add_events(GTK_WIDGET(c->area), GDK_POINTER_MOTION_MASK
                                           | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK
                                           | GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK
                                           | darktable.gui->scroll_mask);
  g_object_set_data(G_OBJECT(c->area), "iop-instance", self);
  gtk_widget_set_can_focus(GTK_WIDGET(c->area), TRUE);
  g_signal_connect(G_OBJECT(c->area), "draw", G_CALLBACK(_area_draw_callback), self);
  g_signal_connect(G_OBJECT(c->area), "button-press-event", G_CALLBACK(_area_button_press_callback), self);
  g_signal_connect(G_OBJECT(c->area), "button-release-event", G_CALLBACK(_area_button_release_callback), self);
  g_signal_connect(G_OBJECT(c->area), "motion-notify-event", G_CALLBACK(_area_motion_notify_callback), self);
  g_signal_connect(G_OBJECT(c->area), "leave-notify-event", G_CALLBACK(_area_leave_notify_callback), self);
  g_signal_connect(G_OBJECT(c->area), "enter-notify-event", G_CALLBACK(_area_enter_notify_callback), self);
  g_signal_connect(G_OBJECT(c->area), "scroll-event", G_CALLBACK(_area_scrolled_callback), self);
  g_signal_connect(G_OBJECT(c->area), "configure-event", G_CALLBACK(_area_resized_callback), self);
  g_signal_connect(G_OBJECT(c->area), "key-press-event", G_CALLBACK(_area_key_press_callback), self);
 
  gtk_widget_add_events(GTK_WIDGET(c->bottom_area), GDK_BUTTON_PRESS_MASK);
  g_signal_connect(G_OBJECT(c->bottom_area), "draw", G_CALLBACK(_bottom_area_draw_callback), self);
  g_signal_connect(G_OBJECT(c->bottom_area), "button-press-event", G_CALLBACK(_bottom_area_button_press_callback),
                   self);
 
  /* From src/common/curve_tools.h :
    #define CUBIC_SPLINE 0
    #define CATMULL_ROM 1
    #define MONOTONE_HERMITE 2
  */
  c->interpolator = dt_bauhaus_combobox_new(darktable.bauhaus, DT_GUI_MODULE(self));
  dt_bauhaus_widget_set_label(c->interpolator, N_("interpolation method"));
  dt_bauhaus_combobox_add(c->interpolator, _("cubic spline"));
  dt_bauhaus_combobox_add(c->interpolator, _("centripetal spline"));
  dt_bauhaus_combobox_add(c->interpolator, _("monotonic spline"));
  gtk_box_pack_start(GTK_BOX(self->widget), c->interpolator, TRUE, TRUE, 0);
  gtk_widget_set_tooltip_text(c->interpolator,
      _("change this method if you see oscillations or cusps in the curve\n"
        "- cubic spline is better to produce smooth curves but oscillates when nodes are too close\n"
        "- centripetal is better to avoids cusps and oscillations with close nodes but is less smooth\n"
        "- monotonic is better for accuracy of pure analytical functions (log, gamma, exp)\n"));
  g_signal_connect(G_OBJECT(c->interpolator), "value-changed", G_CALLBACK(_interpolator_callback), self);
}
 
void gui_update(struct dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)self->params;
 
  dt_bauhaus_combobox_set(g->interpolator, p->curve_type[g->channel]);
 
  dt_gui_throttle_cancel(self);
 
  gtk_widget_queue_draw(self->widget);
}
 
void gui_cleanup(struct dt_iop_module_t *self)
{
  dt_iop_colorzones_gui_data_t *c = (dt_iop_colorzones_gui_data_t *)self->gui_data;
  dt_conf_set_int("plugins/darkroom/colorzones/gui_channel", c->channel);
 
  for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++) dt_draw_curve_destroy(c->minmax_curve[ch]);
 
  dt_gui_throttle_cancel(self);
 
  IOP_GUI_FREE;
}
 
void init_global(dt_iop_module_so_t *module)
{
  const int program = 2; // basic.cl, from programs.conf
  dt_iop_colorzones_global_data_t *gd = malloc(sizeof(dt_iop_colorzones_global_data_t));
  module->data = gd;
  gd->kernel_colorzones = dt_opencl_create_kernel(program, "colorzones");
  gd->kernel_colorzones_v3 = dt_opencl_create_kernel(program, "colorzones_v3");
}
 
void cleanup_global(dt_iop_module_so_t *module)
{
  dt_iop_colorzones_global_data_t *gd = (dt_iop_colorzones_global_data_t *)module->data;
 
  dt_opencl_free_kernel(gd->kernel_colorzones);
  dt_opencl_free_kernel(gd->kernel_colorzones_v3);
 
  dt_free(module->data);
}
 
void commit_params(struct dt_iop_module_t *self, dt_iop_params_t *p1, dt_dev_pixelpipe_t *pipe,
                   dt_dev_pixelpipe_iop_t *piece)
{
  // pull in new params to pipe
  dt_iop_colorzones_data_t *d = (dt_iop_colorzones_data_t *)(piece->data);
  dt_iop_colorzones_params_t *p = (dt_iop_colorzones_params_t *)p1;
  dt_iop_colorzones_gui_data_t *g = (dt_iop_colorzones_gui_data_t *)self->gui_data;
 
  if(dt_dev_pixelpipe_has_preview_output(self->dev, pipe, NULL))
    piece->request_histogram |= (DT_REQUEST_ON);
  else
    piece->request_histogram &= ~(DT_REQUEST_ON);
 
#if 0 // print new preset
  printf("p.channel = %d;\n", p->channel);
  for(int k=0; k<3; k++) for(int i=0; i<DT_IOP_COLORZONES_MAXNODES; i++)
    {
      printf("p.curve[%d][%i].x = %f;\n", k, i, p->curve[k][i].x);
      printf("p.curve[%d][%i].y = %f;\n", k, i, p->curve[k][i].y);
    }
#endif
 
  // display selection don't work with opencl
  piece->process_cl_ready = (g && g->display_mask) ? 0 : 1;
  d->channel = (dt_iop_colorzones_channel_t)p->channel;
  d->mode = p->mode;
 
  if(p->splines_version == DT_IOP_COLORZONES_SPLINES_V1)
  {
    for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++)
    {
      // take care of possible change of curve type or number of nodes (not yet implemented in UI)
      if(d->curve_type[ch] != p->curve_type[ch] || d->curve_nodes[ch] != p->curve_num_nodes[ch])
      {
        dt_draw_curve_destroy(d->curve[ch]);
        d->curve[ch] = dt_draw_curve_new(0.f, 1.f, p->curve_type[ch]);
        d->curve_nodes[ch] = p->curve_num_nodes[ch];
        d->curve_type[ch] = p->curve_type[ch];
 
        if(d->channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_add_point(d->curve[ch], p->curve[ch][p->curve_num_nodes[ch] - 2].x - 1.f,
                                  strength(p->curve[ch][p->curve_num_nodes[ch] - 2].y, p->strength));
        else
          dt_draw_curve_add_point(d->curve[ch], p->curve[ch][p->curve_num_nodes[ch] - 2].x - 1.f,
                                  strength(p->curve[ch][0].y, p->strength));
        for(int k = 0; k < p->curve_num_nodes[ch]; k++)
          dt_draw_curve_add_point(d->curve[ch], p->curve[ch][k].x, strength(p->curve[ch][k].y, p->strength));
        if(d->channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_add_point(d->curve[ch], p->curve[ch][1].x + 1.f, strength(p->curve[ch][1].y, p->strength));
        else
          dt_draw_curve_add_point(d->curve[ch], p->curve[ch][1].x + 1.f,
                                  strength(p->curve[ch][p->curve_num_nodes[ch] - 1].y, p->strength));
      }
      else
      {
        if(d->channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_set_point(d->curve[ch], 0, p->curve[ch][p->curve_num_nodes[ch] - 2].x - 1.f,
                                  strength(p->curve[ch][p->curve_num_nodes[ch] - 2].y, p->strength));
        else
          dt_draw_curve_set_point(d->curve[ch], 0, p->curve[ch][p->curve_num_nodes[ch] - 2].x - 1.f,
                                  strength(p->curve[ch][0].y, p->strength));
        for(int k = 0; k < p->curve_num_nodes[ch]; k++)
          dt_draw_curve_set_point(d->curve[ch], k + 1, p->curve[ch][k].x, strength(p->curve[ch][k].y, p->strength));
        if(d->channel == DT_IOP_COLORZONES_h)
          dt_draw_curve_set_point(d->curve[ch], p->curve_num_nodes[ch] + 1, p->curve[ch][1].x + 1.f,
                                  strength(p->curve[ch][1].y, p->strength));
        else
          dt_draw_curve_set_point(d->curve[ch], p->curve_num_nodes[ch] + 1, p->curve[ch][1].x + 1.f,
                                  strength(p->curve[ch][p->curve_num_nodes[ch] - 1].y, p->strength));
      }
      dt_draw_curve_calc_values(d->curve[ch], 0.f, 1.f, DT_IOP_COLORZONES_LUT_RES, NULL, d->lut[ch]);
    }
  }
  else
  {
    for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++)
    {
      if(d->curve_type[ch] != p->curve_type[ch] || d->curve_nodes[ch] != p->curve_num_nodes[ch]
         || d->curve[ch]->c.m_numAnchors != p->curve_num_nodes[ch])
      {
        dt_draw_curve_destroy(d->curve[ch]);
        d->curve[ch] = dt_draw_curve_new(0.f, 1.f, p->curve_type[ch]);
        d->curve_nodes[ch] = p->curve_num_nodes[ch];
        d->curve_type[ch] = p->curve_type[ch];
 
        for(int k = 0; k < p->curve_num_nodes[ch]; k++)
          dt_draw_curve_add_point(d->curve[ch], p->curve[ch][k].x, strength(p->curve[ch][k].y, p->strength));
      }
      else
      {
        for(int k = 0; k < p->curve_num_nodes[ch]; k++)
          dt_draw_curve_set_point(d->curve[ch], k, p->curve[ch][k].x, strength(p->curve[ch][k].y, p->strength));
      }
      dt_draw_curve_calc_values_V2(d->curve[ch], 0.f, 1.f, DT_IOP_COLORZONES_LUT_RES, NULL, d->lut[ch],
                                   p->channel == DT_IOP_COLORZONES_h);
    }
  }
}
 
void init_pipe(struct dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  dt_iop_colorzones_data_t *d = dt_calloc_align(sizeof(dt_iop_colorzones_data_t));
  dt_iop_colorzones_params_t *default_params = (dt_iop_colorzones_params_t *)self->default_params;
  piece->data = d;
  piece->data_size = sizeof(dt_iop_colorzones_data_t);
 
  for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++)
  {
    d->curve[ch] = dt_draw_curve_new(0.f, 1.f, default_params->curve_type[ch]);
    d->curve_nodes[ch] = default_params->curve_num_nodes[ch];
    d->curve_type[ch] = default_params->curve_type[ch];
    for(int k = 0; k < default_params->curve_num_nodes[ch]; k++)
      dt_draw_curve_add_point(d->curve[ch], default_params->curve[ch][k].x, default_params->curve[ch][k].y);
  }
  d->channel = (dt_iop_colorzones_channel_t)default_params->channel;
  d->mode = default_params->mode;
}
 
void cleanup_pipe(struct dt_iop_module_t *self, dt_dev_pixelpipe_t *pipe, dt_dev_pixelpipe_iop_t *piece)
{
  // clean up everything again.
  dt_iop_colorzones_data_t *d = (dt_iop_colorzones_data_t *)(piece->data);
 
  for(int ch = 0; ch < DT_IOP_COLORZONES_MAX_CHANNELS; ch++) dt_draw_curve_destroy(d->curve[ch]);
 
  dt_free_align(piece->data);
  piece->data = NULL;
}
 
void init(dt_iop_module_t *module)
{
  module->params = calloc(1, sizeof(dt_iop_colorzones_params_t));
  module->default_params = calloc(1, sizeof(dt_iop_colorzones_params_t));
  module->default_enabled = 0; // we're a rather slow and rare op.
  module->params_size = sizeof(dt_iop_colorzones_params_t);
  module->gui_data = NULL;
  module->request_histogram |= (DT_REQUEST_ON);
 
  _reset_parameters(module->default_params, DT_IOP_COLORZONES_h, DT_IOP_COLORZONES_SPLINES_V2);
}
 
#undef DT_IOP_COLORZONES_INSET
#undef DT_IOP_COLORZONES_CURVE_INFL
#undef DT_IOP_COLORZONES_RES
#undef DT_IOP_COLORZONES_LUT_RES
#undef DT_IOP_COLORZONES_BANDS
#undef DT_IOP_COLORZONES_MAXNODES
#undef DT_IOP_COLORZONES_DEFAULT_STEP
#undef DT_IOP_COLORZONES_MIN_X_DISTANCE
 
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