/*
    This file is part of darktable,
    Copyright (C) 2013-2024 darktable developers.

    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/>.
*/

#include "bauhaus/bauhaus.h"
#include "common/debug.h"
#include "common/imagebuf.h"
#include "common/undo.h"
#include "control/conf.h"
#include "control/control.h"
#include "develop/blend.h"
#include "develop/imageop.h"
#include "develop/masks.h"
#include "develop/openmp_maths.h"
#include <assert.h>

static void _path_bounding_box_raw(const float *const points,
                                   const float *border,
                                   const int nb_corner,
                                   const int num_points,
                                   const int num_borders,
                                   float *x_min,
                                   float *x_max,
                                   float *y_min,
                                   float *y_max);

static void _path_bounding_box(const float *const points,
                               const float *border,
                               const int nb_corner,
                               const int num_points,
                               const int num_borders,
                               int *width,
                               int *height,
                               int *posx,
                               int *posy);


/** get the point of the path at pos t [0,1]  */
static void _path_get_XY(const float p0x,
                         const float p0y,
                         const float p1x,
                         const float p1y,
                         const float p2x,
                         const float p2y,
                         const float p3x,
                         const float p3y,
                         const float t,
                         float *x,
                         float *y)
{
  const float ti = 1.0f - t;
  const float a = ti * ti * ti;
  const float b = 3.0f * t * ti * ti;
  const float c = 3.0f * t * t * ti;
  const float d = t * t * t;
  *x = p0x * a + p1x * b + p2x * c + p3x * d;
  *y = p0y * a + p1y * b + p2y * c + p3y * d;
}

/**
 * Get the point of the path at pos t [0,1]  AND the corresponding border point
 *
 * The border point is rad units away in the perpendicular direction.
 *
 * @param p0x x coordinate of the first bezier point
 * @param p0y y coordinate of the first bezier point
 * @param p1x x coordinate of the second bezier point
 * @param p1y y coordinate of the second bezier point
 * @param p2x x coordinate of the third bezier point
 * @param p2y y coordinate of the third bezier point
 * @param p3x x coordinate of the fourth bezier point
 * @param p3y y coordinate of the fourth bezier point
 * @param t position on the path, between 0 and 1
 * @param rad radius of the border at t
 * @param xc x coordinate of the point on the path
 * @param yc y coordinate of the point on the path
 * @param xb x coordinate of the point on the border
 * @param yb y coordinate of the point on the border
 */
static void _path_border_get_XY(const float p0x,
                                const float p0y,
                                const float p1x,
                                const float p1y,
                                const float p2x,
                                const float p2y,
                                const float p3x,
                                const float p3y,
                                const float t,
                                const float rad,
                                float *xc,
                                float *yc,
                                float *xb,
                                float *yb)
{
  // we use double precision math here to avoid rounding issues in
  // paths with sharp corners we get the point
  _path_get_XY(p0x, p0y, p1x, p1y, p2x, p2y, p3x, p3y, t, xc, yc);

  // now we get derivative points
  const double ti = 1.0 - (double)t;

  const double t_t = (double)t * t;
  const double ti_ti = ti * ti;
  const double t_ti = t * ti;

  const double a = 3.0 * ti_ti;
  const double b = 3.0 * (ti_ti - 2.0 * t_ti);
  const double c = 3.0 * (2.0 * t_ti - t_t);
  const double d = 3.0 * t_t;

  const double dx = -p0x * a + p1x * b + p2x * c + p3x * d;
  const double dy = -p0y * a + p1y * b + p2y * c + p3y * d;

  // so we can have the resulting point
  if(dx == 0 && dy == 0)
  {
    *xb = DT_INVALID_COORDINATE;
    *yb = DT_INVALID_COORDINATE;
    return;
  }
  const double l = 1.0 / sqrt(dx * dx + dy * dy);
  *xb = (*xc) + rad * dy * l;
  *yb = (*yc) - rad * dx * l;
}


/**
 * Angle between the line (x_ref, y_ref) -> (x1, y1) and the x-axis.
 *
 * @param[in] x1 x coordinate of the first point
 * @param[in] y1 y coordinate of the first point
 * @param[in] x_ref x coordinate of the reference point
 * @param[in] y_ref y coordinate of the reference point
 *
 * @return The angle in radians between the two points.
 */
static inline
float angle_2d(const float x1, const float y1, const float x_ref, const float y_ref)
{
  return atan2(y1 - y_ref, x1 - x_ref);
}


/**
 * Computes the angle between the line (x_ref, y_ref) -> (x1, y1)
 * and the line (x_ref, y_ref) -> (x2, y2).
 * Bezier control points are given as 0..1 percentages of the
 * image size. However as the image is not a square, the aspect
 * ratio is needed to correct.
 *
 * @param[in] x_ref x coordinate of the reference point
 * @param[in] y_ref y coordinate of the reference point
 * @param[in] x1 x coordinate of the first point
 * @param[in] y1 y coordinate of the first point
 * @param[in] x2 x coordinate of the second point
 * @param[in] y2 y coordinate of the second point
 * @param[in] aspect_ratio aspect ratio of the image
 *
 * @return The angle in radians between the two lines.
 */
static inline
float _get_ctrl_angle(const float x_ref,
                      const float y_ref,
                      const float x1,
                      const float y1,
                      const float x2,
                      const float y2,
                      const float aspect_ratio)
{
  const float x1a = x1 * aspect_ratio;
  const float x2a = x2 * aspect_ratio;
  const float x_refa = x_ref * aspect_ratio;
  return angle_2d(x2a, y2, x_refa, y_ref) - angle_2d(x1a, y1, x_refa, y_ref);
}

/**
 * Set the angle between two bezier control points.
 *
 * @param[in] x_ref x coordinate of the reference point
 * @param[in] y_ref y coordinate of the reference point
 * @param[in] angle the angle in radians to set between the two points
 * @param[in] move_p2 whether to move the first or second point
 * @param[in,out] x1 x coordinate of the first point
 * @param[in,out] y1 y coordinate of the first point
 * @param[in,out] x2 x coordinate of the second point
 * @param[in,out] y2 y coordinate of the second point
 * @param[in] aspect_ratio aspect ratio of the image
 */
static
void _set_ctrl_angle(const float x_ref,
                     const float y_ref,
                     const float angle,
                     const gboolean move_p2,
                     float *x1,
                     float *y1,
                     float *x2,
                     float *y2,
                     const float aspect_ratio)
{

  const float x1a = *x1 * aspect_ratio;
  const float x2a = *x2 * aspect_ratio;
  const float x_refa = x_ref * aspect_ratio;

  if(!move_p2) // move p1
  {
    const float length1 = sqrt((x1a - x_refa) * (x1a - x_refa) + (*y1 - y_ref) * (*y1 - y_ref));
    const float angle2 = angle_2d(x2a, *y2, x_refa, y_ref);
    const float angle1 = angle2 - angle;

    *x1 = (x_refa + length1 * cos(angle1)) / aspect_ratio;
    *y1 = y_ref + length1 * sin(angle1);
  }
  else // move p2
{
    const float length2 = sqrt((x2a - x_refa) * (x2a - x_refa) + (*y2 - y_ref) * (*y2 - y_ref));
    const float angle1 = angle_2d(x1a, *y1, x_refa, y_ref);
    const float angle2 = angle1 + angle;

    *x2 = (x_refa + length2 * cos(angle2)) / aspect_ratio;
    *y2 = y_ref + length2 * sin(angle2);
  }
}

/**
 * Computes the distance ratio of the bezier control points.
 *
 * @param[in] x_ref x coordinate of the reference point
 * @param[in] y_ref y coordinate of the reference point
 * @param[in] x1 x coordinate of the first point
 * @param[in] y1 y coordinate of the first point
 * @param[in] x2 x coordinate of the second point
 * @param[in] y2 y coordinate of the second point
 * @param[in] aspect_ratio aspect ratio of the image
 *
 * @return The length ratio between the two points.
 */
static inline
float _get_ctrl_scale(const float x_ref,
                      const float y_ref,
                      const float x1,
                      const float y1,
                      const float x2,
                      const float y2,
                      const float aspect_ratio)
{
  const float x1a = x1 * aspect_ratio;
  const float x2a = x2 * aspect_ratio;
  const float x_refa = x_ref * aspect_ratio;

  const float length1 = sqrt((x1a - x_refa) * (x1a - x_refa) + (y1 - y_ref) * (y1 - y_ref));
  const float length2 = sqrt((x2a - x_refa) * (x2a - x_refa) + (y2 - y_ref) * (y2 - y_ref));
  return length1 / length2;
}

/**
 * Scales the distance of one of the two bezier control points.
 *
 * @param[in] x_ref x coordinate of the reference point
 * @param[in] y_ref y coordinate of the reference point
 * @param[in] scale scale factor to apply
 * @param[in] move_p2 whether to move the second control point
 * @param[in,out] x1 x coordinate of the first point
 * @param[in,out] y1 y coordinate of the first point
 * @param[in,out] x2 x coordinate of the second point
 * @param[in,out] y2 y coordinate of the second point
 * @param[in] aspect_ratio aspect ratio of the image
 */
static
void _set_ctrl_scale(const float x_ref,
                     const float y_ref,
                     const float scale,
                     const gboolean move_p2,
                     float *x1,
                     float *y1,
                     float *x2,
                     float *y2,
                     const float aspect_ratio)
{
  // x,y coordinates are in a 0..1 range, but the image is not square.
  // Therefore use the x coordinate to correct.
  const float x1a = *x1 * aspect_ratio;
  const float x2a = *x2 * aspect_ratio;
  const float x_refa = x_ref * aspect_ratio;

  if(!move_p2) // move p1
  {
    const float length2 = sqrt((x2a - x_refa) * (x2a - x_refa) + (*y2 - y_ref) * (*y2 - y_ref));
    const float angle1 = angle_2d(x1a, *y1, x_refa, y_ref);
    const float length1 = length2 * scale;

    *x1 = (x_refa + length1 * cos(angle1)) / aspect_ratio;
    *y1 = y_ref + length1 * sin(angle1);
  }
  else // move p2
  {
    const float length1 = sqrt((x1a - x_refa) * (x1a - x_refa) + (*y1 - y_ref) * (*y1 - y_ref));
    const float angle2 = angle_2d(x2a, *y2, x_refa, y_ref);
    const float length2 = length1 / scale;

    *x2 = (x_refa + length2 * cos(angle2)) / aspect_ratio;
    *y2 = y_ref + length2 * sin(angle2);
  }
}

/**
 * Force a bezier control point to be symmetric opposite the other one.
 *
 * @param[in] x_ref x coordinate of the reference point
 * @param[in] y_ref y coordinate of the reference point
 * @param[in] move_p2 whether to move the second control point
 * @param[in,out] x1 x coordinate of the first point
 * @param[in,out] y1 y coordinate of the first point
 * @param[in,out] x2 x coordinate of the second point
 * @param[in,out] y2 y coordinate of the second point
 */
static
void _set_ctrl_symmetric(const float x_ref,
                         const float y_ref,
                         const gboolean move_p2,
                         float *x1,
                         float *y1,
                         float *x2,
                         float *y2)
{
  if(!move_p2) // move p1
  {
    *x1 = x_ref - (*x2 - x_ref);
    *y1 = y_ref - (*y2 - y_ref);
  }
  else // move p2
  {
    *x2 = x_ref - (*x1 - x_ref);
    *y2 = y_ref - (*y1 - y_ref);
  }
}



/**
 * Update the bezier control points of a corner, when the user drags the other
 * control point.
 *
 * @param[in] point the path point to update
 * @param[in] new_x the new x coordinate of the control point to update
 * @param[in] new_y the new y coordinate of the control point to update
 * @param[in] ctrl_select the control point that the user selected (1 or 2)
 * @param[in] ctrl_mode the edit mode to apply (user holds SHIFT or CRTL?)
 * @param[in] ctrl_angle the angle to preserve, if required by the edit mode
 * @param[in] ctrl_scale the distance ratio to preserve, if required by the edit mode
 * @param[in] aspect_ratio the aspect ratio of the image
 */
void _update_bezier_ctrl_points(dt_masks_point_path_t* point,
                                const float new_x,
                                const float new_y,
                                const dt_masks_path_ctrl_t ctrl_select,
                                const dt_masks_path_edit_mode_t ctrl_mode,
                                const float ctrl_angle,
                                const float ctrl_scale,
                                const float aspect_ratio)
{
  gboolean move_p2; // is p2 the dependend node that is moved if restrictions apply?

  if(ctrl_select == DT_MASKS_PATH_CTRL1)
  {
    point->ctrl1[0] = new_x;
    point->ctrl1[1] = new_y;
    move_p2 = TRUE;
  }
  else
  {
    assert(ctrl_select == DT_MASKS_PATH_CTRL2);
    point->ctrl2[0] = new_x;
    point->ctrl2[1] = new_y;
    move_p2 = FALSE;
  }

  switch (ctrl_mode)
  {
    case DT_MASKS_BEZIER_NONE:
      _set_ctrl_scale(point->corner[0], point->corner[1],
                     ctrl_scale, move_p2,
                     &point->ctrl1[0], &point->ctrl1[1],
                     &point->ctrl2[0], &point->ctrl2[1],
                     aspect_ratio);
      _set_ctrl_angle(point->corner[0], point->corner[1],
                     ctrl_angle, move_p2,
                     &point->ctrl1[0], &point->ctrl1[1],
                     &point->ctrl2[0], &point->ctrl2[1],
                     aspect_ratio);
      break;
    case DT_MASKS_BEZIER_SINGLE:
      break;
    case DT_MASKS_BEZIER_SYMMETRIC:
      _set_ctrl_symmetric(point->corner[0], point->corner[1],
                         move_p2,
                         &point->ctrl1[0], &point->ctrl1[1],
                         &point->ctrl2[0], &point->ctrl2[1]);
      break;
    case DT_MASKS_BEZIER_SING_SYMM:
      _set_ctrl_angle(point->corner[0], point->corner[1],
                     ctrl_angle, move_p2,
                     &point->ctrl1[0], &point->ctrl1[1],
                     &point->ctrl2[0], &point->ctrl2[1],
                     aspect_ratio);
      break;
    default:
      assert(FALSE);
  }
}

/** Get the control points of a segment to match exactly a catmull-rom
 * spline */
static void _path_catmull_to_bezier(const float x1,
                                    const float y1,
                                    const float x2,
                                    const float y2,
                                    const float x3,
                                    const float y3,
                                    const float x4,
                                    const float y4,
                                    float *bx1,
                                    float *by1,
                                    float *bx2,
                                    float *by2)
{
  *bx1 = (-x1 + 6 * x2 + x3) / 6;
  *by1 = (-y1 + 6 * y2 + y3) / 6;
  *bx2 = (x2 + 6 * x3 - x4) / 6;
  *by2 = (y2 + 6 * y3 - y4) / 6;
}

/** initialise all control points to eventually match a catmull-rom
 * like spline */
static void _path_init_ctrl_points(dt_masks_form_t *form)
{
  // if we have less that 3 points, what to do ??
  const guint nb = g_list_length(form->points);
  if(nb < 2) return;

  const GList *form_points = form->points;
  for(int k = 0; k < nb; k++)
  {
    dt_masks_point_path_t *point3 = form_points->data;
    // if the point has not been set manually, we redefine it
    if(point3->state & DT_MASKS_POINT_STATE_NORMAL)
    {
      // we want to get point-2 (into pt1), point-1 (into pt2),
      // point+1 (into pt4), point+2 (into pt5), wrapping around to
      // the other end of the list
      // prev, wrapping around if already on first element
      const GList *pt2 = g_list_prev_wraparound(form_points);
      const GList *pt1 = g_list_prev_wraparound(pt2);
       // next, wrapping around if on last element
      const GList *pt4 = g_list_next_wraparound(form_points, form->points);
      const GList *pt5 = g_list_next_wraparound(pt4, form->points);
      dt_masks_point_path_t *point1 = pt1->data;
      dt_masks_point_path_t *point2 = pt2->data;
      dt_masks_point_path_t *point4 = pt4->data;
      dt_masks_point_path_t *point5 = pt5->data;

      float bx1 = 0.0f, by1 = 0.0f, bx2 = 0.0f, by2 = 0.0f;
      _path_catmull_to_bezier(point1->corner[0], point1->corner[1],
                              point2->corner[0], point2->corner[1],
                              point3->corner[0], point3->corner[1],
                              point4->corner[0], point4->corner[1],
                              &bx1, &by1, &bx2, &by2);
      if(point2->ctrl2[0] == -1.0) point2->ctrl2[0] = bx1;
      if(point2->ctrl2[1] == -1.0) point2->ctrl2[1] = by1;
      point3->ctrl1[0] = bx2;
      point3->ctrl1[1] = by2;
      _path_catmull_to_bezier(point2->corner[0], point2->corner[1],
                              point3->corner[0], point3->corner[1],
                              point4->corner[0], point4->corner[1],
                              point5->corner[0], point5->corner[1],
                              &bx1, &by1, &bx2, &by2);
      if(point4->ctrl1[0] == -1.0) point4->ctrl1[0] = bx2;
      if(point4->ctrl1[1] == -1.0) point4->ctrl1[1] = by2;
      point3->ctrl2[0] = bx1;
      point3->ctrl2[1] = by1;
    }
    // keep form_points tracking the kth element of form->points
    form_points = g_list_next(form_points);
  }
}

static gboolean _path_is_clockwise(dt_masks_form_t *form)
{
  if(!g_list_shorter_than(form->points,3)) // if we have at least three points...
  {
    float sum = 0.0f;
    for(const GList *form_points = form->points;
        form_points;
        form_points = g_list_next(form_points))
    {
      // next, wrapping around if on last elt
      const GList *next = g_list_next_wraparound(form_points, form->points);
      // kth element of form->points
      dt_masks_point_path_t *point1 = form_points->data;
      dt_masks_point_path_t *point2 = next->data;
      sum += (point2->corner[0] - point1->corner[0])
        * (point2->corner[1] + point1->corner[1]);
    }
    return (sum < 0);
  }
  // return dummy answer
  return TRUE;
}

/** fill eventual gaps between 2 points with a line */
static int _path_fill_gaps(const int lastx,
                           const int lasty,
                           const int x,
                           const int y,
                           dt_masks_dynbuf_t *points)
{
  dt_masks_dynbuf_reset(points);
  dt_masks_dynbuf_add_2(points, x, y);

  // now we want to be sure everything is continuous
  if(x - lastx > 1)
  {
    for(int j = x - 1; j > lastx; j--)
    {
      const int yyy = (j - lastx) * (y - lasty) / (float)(x - lastx) + lasty;
      const int lasty2 = dt_masks_dynbuf_get(points, -1);
      if(lasty2 - yyy > 1)
      {
        for(int jj = lasty2 + 1; jj < yyy; jj++)
        {
          dt_masks_dynbuf_add_2(points, j, jj);
        }
      }
      else if(lasty2 - yyy < -1)
      {
        for(int jj = lasty2 - 1; jj > yyy; jj--)
        {
          dt_masks_dynbuf_add_2(points, j, jj);
        }
      }
      dt_masks_dynbuf_add_2(points, j, yyy);
    }
  }
  else if(x - lastx < -1)
  {
    for(int j = x + 1; j < lastx; j++)
    {
      int yyy = (j - lastx) * (y - lasty) / (float)(x - lastx) + lasty;
      int lasty2 = dt_masks_dynbuf_get(points, -1);
      if(lasty2 - yyy > 1)
      {
        for(int jj = lasty2 + 1; jj < yyy; jj++)
        {
          dt_masks_dynbuf_add_2(points, j, jj);
        }
      }
      else if(lasty2 - yyy < -1)
      {
        for(int jj = lasty2 - 1; jj > yyy; jj--)
        {
          dt_masks_dynbuf_add_2(points, j, jj);
        }
      }
      dt_masks_dynbuf_add_2(points, j, yyy);
    }
  }
  return 1;
}

/**
 * fill the gap between 2 points with an arc of circle
 * this function is here because we can have gap in border, esp. if
 * the corner is very sharp. It is used for convex and concave corners,
 * overlapping segemts are cut out later.
 *
 * @param cmax the center point of the circle
 * @param bmin starting point of border
 * @param bmax ending point of border
 * @param dpoints the dynbuf where we the points are stored
 * @param dborder the dynbuf where we the border points are stored
 * @param fill_seg_indexes store the indexes of the points
 *                         added to the dynbufs
 * @param clockwise whether to turn clockwise or anti-clockwise
 */
static void _path_points_fill_border_gaps(float *cmax,
                                          float *bmin,
                                          float *bmax,
                                          dt_masks_dynbuf_t *dpoints,
                                          dt_masks_dynbuf_t *dborder,
                                          dt_masks_intbuf_t *fill_seg_indexes,
                                          const gboolean clockwise)
{
  // we want to find the start and end angles
  double a1 = angle_2d(bmin[0], bmin[1], cmax[0], cmax[1]);
  double a2 = angle_2d(bmax[0], bmax[1], cmax[0], cmax[1]);

  if(a1 == a2) return;

  // we have to be sure that we turn in the correct direction
  if(a2 < a1 && clockwise)
  {
    a2 += 2 * M_PI;
  }
  if(a2 > a1 && !clockwise)
  {
    a1 += 2 * M_PI;
  }

  // we determine start and end radius too
  const float r1 = sqrtf((bmin[1] - cmax[1]) * (bmin[1] - cmax[1])
                         + (bmin[0] - cmax[0]) * (bmin[0] - cmax[0]));
  const float r2 = sqrtf((bmax[1] - cmax[1]) * (bmax[1] - cmax[1])
                         + (bmax[0] - cmax[0]) * (bmax[0] - cmax[0]));

  // and the max length of the circle arc
  int l = 0;
  if(a2 > a1)
    l = (a2 - a1) * fmaxf(r1, r2);
  else
    l = (a1 - a2) * fmaxf(r1, r2);
  if(l < 2) return;

  // and now we add the points
  const float incra = (a2 - a1) / l;
  const float incrr = (r2 - r1) / l;
  float rr = r1 + incrr;
  float aa = a1 + incra;

  // remember the indexes of the points we add
  const int start_pt_index = dt_masks_dynbuf_position(dpoints)/2;
  dt_masks_intbuf_add2(fill_seg_indexes, start_pt_index, start_pt_index + 2*(l-1));

  // allocate entries in the dynbufs
  float *dpoints_ptr = dt_masks_dynbuf_reserve_n(dpoints, 2*(l-1));
  float *dborder_ptr = dborder ? dt_masks_dynbuf_reserve_n(dborder, 2*(l-1)) : NULL;
  // and fill them in: the same center pos for each point in dpoints,
  //  and the corresponding border point at successive angular
  //  positions for dborder
  if(dpoints_ptr)
  {
    for(int i = 1; i < l; i++)
    {
      *dpoints_ptr++ = cmax[0];
      *dpoints_ptr++ = cmax[1];
      if(dborder_ptr)
      {
        *dborder_ptr++ = cmax[0] + rr * cosf(aa);
        *dborder_ptr++ = cmax[1] + rr * sinf(aa);
      }
      rr += incrr;
      aa += incra;
    }
  }
}

static inline
float _smoothstep(const float p1, const float p2, const float t)
{
  return p1 + (p2 - p1) * t * t * (3.0 - 2.0 * t);
}

/** recursive function to get all points of the path AND all point of the border */
/** the function take care to avoid big gaps between points */
static void _path_points_recurs(float *p1,
                                float *p2,
                                const double tmin,
                                const double tmax,
                                float *path_min,
                                float *path_max,
                                float *border_min,
                                float *border_max,
                                float *rpath,
                                float *rborder,
                                dt_masks_dynbuf_t *dpoints,
                                dt_masks_dynbuf_t *dborder,
                                const int withborder)
{
  // we calculate points if needed
  // Caveat: When the border distance changes by a lot, the resulting border
  //         that is offset from the bezier curve can make strange bends.
  if(path_min[0] == DT_INVALID_COORDINATE)
  {
    _path_border_get_XY(p1[0], p1[1], p1[2], p1[3], p2[2], p2[3], p2[0], p2[1], tmin,
                        _smoothstep(p1[4], p2[4], tmin),
                        path_min, path_min + 1,
                        border_min, border_min + 1);
  }
  if(path_max[0] == DT_INVALID_COORDINATE)
  {
    _path_border_get_XY(p1[0], p1[1], p1[2], p1[3], p2[2], p2[3], p2[0], p2[1], tmax,
                        _smoothstep(p1[4], p2[4], tmax),
                        path_max, path_max + 1,
                        border_max, border_max + 1);
  }
  // are the points near ?
  if((tmax - tmin < 0.0001)
     || ((int)path_min[0] - (int)path_max[0] < 1
         && (int)path_min[0] - (int)path_max[0] > -1
         && (int)path_min[1] - (int)path_max[1] < 1
         && (int)path_min[1] - (int)path_max[1] > -1
         && (!withborder
             || ((int)border_min[0] - (int)border_max[0] < 1
                 && (int)border_min[0] - (int)border_max[0] > -1
                 && (int)border_min[1] - (int)border_max[1] < 1
                 && (int)border_min[1] - (int)border_max[1] > -1))))
  {
    dt_masks_dynbuf_add_2(dpoints, path_max[0], path_max[1]);
    rpath[0] = path_max[0];
    rpath[1] = path_max[1];

    if(withborder)
    {
      dt_masks_dynbuf_add_2(dborder, border_max[0], border_max[1]);
      rborder[0] = border_max[0];
      rborder[1] = border_max[1];
    }
    return;
  }

  // we split in two part
  double tx = (tmin + tmax) / 2.0;
  float c[2] = { DT_INVALID_COORDINATE, DT_INVALID_COORDINATE };
  float b[2] = { DT_INVALID_COORDINATE, DT_INVALID_COORDINATE };
  float rc[2] = { 0 }, rb[2] = { 0 };
  _path_points_recurs(p1, p2, tmin, tx, path_min, c, border_min, b, rc, rb,
                      dpoints, dborder, withborder);
  _path_points_recurs(p1, p2, tx, tmax, rc, path_max, rb,
                      border_max, rpath, rborder, dpoints, dborder, withborder);
}


static inline
float _dist_squared_2d(const float x1, const float y1, const float x2, const float y2)
{
  return (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
}

/* Border point indexes are in range [min, max), indexes >= max are
   wrapped around */
static inline
int _border_index_wrap_around(const int min, const int max, const int idx)
{
  return ((idx - min) % (max - min)) + min;
}

/* Bring border point indexes into a consistent order for comparison,
   despite the wrap-around. */
static inline
int _border_index_order(const int index, const int wrap_index, const int offset)
{
  return index >= wrap_index ? index : index + offset;
}

/**
 * Part of intersection point optimization.
 * Check if one of the neighbors of idx_target is closer to idx_source
 * than idx_target itself.
 *
 * @param border array of points which make up the border
 * @param border_first start index of the border
 * @param border_last end index of the border
 * @param idx_fixed index of the fixed point
 * @param idx_optimize index of the point to optimize
 *
 * @return index of the point in the border which is closer to idx_fixed
 *
 * This function does not optimize across border_wrap.
 */
static inline
int _find_closer_point(const float* const border,
                       const int border_first,
                       const int border_last,
                       const int idx_fixed,
                       const int idx_optimize)
{
  float min_dist = _dist_squared_2d(border[idx_fixed * 2], border[idx_fixed * 2 + 1],
                                   border[idx_optimize * 2], border[idx_optimize * 2 + 1]);
  int min_idx = idx_optimize;

  int neighbors[] = { _border_index_wrap_around(border_first, border_last, idx_optimize - 1),
                      _border_index_wrap_around(border_first, border_last, idx_optimize + 1) };

  for(int i = 0; i < 2; i++)
  {
    const float dist = _dist_squared_2d(border[neighbors[i] * 2], border[neighbors[i] * 2 + 1],
                                  border[idx_fixed * 2], border[idx_fixed * 2 + 1]);
    if(dist < min_dist)
    {
      min_dist = dist;
      min_idx = neighbors[i];
    }
  }

  return min_idx;
}


/**
 * Optimize to find closer intersection points.
 *
 * Does not optimize acress border_wrap.
 * Preserves bounds on both sides, so the order of intersections in
 * find_intersection will not be messed up.
 *
 * @param border the border array
 * @param border_first the first point index in the border array
 * @param border_wrap the rightmost point in the shape (start of find_intersection)
 * @param border_last the last index in the border array
 * @param idx1 a pointer to the index of the first intersection point
 * @param idx2 a pointer to the index of the second intersection point
 * @param idx1_min_ord the ordered minimum index for the first intersection point
 * @param idx1_max_ord the ordered maximum index for the first intersection point
 * @param idx2_min_ord the ordered minimum index for the second intersection point
 * @param idx2_max_ord the ordered maximum index for the second intersection point
 */
static void _optimize_intersection_points(const float* const border,
                                          const int border_first,
                                          const int border_wrap,
                                          const int border_last,
                                          int *idx1,
                                          int *idx2,
                                          const int idx1_min_ord,
                                          const int idx1_max_ord,
                                          const int idx2_min_ord,
                                          const int idx2_max_ord)
{
  const int MAX_ITER = 20;
  int iter = 0;
  int new_idx1, new_idx2, new_idx1_ord, new_idx2_ord;
  gboolean idx1_updated;

  const int nb_border_p = border_last - border_first;

  // idx1, idx2 may have been wrapped around, ensure correct order
  const int idx1_ord = _border_index_order(*idx1, border_wrap, nb_border_p);
  const int idx2_ord = _border_index_order(*idx2, border_wrap, nb_border_p);

  // Don't optimize segments that are very short.
  // Also make sure the resulting intersection is not length <= 0.
  // (We move at most by 1 point per iteration on each side.)
  if(idx1_ord + 2 * (MAX_ITER + 1) > idx2_ord) return;

  // In the optimization loop, we take turns, trying to move point 1
  // and then point 2. We stop, if we make no progress during an
  // iteration, or when we have reached MAX_ITER.
  while(iter < MAX_ITER)
  {

    // Optimize point 1
    new_idx1 = _find_closer_point(border, border_first, border_last, *idx2, *idx1);

    if((*idx1 >= border_wrap) != (new_idx1 >= border_wrap))
    {
      new_idx1 = *idx1; // revert, don't move a point across border_wrap
    }

    new_idx1_ord = _border_index_order(new_idx1, border_wrap, nb_border_p);
    if((new_idx1_ord < idx1_min_ord) || (new_idx1_ord > idx1_max_ord))
    {
      new_idx1 = *idx1; // revert, don't move a point out of bounds
    }

    if(new_idx1 != *idx1)
    {
      *idx1 = new_idx1;
      idx1_updated = TRUE;
    }
    else
    {
      idx1_updated = FALSE;
    }

    // Optimize point 2
    new_idx2 = _find_closer_point(border, border_first, border_last, *idx1, *idx2);

    if((*idx2 >= border_wrap) != (new_idx2 >= border_wrap))
    {
      new_idx2 = *idx2; // revert, don't move a point across border_wrap
    }

    new_idx2_ord = _border_index_order(new_idx2, border_wrap, nb_border_p);
    if((new_idx2_ord < idx2_min_ord) || (new_idx2_ord > idx2_max_ord))
    {
      new_idx2 = *idx2; // revert, don't move a point out of bounds
    }

    if(new_idx2 != *idx2)
    {
      *idx2 = new_idx2;
    }
    else
    {
      if(!idx1_updated) break; // Optimization tried both sides and did not find an improvement.
    };

    iter++;
  }
}


/**
 * In general we don't want to cut out intersecting segments that
 * go "outside" of the shape, only loops that go "inside". We test
 * for this by making sure that the segment does not contain the
 * index of any extremum.
 * However the circles created by _path_points_fill_border_gaps
 * may weirdly loop around concave control points, so we make an
 * exception and cut them, even if they contain an extremum.
 *
 * @param seg_start the start of the potential segment to cut
 * @param seg_end the end of the segment
 * @param extrema_ord the 4 extrema of the shape in order
 * @param gap_fill_segments filler segments that can be cut,
 *                          even if containing extrema
 *
 * @return true if the segment can be cut out
 */
static gboolean _check_cutable(const int seg_start,
                               const int seg_end,
                               const int* const extrema_ord,
                               const dt_masks_intbuf_t* const gap_fill_segments)
{

  // Relative amount of fill points that make it acceptable
  // to cut out the segment. This parameter can be tweaked.
  const float FILL_POINT_CUT_RATIO = 0.5f;
  const float seg_len = seg_end - seg_start;
  float fill_len = 0.0f;

  for(int i=0; i < gap_fill_segments->pos; i+=2)
  {
    const int fill_start = gap_fill_segments->buffer[i];
    const int fill_end   = gap_fill_segments->buffer[i+1];

    if(fill_end >= seg_start && fill_start <= seg_end)
    {
      fill_len += MIN(seg_end, fill_end) - MAX(seg_start, fill_start);
    }
  }
  if((fill_len / seg_len) > FILL_POINT_CUT_RATIO)
  {
    return TRUE;
  }

  // This is not a segment that mostly consists of fill points, but it
  // can still be cut, if it does not contain an extremum.
  for(int i=0; i<4; i++)
  {
    if(seg_start < extrema_ord[i] && extrema_ord[i] < seg_end)
    {
      return FALSE;
    }
  }

  return TRUE;
}


/**
 * Each corner has two bezier controls, so the total is 3*nb_point
 */
static inline int _nb_wctrl_points(const int nb_point)
{
  return nb_point * 3;
}

/**
 * Find all self-intersections in a path.
 *
 * \param[in,out] inter intersections as pairs of (start, end) indexes into "border"
 * \param[in] gap_fill_segments indexes of filler arcs (start,end)
 * \param[in] nb_corners number of corners
 * \param[in] border shape border, control points first, then all points
 * \param[in] border_len number of points in "border"
 *
 * \return number of self-intersections found
 */
static int _path_find_self_intersection(dt_masks_dynbuf_t *inter,
                                        const dt_masks_intbuf_t* const gap_fill_segments,
                                        const int nb_corners,
                                        float* const border,
                                        const int border_len)
{
  if(nb_corners == 0 || border_len == 0) return 0;

  int inter_count = 0;

  const int border_first = _nb_wctrl_points(nb_corners); // index of the first non-control point
  const int nb_border_p = border_len - border_first;     // number of bp without control points

  // we search extrema of the shape in x and y
  int xmin = INT_MAX, xmax = INT_MIN, ymin = INT_MAX, ymax = INT_MIN;
  int posextr[4] = { -1 }; // xmin,xmax,ymin,ymax
  for(int i = border_first; i < border_len; i++)
  {
    if((border[i * 2] == DT_INVALID_COORDINATE) || (border[i * 2 + 1] == DT_INVALID_COORDINATE))
    {
      border[i * 2] = border[i * 2 - 2];
      border[i * 2 + 1] = border[i * 2 - 1];
    }
    if(xmin > border[i * 2])
    {
      xmin = border[i * 2];
      posextr[0] = i;
    }
    if(xmax < border[i * 2])
    {
      xmax = border[i * 2];
      posextr[1] = i;
    }
    if(ymin > border[i * 2 + 1])
    {
      ymin = border[i * 2 + 1];
      posextr[2] = i;
    }
    if(ymax < border[i * 2 + 1])
    {
      ymax = border[i * 2 + 1];
      posextr[3] = i;
    }
  }

  // posextr[1] will be our loop start, we go from [posextr[1] to border_len) and
  // then from [border_first to posextr[1]). This makes comparing the order
  // of indexes difficult, since there is a wrap-around in the middle.
  // This is solved by introducing "_ord" variants of variables. The new
  // index range is [posextr[1] to posextr[1] + nb_border_p).
  int posextr_ord[4];
  for(int i = 0; i < 4; i++)
  {
    posextr_ord[i] = _border_index_order(posextr[i], posextr[1], nb_border_p);
  }

  const int border_last_ord = posextr_ord[1] + nb_border_p - 1;

  // *binter is a bitmap that can fit the the shape and stores ome
  // index of a point from *border per pixel. It is used to find pixels
  // that are visited twice => self-intersections.
  xmin -= 1, ymin -= 1;
  xmax += 1, ymax += 1;
  const int hb = ymax - ymin;
  const int wb = xmax - xmin;

  const size_t ss = (size_t)hb * wb;
  if(ss < 10 || hb < 0 || wb < 0) return 0;

  int *binter = dt_alloc_align_int(ss);
  if(binter == NULL) return 0;
  memset(binter, 0, sizeof(int) * ss);

  // Buffer for extra points to fill gaps between points in *border
  dt_masks_dynbuf_t *extra = dt_masks_dynbuf_init(100000, "path extra");
  if(extra == NULL)
  {
    dt_free_align(binter);
    return 0;
  }

  // We'll iterate through all border points, but we can't start at
  // border[border_first] because it may be in a self-intersected
  // section so we choose a point where we are sure there's no intersection:
  // one from border shape extrema (here x_max).
  int lastx = border[(posextr[1] - 1) * 2];
  int lasty = border[(posextr[1] - 1) * 2 + 1];

  for(int ii = border_first; ii < border_len; ii++)
  {
    // we want to loop from one border extremity
    // i: [posextr[1]...border_len) ... [border_first...posextr[1])
    int i = ii - border_first + posextr[1];
    if(i >= border_len) i = i - nb_border_p;

    if(inter_count >= nb_corners * 4) break;

    // we want to be sure everything is continuous
    _path_fill_gaps(lastx, lasty, border[i * 2], border[i * 2 + 1], extra);

    // extra represent all the points between the last one and the current one
    // for all the points in extra, we'll check for self-intersection
    // and "register" them in binter
    for(int j = dt_masks_dynbuf_position(extra) / 2 - 1; j >= 0; j--)
    {
      const int xx = (dt_masks_dynbuf_buffer(extra))[j * 2];
      const int yy = (dt_masks_dynbuf_buffer(extra))[j * 2 + 1];

      const int pixel = (yy - ymin) * wb + (xx - xmin);
      if(pixel < 0 || pixel > ss)
      {
        dt_free_align(binter);
        return 0;
      }
      if((xx == lastx && yy == lasty))
      {
        // we haven't move from last pixel.
        // this is not a real self-interesection, so we just update binter
        binter[pixel] = i;
        continue;
      }
      lastx = xx;
      lasty = yy;

      // we check also 2 points around to be sure catching intersection
      int v[3] = { 0 };
      v[0] = binter[pixel];
      if(xx > xmin) v[1] = binter[pixel - 1];
      if(yy > ymin) v[2] = binter[pixel - wb];

      for(int k = 0; k < 3; k++)
      {

        // Check if we have moved on from the last point
        if(v[k] == i || v[k] == i - 1) continue;

        if(v[k] == 0)
        {
          // there wasn't anything "registered" at this place in binter yet
          // we do it now
          binter[pixel] = i;
          continue;
        }

        // there's already a border point "registered" at this
        // coordinate.  so we've potentially found a
        // self-intersection portion between v[k] and i
        const int curr_start = v[k];
        const int curr_end = i;

        const int curr_start_ord = _border_index_order(curr_start, posextr[1], nb_border_p);
        const int curr_end_ord = _border_index_order(curr_end, posextr[1], nb_border_p);

        assert(curr_start != curr_end);
        assert(curr_start_ord < curr_end_ord);

        if(_check_cutable(curr_start_ord, curr_end_ord, posextr_ord, gap_fill_segments))
        {
          // we have found a self-intersection portion, between curr_start
          // and curr_end and we are sure that this portion either doesn't
          // include one of the shape extrema or it is mostly a filler
          // segment.

          if(inter_count == 0)
          {
            // we have found the first self-intersection portion

            int opt_start = curr_start;
            int opt_end = curr_end;
            // Invariant limits to keep inter consistent
            // idx1_min_ord: posextr[1] - dummy, minimum ordered index
            // idx1_max_ord: border_last_ord - dummy, maximum ordered index
            // idx2_min_ord: posextr[1] - dummy, minimum ordered index
            // idx2_max_ord: curr_end_ord - don't go beyond the current loop index
            _optimize_intersection_points(border, border_first, posextr[1], border_len, &opt_start, &opt_end,
                                          posextr[1], border_last_ord, posextr[1], curr_end_ord);

            dt_masks_dynbuf_add_2(inter, opt_start, opt_end);
            inter_count++;
            continue;
          }

          // We want to check, if the new self-intersection partially
          // or fully overlaps with any previous one.
          int prev_start;
          int prev_end;
          int prev_start_ord;
          int prev_end_ord;

          // Loop over all previously found self-intersections
          int n;
          for(n = 0; n < inter_count; n++)
          {
            prev_start = dt_masks_dynbuf_get_absolute(inter, n * 2);
            prev_end = dt_masks_dynbuf_get_absolute(inter, n * 2 + 1);

            prev_start_ord = _border_index_order(prev_start, posextr[1], nb_border_p);
            prev_end_ord = _border_index_order(prev_end, posextr[1], nb_border_p);

            assert(prev_start_ord <= prev_end_ord);
            assert(prev_end_ord <= curr_end_ord);

            if(prev_start_ord <= curr_start_ord && curr_start_ord <= prev_end_ord)
            {
              // The new self-intersection starts in a previous self-intersection,
              // there is nothing to do (the start is on a segment that does not exist,
              // so it makes no sense to cut).
              break;
            }
            if(curr_start_ord < prev_start_ord && prev_end_ord < curr_end_ord)
            {
              // The new self-intersection fully contains an old one.

              // Update the old intersection.
              // All further known intersecting segments also have to be contained
              // in this updated one.
              // Look at a segment "later" that is in the list after "prev".
              // - curr_start < prev_start < prev_end < curr_end
              // - Segment ends are monotonus: prev_end < later_end < curr_end
              // Cases for later_start:
              // if later_start < prev_start => later fully contains prev, so
              //                                prev would have been updated already
              // else "later" is contained in "curr".
              dt_masks_dynbuf_reset_position(inter, n * 2);
              inter_count = n + 1;

              int opt_start = curr_start;
              int opt_end = curr_end;

              // Invariant limits to keep inter consistent
              // idx1_min_ord: posextr[1] - dummy, minimum ordered index
              // idx1_max_ord: prev_start_ord - preserve "curr_start_ord < prev_start_ord"
              // idx2_min_ord: prev_end_ord - preserve "prev_end_ord < curr_end_ord"
              // idx2_max_ord: curr_end_ord - don't go beyond the current loop index
              _optimize_intersection_points(border, border_first, posextr[1], border_len, &opt_start, &opt_end,
                                            posextr[1], prev_start_ord, prev_end_ord, curr_end_ord);

              dt_masks_dynbuf_add_2(inter, opt_start, opt_end);

              break;
            }
          }

          if(n == inter_count // for loop did not exit with break
             && prev_end_ord < curr_start_ord)
          {
            // We have a new self-intersection that does not overlap the last one.

            int opt_start = curr_start;
            int opt_end = curr_end;

            // Invariant limits to keep inter consistent
            // idx1_min_ord: prev_end_ord - preserve "prev_end_ord < curr_start_ord"
            // idx1_max_ord: border_last_ord - dummy, maximum ordered index
            // idx2_min_ord: posextr[1] - dummy, minimum ordered index
            // idx2_max_ord: curr_end_ord - don't go beyond the current loop index
            _optimize_intersection_points(border, border_first, posextr[1], border_len, &opt_start, &opt_end,
                                          prev_end_ord, border_last_ord, posextr[1], curr_end_ord);

            dt_masks_dynbuf_add_2(inter, opt_start, opt_end);

            inter_count++;
          }
        }
      }
    }
  }

  dt_masks_dynbuf_free(extra);
  dt_free_align(binter);

  // and we return the number of self-intersection found
  return inter_count;
}

/** get all points of the path and the border */
/** this take care of gaps and self-intersection and iop distortions */
static int _path_get_pts_border(dt_develop_t *dev,
                                dt_masks_form_t *form,
                                const double iop_order,
                                const int transf_direction,
                                dt_dev_pixelpipe_t *pipe,
                                float **points,
                                int *points_count,
                                float **border,
                                int *border_count,
                                const gboolean source)
{
  double start2 = dt_get_debug_wtime();

  const float wd = pipe->iwidth, ht = pipe->iheight;
  const guint nb = g_list_length(form->points);

  dt_masks_dynbuf_t *dpoints = NULL, *dborder = NULL, *intersections = NULL;
  dt_masks_intbuf_t *gap_fill_segs = NULL;

  *points = NULL;
  *points_count = 0;
  if(border) *border = NULL;
  if(border) *border_count = 0;

  dpoints = dt_masks_dynbuf_init(1000000, "path dpoints");
  if(dpoints == NULL) return 0;

  if(border)
  {
    dborder = dt_masks_dynbuf_init(1000000, "path dborder");
    if(dborder == NULL)
    {
      dt_masks_dynbuf_free(dpoints);
      return 0;
    }
  }

  intersections = dt_masks_dynbuf_init(10 * MAX(nb, 1), "path intersections");
  gap_fill_segs = dt_masks_intbuf_init(10 * MAX(nb, 1), "path gap_fill_segs");

  if(intersections == NULL || gap_fill_segs == NULL)
  {
    dt_masks_dynbuf_free(dpoints);
    dt_masks_dynbuf_free(dborder);

    if(intersections) dt_masks_dynbuf_free(intersections);
    if(gap_fill_segs) dt_masks_intbuf_free(gap_fill_segs);
    return 0;
  }

  // we store all points
  float dx = 0.0f, dy = 0.0f;

  if(source && nb > 0 && transf_direction != DT_DEV_TRANSFORM_DIR_ALL)
  {
    dt_masks_point_path_t *pt = form->points->data;
    dx = (pt->corner[0] - form->source[0]) * wd;
    dy = (pt->corner[1] - form->source[1]) * ht;
  }
  for(const GList *l = form->points; l; l = g_list_next(l))
  {
    const dt_masks_point_path_t *const pt = l->data;
    float *const buf = dt_masks_dynbuf_reserve_n(dpoints, 6);
    if(buf)
    {
      buf[0] = pt->ctrl1[0] * wd - dx;
      buf[1] = pt->ctrl1[1] * ht - dy;
      buf[2] = pt->corner[0] * wd - dx;
      buf[3] = pt->corner[1] * ht - dy;
      buf[4] = pt->ctrl2[0] * wd - dx;
      buf[5] = pt->ctrl2[1] * ht - dy;
    }
  }
  // for the border, we store value too
  if(dborder)
  {
    dt_masks_dynbuf_add_zeros(dborder, 6 * nb);  // need six zeros for each border point
  }

  float *border_init = dt_alloc_align_float((size_t)6 * nb);
  int cw = _path_is_clockwise(form);
  if(cw == 0) cw = -1;

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_points init took %0.04f sec", form->name,
           dt_get_lap_time(&start2));

  // we render all segments
  const GList *form_points = form->points;
  for(int k = 0; k < nb; k++)
  {
    const int pb = dborder ? dt_masks_dynbuf_position(dborder) : 0;
    border_init[k * 6 + 2] = -pb;
    // next, wrapping around if on last element
    const GList *pt2 = g_list_next_wraparound(form_points, form->points);
    const GList *pt3 = g_list_next_wraparound(pt2, form->points);
    // kth element of form->points
    dt_masks_point_path_t *point1 = form_points->data;
    dt_masks_point_path_t *point2 = pt2->data;
    dt_masks_point_path_t *point3 = pt3->data;
    float p1[5] = { point1->corner[0] * wd - dx,
                    point1->corner[1] * ht - dy,
                    point1->ctrl2[0] * wd - dx,
                    point1->ctrl2[1] * ht - dy,
                    cw * point1->border[1] * MIN(wd, ht) };
    float p2[5] = { point2->corner[0] * wd - dx,
                    point2->corner[1] * ht - dy,
                    point2->ctrl1[0] * wd - dx,
                    point2->ctrl1[1] * ht - dy,
                    cw * point2->border[0] * MIN(wd, ht) };
    float p3[5] = { point2->corner[0] * wd - dx,
                    point2->corner[1] * ht - dy,
                    point2->ctrl2[0] * wd - dx,
                    point2->ctrl2[1] * ht - dy,
                    cw * point2->border[1] * MIN(wd, ht) };
    float p4[5] = { point3->corner[0] * wd - dx,
                    point3->corner[1] * ht - dy,
                    point3->ctrl1[0] * wd - dx,
                    point3->ctrl1[1] * ht - dy,
                    cw * point3->border[0] * MIN(wd, ht) };

    // advance form_points for next iteration so that it tracks the
    // kth element of form->points
    form_points = g_list_next(form_points);

    // and we determine all points by recursion (to be sure the
    // distance between 2 points is <=1)
    float rc[2] = { 0 }, rb[2] = { 0 };
    float bmin[2] = { DT_INVALID_COORDINATE, DT_INVALID_COORDINATE };
    float bmax[2] = { DT_INVALID_COORDINATE, DT_INVALID_COORDINATE };
    float cmin[2] = { DT_INVALID_COORDINATE, DT_INVALID_COORDINATE };
    float cmax[2] = { DT_INVALID_COORDINATE, DT_INVALID_COORDINATE };

    _path_points_recurs(p1, p2, 0.0, 1.0, cmin, cmax, bmin, bmax,
                        rc, rb, dpoints, dborder, border && (nb >= 3));

    // we check gaps in the border (sharp edges)
    if(dborder && (fabs(dt_masks_dynbuf_get(dborder, -2) - rb[0]) > 1.0f
                   || fabs(dt_masks_dynbuf_get(dborder, -1) - rb[1]) > 1.0f))
    {
      bmin[0] = dt_masks_dynbuf_get(dborder, -2);
      bmin[1] = dt_masks_dynbuf_get(dborder, -1);
    }

    dt_masks_dynbuf_add_2(dpoints, rc[0], rc[1]);

    border_init[k * 6 + 4] = dborder ? -dt_masks_dynbuf_position(dborder) : 0;

    if(dborder)
    {
      if(rb[0] == DT_INVALID_COORDINATE)
      {
        if(dt_masks_dynbuf_get(dborder, - 2) == DT_INVALID_COORDINATE)
        {
          dt_masks_dynbuf_set(dborder, -2, dt_masks_dynbuf_get(dborder, -4));
          dt_masks_dynbuf_set(dborder, -1, dt_masks_dynbuf_get(dborder, -3));
        }
        rb[0] = dt_masks_dynbuf_get(dborder, -2);
        rb[1] = dt_masks_dynbuf_get(dborder, -1);
      }
      dt_masks_dynbuf_add_2(dborder, rb[0], rb[1]);

      (dt_masks_dynbuf_buffer(dborder))[k * 6] =
        border_init[k * 6] = (dt_masks_dynbuf_buffer(dborder))[pb];
      (dt_masks_dynbuf_buffer(dborder))[k * 6 + 1] =
        border_init[k * 6 + 1] = (dt_masks_dynbuf_buffer(dborder))[pb + 1];
    }

    // we first want to be sure that there are no gaps in border
    if(dborder && nb >= 3)
    {
      // we get the next point (start of the next segment) t=0.00001f
      // to workaround rounding effects with full optimization that
      // result in bmax[0] NOT being set to DT_INVALID_COORDINATE when
      // t=0 and the two points in p3 are identical (as is the case on
      // a control node set to sharp corner)
      _path_border_get_XY(p3[0], p3[1], p3[2], p3[3], p4[2], p4[3], p4[0], p4[1],
                          0.00001f, p3[4], cmin, cmin + 1, bmax, bmax + 1);
      if(bmax[0] == DT_INVALID_COORDINATE)
      {
        _path_border_get_XY(p3[0], p3[1], p3[2], p3[3], p4[2], p4[3], p4[0], p4[1],
                            0.00001f, p3[4], cmin, cmin + 1, bmax, bmax + 1);
      }
      if(bmax[0] - rb[0] > 1
         || bmax[0] - rb[0] < -1
         || bmax[1] - rb[1] > 1
         || bmax[1] - rb[1] < -1)
      {

        _path_points_fill_border_gaps(rc, rb, bmax,
                                      dpoints, dborder, gap_fill_segs,
                                      _path_is_clockwise(form));
      }
    }
  }

  *points_count = dt_masks_dynbuf_position(dpoints) / 2;
  *points = dt_masks_dynbuf_harvest(dpoints);
  dt_masks_dynbuf_free(dpoints);

  if(dborder)
  {
    *border_count = dt_masks_dynbuf_position(dborder) / 2;
    *border = dt_masks_dynbuf_harvest(dborder);
    dt_masks_dynbuf_free(dborder);
  }

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_points point recurs %0.04f sec",
           form->name, dt_get_lap_time(&start2));

  // we don't want the border to self-intersect
  int inter_count = 0;
  if(border)
  {

    inter_count = _path_find_self_intersection(intersections, gap_fill_segs, nb, *border, *border_count);

    dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
             "[masks %s] path_points self-intersect took %0.04f sec", form->name,
             dt_get_lap_time(&start2));
  }

  // and we transform them with all distorted modules
  if(source && transf_direction == DT_DEV_TRANSFORM_DIR_ALL)
  {
    // we transform with all distortion that happen *before* the module
    // so we have now the TARGET points in module input reference
    if(dt_dev_distort_transform_plus(dev, pipe, iop_order,
                                     DT_DEV_TRANSFORM_DIR_BACK_EXCL,
                                     *points, *points_count))
    {
      // now we move all the points by the shift
      // so we have now the SOURCE points in module input reference
      float pts[2] = { form->source[0] * wd, form->source[1] * ht };
      if(!dt_dev_distort_transform_plus(dev, pipe, iop_order,
                                        DT_DEV_TRANSFORM_DIR_BACK_EXCL, pts, 1))
        goto fail;

      dx = pts[0] - (*points)[2];
      dy = pts[1] - (*points)[3];
      float *const ptsbuf = DT_IS_ALIGNED(*points);

      DT_OMP_FOR(if(*points_count > 100))
      for(int i = 0; i < *points_count; i++)
      {
        ptsbuf[i * 2]     += dx;
        ptsbuf[i * 2 + 1] += dy;
      }

      // we apply the rest of the distortions (those after the module)
      // so we have now the SOURCE points in final image reference
      if(!dt_dev_distort_transform_plus(dev, pipe, iop_order,
                                        DT_DEV_TRANSFORM_DIR_FORW_INCL, *points,
                                        *points_count))
        goto fail;
    }

    dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
             "[masks %s] path_points end took %0.04f sec",
             form->name, dt_get_lap_time(&start2));

    dt_masks_dynbuf_free(intersections);
    dt_masks_intbuf_free(gap_fill_segs);

    dt_free_align(border_init);
    return 1;
  }
  else if(dt_dev_distort_transform_plus(dev, pipe, iop_order, transf_direction,
                                        *points, *points_count))
  {
    if(!border
       || dt_dev_distort_transform_plus(dev, pipe, iop_order,
                                        transf_direction, *border, *border_count))
    {
      dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
               "[masks %s] path_points transform took %0.04f sec", form->name,
               dt_get_lap_time(&start2));

      if(border)
      {
        // we don't want to copy the falloff points
        for(int k = 0; k < nb; k++)
          for(int i = 2; i < 6; i++) (*border)[k * 6 + i] = border_init[k * 6 + i];

        // now we want to write the skipping zones
        for(int i = 0; i < inter_count; i++)
        {
          const int v = (dt_masks_dynbuf_buffer(intersections))[i * 2];
          const int w = (dt_masks_dynbuf_buffer(intersections))[ i * 2 + 1];
          if(v <= w)
          {
            (*border)[v * 2] = DT_INVALID_COORDINATE;
            (*border)[v * 2 + 1] = w;
          }
          else
          {
            if(w > _nb_wctrl_points(nb))
            {
              if(((*border)[nb * 6] == DT_INVALID_COORDINATE) && ((*border)[nb * 6 + 1] == DT_INVALID_COORDINATE))
                (*border)[nb * 6 + 1] = w;
              else if((*border)[nb * 6] == DT_INVALID_COORDINATE)
                (*border)[nb * 6 + 1] = MAX((*border)[nb * 6 + 1], w);
              else
                (*border)[nb * 6 + 1] = w;
              (*border)[nb * 6] = DT_INVALID_COORDINATE;
            }
            (*border)[v * 2] = DT_INVALID_COORDINATE;
            (*border)[v * 2 + 1] = DT_INVALID_COORDINATE;
          }
        }
      }

      dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
               "[masks %s] path_points end took %0.04f sec", form->name,
               dt_get_lap_time(&start2));

      dt_masks_dynbuf_free(intersections);
      dt_masks_intbuf_free(gap_fill_segs);
      dt_free_align(border_init);
      return 1;
    }
  }

  // if we failed, then free all and return
fail:
  dt_masks_dynbuf_free(intersections);
  dt_masks_intbuf_free(gap_fill_segs);
  dt_free_align(border_init);
  dt_free_align(*points);
  *points = NULL;
  *points_count = 0;
  if(border) dt_free_align(*border);
  if(border) *border = NULL;
  if(border) *border_count = 0;
  return 0;
}

/** get the distance between point (x,y) and the path */
static void _path_get_distance(const float x,
                               const float y,
                               const float as,
                               dt_masks_form_gui_t *gui,
                               const int index,
                               const int corner_count,
                               gboolean *inside,
                               gboolean *inside_border,
                               int *near,
                               gboolean *inside_source,
                               float *dist)
{
  // initialise returned values
  *inside_source = FALSE;
  *inside = FALSE;
  *inside_border = FALSE;
  *near = -1;
  *dist = FLT_MAX;

  if(!gui) return;

  dt_masks_form_gui_points_t *gpt = g_list_nth_data(gui->points, index);
  if(!gpt) return;

  // we first check if we are inside the source form
  if(dt_masks_point_in_form_exact(x, y, gpt->source, corner_count * 6, gpt->source_count))
  {
    *inside_source = TRUE;
    *inside = TRUE;

    float x_min = FLT_MAX, y_min = FLT_MAX;
    float x_max = FLT_MIN, y_max = FLT_MIN;

    for(int i = _nb_wctrl_points(corner_count); i < gpt->source_count; i++)
    {
      const float xx = gpt->source[i * 2];
      const float yy = gpt->source[i * 2 + 1];

      x_min = fminf(x_min, xx);
      x_max = fmaxf(x_max, xx);
      y_min = fminf(y_min, yy);
      y_max = fmaxf(y_max, yy);

      const float dd = sqf(xx - x) + sqf(yy - y);
      *dist = fminf(*dist, dd);
    }

    const float cx = x - (x_min + (x_max - x_min) / 2.0f);
    const float cy = y - (y_min + (y_max - y_min) / 2.0f);
    const float dd = sqf(cx) + sqf(cy);
    *dist = fminf(*dist, dd);

    return;
  }

  // we check if it's inside borders
  if(!dt_masks_point_in_form_near(x, y, gpt->border,
                                  _nb_wctrl_points(corner_count), gpt->border_count,
                                  as, near))
  {
    if(*near != -1)
    {
      *inside_border = TRUE;
    }
    else
      return;
  }
  else
    *inside_border = TRUE;

  *inside = TRUE;

  // and we check if it's inside form
  if(gpt->points_count > 2 + _nb_wctrl_points(corner_count))
  {
    const float as2 = sqf(as);
    int current_seg = 1;

    float x_min = FLT_MAX, y_min = FLT_MAX;
    float x_max = FLT_MIN, y_max = FLT_MIN;

    for(int i = _nb_wctrl_points(corner_count); i < gpt->points_count; i++)
    {
      //if we need to jump to skip points (in case of deleted point,
      //because of self-intersection)
      if(gpt->points[i * 2] == DT_INVALID_COORDINATE)
      {
        if(gpt->points[i * 2 + 1] == DT_INVALID_COORDINATE)
          break;
        i = (int)gpt->points[i * 2 + 1] - 1;
        continue;
      }
      // do we change of path segment ?
      if(gpt->points[i * 2 + 1] == gpt->points[current_seg * 6 + 3]
         && gpt->points[i * 2] == gpt->points[current_seg * 6 + 2])
      {
        current_seg = (current_seg + 1) % corner_count;
      }
      //distance from tested point to current form point
      const float xx = gpt->points[i * 2];
      const float yy = gpt->points[i * 2 + 1];

      x_min = fminf(x_min, xx);
      x_max = fmaxf(x_max, xx);
      y_min = fminf(y_min, yy);
      y_max = fmaxf(y_max, yy);

      const float dd = sqf(xx - x) + sqf(yy - y);
      *dist = fminf(*dist, dd);

      if(dd < as2)
      {
        if(current_seg == 0)
          *near = corner_count - 1;
        else
          *near = current_seg - 1;
      }
    }

    const float cx = x - (x_min + (x_max - x_min) / 2.0f);
    const float cy = y - (y_min + (y_max - y_min) / 2.0f);
    const float dd = sqf(cx) + sqf(cy);
    *dist = fminf(*dist, dd);
  }
}

static int _path_get_points_border(dt_develop_t *dev,
                                   dt_masks_form_t *form,
                                   float **points,
                                   int *points_count,
                                   float **border,
                                   int *border_count,
                                   const int source,
                                   const dt_iop_module_t *module)
{
  if(source && !module) return 0;
  const double ioporder = (module) ? module->iop_order : 0.0f;
  return _path_get_pts_border(dev, form, ioporder,
                              DT_DEV_TRANSFORM_DIR_ALL, dev->preview_pipe, points,
                              points_count, border, border_count, source);
}

static int _path_events_mouse_scrolled(dt_iop_module_t *module,
                                       const float pzx,
                                       const float pzy,
                                       const int up,
                                       const uint32_t state,
                                       dt_masks_form_t *form,
                                       const dt_mask_id_t parentid,
                                       dt_masks_form_gui_t *gui,
                                       const int index)
{
  // resize a shape even if on a node or segment
  if(gui->form_selected
     || gui->point_selected >= 0
     || gui->feather_selected >= 0  // bezier control points
     || gui->seg_selected >= 0
     || gui->point_border_selected >= 0)
  {
    // we register the current position
    if(gui->scrollx == 0.0f && gui->scrolly == 0.0f)
    {
      gui->scrollx = pzx;
      gui->scrolly = pzy;
    }
    if(dt_modifier_is(state, GDK_CONTROL_MASK))
    {
      // we try to change the opacity
      dt_masks_form_change_opacity(form, parentid, up ? 0.05f : -0.05f);
    }
    else
    {
      // resize don't care where the mouse is inside a shape
      if(dt_modifier_is(state, GDK_SHIFT_MASK))
      {
        float feather_size = 0.0f;

        // do not exceed upper limit of 1.0
        for(const GList *l = form->points; l; l = g_list_next(l))
        {
          const dt_masks_point_path_t *point = l->data;
          if(up
             && (point->border[0] > 1.0f
                 || point->border[1] > 1.0f))
            return 1;
        }
        for(const GList *l = form->points; l; l = g_list_next(l))
        {
          dt_masks_point_path_t *point = l->data;

          point->border[0] = dt_masks_change_size
            (up,
             point->border[0],
             0.0005f,
             0.5f);
          point->border[1] = dt_masks_change_size
            (up,
             point->border[1],
             0.0005f,
             0.5f);

          feather_size += point->border[0] + point->border[1];
        }

        const float masks_border = dt_masks_change_size
          (up,
           dt_conf_get_float(DT_MASKS_CONF(form->type, path, border)),
           0.0005f,
           0.5f);

        dt_conf_set_float(DT_MASKS_CONF(form->type, path, border), masks_border);
        dt_toast_log(_("feather size: %3.2f%%"),
                     feather_size * 50.0f / g_list_length(form->points));
      }
      else if(gui->edit_mode == DT_MASKS_EDIT_FULL)
      {
        // get the center of gravity of the form (like if it was a simple polygon)
        float bx = 0.0f;
        float by = 0.0f;
        float surf = 0.0f;

        for(const GList *form_points = form->points;
            form_points;
            form_points = g_list_next(form_points))
        {
          const GList *next =
            g_list_next_wraparound(form_points, form->points); // next w/ wrap
          dt_masks_point_path_t *point1 = form_points->data; // kth element of form->points
          dt_masks_point_path_t *point2 = next->data;

          surf += point1->corner[0] * point2->corner[1]
            - point2->corner[0] * point1->corner[1];

          bx += (point1->corner[0] + point2->corner[0])
                * (point1->corner[0] * point2->corner[1]
                   - point2->corner[0] * point1->corner[1]);
          by += (point1->corner[1] + point2->corner[1])
                * (point1->corner[0] * point2->corner[1]
                   - point2->corner[0] * point1->corner[1]);
        }
        bx /= 3.0f * surf;
        by /= 3.0f * surf;

        surf = sqrtf(fabsf(surf));
        if(!up && surf < 0.001f) return 1;
        if(up && surf > 2.0f) return 1;

        // now we move each point
        for(GList *l = form->points; l; l = g_list_next(l))
        {
          dt_masks_point_path_t *point = l->data;
          const float x = dt_masks_change_size(up, point->corner[0] - bx, -FLT_MAX, FLT_MAX);
          const float y = dt_masks_change_size(up, point->corner[1] - by, -FLT_MAX, FLT_MAX);

          // we stretch ctrl points
          const float ct1x = dt_masks_change_size
            (up, point->ctrl1[0] - point->corner[0], -FLT_MAX, FLT_MAX);
          const float ct1y = dt_masks_change_size
            (up, point->ctrl1[1] - point->corner[1], -FLT_MAX, FLT_MAX);
          const float ct2x = dt_masks_change_size
            (up, point->ctrl2[0] - point->corner[0], -FLT_MAX, FLT_MAX);
          const float ct2y = dt_masks_change_size
            (up, point->ctrl2[1] - point->corner[1], -FLT_MAX, FLT_MAX);

          // and we set the new points
          point->corner[0] = bx + x;
          point->corner[1] = by + y;
          point->ctrl1[0] = point->corner[0] + ct1x;
          point->ctrl1[1] = point->corner[1] + ct1y;
          point->ctrl2[0] = point->corner[0] + ct2x;
          point->ctrl2[1] = point->corner[1] + ct2y;
        }

        // now the redraw/save stuff
        _path_init_ctrl_points(form);

        surf = dt_masks_change_size(up, surf, -FLT_MAX, FLT_MAX);
        dt_toast_log(_("size: %3.2f%%"), surf * 50.0f);
      }
      else
      {
        return 0;
      }

      dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

      // we recreate the form points
      dt_masks_gui_form_create(form, gui, index, module);
    }
    return 1;
  }
  return 0;
}

static int _path_events_button_pressed(dt_iop_module_t *module,
                                       const float pzx,
                                       const float pzy,
                                       const double pressure,
                                       const int which,
                                       const int type,
                                       const uint32_t state,
                                       dt_masks_form_t *form,
                                       const dt_mask_id_t parentid,
                                       dt_masks_form_gui_t *gui,
                                       const int index)
{
  if(type == GDK_2BUTTON_PRESS
     || type == GDK_3BUTTON_PRESS)
    return 1;

  if(!gui) return 0;

  dt_masks_form_gui_points_t *gpt = g_list_nth_data(gui->points, index);
  if(!gpt) return 0;

  float wd, ht, iwidth, iheight;
  dt_masks_get_image_size(&wd, &ht, &iwidth, &iheight);

  const float masks_border =
    MIN(dt_conf_get_float(DT_MASKS_CONF(form->type, path, border)), 0.5f);

  if(gui->creation
     && which == GDK_BUTTON_PRIMARY
     && form->points == NULL
     && (dt_modifier_is(state, GDK_CONTROL_MASK | GDK_SHIFT_MASK)
         || dt_modifier_is(state, GDK_SHIFT_MASK)))
  {
    // set some absolute or relative position for the source of the clone mask
    if(form->type & DT_MASKS_CLONE)
      dt_masks_set_source_pos_initial_state(gui, state, pzx, pzy);

    return 1;
  }
  else if(gui->creation
          && (which == GDK_BUTTON_SECONDARY || gui->creation_closing_form))
  {
    // we don't want a form with less than 3 points
    if(g_list_shorter_than(form->points, 4))
    {
      // we don't really have a way to know if the user wants to
      // cancel the continuous add here or just cancelling this mask,
      // let's assume that this is not a mistake and cancel the
      // continuous add
      gui->creation_continuous = FALSE;
      gui->creation_continuous_module = NULL;
      dt_masks_set_edit_mode(module, DT_MASKS_EDIT_FULL);
      dt_masks_iop_update(module);
      dt_control_queue_redraw_center();
      return 1;
    }
    else
    {
      // we delete last point (the one we are currently dragging)
      dt_masks_point_path_t *point = g_list_last(form->points)->data;
      form->points = g_list_remove(form->points, point);
      free(point);
      point = NULL;

      gui->point_dragging = -1;

      _path_init_ctrl_points(form);

      dt_masks_gui_form_create(form, gui, index, module);

      // we save the form and quit creation mode
      dt_iop_module_t *crea_module = gui->creation_module;
      dt_masks_gui_form_save_creation(darktable.develop, crea_module, form, gui);

      if(crea_module)
      {
        dt_dev_add_history_item(darktable.develop, crea_module, TRUE);
        // and we switch in edit mode to show all the forms
        // spots and retouch have their own handling of creation_continuous
        if(gui->creation_continuous
           && (dt_iop_module_is(crea_module->so, "spots")
               || dt_iop_module_is(crea_module->so, "retouch")))
          dt_masks_set_edit_mode_single_form(crea_module, form->formid, DT_MASKS_EDIT_FULL);
        else if(!gui->creation_continuous)
          dt_masks_set_edit_mode(crea_module, DT_MASKS_EDIT_FULL);
        dt_masks_iop_update(crea_module);
      }

      dt_dev_masks_selection_change(darktable.develop, crea_module, form->formid);
      gui->creation_module = NULL;

      if(gui->creation_continuous)
      {
        //spot and retouch manage creation_continuous in their own way
        if(crea_module
           && !dt_iop_module_is(crea_module->so, "spots")
           && !dt_iop_module_is(crea_module->so, "retouch"))
        {
          dt_iop_gui_blend_data_t *bd = crea_module->blend_data;
          for(int n = 0; n < DEVELOP_MASKS_NB_SHAPES; n++)
            if(bd->masks_type[n] == form->type)
              gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(bd->masks_shapes[n]), TRUE);

          gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(bd->masks_edit), FALSE);
          dt_masks_form_t *newform = dt_masks_create(form->type);
          dt_masks_change_form_gui(newform);
          darktable.develop->form_gui->creation = TRUE;
          darktable.develop->form_gui->creation_module = crea_module;
          darktable.develop->form_gui->creation_continuous = TRUE;
          darktable.develop->form_gui->creation_continuous_module = crea_module;
        }
        else
        {
          dt_masks_form_t *form_new = dt_masks_create(form->type);
          dt_masks_change_form_gui(form_new);
          darktable.develop->form_gui->creation_module = gui->creation_continuous_module;
        }
      }
      else if(form->type & (DT_MASKS_CLONE | DT_MASKS_NON_CLONE))
      {
        dt_masks_form_t *grp = darktable.develop->form_visible;
        if(!grp || !(grp->type & DT_MASKS_GROUP)) return 1;
        int pos3 = 0, pos2 = -1;
        for(GList *fs = grp->points; fs; fs = g_list_next(fs))
        {
          dt_masks_point_group_t *pt = fs->data;
          if(pt->formid == form->formid)
          {
            pos2 = pos3;
            break;
          }
          pos3++;
        }
        if(pos2 < 0) return 1;
        dt_masks_form_gui_t *gui2 = darktable.develop->form_gui;
        if(!gui2) return 1;
        gui2->group_selected = pos2;

        dt_masks_select_form(crea_module,
                             dt_masks_get_from_id(darktable.develop, form->formid));
      }

      dt_control_queue_redraw_center();
    }
  }
  else if(which == GDK_BUTTON_PRIMARY)
  {
    if(gui->creation)
    {
      dt_masks_point_path_t *bzpt = malloc(sizeof(dt_masks_point_path_t));
      int nb = g_list_length(form->points);
      // change the values
      float pts[2] = { pzx * wd, pzy * ht };
      dt_dev_distort_backtransform(darktable.develop, pts, 1);

      bzpt->corner[0] = pts[0] / iwidth;
      bzpt->corner[1] = pts[1] / iheight;
      bzpt->ctrl1[0] = bzpt->ctrl1[1] = bzpt->ctrl2[0] = bzpt->ctrl2[1] = -1.0;
      bzpt->state = DT_MASKS_POINT_STATE_NORMAL;

      bzpt->border[0] = bzpt->border[1] = MAX(0.0005f, masks_border);

      // if that's the first point we should had another one as base point
      if(nb == 0)
      {
        dt_masks_point_path_t *bzpt2 = malloc(sizeof(dt_masks_point_path_t));
        bzpt2->corner[0] = pts[0] / iwidth;
        bzpt2->corner[1] = pts[1] / iheight;
        bzpt2->ctrl1[0] = bzpt2->ctrl1[1] = bzpt2->ctrl2[0] = bzpt2->ctrl2[1] = -1.0;
        bzpt2->border[0] = bzpt2->border[1] = MAX(0.0005f, masks_border);
        bzpt2->state = DT_MASKS_POINT_STATE_NORMAL;
        form->points = g_list_append(form->points, bzpt2);

        if(form->type & DT_MASKS_CLONE)
        {
          dt_masks_set_source_pos_initial_value(gui, DT_MASKS_PATH, form, pzx, pzy);
        }
        else
        {
          // not used by regular masks
          form->source[0] = form->source[1] = 0.0f;
        }
        nb++;
      }
      form->points = g_list_append(form->points, bzpt);

      // if this is a ctrl click, the last created point is a sharp one
      if(dt_modifier_is(state, GDK_CONTROL_MASK))
      {
        dt_masks_point_path_t *bzpt3 = g_list_nth_data(form->points, nb - 1);
        bzpt3->ctrl1[0] = bzpt3->ctrl2[0] = bzpt3->corner[0];
        bzpt3->ctrl1[1] = bzpt3->ctrl2[1] = bzpt3->corner[1];
        bzpt3->state = DT_MASKS_POINT_STATE_USER;
      }

      gui->point_dragging = nb;

      _path_init_ctrl_points(form);

      // we recreate the form points
      dt_masks_gui_form_create(form, gui, index, module);

      dt_control_queue_redraw_center();
      return 1;
    }
    else if(gui->source_selected && gui->edit_mode == DT_MASKS_EDIT_FULL)
    {
      if(!gpt) return 0;
      // we start the form dragging
      gui->source_dragging = TRUE;
      gui->point_edited = -1;
      gui->dx = gpt->source[2] - gui->posx;
      gui->dy = gpt->source[3] - gui->posy;
      return 1;
    }
    else if(gui->form_selected && gui->edit_mode == DT_MASKS_EDIT_FULL)
    {
      gui->form_dragging = TRUE;
      gui->point_edited = -1;
      gui->dx = gpt->points[2] - gui->posx;
      gui->dy = gpt->points[3] - gui->posy;
      return 1;
    }
    else if(gui->point_selected >= 0)
    {
      // if ctrl is pressed, we change the type of point
      if(gui->point_edited == gui->point_selected
         && dt_modifier_is(state, GDK_CONTROL_MASK))
      {
        dt_masks_point_path_t *point
            = (dt_masks_point_path_t *)g_list_nth_data(form->points, gui->point_edited);
        if(point == NULL)
        {
          gui->point_selected = -1;
          return 1;
        }
        if(point->state != DT_MASKS_POINT_STATE_NORMAL)
        {
          point->state = DT_MASKS_POINT_STATE_NORMAL;
          _path_init_ctrl_points(form);
        }
        else
        {
          point->ctrl1[0] = point->ctrl2[0] = point->corner[0];
          point->ctrl1[1] = point->ctrl2[1] = point->corner[1];
          point->state = DT_MASKS_POINT_STATE_USER;
        }
        dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

        // we recreate the form points
        dt_masks_gui_form_create(form, gui, index, module);
        gpt->clockwise = _path_is_clockwise(form);
        return 1;
      }
      // we register the current position to avoid accidental move
      if(gui->point_edited < 0 && gui->scrollx == 0.0f && gui->scrolly == 0.0f)
      {
        gui->scrollx = pzx;
        gui->scrolly = pzy;
      }
      gui->point_edited = gui->point_dragging = gui->point_selected;
      gpt->clockwise = _path_is_clockwise(form);
      dt_control_queue_redraw_center();
      return 1;
    }
    else if(gui->feather_selected >= 0)  // Bézier control point
    {
      gui->feather_dragging = gui->feather_selected;

      gui->bezier_mode = DT_MASKS_BEZIER_NONE;
      if(dt_modifier_is(state, GDK_SHIFT_MASK))
        gui->bezier_mode = DT_MASKS_BEZIER_SINGLE;
      else if(dt_modifier_is(state, GDK_CONTROL_MASK))
        gui->bezier_mode = DT_MASKS_BEZIER_SYMMETRIC;
      else if(dt_modifier_is(state, GDK_CONTROL_MASK | GDK_SHIFT_MASK))
        gui->bezier_mode = DT_MASKS_BEZIER_SING_SYMM;

      dt_masks_point_path_t *point
          = (dt_masks_point_path_t *)g_list_nth_data(form->points, gui->feather_selected);
      gui->bezier_ctrl_angle = _get_ctrl_angle(point->corner[0], point->corner[1],
                                             point->ctrl1[0], point->ctrl1[1],
                                             point->ctrl2[0], point->ctrl2[1],
                                             iwidth/iheight);
      gui->bezier_ctrl_scale = _get_ctrl_scale(point->corner[0], point->corner[1],
                                             point->ctrl1[0], point->ctrl1[1],
                                             point->ctrl2[0], point->ctrl2[1],
                                             iwidth/iheight);

      dt_control_queue_redraw_center();
      return 1;
    }
    else if(gui->point_border_selected >= 0)
    {
      gui->point_edited = -1;
      gui->point_border_dragging = gui->point_border_selected;
      dt_control_queue_redraw_center();
      return 1;
    }
    else if(gui->seg_selected >= 0)
    {
      gui->point_edited = -1;
      if(dt_modifier_is(state, GDK_CONTROL_MASK))
      {
        // we add a new point to the path
        dt_masks_point_path_t *bzpt = malloc(sizeof(dt_masks_point_path_t));
        // change the values
        float pts[2] = { pzx * wd, pzy * ht };
        dt_dev_distort_backtransform(darktable.develop, pts, 1);

        bzpt->corner[0] = pts[0] / iwidth;
        bzpt->corner[1] = pts[1] / iheight;
        bzpt->ctrl1[0] = bzpt->ctrl1[1] = bzpt->ctrl2[0] = bzpt->ctrl2[1] = -1.0;
        bzpt->state = DT_MASKS_POINT_STATE_NORMAL;

        // interpolate the border width of the two neighbour points'
        const GList* first = g_list_nth(form->points, gui->seg_selected);
        // next, wrapping around if on last element
        const GList* second = g_list_next_wraparound(first, form->points);
        dt_masks_point_path_t *left = first->data;
        dt_masks_point_path_t *right = second->data;
        bzpt->border[0] = MAX(0.0005f, (left->border[0] + right->border[0]) * 0.5);
        bzpt->border[1] = MAX(0.0005f, (left->border[1] + right->border[1]) * 0.5);

        form->points = g_list_insert(form->points, bzpt, gui->seg_selected + 1);
        _path_init_ctrl_points(form);
        dt_masks_gui_form_create(form, gui, index, module);
        gui->point_edited = gui->point_dragging =
          gui->point_selected = gui->seg_selected + 1;
        gui->seg_selected = -1;
        dt_control_queue_redraw_center();
      }
      else
      {
        // we move the entire segment
        gui->seg_dragging = gui->seg_selected;
        gui->dx = gpt->points[gui->seg_selected * 6 + 2] - gui->posx;
        gui->dy = gpt->points[gui->seg_selected * 6 + 3] - gui->posy;
      }
      return 1;
    }
    gui->point_edited = -1;
  }
  else if(which == GDK_BUTTON_SECONDARY && gui->point_selected >= 0)
  {
    // we remove the point (and the entire form if there is too few points)
    if(g_list_shorter_than(form->points, 4))
    {
      // if the form doesn't belong to a group, we don't delete it
      if(!dt_is_valid_maskid(parentid)) return 1;

      // we hide the form
      if(!(darktable.develop->form_visible->type & DT_MASKS_GROUP))
        dt_masks_change_form_gui(NULL);
      else if(g_list_shorter_than(darktable.develop->form_visible->points, 2))
        dt_masks_change_form_gui(NULL);
      else
      {
        const int emode = gui->edit_mode;
        dt_masks_clear_form_gui(darktable.develop);
        for(GList *forms = darktable.develop->form_visible->points;
            forms;
            forms = g_list_next(forms))
        {
          dt_masks_point_group_t *guipt = forms->data;
          if(guipt->formid == form->formid)
          {
            darktable.develop->form_visible->points
                = g_list_remove(darktable.develop->form_visible->points, guipt);
            free(guipt);
            break;
          }
        }
        gui->edit_mode = emode;
      }

      // we delete or remove the shape
      dt_masks_form_remove(module, NULL, form);
      dt_control_queue_redraw_center();
      return 1;
    }
    dt_masks_point_path_t *point
        = (dt_masks_point_path_t *)g_list_nth_data(form->points, gui->point_selected);
    if(point == NULL)
    {
      gui->point_selected = -1;
      return 1;
    }
    form->points = g_list_remove(form->points, point);
    free(point);
    gui->point_selected = -1;
    _path_init_ctrl_points(form);

    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);
    gpt->clockwise = _path_is_clockwise(form);

    return 1;
  }
  else if(which == GDK_BUTTON_SECONDARY && gui->feather_selected >= 0)  // right-click to reset Bézier controls
  {
    dt_masks_point_path_t *point
        = (dt_masks_point_path_t *)g_list_nth_data(form->points, gui->feather_selected);
    if(point != NULL
       && point->state != DT_MASKS_POINT_STATE_NORMAL)
    {
      point->state = DT_MASKS_POINT_STATE_NORMAL;
      _path_init_ctrl_points(form);

      dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

      // we recreate the form points
      dt_masks_gui_form_create(form, gui, index, module);
      gpt->clockwise = _path_is_clockwise(form);
    }
    return 1;
  }
  else if(which == GDK_BUTTON_SECONDARY
          && dt_is_valid_maskid(parentid)
          && gui->edit_mode == DT_MASKS_EDIT_FULL)
  {
    // we hide the form
    if(!(darktable.develop->form_visible->type & DT_MASKS_GROUP))
      dt_masks_change_form_gui(NULL);
    else if(g_list_shorter_than(darktable.develop->form_visible->points, 2))
      dt_masks_change_form_gui(NULL);
    else
    {
      dt_masks_clear_form_gui(darktable.develop);
      for(GList *forms = darktable.develop->form_visible->points;
          forms;
          forms = g_list_next(forms))
      {
        dt_masks_point_group_t *guipt = forms->data;
        if(guipt->formid == form->formid)
        {
          darktable.develop->form_visible->points
              = g_list_remove(darktable.develop->form_visible->points, guipt);
          free(guipt);
          break;
        }
      }
      gui->edit_mode = DT_MASKS_EDIT_FULL;
    }

    // we remove the shape
    dt_dev_masks_list_remove(darktable.develop, form->formid, parentid);
    dt_masks_form_remove(module, dt_masks_get_from_id(darktable.develop, parentid), form);
    return 1;
  }

  return 0;
}

static int _path_events_button_released(dt_iop_module_t *module,
                                        const float pzx,
                                        const float pzy,
                                        const int which,
                                        const uint32_t state,
                                        dt_masks_form_t *form,
                                        const dt_mask_id_t parentid,
                                        dt_masks_form_gui_t *gui,
                                        const int index)
{
  if(!gui) return 0;
  if(gui->creation) return 1;

  dt_masks_form_gui_points_t *gpt = g_list_nth_data(gui->points, index);
  if(!gpt) return 0;

  float wd, ht; // Backbuffer width and height
  float iwidth, iheight; // Image width and height
  dt_masks_get_image_size(&wd, &ht, &iwidth, &iheight);

  if(gui->form_dragging)
  {
    // we end the form dragging
    gui->form_dragging = FALSE;

    // we get point0 new values
    dt_masks_point_path_t *point = form->points->data;
    float pts[2] = { pzx * wd + gui->dx, pzy * ht + gui->dy };
    dt_dev_distort_backtransform(darktable.develop, pts, 1);
    const float dx = pts[0] / iwidth - point->corner[0];
    const float dy = pts[1] / iheight - point->corner[1];

    // we move all points
    for(GList *points = form->points; points; points = g_list_next(points))
    {
      point = (dt_masks_point_path_t *)points->data;
      point->corner[0] += dx;
      point->corner[1] += dy;
      point->ctrl1[0] += dx;
      point->ctrl1[1] += dy;
      point->ctrl2[0] += dx;
      point->ctrl2[1] += dy;
    }

    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);

    return 1;
  }
  else if(gui->source_dragging)
  {
    // we end the form dragging
    gui->source_dragging = FALSE;

    // we change the source value
    float pts[2] = { pzx * wd + gui->dx, pzy * ht + gui->dy };
    dt_dev_distort_backtransform(darktable.develop, pts, 1);
    form->source[0] = pts[0] / iwidth;
    form->source[1] = pts[1] / iheight;
    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);

    return 1;
  }
  else if(gui->seg_dragging >= 0)
  {
    gui->seg_dragging = -1;
    gpt->clockwise = _path_is_clockwise(form);
    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);
    return 1;
  }
  else if(gui->point_dragging >= 0)
  {
    dt_masks_point_path_t *point
        = (dt_masks_point_path_t *)g_list_nth_data(form->points, gui->point_dragging);
    gui->point_dragging = -1;
    if(gui->scrollx != 0.0f || gui->scrolly != 0.0f)
    {
      gui->scrollx = gui->scrolly = 0;
      return 1;
    }
    gui->scrollx = gui->scrolly = 0;
    float pts[2] = { pzx * wd, pzy * ht };
    dt_dev_distort_backtransform(darktable.develop, pts, 1);
    const float dx = pts[0] / iwidth - point->corner[0];
    const float dy = pts[1] / iheight - point->corner[1];

    point->corner[0] += dx;
    point->corner[1] += dy;
    point->ctrl1[0] += dx;
    point->ctrl1[1] += dy;
    point->ctrl2[0] += dx;
    point->ctrl2[1] += dy;

    _path_init_ctrl_points(form);

    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);
    gpt->clockwise = _path_is_clockwise(form);

    return 1;
  }
  else if(gui->feather_dragging >= 0)  // Bézier control point
  {
    dt_masks_point_path_t *point
        = (dt_masks_point_path_t *)g_list_nth_data(form->points, gui->feather_dragging);
    gui->feather_dragging = -1;
    float pts[2] = { pzx * wd, pzy * ht };
    dt_dev_distort_backtransform(darktable.develop, pts, 1);

    _update_bezier_ctrl_points(point, pts[0] / iwidth, pts[1] / iheight,
                               gui->bezier_ctrl, gui->bezier_mode,
                               gui->bezier_ctrl_angle, gui->bezier_ctrl_scale, iwidth/iheight);
    gui->bezier_mode = DT_MASKS_BEZIER_NONE;
    point->state = DT_MASKS_POINT_STATE_USER;

    _path_init_ctrl_points(form);

    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);
    gpt->clockwise = _path_is_clockwise(form);

    return 1;
  }
  else if(gui->point_border_dragging >= 0)
  {
    gui->point_border_dragging = -1;

    // we save the move
    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);
    return 1;
  }

  return 0;
}

static int _path_events_mouse_moved(dt_iop_module_t *module,
                                    float pzx,
                                    float pzy,
                                    const double pressure,
                                    const int which,
                                    const float zoom_scale,
                                    dt_masks_form_t *form,
                                    const dt_mask_id_t parentid,
                                    dt_masks_form_gui_t *gui,
                                    const int index)
{
  // centre view will have zoom_scale * backbuf_width pixels, we want
  // the handle offset to scale with DPI:
  const float as = dt_masks_sensitive_dist(zoom_scale);

  if(!gui) return 0;
  dt_masks_form_gui_points_t *gpt = g_list_nth_data(gui->points, index);
  if(!gpt) return 0;

  float wd, ht, iwidth, iheight;
  dt_masks_get_image_size(&wd, &ht, &iwidth, &iheight);

  if(gui->point_dragging >= 0)
  {
    float pts[2] = { pzx * wd, pzy * ht };
    if(gui->creation && !g_list_shorter_than(form->points, 4))
    {
      // if we are near the first point, we have to say that the form should be closed
      if(pts[0] - gpt->points[2] < as
         && pts[0] - gpt->points[2] > -as
         && pts[1] - gpt->points[3] < as
         && pts[1] - gpt->points[3] > -as)
      {
        gui->creation_closing_form = TRUE;
      }
      else
      {
        gui->creation_closing_form = FALSE;
      }
    }

    dt_dev_distort_backtransform(darktable.develop, pts, 1);
    dt_masks_point_path_t *bzpt = g_list_nth_data(form->points, gui->point_dragging);
    pzx = pts[0] / iwidth;
    pzy = pts[1] / iheight;

    // if first point, adjust the source accordingly
    if((form->type & DT_MASKS_CLONE)
       && gui->point_dragging == 0)
    {
      form->source[0] += (pzx - bzpt->corner[0]);
      form->source[1] += (pzy - bzpt->corner[1]);
    }

    bzpt->ctrl1[0] += pzx - bzpt->corner[0];
    bzpt->ctrl2[0] += pzx - bzpt->corner[0];
    bzpt->ctrl1[1] += pzy - bzpt->corner[1];
    bzpt->ctrl2[1] += pzy - bzpt->corner[1];
    bzpt->corner[0] = pzx;
    bzpt->corner[1] = pzy;

    _path_init_ctrl_points(form);

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);
    dt_control_queue_redraw_center();
    return 1;
  }
  else if(gui->seg_dragging >= 0)
  {
    // we get point0 new values
    const GList *const pt = g_list_nth(form->points, gui->seg_dragging);
    const GList *const pt2 = g_list_next_wraparound(pt, form->points);
    dt_masks_point_path_t *point = pt->data;
    dt_masks_point_path_t *point2 = pt2->data;
    float pts[2] = { pzx * wd + gui->dx, pzy * ht + gui->dy };
    dt_dev_distort_backtransform(darktable.develop, pts, 1);
    const float dx = pts[0] / iwidth - point->corner[0];
    const float dy = pts[1] / iheight - point->corner[1];

    // if first or last segment, adjust the source accordingly as the source point
    // is at the end of the first segment and at the start of the last one.
    if((form->type & DT_MASKS_CLONE)
       && (gui->seg_dragging == 0
           || gui->seg_dragging == (g_list_length(form->points) - 1)))
    {
      form->source[0] += dx;
      form->source[1] += dy;
    }

    // we move all points
    point->corner[0] += dx;
    point->corner[1] += dy;
    point->ctrl1[0]  += dx;
    point->ctrl1[1]  += dy;
    point->ctrl2[0]  += dx;
    point->ctrl2[1]  += dy;

    point2->corner[0] += dx;
    point2->corner[1] += dy;
    point2->ctrl1[0]  += dx;
    point2->ctrl1[1]  += dy;
    point2->ctrl2[0]  += dx;
    point2->ctrl2[1]  += dy;

    _path_init_ctrl_points(form);

    dt_dev_add_masks_history_item(darktable.develop, module, TRUE);

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);

    dt_control_queue_redraw_center();
    return 1;
  }
  else if(gui->feather_dragging >= 0)
  {
    float pts[2] = { pzx * wd, pzy * ht };
    dt_dev_distort_backtransform(darktable.develop, pts, 1);
    dt_masks_point_path_t *point
        = (dt_masks_point_path_t *)g_list_nth_data(form->points, gui->feather_dragging);

    _update_bezier_ctrl_points(point, pts[0] / iwidth, pts[1] / iheight,
                               gui->bezier_ctrl, gui->bezier_mode,
                               gui->bezier_ctrl_angle, gui->bezier_ctrl_scale, iwidth/iheight);
    point->state = DT_MASKS_POINT_STATE_USER;

    _path_init_ctrl_points(form);
    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);
    dt_control_queue_redraw_center();
    return 1;
  }
  else if(gui->point_border_dragging >= 0)
  {
    const int k = gui->point_border_dragging;

    // now we want to know the position reflected on actual corner/border segment
    const float a = (gpt->border[k * 6 + 1] - gpt->points[k * 6 + 3])
                    / (float)(gpt->border[k * 6] - gpt->points[k * 6 + 2]);
    const float b = gpt->points[k * 6 + 3] - a * gpt->points[k * 6 + 2];

    float pts[2] = { (a * pzy * ht + pzx * wd - b * a) / (a * a + 1.0), a * pts[0] + b };

    dt_dev_distort_backtransform(darktable.develop, pts, 1);

    dt_masks_point_path_t *point = g_list_nth_data(form->points, k);
    const float nx = point->corner[0] * iwidth;
    const float ny = point->corner[1] * iheight;
    const float nr = sqrtf((pts[0] - nx) * (pts[0] - nx) + (pts[1] - ny) * (pts[1] - ny));
    const float bdr = nr / fminf(iwidth,
                                 iheight);

    point->border[0] = point->border[1] = bdr;

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);
    dt_control_queue_redraw_center();
    return 1;
  }
  else if(gui->form_dragging || gui->source_dragging)
  {
    float pts[2] = { pzx * wd + gui->dx, pzy * ht + gui->dy };
    dt_dev_distort_backtransform(darktable.develop, pts, 1);

    // we move all points
    if(gui->form_dragging)
    {
      dt_masks_point_path_t *point = form->points->data;
      const float dx = pts[0] / iwidth - point->corner[0];
      const float dy = pts[1] / iheight - point->corner[1];
      for(GList *points = form->points; points; points = g_list_next(points))
      {
        point = (dt_masks_point_path_t *)points->data;
        point->corner[0] += dx;
        point->corner[1] += dy;
        point->ctrl1[0] += dx;
        point->ctrl1[1] += dy;
        point->ctrl2[0] += dx;
        point->ctrl2[1] += dy;
      }
    }
    else
    {
      form->source[0] = pts[0] / iwidth;
      form->source[1] = pts[1] / iheight;
    }

    // we recreate the form points
    dt_masks_gui_form_create(form, gui, index, module);
    dt_control_queue_redraw_center();
    return 1;
  }

  gui->form_selected = FALSE;
  gui->border_selected = FALSE;
  gui->source_selected = FALSE;
  gui->feather_selected = -1;
  gui->point_selected = -1;
  gui->seg_selected = -1;
  gui->point_border_selected = -1;
  // are we near a point or feather ?
  const guint nb = g_list_length(form->points);

  pzx *= wd;
  pzy *= ht;

  if((gui->group_selected == index) && gui->point_edited >= 0)
  {
      const int k = gui->point_edited;
    // we only select feather if the point is not "sharp"
    if(gpt->points[k * 6 + 2] != gpt->points[k * 6 + 4]
       && gpt->points[k * 6 + 3] != gpt->points[k * 6 + 5])
    {
      if(pzx - gpt->points[k * 6] > -as
         && pzx - gpt->points[k * 6] < as
         && pzy - gpt->points[k * 6 + 1] > -as
         && pzy - gpt->points[k * 6 + 1] < as)
      {
        gui->feather_selected = k;
        gui->bezier_ctrl = DT_MASKS_PATH_CTRL1;
        dt_control_queue_redraw_center();
        return 1;
      }

      if(pzx - gpt->points[k * 6 + 4] > -as
         && pzx - gpt->points[k * 6 + 4] < as
         && pzy - gpt->points[k * 6 + 5] > -as
         && pzy - gpt->points[k * 6 + 5] < as)
      {
        gui->feather_selected = k;
        gui->bezier_ctrl = DT_MASKS_PATH_CTRL2;
        dt_control_queue_redraw_center();
        return 1;
      }
    }
    // corner ??
    if(pzx - gpt->points[k * 6 + 2] > -as
       && pzx - gpt->points[k * 6 + 2] < as
       && pzy - gpt->points[k * 6 + 3] > -as
       && pzy - gpt->points[k * 6 + 3] < as)
    {
      gui->point_selected = k;
      dt_control_queue_redraw_center();
      return 1;
    }
  }

  for(int k = 0; k < nb; k++)
  {
    // corner ??
    if(pzx - gpt->points[k * 6 + 2] > -as
       && pzx - gpt->points[k * 6 + 2] < as
       && pzy - gpt->points[k * 6 + 3] > -as
       && pzy - gpt->points[k * 6 + 3] < as)
    {
      gui->point_selected = k;
      dt_control_queue_redraw_center();
      return 1;
    }

    // border corner ??
    if(pzx - gpt->border[k * 6] > -as
       && pzx - gpt->border[k * 6] < as
       && pzy - gpt->border[k * 6 + 1] > -as
       && pzy - gpt->border[k * 6 + 1] < as)
    {
      gui->point_border_selected = k;
      dt_control_queue_redraw_center();
      return 1;
    }
  }

  // are we inside the form or the borders or near a segment ???
  gboolean in = FALSE, inb = FALSE, ins = FALSE;
  int near = 0;
  float dist = 0;
  _path_get_distance(pzx, pzy, as, gui, index, nb, &in, &inb, &near, &ins, &dist);
  gui->seg_selected = dist < sqf(as) ? near : -1;

  // no segment selected, set form or source selection
  if(near < 0)
  {
    if(ins)
    {
      gui->form_selected = TRUE;
      gui->source_selected = TRUE;
    }
    else if(inb)
    {
      gui->form_selected = TRUE;
      gui->border_selected = TRUE;
    }
    else if(in)
    {
      gui->form_selected = TRUE;
    }
  }
  dt_control_queue_redraw_center();
  if(!gui->form_selected && !gui->border_selected && gui->seg_selected < 0)
    return 0;
  if(gui->edit_mode != DT_MASKS_EDIT_FULL)
    return 0;
  return 1;
}

static void _path_events_post_expose(cairo_t *cr,
                                     const float zoom_scale,
                                     dt_masks_form_gui_t *gui,
                                     const int index,
                                     const int nb)
{
  if(!gui) return;
  dt_masks_form_gui_points_t *gpt = g_list_nth_data(gui->points, index);
  if(!gpt) return;

  // draw path
  if(gpt->points_count > _nb_wctrl_points(nb) + 6)
  {
    cairo_move_to(cr, gpt->points[nb * 6], gpt->points[nb * 6 + 1]);
    int seg = 1, seg2 = 0;
    for(int i = _nb_wctrl_points(nb); i < gpt->points_count; i++)
    {
      cairo_line_to(cr, gpt->points[i * 2], gpt->points[i * 2 + 1]);
      // we decide to highlight the form segment by segment
      if(gpt->points[i * 2 + 1] == gpt->points[seg * 6 + 3]
         && gpt->points[i * 2] == gpt->points[seg * 6 + 2])
      {
        // this is the end of the last segment, so we have to draw it

        dt_masks_line_stroke
          (cr, FALSE, FALSE,
           (gui->group_selected == index)
           && (gui->form_selected || gui->form_dragging || gui->seg_selected == seg2),
           zoom_scale);
        // and we update the segment number
        seg = (seg + 1) % nb;
        seg2++;
        cairo_move_to(cr, gpt->points[i * 2], gpt->points[i * 2 + 1]);
      }
    }
  }

  // draw corners
  if(gui->group_selected == index && gpt->points_count > _nb_wctrl_points(nb) + 6)
  {
    for(int k = 0; k < nb; k++)
      dt_masks_draw_anchor(cr,
                           k == gui->point_dragging
                           || k == gui->point_selected,
                           zoom_scale,
                           gpt->points[k * 6 + 2],
                           gpt->points[k * 6 + 3]);
  }

  // draw Bézier control points
  if((gui->group_selected == index) && gui->point_edited >= 0)
  {
    const int k = gui->point_edited;

    cairo_move_to(cr, gpt->points[k*6+2], gpt->points[k*6+3]);
    cairo_line_to(cr, gpt->points[k*6], gpt->points[k*6+1]);
    dt_masks_line_stroke(cr, TRUE, FALSE, FALSE, zoom_scale);
    dt_masks_draw_ctrl(cr, gpt->points[k*6], gpt->points[k*6+1], zoom_scale,
                       k == gui->feather_dragging || k == gui->feather_selected);


    cairo_move_to(cr, gpt->points[k*6+2], gpt->points[k*6+3]);
    cairo_line_to(cr, gpt->points[k*6+4], gpt->points[k*6+5]);
    dt_masks_line_stroke(cr, TRUE, FALSE, FALSE, zoom_scale);
    dt_masks_draw_ctrl(cr, gpt->points[k*6+4], gpt->points[k*6+5], zoom_scale,
                       k == gui->feather_dragging || k == gui->feather_selected);
  }

  // draw border and corners
  if((gui->show_all_feathers
      || gui->group_selected == index)
     && gpt->border_count > _nb_wctrl_points(nb) + 6)
  {
    int dep = 1;
    for(int i = _nb_wctrl_points(nb); i < gpt->border_count; i++)
    {
      if(gpt->border[i * 2] == DT_INVALID_COORDINATE)
      {
        if(gpt->border[i * 2 + 1] == DT_INVALID_COORDINATE) break;
        i = gpt->border[i * 2 + 1] - 1;
        continue;
      }
      if(dep)
      {
        cairo_move_to(cr, gpt->border[i * 2], gpt->border[i * 2 + 1]);
        dep = 0;
      }
      else
        cairo_line_to(cr, gpt->border[i * 2], gpt->border[i * 2 + 1]);
    }
    // we execute the drawing
    dt_masks_line_stroke(cr, TRUE, FALSE, gui->border_selected, zoom_scale);

    // we draw the path segment by segment
    for(int k = 0; k < nb; k++)
    {
      if(gui->point_border_selected == k)
      {
        // visually connect the selected border control point to the original point
        cairo_move_to(cr, gpt->points[k * 6 + 2], gpt->points[k * 6 + 3]);
        cairo_line_to(cr, gpt->border[k * 6],     gpt->border[k * 6 + 1]);
        dt_masks_line_stroke(cr, TRUE, FALSE, FALSE, zoom_scale);
      }

      // draw the border control point
      dt_masks_draw_anchor(cr,
                           gui->point_border_selected == k,
                           zoom_scale,
                           gpt->border[k * 6],
                           gpt->border[k * 6 + 1]);
    }
  }

  // draw a cross where the source will be created
  if(gui->creation
     && darktable.develop->form_visible
     && (darktable.develop->form_visible->type & DT_MASKS_CLONE))
  {
    const int k = nb - 1;
    if((k * 6 + 2) >= 0)
    {
      float x = 0.f, y = 0.f;
      dt_masks_calculate_source_pos_value(gui, DT_MASKS_PATH,
                                          gpt->points[2], gpt->points[3],
                                          gpt->points[k * 6 + 2], gpt->points[k * 6 + 3],
                                          &x, &y, TRUE);
      dt_masks_draw_clone_source_pos(cr, zoom_scale, x, y);
    }
    else
    {
      float x = 0.0f, y = 0.0f;
      dt_masks_calculate_source_pos_value(gui, DT_MASKS_PATH,
                                          gui->posx, gui->posy,
                                          gui->posx, gui->posy,
                                          &x, &y, FALSE);
      dt_masks_draw_clone_source_pos(cr, zoom_scale, x, y);
    }
  }

  // draw the source if needed
  if(!gui->creation && gpt->source_count > _nb_wctrl_points(nb) + 6)
  {
    // look for the destination point closest to the source to avoid
    // the arrow to cross the mask.
    float to_x = 0.0f;
    float to_y = 0.0f;
    float from_x = 0.0f;
    float from_y = 0.0f;

    int width = 0;
    int height = 0;
    int posx = 0;
    int posy = 0;

    // 1. find source path bounding box
    _path_bounding_box(gpt->source, NULL, nb,
                       gpt->source_count, 0,
                       &width, &height, &posx, &posy);

    // 2. source area center
    const float center_x = (float)posx + (float)width / 2.f;
    const float center_y = (float)posy + (float)height / 2.f;

    // 3. dest border, closest to source area center
    dt_masks_closest_point(gpt->points_count,
                           _nb_wctrl_points(nb),
                           gpt->points,
                           center_x, center_y,
                           &to_x, &to_y);

    // 4. source border, closest to point border
    dt_masks_closest_point(gpt->source_count,
                           _nb_wctrl_points(nb),
                           gpt->source,
                           to_x, to_y,
                           &from_x, &from_y);

    // 5. we draw the line between source and dest
    dt_masks_draw_arrow(cr,
                        from_x, from_y,
                        to_x, to_y,
                        zoom_scale,
                        FALSE);

    dt_masks_stroke_arrow(cr, gui, index, zoom_scale);

    // we draw the source
    cairo_move_to(cr, gpt->source[nb * 6], gpt->source[nb * 6 + 1]);

    for(int i = _nb_wctrl_points(nb); i < gpt->source_count; i++)
      cairo_line_to(cr, gpt->source[i * 2], gpt->source[i * 2 + 1]);

    cairo_line_to(cr, gpt->source[nb * 6], gpt->source[nb * 6 + 1]);

    dt_masks_line_stroke
      (cr, FALSE, TRUE,
       (gui->group_selected == index) && (gui->form_selected || gui->form_dragging),
       zoom_scale);
  }
}

static void _path_bounding_box_raw(const float *const points,
                                   const float *border,
                                   const int nb_corner,
                                   const int num_points,
                                   const int num_borders,
                                   float *x_min,
                                   float *x_max,
                                   float *y_min,
                                   float *y_max)
{
  float xmin, xmax, ymin, ymax;
  xmin = ymin = FLT_MAX;
  xmax = ymax = FLT_MIN;

  for(int i = _nb_wctrl_points(nb_corner); i < num_borders; i++)
  {
    // we look at the borders
    const float xx = border[i * 2];
    const float yy = border[i * 2 + 1];
    if(xx == DT_INVALID_COORDINATE)
    {
     if(yy == DT_INVALID_COORDINATE) break; // that means we have to skip the end of the border path
      i = yy - 1;
      continue;
    }
    xmin = MIN(xx, xmin);
    xmax = MAX(xx, xmax);
    ymin = MIN(yy, ymin);
    ymax = MAX(yy, ymax);
  }
  for(int i = _nb_wctrl_points(nb_corner); i < num_points; i++)
  {
    // we look at the path too
    const float xx = points[i * 2];
    const float yy = points[i * 2 + 1];
    xmin = MIN(xx, xmin);
    xmax = MAX(xx, xmax);
    ymin = MIN(yy, ymin);
    ymax = MAX(yy, ymax);
  }

  *x_min = xmin;
  *x_max = xmax;
  *y_min = ymin;
  *y_max = ymax;
}

static void _path_bounding_box(const float *const points,
                               const float *border,
                               const int nb_corner,
                               const int num_points,
                               const int num_borders,
                               int *width,
                               int *height,
                               int *posx,
                               int *posy)
{
  // now we want to find the area, so we search min/max points
  float xmin, xmax, ymin, ymax;
  _path_bounding_box_raw(points, border, nb_corner, num_points,
                         num_borders, &xmin, &xmax, &ymin, &ymax);
  *height = ymax - ymin + 4;
  *width = xmax - xmin + 4;
  *posx = xmin - 2;
  *posy = ymin - 2;
}

static int _get_area(const dt_iop_module_t *const module,
                     const dt_dev_pixelpipe_iop_t *const piece,
                     dt_masks_form_t *const form,
                     int *width,
                     int *height,
                     int *posx,
                     int *posy,
                     const gboolean get_source)
{
  if(!module) return 0;

  // we get buffers for all points
  float *points = NULL, *border = NULL;
  int points_count = 0, border_count = 0;

  if(!_path_get_pts_border(module->dev, form, module->iop_order,
                           DT_DEV_TRANSFORM_DIR_BACK_INCL, piece->pipe,
                           &points, &points_count,
                           &border, &border_count, get_source))
  {
    dt_free_align(points);
    dt_free_align(border);
    return 0;
  }

  const guint nb_corner = g_list_length(form->points);
  _path_bounding_box(points, border, nb_corner, points_count, border_count,
                     width, height, posx, posy);

  dt_free_align(points);
  dt_free_align(border);
  return 1;
}

static int _path_get_source_area(dt_iop_module_t *module,
                                 dt_dev_pixelpipe_iop_t *piece,
                                 dt_masks_form_t *form,
                                 int *width,
                                 int *height,
                                 int *posx,
                                 int *posy)
{
  return _get_area(module, piece, form, width, height, posx, posy, TRUE);
}

static int _path_get_area(const dt_iop_module_t *const module,
                          const dt_dev_pixelpipe_iop_t *const piece,
                          dt_masks_form_t *const form,
                          int *width,
                          int *height,
                          int *posx,
                          int *posy)
{
  return _get_area(module, piece, form, width, height, posx, posy, FALSE);
}

/** we write a falloff segment */
static void _path_falloff(float *const restrict buffer,
                          int *p0,
                          int *p1,
                          const int posx,
                          const int posy,
                          const int bw)
{
  // segment length
  int l = sqrtf(sqf(p1[0] - p0[0]) + sqf(p1[1] - p0[1])) + 1;

  const float lx = p1[0] - p0[0];
  const float ly = p1[1] - p0[1];

  for(int i = 0; i < l; i++)
  {
    // position
    const int x = (int)((float)i * lx / (float)l) + p0[0] - posx;
    const int y = (int)((float)i * ly / (float)l) + p0[1] - posy;
    const float op = 1.0 - (float)i / (float)l;
    size_t idx = y * bw + x;
    buffer[idx] = fmaxf(buffer[idx], op);
    // this one is to avoid gap due to int rounding
    if(x > 0)
      buffer[idx - 1] = fmaxf(buffer[idx - 1], op);
    // this one is to avoid gap due to int rounding
    if(y > 0)
      buffer[idx - bw] = fmaxf(buffer[idx - bw], op);
  }
}

static int _path_get_mask(const dt_iop_module_t *const module,
                          const dt_dev_pixelpipe_iop_t *const piece,
                          dt_masks_form_t *const form,
                          float **buffer,
                          int *width,
                          int *height,
                          int *posx,
                          int *posy)
{
  if(!module) return 0;
  double start = dt_get_debug_wtime();
  double start2 = start;

  // we get buffers for all points
  float *points = NULL, *border = NULL;
  int points_count, border_count;
  if(!_path_get_pts_border(module->dev, form, module->iop_order,
                           DT_DEV_TRANSFORM_DIR_BACK_INCL, piece->pipe,
                           &points, &points_count,
                           &border, &border_count, FALSE))
  {
    dt_free_align(points);
    dt_free_align(border);
    return 0;
  }

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path points took %0.04f sec",
           form->name, dt_get_lap_time(&start));
  start2 = start;

  // now we want to find the area, so we search min/max points
  const guint nb_corner = g_list_length(form->points);
  _path_bounding_box(points, border, nb_corner, points_count, border_count,
                     width, height, posx, posy);

  const int hb = *height;
  const int wb = *width;

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_fill min max took %0.04f sec", form->name,
           dt_get_lap_time(&start2));

  // we allocate the buffer
  const size_t bufsize = (size_t)(*width) * (*height);
  // ensure that the buffer is zeroed, as the following code only
  // actually sets the path+falloff pixels
  float *const restrict bufptr = *buffer = dt_calloc_align_float(bufsize);
  if(*buffer == NULL)
  {
    dt_free_align(points);
    dt_free_align(border);
    return 0;
  }

  // we write all the point around the path into the buffer
  const int nbp = border_count;
  if(nbp > 2)
  {
    int lastx = (int)points[(nbp - 1) * 2];
    int lasty = (int)points[(nbp - 1) * 2 + 1];
    int lasty2 = (int)points[(nbp - 2) * 2 + 1];

    int just_change_dir = 0;
    for(int ii = _nb_wctrl_points(nb_corner);
        ii < 2 * nbp - _nb_wctrl_points(nb_corner);
        ii++)
    {
      // we are writing more than 1 loop in the case the dir in y change
      // exactly at start/end point
      int i = ii;
      if(ii >= nbp)
        i = (ii - _nb_wctrl_points(nb_corner))
          % (nbp - _nb_wctrl_points(nb_corner)) + _nb_wctrl_points(nb_corner);
      const int xx = (int)points[i * 2];
      const int yy = (int)points[i * 2 + 1];

      // we don't store the point if it has the same y value as the last one
      if(yy == lasty) continue;

      // we want to be sure that there is no y jump
      if(yy - lasty > 1 || yy - lasty < -1)
      {
        if(yy < lasty)
        {
          for(int j = yy + 1; j < lasty; j++)
          {
            const int nx = (j - yy) * (lastx - xx) / (float)(lasty - yy) + xx;
            const size_t idx = (size_t)(j - (*posy)) * (*width) + nx - (*posx);
            assert(idx < bufsize);
            bufptr[idx] = 1.0f;
          }
          lasty2 = yy + 2;
          lasty = yy + 1;
        }
        else
        {
          for(int j = lasty + 1; j < yy; j++)
          {
            const int nx = (j - lasty) * (xx - lastx) / (float)(yy - lasty) + lastx;
            const size_t idx = (size_t)(j - (*posy)) * (*width) + nx - (*posx);
            assert(idx < bufsize);
            bufptr[idx] = 1.0f;
          }
          lasty2 = yy - 2;
          lasty = yy - 1;
        }
      }
      // if we change the direction of the path (in y), then we add a extra point
      if((lasty - lasty2) * (lasty - yy) > 0)
      {
        const size_t idx = (size_t)(lasty - (*posy)) * (*width) + lastx + 1 - (*posx);
        assert(idx < bufsize);
        bufptr[idx] = 1.0f;
        just_change_dir = 1;
      }
      // we add the point
      if(just_change_dir && ii == i)
      {
        // if we have changed the direction, we have to be careful
        // that point can be at the same place as the previous one,
        // especially on sharp edges
        const size_t idx = (size_t)(yy - (*posy)) * (*width) + xx - (*posx);
        assert(idx < bufsize);
        float v = bufptr[idx];
        if(v > 0.0)
        {
          if(xx - (*posx) > 0)
          {
            const size_t idx_ = (size_t)(yy - (*posy)) * (*width) + xx - 1 - (*posx);
            assert(idx_ < bufsize);
            bufptr[idx_] = 1.0f;
          }
          else if(xx - (*posx) < (*width) - 1)
          {
            const size_t idx_ = (size_t)(yy - (*posy)) * (*width) + xx + 1 - (*posx);
            assert(idx_ < bufsize);
            bufptr[idx_] = 1.0f;
          }
        }
        else
        {
          const size_t idx_ = (size_t)(yy - (*posy)) * (*width) + xx - (*posx);
          assert(idx_ < bufsize);
          bufptr[idx_] = 1.0f;
          just_change_dir = 0;
        }
      }
      else
      {
        const size_t idx_ = (size_t)(yy - (*posy)) * (*width) + xx - (*posx);
        assert(idx_ < bufsize);
        bufptr[idx_] = 1.0f;
      }
      // we change last values
      lasty2 = lasty;
      lasty = yy;
      lastx = xx;
      if(ii != i) break;
    }
  }
  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_fill draw path took %0.04f sec", form->name,
           dt_get_lap_time(&start2));

  DT_OMP_FOR()
  for(int yy = 0; yy < hb; yy++)
  {
    int state = 0;
    for(int xx = 0; xx < wb; xx++)
    {
      const float v = bufptr[yy * wb + xx];
      if(v == 1.0f) state = !state;
      if(state) bufptr[yy * wb + xx] = 1.0f;
    }
  }

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_fill fill plain took %0.04f sec", form->name,
           dt_get_lap_time(&start2));

  // now we fill the falloff
  int p0[2] = { 0 }, p1[2] = { 0 };
  float pf1[2] = { 0.0f };
  int last0[2] = { -100, -100 }, last1[2] = { -100, -100 };
  int next = 0;
  for(int i = _nb_wctrl_points(nb_corner); i < border_count; i++)
  {
    p0[0] = points[i * 2];
    p0[1] = points[i * 2 + 1];
    if(next > 0)
      p1[0] = pf1[0] = border[next * 2], p1[1] = pf1[1] = border[next * 2 + 1];
    else
      p1[0] = pf1[0] = border[i * 2], p1[1] = pf1[1] = border[i * 2 + 1];

    // now we check p1 value to know if we have to skip a part
    if(next == i) next = 0;
    while(pf1[0] == DT_INVALID_COORDINATE)
    {
      if(pf1[1] == DT_INVALID_COORDINATE)
        next = i - 1;
      else
        next = p1[1];
      p1[0] = pf1[0] = border[next * 2];
      p1[1] = pf1[1] = border[next * 2 + 1];
    }

    // and we draw the falloff
    if(last0[0] != p0[0]
       || last0[1] != p0[1]
       || last1[0] != p1[0]
       || last1[1] != p1[1])
    {
      _path_falloff(bufptr, p0, p1, *posx, *posy, *width);
      last0[0] = p0[0];
      last0[1] = p0[1];
      last1[0] = p1[0];
      last1[1] = p1[1];
    }
  }

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_fill fill falloff took %0.04f sec", form->name,
           dt_get_lap_time(&start2));

  dt_free_align(points);
  dt_free_align(border);

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path fill buffer took %0.04f sec", form->name,
           dt_get_lap_time(&start));

  return 1;
}


/** crop path to roi given by xmin, xmax, ymin, ymax. path segments
    outside of roi are replaced by nodes lying on roi borders. */
static int _path_crop_to_roi(float *path,
                             const int point_count,
                             const float xmin,
                             const float xmax,
                             const float ymin,
                             const float ymax)
{
  int point_start = -1;
  int l = -1, r = -1;


  // first try to find a node clearly inside roi
  for(int k = 0; k < point_count; k++)
  {
    const float x = path[2 * k];
    const float y = path[2 * k + 1];

    if(x >= xmin + 1
       && y >= ymin + 1
       && x <= xmax - 1
       && y <= ymax - 1)
    {
      point_start = k;
      break;
    }
  }

  if(point_start < 0)
    return 0; // no point means roi lies completely within path

  // find the crossing points with xmin and replace segment by nodes
  // on border
  for(int k = 0; k < point_count; k++)
  {
    const int kk = (k + point_start) % point_count;

    if(l < 0 && path[2 * kk] < xmin) l = k;       // where we leave roi
    if(l >= 0 && path[2 * kk] >= xmin) r = k - 1; // where we re-enter roi

    // replace that segment
    if(l >= 0 && r >= 0)
    {
      const int count = r - l + 1;
      const int ll = (l - 1 + point_start) % point_count;
      const int rr = (r + 1 + point_start) % point_count;
      const float delta_y = (count == 1)
        ? 0
        : (path[2 * rr + 1] - path[2 * ll + 1]) / (count - 1);

      const float start_y = path[2 * ll + 1];

      for(int n = 0; n < count; n++)
      {
        const int nn = (n + l + point_start) % point_count;
        path[2 * nn] = xmin;
        path[2 * nn + 1] = start_y + n * delta_y;
      }

      l = r = -1;
    }
  }

  // find the crossing points with xmax and replace segment by nodes on border
  for(int k = 0; k < point_count; k++)
  {
    const int kk = (k + point_start) % point_count;

    if(l < 0 && path[2 * kk] > xmax) l = k;       // where we leave roi
    if(l >= 0 && path[2 * kk] <= xmax) r = k - 1; // where we re-enter roi

    // replace that segment
    if(l >= 0 && r >= 0)
    {
      const int count = r - l + 1;
      const int ll = (l - 1 + point_start) % point_count;
      const int rr = (r + 1 + point_start) % point_count;
      const float delta_y = (count == 1)
        ? 0
        : (path[2 * rr + 1] - path[2 * ll + 1]) / (count - 1);

      const float start_y = path[2 * ll + 1];

      for(int n = 0; n < count; n++)
      {
        const int nn = (n + l + point_start) % point_count;
        path[2 * nn] = xmax;
        path[2 * nn + 1] = start_y + n * delta_y;
      }

      l = r = -1;
    }
  }

  // find the crossing points with ymin and replace segment by nodes on border
  for(int k = 0; k < point_count; k++)
  {
    const int kk = (k + point_start) % point_count;

    if(l < 0 && path[2 * kk + 1] < ymin) l = k;       // where we leave roi
    if(l >= 0 && path[2 * kk + 1] >= ymin) r = k - 1; // where we re-enter roi

    // replace that segment
    if(l >= 0 && r >= 0)
    {
      const int count = r - l + 1;
      const int ll = (l - 1 + point_start) % point_count;
      const int rr = (r + 1 + point_start) % point_count;
      const float delta_x = (count == 1)
        ? 0
        : (path[2 * rr] - path[2 * ll]) / (count - 1);

      const float start_x = path[2 * ll];

      for(int n = 0; n < count; n++)
      {
        const int nn = (n + l + point_start) % point_count;
        path[2 * nn] = start_x + n * delta_x;
        path[2 * nn + 1] = ymin;
      }

      l = r = -1;
    }
  }

  // find the crossing points with ymax and replace segment by nodes on border
  for(int k = 0; k < point_count; k++)
  {
    const int kk = (k + point_start) % point_count;

    if(l < 0 && path[2 * kk + 1] > ymax) l = k;       // where we leave roi
    if(l >= 0 && path[2 * kk + 1] <= ymax) r = k - 1; // where we re-enter roi

    // replace that segment
    if(l >= 0 && r >= 0)
    {
      const int count = r - l + 1;
      const int ll = (l - 1 + point_start) % point_count;
      const int rr = (r + 1 + point_start) % point_count;
      const float delta_x = (count == 1)
        ? 0
        : (path[2 * rr] - path[2 * ll]) / (count - 1);

      const float start_x = path[2 * ll];

      for(int n = 0; n < count; n++)
      {
        const int nn = (n + l + point_start) % point_count;
        path[2 * nn] = start_x + n * delta_x;
        path[2 * nn + 1] = ymax;
      }

      l = r = -1;
    }
  }
  return 1;
}

/** we write a falloff segment respecting limits of buffer */
static void _path_falloff_roi(float *buffer,
                              int *p0,
                              int *p1,
                              const int bw,
                              const int bh)
{
  // segment length
  const int l = sqrt((p1[0] - p0[0]) * (p1[0] - p0[0])
                     + (p1[1] - p0[1]) * (p1[1] - p0[1])) + 1;

  const float lx = p1[0] - p0[0];
  const float ly = p1[1] - p0[1];

  const int dx = lx < 0 ? -1 : 1;
  const int dy = ly < 0 ? -1 : 1;
  const int dpy = dy * bw;

  for(int i = 0; i < l; i++)
  {
    // position
    const int x = (int)((float)i * lx / (float)l) + p0[0];
    const int y = (int)((float)i * ly / (float)l) + p0[1];
    const float op = 1.0f - (float)i / (float)l;
    float *buf = buffer + (size_t)y * bw + x;

    if(x >= 0 && x < bw && y >= 0 && y < bh)
      buf[0] = MAX(buf[0], op);
    if(x + dx >= 0 && x + dx < bw && y >= 0 && y < bh)
      buf[dx] = MAX(buf[dx], op); // this one is to avoid gap due to int rounding
    if(x >= 0 && x < bw && y + dy >= 0 && y + dy < bh)
      buf[dpy] = MAX(buf[dpy], op); // this one is to avoid gap due to int rounding
  }
}

// build a stamp which can be combined with other shapes in the same group
// prerequisite: 'buffer' is all zeros
static int _path_get_mask_roi(const dt_iop_module_t *const module,
                              const dt_dev_pixelpipe_iop_t *const piece,
                              dt_masks_form_t *const form,
                              const dt_iop_roi_t *roi,
                              float *buffer)
{
  if(!module) return 0;
  double start = dt_get_debug_wtime();
  double start2 = 0.0;

  const int px = roi->x;
  const int py = roi->y;
  const int width = roi->width;
  const int height = roi->height;
  const float scale = roi->scale;

  // we need to take care of four different cases:
  // 1) path and feather are outside of roi
  // 2) path is outside of roi, feather reaches into roi
  // 3) roi lies completely within path
  // 4) all other situations :)
  int path_in_roi = 0;
  int feather_in_roi = 0;
  int path_encircles_roi = 0;

  // we get buffers for all points
  float *points = NULL, *border = NULL;
  int points_count = 0, border_count = 0;
  if(!_path_get_pts_border(module->dev, form, module->iop_order,
                           DT_DEV_TRANSFORM_DIR_BACK_INCL, piece->pipe,
                           &points, &points_count,
                           &border, &border_count, FALSE) || (points_count <= 2))
  {
    dt_free_align(points);
    dt_free_align(border);
    return 0;
  }

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path points took %0.04f sec",
           form->name, dt_get_lap_time(&start));
  start2 = start;

  const guint nb_corner = g_list_length(form->points);

  // we shift and scale down path and border
  for(int i = _nb_wctrl_points(nb_corner); i < border_count; i++)
  {
    const float xx = border[2 * i];
    const float yy = border[2 * i + 1];
    if(xx == DT_INVALID_COORDINATE)
    {
      if(yy == DT_INVALID_COORDINATE) break; // that means we have to skip the end of the border path
      i = yy - 1;
      continue;
    }
    border[2 * i] = xx * scale - px;
    border[2 * i + 1] = yy * scale - py;
  }
  for(int i = _nb_wctrl_points(nb_corner); i < points_count; i++)
  {
    const float xx = points[2 * i];
    const float yy = points[2 * i + 1];
    points[2 * i] = xx * scale - px;
    points[2 * i + 1] = yy * scale - py;
  }

  // now check if path is at least partially within roi
  for(int i = _nb_wctrl_points(nb_corner); i < points_count; i++)
  {
    const int xx = points[i * 2];
    const int yy = points[i * 2 + 1];

    if(xx > 1 && yy > 1 && xx < width - 2 && yy < height - 2)
    {
      path_in_roi = 1;
      break;
    }
  }

  // if not this still might mean that path fully encircles roi -> we
  // need to check that
  if(!path_in_roi)
  {
    int nb = 0;
    int last = -9999;
    const int x = width / 2;
    const int y = height / 2;

    for(int i = _nb_wctrl_points(nb_corner); i < points_count; i++)
    {
      const int yy = (int)points[2 * i + 1];
      if(yy != last && yy == y)
      {
        if(points[2 * i] > x) nb++;
      }
      last = yy;
    }
    // if there is an uneven number of intersection points roi lies
    // within path
    if(nb & 1)
    {
      path_in_roi = 1;
      path_encircles_roi = 1;
    }
  }

  // now check if feather is at least partially within roi
  for(int i = _nb_wctrl_points(nb_corner); i < border_count; i++)
  {
    const float xx = border[i * 2];
    const float yy = border[i * 2 + 1];
    if(xx == DT_INVALID_COORDINATE)
    {
      if(yy == DT_INVALID_COORDINATE) break; // that means we have to skip the end of the border path
      i = yy - 1;
      continue;
    }
    if(xx > 1 && yy > 1 && xx < width - 2 && yy < height - 2)
    {
      feather_in_roi = 1;
      break;
    }
  }

  // if path and feather completely lie outside of roi -> we're
  // done/mask remains empty
  if(!path_in_roi && !feather_in_roi)
  {
    dt_free_align(points);
    dt_free_align(border);
    return 1;
  }

  // now get min/max values
  float xmin, xmax, ymin, ymax;
  _path_bounding_box_raw(points, border, nb_corner, points_count, border_count,
                         &xmin, &xmax, &ymin, &ymax);

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_fill min max took %0.04f sec", form->name,
           dt_get_lap_time(&start2));

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path_fill clear mask took %0.04f sec", form->name,
           dt_get_lap_time(&start2));

  // deal with path if it does not lie outside of roi
  if(path_in_roi)
  {
    // second copy of path which we can modify when cropping to roi
    float *cpoints = dt_alloc_align_float((size_t)2 * points_count);
    if(cpoints == NULL)
    {
      dt_free_align(points);
      dt_free_align(border);
      return 0;
    }
    memcpy(cpoints, points, sizeof(float) * 2 * points_count);

    // now we clip cpoints to roi -> catch special case when roi lies
    // completely within path.  dirty trick: we allow path to extend
    // one pixel beyond height-1. this avoids need of special handling
    // of the last roi line in the following edge-flag polygon fill
    // algorithm.
    const int crop_success = _path_crop_to_roi(cpoints + 2 * _nb_wctrl_points(nb_corner),
                                               points_count - _nb_wctrl_points(nb_corner),
                                               0,
                                               width - 1,
                                               0,
                                               height);
    path_encircles_roi = path_encircles_roi || !crop_success;

    dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
             "[masks %s] path_fill crop to roi took %0.04f sec", form->name,
             dt_get_lap_time(&start2));

    if(path_encircles_roi)
    {
      // roi lies completely within path
      for(size_t k = 0; k < (size_t)width * height; k++)
        buffer[k] = 1.0f;
    }
    else
    {
      // all other cases

      // edge-flag polygon fill: we write all the point around the path into the buffer
      float xlast = cpoints[(points_count - 1) * 2];
      float ylast = cpoints[(points_count - 1) * 2 + 1];

      for(int i = _nb_wctrl_points(nb_corner); i < points_count; i++)
      {
        float xstart = xlast;
        float ystart = ylast;

        float xend = xlast = cpoints[i * 2];
        float yend = ylast = cpoints[i * 2 + 1];

        if(ystart > yend)
        {
          float tmp;
          tmp = ystart, ystart = yend, yend = tmp;
          tmp = xstart, xstart = xend, xend = tmp;
        }

        // we don't need special handling of ystart==yend
        // as following loop will take care
        const float m = (xstart - xend) / (ystart - yend);

        for(int yy = (int)ceilf(ystart);
            (float)yy < yend;
            yy++) // this would normally never touch the last roi line
                  // => see comment further above
        {
          const float xcross = xstart + m * (yy - ystart);

          int xx = floorf(xcross);
          if((float)xx + 0.5f <= xcross)
            xx++;

          if(xx < 0 || xx >= width || yy < 0 || yy >= height)
            continue; // sanity check just to be on the safe side

          const size_t index = (size_t)yy * width + xx;

          buffer[index] = 1.0f - buffer[index];
        }
      }

      dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
               "[masks %s] path_fill draw path took %0.04f sec", form->name,
               dt_get_lap_time(&start2));

      // we fill the inside plain
      // we don't need to deal with parts of shape outside of roi
      const int xxmin = MAX(xmin, 0);
      const int xxmax = MIN(xmax, width - 1);
      const int yymin = MAX(ymin, 0);
      const int yymax = MIN(ymax, height - 1);

      DT_OMP_FOR(num_threads(MIN(8, dt_get_num_threads())))
      for(int yy = yymin; yy <= yymax; yy++)
      {
        int state = 0;
        for(int xx = xxmin; xx <= xxmax; xx++)
        {
          const size_t index = (size_t)yy * width + xx;
          const float v = buffer[index];
          if(v > 0.5f) state = !state;
          if(state) buffer[index] = 1.0f;
        }
      }

      dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
               "[masks %s] path_fill fill plain took %0.04f sec", form->name,
               dt_get_lap_time(&start2));
    }
    dt_free_align(cpoints);
  }

  // deal with feather if it does not lie outside of roi
  if(!path_encircles_roi)
  {
    int *dpoints = dt_alloc_align_int(4 * border_count);
    if(dpoints == NULL)
    {
      dt_free_align(points);
      dt_free_align(border);
      return 0;
    }

    int dindex = 0;
    int p0[2], p1[2];
    float pf1[2];
    int last0[2] = { -100, -100 };
    int last1[2] = { -100, -100 };
    int next = 0;
    for(int i = _nb_wctrl_points(nb_corner); i < border_count; i++)
    {
      p0[0] = floorf(points[i * 2] + 0.5f);
      p0[1] = ceilf(points[i * 2 + 1]);
      if(next > 0)
      {
        p1[0] = pf1[0] = border[next * 2];
        p1[1] = pf1[1] = border[next * 2 + 1];
      }
      else
      {
        p1[0] = pf1[0] = border[i * 2];
        p1[1] = pf1[1] = border[i * 2 + 1];
      }

      // now we check p1 value to know if we have to skip a part
      if(next == i) next = 0;
      while(pf1[0] == DT_INVALID_COORDINATE)
      {
        if(pf1[1] == DT_INVALID_COORDINATE)
          next = i - 1;
        else
          next = p1[1];
        p1[0] = pf1[0] = border[next * 2];
        p1[1] = pf1[1] = border[next * 2 + 1];
      }

      // and we draw the falloff
      if(last0[0] != p0[0]
         || last0[1] != p0[1]
         || last1[0] != p1[0]
         || last1[1] != p1[1])
      {
        dpoints[dindex] = p0[0];
        dpoints[dindex + 1] = p0[1];
        dpoints[dindex + 2] = p1[0];
        dpoints[dindex + 3] = p1[1];
        dindex += 4;

        last0[0] = p0[0];
        last0[1] = p0[1];
        last1[0] = p1[0];
        last1[1] = p1[1];
      }
    }

    DT_OMP_FOR()
    for(int n = 0; n < dindex; n += 4)
      _path_falloff_roi(buffer, dpoints + n, dpoints + n + 2, width, height);

    dt_free_align(dpoints);

    dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
             "[masks %s] path_fill fill falloff took %0.04f sec", form->name,
             dt_get_lap_time(&start2));
  }

  dt_free_align(points);
  dt_free_align(border);

  dt_print(DT_DEBUG_MASKS | DT_DEBUG_PERF,
           "[masks %s] path fill buffer took %0.04f sec", form->name,
           dt_get_lap_time(&start));

  return 1;
}

static GSList *_path_setup_mouse_actions(const dt_masks_form_t *const form)
{
  GSList *lm = NULL;
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_LEFT, 0,
                                     _("[PATH creation] add a smooth node"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_LEFT, GDK_CONTROL_MASK,
                                     _("[PATH creation] add a sharp node"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_RIGHT, 0,
                                     _("[PATH creation] terminate path creation"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_LEFT, GDK_CONTROL_MASK,
                                     _("[PATH on node] switch between smooth/sharp node"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_RIGHT, 0,
                                     _("[PATH on node] remove the node"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_RIGHT, 0,
                                     _("[PATH on feather] reset curvature"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_LEFT, GDK_CONTROL_MASK,
                                     _("[PATH on segment] add node"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_SCROLL, 0,
                                     _("[PATH] change size"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_SCROLL,
                                     GDK_SHIFT_MASK, _("[PATH] change feather size"));
  lm = dt_mouse_action_create_simple(lm, DT_MOUSE_ACTION_SCROLL,
                                     GDK_CONTROL_MASK, _("[PATH] change opacity"));
  return lm;
}

static void _path_sanitize_config(dt_masks_type_t type)
{
  // nothing to do (yet?)
}

static void _path_set_form_name(dt_masks_form_t *const form,
                                const size_t nb)
{
  snprintf(form->name, sizeof(form->name), _("path #%d"), (int)nb);
}

static void _path_set_hint_message(const dt_masks_form_gui_t *const gui,
                                   const dt_masks_form_t *const form,
                                   const int opacity,
                                   char *const restrict msgbuf,
                                   const size_t msgbuf_len)
{
  if(gui->creation && g_list_length(form->points) < 4)
    g_strlcat(msgbuf,
              _("<b>add node</b>: click, <b>add sharp node</b>: ctrl+click\n"
                "<b>cancel</b>: right-click"),
              msgbuf_len);
  else if(gui->creation)
    g_strlcat(msgbuf,
              _("<b>add node</b>: click, <b>add sharp node</b>: ctrl+click\n"
                "<b>finish path</b>: right-click"),
              msgbuf_len);
  else if(gui->point_selected >= 0)
    g_strlcat(msgbuf,
              _("<b>move node</b>: drag, <b>remove node</b>: right-click\n"
                "<b>switch smooth/sharp mode</b>: ctrl+click"),
              msgbuf_len);
  else if(gui->feather_selected >= 0)
    g_strlcat(msgbuf,
              _("<b>node curvature</b>: drag, <b>force symmetry</b>: ctrl+drag,\n"
                "<b>move single handle</b>: shift+drag, <b>reset curvature</b>: right-click"),
              msgbuf_len);
  else if(gui->seg_selected >= 0)
    g_strlcat(msgbuf,
              _("<b>move segment</b>: drag, <b>add node</b>: ctrl+click\n"
                "<b>remove path</b>: right-click"),
              msgbuf_len);
  else if(gui->form_selected)
    g_snprintf(msgbuf,
               msgbuf_len,
               _("<b>size</b>: scroll, <b>feather size</b>: shift+scroll\n"
                 "<b>opacity</b>: ctrl+scroll (%d%%)"),
               opacity);
}

static void _path_duplicate_points(dt_develop_t *const dev,
                                   dt_masks_form_t *const base,
                                   dt_masks_form_t *const dest)
{
  (void)dev; // unused arg, keep compiler from complaining
  for(const GList *pts = base->points; pts; pts = g_list_next(pts))
  {
    dt_masks_point_path_t *pt = pts->data;
    dt_masks_point_path_t *npt = malloc(sizeof(dt_masks_point_path_t));
    memcpy(npt, pt, sizeof(dt_masks_point_path_t));
    dest->points = g_list_append(dest->points, npt);
  }
}

static void _path_initial_source_pos(const float iwd,
                                     const float iht,
                                     float *x,
                                     float *y)
{
  *x = (0.02f * iwd);
  *y = (0.02f * iht);
}

static void _path_modify_property(dt_masks_form_t *const form,
                                  dt_masks_property_t prop,
                                  const float old_val,
                                  const float new_val,
                                  float *sum,
                                  int *count,
                                  float *min,
                                  float *max)
{
  float ratio = (!old_val || !new_val) ? 1.0f : new_val / old_val;

  switch(prop)
  {
    case DT_MASKS_PROPERTY_SIZE:;
      // get the center of gravity of the form (like if it was a simple polygon)
      float bx = 0.0f;
      float by = 0.0f;
      float surf = 0.0f;

      for(const GList *form_points = form->points;
          form_points;
          form_points = g_list_next(form_points))
      {
        const GList *next = g_list_next_wraparound(form_points, form->points);
        float *point1 = ((dt_masks_point_path_t *)form_points->data)->corner;
        float *point2 = ((dt_masks_point_path_t *)next->data)->corner;
        surf += point1[0] * point2[1] - point2[0] * point1[1];

        bx += (point1[0] + point2[0]) * (point1[0] * point2[1] - point2[0] * point1[1]);
        by += (point1[1] + point2[1]) * (point1[0] * point2[1] - point2[0] * point1[1]);
      }
      bx /= 3.0f * surf;
      by /= 3.0f * surf;

      if(surf)
      {
        surf = sqrtf(fabsf(surf));
        ratio = fminf(fmaxf(ratio, 0.001f / surf), 2.0f / surf);
      }

      // now we move each point
      for(GList *l = form->points; l; l = g_list_next(l))
      {
        dt_masks_point_path_t *point = l->data;
        const float x = (point->corner[0] - bx) * ratio;
        const float y = (point->corner[1] - by) * ratio;

        // we stretch ctrl points
        const float ct1x = (point->ctrl1[0] - point->corner[0]) * ratio;
        const float ct1y = (point->ctrl1[1] - point->corner[1]) * ratio;
        const float ct2x = (point->ctrl2[0] - point->corner[0]) * ratio;
        const float ct2y = (point->ctrl2[1] - point->corner[1]) * ratio;

        // and we set the new points
        point->corner[0] = bx + x;
        point->corner[1] = by + y;
        point->ctrl1[0] = point->corner[0] + ct1x;
        point->ctrl1[1] = point->corner[1] + ct1y;
        point->ctrl2[0] = point->corner[0] + ct2x;
        point->ctrl2[1] = point->corner[1] + ct2y;
      }

      // now the redraw/save stuff
      _path_init_ctrl_points(form);

      surf *= ratio;
      *max = fminf(*max, 2.0f / surf);
      *min = fmaxf(*min, 0.001f / surf);
      *sum += surf / 2.0f;
      ++*count;
      break;
    case DT_MASKS_PROPERTY_FEATHER:;
      for(const GList *l = form->points; l; l = g_list_next(l))
      {
        dt_masks_point_path_t *point = l->data;
        point->border[0] = CLAMP(point->border[0] * ratio, 0.0005f, 1.0f);
        point->border[1] = CLAMP(point->border[1] * ratio, 0.0005f, 1.0f);
        *sum += point->border[0] + point->border[1];
        *max = fminf(*max, fminf(1.0f / point->border[0], 1.0f / point->border[1]));
        *min = fmaxf(*min, fmaxf(0.0005f / point->border[0], 0.0005f / point->border[1]));
        *count += 2;
      }
      break;
    default:;
  }
}

// The function table for paths.  This must be public, i.e. no "static" keyword.
const dt_masks_functions_t dt_masks_functions_path = {
  .point_struct_size = sizeof(struct dt_masks_point_path_t),
  .sanitize_config = _path_sanitize_config,
  .setup_mouse_actions = _path_setup_mouse_actions,
  .set_form_name = _path_set_form_name,
  .set_hint_message = _path_set_hint_message,
  .modify_property = _path_modify_property,
  .duplicate_points = _path_duplicate_points,
  .initial_source_pos = _path_initial_source_pos,
  .get_distance = _path_get_distance,
  .get_points_border = _path_get_points_border,
  .get_mask = _path_get_mask,
  .get_mask_roi = _path_get_mask_roi,
  .get_area = _path_get_area,
  .get_source_area = _path_get_source_area,
  .mouse_moved = _path_events_mouse_moved,
  .mouse_scrolled = _path_events_mouse_scrolled,
  .button_pressed = _path_events_button_pressed,
  .button_released = _path_events_button_released,
  .post_expose = _path_events_post_expose
};


// clang-format off
// modelines: These editor modelines have been set for all relevant files by tools/update_modelines.py
// vim: shiftwidth=2 expandtab tabstop=2 cindent
// kate: tab-indents: off; indent-width 2; replace-tabs on; indent-mode cstyle; remove-trailing-spaces modified;
// clang-format on
