src/hb-cairo-utils.cc - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 2022  Red Hat, Inc
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
  * Permission is hereby granted, without written agreement and without
  * license or royalty fees, to use, copy, modify, and distribute this
  * software and its documentation for any purpose, provided that the
  * above copyright notice and the following two paragraphs appear in
  * all copies of this software.
  *
  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  * DAMAGE.
  *
  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  *
  * Google Author(s): Matthias Clasen
  */

 #include "hb.hh"

 #ifdef HAVE_CAIRO

 #include "hb-cairo-utils.hh"

 #include <cairo.h>

 #define PREALLOCATED_COLOR_STOPS 16

 #define _2_M_PIf (2.f * float (M_PI))

 typedef struct {
   float r, g, b, a;
 } hb_cairo_color_t;

 static inline cairo_extend_t
 hb_cairo_extend (hb_paint_extend_t extend)
 {
   switch (extend)
     {
     case HB_PAINT_EXTEND_PAD: return CAIRO_EXTEND_PAD;
     case HB_PAINT_EXTEND_REPEAT: return CAIRO_EXTEND_REPEAT;
     case HB_PAINT_EXTEND_REFLECT: return CAIRO_EXTEND_REFLECT;
     default: break;
     }

   return CAIRO_EXTEND_PAD;
 }

 #ifdef CAIRO_HAS_PNG_FUNCTIONS
 typedef struct
 {
   hb_blob_t *blob;
   unsigned int offset;
 } hb_cairo_read_blob_data_t;

 static cairo_status_t
 hb_cairo_read_blob (void *closure,
 		    unsigned char *data,
 		    unsigned int length)
 {
   hb_cairo_read_blob_data_t *r = (hb_cairo_read_blob_data_t *) closure;
   const char *d;
   unsigned int size;

   d = hb_blob_get_data (r->blob, &size);

   if (r->offset + length > size)
     return CAIRO_STATUS_READ_ERROR;

   memcpy (data, d + r->offset, length);
   r->offset += length;

   return CAIRO_STATUS_SUCCESS;
 }
 #endif

 static const cairo_user_data_key_t *_hb_cairo_surface_blob_user_data_key = {0};

 static void
 _hb_cairo_destroy_blob (void *p)
 {
   hb_blob_destroy ((hb_blob_t *) p);
 }

 hb_bool_t
 _hb_cairo_paint_glyph_image (hb_cairo_context_t *c,
 			     hb_blob_t *blob,
 			     unsigned width,
 			     unsigned height,
 			     hb_tag_t format,
 			     float slant,
 			     hb_glyph_extents_t *extents)
 {
   cairo_t *cr = c->cr;

   if (!extents) /* SVG currently. */
     return false;

   cairo_surface_t *surface = nullptr;

 #ifdef CAIRO_HAS_PNG_FUNCTIONS
   if (format == HB_PAINT_IMAGE_FORMAT_PNG)
   {
     hb_cairo_read_blob_data_t r;
     r.blob = blob;
     r.offset = 0;
     surface = cairo_image_surface_create_from_png_stream (hb_cairo_read_blob, &r);

     /* For PNG, width,height can be unreliable, as is the case for NotoColorEmoji :(.
      * Just pull them out of the surface. */
     width = cairo_image_surface_get_width (surface);
     height = cairo_image_surface_get_width (surface);
   }
   else
 #endif
   if (format == HB_PAINT_IMAGE_FORMAT_BGRA)
   {
     /* Byte-endian conversion. */
     unsigned data_size = hb_blob_get_length (blob);
     if (data_size < width * height * 4)
       return false;

     unsigned char *data;
 #ifdef __BYTE_ORDER
     if (__BYTE_ORDER == __BIG_ENDIAN)
     {
       data = (unsigned char *) hb_blob_get_data_writable (blob, nullptr);
       if (!data)
         return false;

       unsigned count = width * height * 4;
       for (unsigned i = 0; i < count; i += 4)
       {
         unsigned char b;
 	b = data[i];
 	data[i] = data[i+3];
 	data[i+3] = b;
 	b = data[i+1];
 	data[i+1] = data[i+2];
 	data[i+2] = b;
       }
     }
     else
 #endif
       data = (unsigned char *) hb_blob_get_data (blob, nullptr);

     surface = cairo_image_surface_create_for_data (data,
 						   CAIRO_FORMAT_ARGB32,
 						   width, height,
 						   width * 4);

     cairo_surface_set_user_data (surface,
 				 _hb_cairo_surface_blob_user_data_key,
 				 hb_blob_reference (blob),
 				 _hb_cairo_destroy_blob);
   }

   if (!surface)
     return false;

   cairo_save (cr);
   /* this clip is here to work around recording surface limitations */
   cairo_rectangle (cr,
                    extents->x_bearing,
                    extents->y_bearing,
                    extents->width,
                    extents->height);
   cairo_clip (cr);

   cairo_pattern_t *pattern = cairo_pattern_create_for_surface (surface);
   cairo_pattern_set_extend (pattern, CAIRO_EXTEND_PAD);

   cairo_matrix_t matrix = {(double) width, 0, 0, (double) height, 0, 0};
   cairo_pattern_set_matrix (pattern, &matrix);

   /* Undo slant in the extents and apply it in the context. */
   extents->width -= extents->height * slant;
   extents->x_bearing -= extents->y_bearing * slant;
   cairo_matrix_t cairo_matrix = {1., 0., (double) slant, 1., 0., 0.};
   cairo_transform (cr, &cairo_matrix);

   cairo_translate (cr, extents->x_bearing, extents->y_bearing);
   cairo_scale (cr, extents->width, extents->height);
   cairo_set_source (cr, pattern);

   cairo_paint (cr);

   cairo_pattern_destroy (pattern);
   cairo_surface_destroy (surface);

   cairo_restore (cr);

   return true;
 }

 static void
 _hb_cairo_reduce_anchors (float x0, float y0,
 			  float x1, float y1,
 			  float x2, float y2,
 			  float *xx0, float *yy0,
 			  float *xx1, float *yy1)
 {
   float q1x, q1y, q2x, q2y;
   float s;
   float k;

   q2x = x2 - x0;
   q2y = y2 - y0;
   q1x = x1 - x0;
   q1y = y1 - y0;

   s = q2x * q2x + q2y * q2y;
   if (s < 0.000001f)
     {
       *xx0 = x0; *yy0 = y0;
       *xx1 = x1; *yy1 = y1;
       return;
     }

   k = (q2x * q1x + q2y * q1y) / s;
   *xx0 = x0;
   *yy0 = y0;
   *xx1 = x1 - k * q2x;
   *yy1 = y1 - k * q2y;
 }

 static int
 _hb_cairo_cmp_color_stop (const void *p1,
 			  const void *p2)
 {
   const hb_color_stop_t *c1 = (const hb_color_stop_t *) p1;
   const hb_color_stop_t *c2 = (const hb_color_stop_t *) p2;

   if (c1->offset < c2->offset)
     return -1;
   else if (c1->offset > c2->offset)
     return 1;
   else
     return 0;
 }

 static void
 _hb_cairo_normalize_color_line (hb_color_stop_t *stops,
 				unsigned int len,
 				float *omin,
 				float *omax)
 {
   float min, max;

   hb_qsort (stops, len, sizeof (hb_color_stop_t), _hb_cairo_cmp_color_stop);

   min = max = stops[0].offset;
   for (unsigned int i = 0; i < len; i++)
     {
       min = hb_min (min, stops[i].offset);
       max = hb_max (max, stops[i].offset);
     }

   if (min != max)
     {
       for (unsigned int i = 0; i < len; i++)
         stops[i].offset = (stops[i].offset - min) / (max - min);
     }

   *omin = min;
   *omax = max;
 }

 void
 _hb_cairo_paint_linear_gradient (hb_cairo_context_t *c,
 				 hb_color_line_t *color_line,
 				 float x0, float y0,
 				 float x1, float y1,
 				 float x2, float y2)
 {
   cairo_t *cr = c->cr;

   hb_color_stop_t stops_[PREALLOCATED_COLOR_STOPS];
   hb_color_stop_t *stops = stops_;
   unsigned int len;
   float xx0, yy0, xx1, yy1;
   float xxx0, yyy0, xxx1, yyy1;
   float min, max;
   cairo_pattern_t *pattern;

   len = hb_color_line_get_color_stops (color_line, 0, nullptr, nullptr);
   if (len > PREALLOCATED_COLOR_STOPS)
     stops = (hb_color_stop_t *) hb_malloc (len * sizeof (hb_color_stop_t));
   hb_color_line_get_color_stops (color_line, 0, &len, stops);

   _hb_cairo_reduce_anchors (x0, y0, x1, y1, x2, y2, &xx0, &yy0, &xx1, &yy1);
   _hb_cairo_normalize_color_line (stops, len, &min, &max);

   xxx0 = xx0 + min * (xx1 - xx0);
   yyy0 = yy0 + min * (yy1 - yy0);
   xxx1 = xx0 + max * (xx1 - xx0);
   yyy1 = yy0 + max * (yy1 - yy0);

   pattern = cairo_pattern_create_linear ((double) xxx0, (double) yyy0, (double) xxx1, (double) yyy1);
   cairo_pattern_set_extend (pattern, hb_cairo_extend (hb_color_line_get_extend (color_line)));
   for (unsigned int i = 0; i < len; i++)
     {
       double r, g, b, a;
       r = hb_color_get_red (stops[i].color) / 255.;
       g = hb_color_get_green (stops[i].color) / 255.;
       b = hb_color_get_blue (stops[i].color) / 255.;
       a = hb_color_get_alpha (stops[i].color) / 255.;
       cairo_pattern_add_color_stop_rgba (pattern, (double) stops[i].offset, r, g, b, a);
     }

   cairo_set_source (cr, pattern);
   cairo_paint (cr);

   cairo_pattern_destroy (pattern);

   if (stops != stops_)
     hb_free (stops);
 }

 void
 _hb_cairo_paint_radial_gradient (hb_cairo_context_t *c,
 				 hb_color_line_t *color_line,
 				 float x0, float y0, float r0,
 				 float x1, float y1, float r1)
 {
   cairo_t *cr = c->cr;

   hb_color_stop_t stops_[PREALLOCATED_COLOR_STOPS];
   hb_color_stop_t *stops = stops_;
   unsigned int len;
   float min, max;
   float xx0, yy0, xx1, yy1;
   float rr0, rr1;
   cairo_pattern_t *pattern;

   len = hb_color_line_get_color_stops (color_line, 0, nullptr, nullptr);
   if (len > PREALLOCATED_COLOR_STOPS)
     stops = (hb_color_stop_t *) hb_malloc (len * sizeof (hb_color_stop_t));
   hb_color_line_get_color_stops (color_line, 0, &len, stops);

   _hb_cairo_normalize_color_line (stops, len, &min, &max);

   xx0 = x0 + min * (x1 - x0);
   yy0 = y0 + min * (y1 - y0);
   xx1 = x0 + max * (x1 - x0);
   yy1 = y0 + max * (y1 - y0);
   rr0 = r0 + min * (r1 - r0);
   rr1 = r0 + max * (r1 - r0);

   pattern = cairo_pattern_create_radial ((double) xx0, (double) yy0, (double) rr0, (double) xx1, (double) yy1, (double) rr1);
   cairo_pattern_set_extend (pattern, hb_cairo_extend (hb_color_line_get_extend (color_line)));

   for (unsigned int i = 0; i < len; i++)
     {
       double r, g, b, a;
       r = hb_color_get_red (stops[i].color) / 255.;
       g = hb_color_get_green (stops[i].color) / 255.;
       b = hb_color_get_blue (stops[i].color) / 255.;
       a = hb_color_get_alpha (stops[i].color) / 255.;
       cairo_pattern_add_color_stop_rgba (pattern, (double) stops[i].offset, r, g, b, a);
     }

   cairo_set_source (cr, pattern);
   cairo_paint (cr);

   cairo_pattern_destroy (pattern);

   if (stops != stops_)
     hb_free (stops);
 }

 typedef struct {
   float x, y;
 } hb_cairo_point_t;

 static inline float
 _hb_cairo_interpolate (float f0, float f1, float f)
 {
   return f0 + f * (f1 - f0);
 }

 static inline void
 _hb_cairo_premultiply (hb_cairo_color_t *c)
 {
   c->r *= c->a;
   c->g *= c->a;
   c->b *= c->a;
 }

 static inline void
 _hb_cairo_unpremultiply (hb_cairo_color_t *c)
 {
   if (c->a != 0.f)
   {
      c->r /= c->a;
      c->g /= c->a;
      c->b /= c->a;
   }
 }

 static void
 _hb_cairo_interpolate_colors (hb_cairo_color_t *c0, hb_cairo_color_t *c1, float k, hb_cairo_color_t *c)
 {
   // According to the COLR specification, gradients
   // should be interpolated in premultiplied form
   _hb_cairo_premultiply (c0);
   _hb_cairo_premultiply (c1);
   c->r = c0->r + k * (c1->r - c0->r);
   c->g = c0->g + k * (c1->g - c0->g);
   c->b = c0->b + k * (c1->b - c0->b);
   c->a = c0->a + k * (c1->a - c0->a);
   _hb_cairo_unpremultiply (c);
 }

 static inline float
 _hb_cairo_dot (hb_cairo_point_t p, hb_cairo_point_t q)
 {
   return p.x * q.x + p.y * q.y;
 }

 static inline hb_cairo_point_t
 _hb_cairo_normalize (hb_cairo_point_t p)
 {
   float len = sqrtf (_hb_cairo_dot (p, p));

   return hb_cairo_point_t { p.x / len, p.y / len };
 }

 static inline hb_cairo_point_t
 _hb_cairo_sum (hb_cairo_point_t p, hb_cairo_point_t q)
 {
   return hb_cairo_point_t { p.x + q.x, p.y + q.y };
 }

 static inline hb_cairo_point_t
 _hb_cairo_difference (hb_cairo_point_t p, hb_cairo_point_t q)
 {
   return hb_cairo_point_t { p.x - q.x, p.y - q.y };
 }

 static inline hb_cairo_point_t
 _hb_cairo_scale (hb_cairo_point_t p, float f)
 {
   return hb_cairo_point_t { p.x * f, p.y * f };
 }

 typedef struct {
   hb_cairo_point_t center, p0, c0, c1, p1;
   hb_cairo_color_t color0, color1;
 } hb_cairo_patch_t;

 static void
 _hb_cairo_add_patch (cairo_pattern_t *pattern, hb_cairo_point_t *center, hb_cairo_patch_t *p)
 {
   cairo_mesh_pattern_begin_patch (pattern);
   cairo_mesh_pattern_move_to (pattern, (double) center->x, (double) center->y);
   cairo_mesh_pattern_line_to (pattern, (double) p->p0.x, (double) p->p0.y);
   cairo_mesh_pattern_curve_to (pattern,
                                (double) p->c0.x, (double) p->c0.y,
                                (double) p->c1.x, (double) p->c1.y,
                                (double) p->p1.x, (double) p->p1.y);
   cairo_mesh_pattern_line_to (pattern, (double) center->x, (double) center->y);
   cairo_mesh_pattern_set_corner_color_rgba (pattern, 0,
                                             (double) p->color0.r,
                                             (double) p->color0.g,
                                             (double) p->color0.b,
                                             (double) p->color0.a);
   cairo_mesh_pattern_set_corner_color_rgba (pattern, 1,
                                             (double) p->color0.r,
                                             (double) p->color0.g,
                                             (double) p->color0.b,
                                             (double) p->color0.a);
   cairo_mesh_pattern_set_corner_color_rgba (pattern, 2,
                                             (double) p->color1.r,
                                             (double) p->color1.g,
                                             (double) p->color1.b,
                                             (double) p->color1.a);
   cairo_mesh_pattern_set_corner_color_rgba (pattern, 3,
                                             (double) p->color1.r,
                                             (double) p->color1.g,
                                             (double) p->color1.b,
                                             (double) p->color1.a);
   cairo_mesh_pattern_end_patch (pattern);
 }

 #define MAX_ANGLE ((float) M_PI / 8.f)

 static void
 _hb_cairo_add_sweep_gradient_patches1 (float cx, float cy, float radius,
 				       float a0, hb_cairo_color_t *c0,
 				       float a1, hb_cairo_color_t *c1,
 				       cairo_pattern_t *pattern)
 {
   hb_cairo_point_t center = hb_cairo_point_t { cx, cy };
   int num_splits;
   hb_cairo_point_t p0;
   hb_cairo_color_t color0, color1;

   num_splits = ceilf (fabsf (a1 - a0) / MAX_ANGLE);
   p0 = hb_cairo_point_t { cosf (a0), sinf (a0) };
   color0 = *c0;

   for (int a = 0; a < num_splits; a++)
     {
       float k = (a + 1.) / num_splits;
       float angle1;
       hb_cairo_point_t p1;
       hb_cairo_point_t A, U;
       hb_cairo_point_t C0, C1;
       hb_cairo_patch_t patch;

       angle1 = _hb_cairo_interpolate (a0, a1, k);
       _hb_cairo_interpolate_colors (c0, c1, k, &color1);

       patch.color0 = color0;
       patch.color1 = color1;

       p1 = hb_cairo_point_t { cosf (angle1), sinf (angle1) };
       patch.p0 = _hb_cairo_sum (center, _hb_cairo_scale (p0, radius));
       patch.p1 = _hb_cairo_sum (center, _hb_cairo_scale (p1, radius));

       A = _hb_cairo_normalize (_hb_cairo_sum (p0, p1));
       U = hb_cairo_point_t { -A.y, A.x };
       C0 = _hb_cairo_sum (A, _hb_cairo_scale (U, _hb_cairo_dot (_hb_cairo_difference (p0, A), p0) / _hb_cairo_dot (U, p0)));
       C1 = _hb_cairo_sum (A, _hb_cairo_scale (U, _hb_cairo_dot (_hb_cairo_difference (p1, A), p1) / _hb_cairo_dot (U, p1)));

       patch.c0 = _hb_cairo_sum (center, _hb_cairo_scale (_hb_cairo_sum (C0, _hb_cairo_scale (_hb_cairo_difference (C0, p0), 0.33333f)), radius));
       patch.c1 = _hb_cairo_sum (center, _hb_cairo_scale (_hb_cairo_sum (C1, _hb_cairo_scale (_hb_cairo_difference (C1, p1), 0.33333f)), radius));

       _hb_cairo_add_patch (pattern, &center, &patch);

       p0 = p1;
       color0 = color1;
     }
 }

 static void
 _hb_cairo_add_sweep_gradient_patches (hb_color_stop_t *stops,
 				      unsigned int n_stops,
 				      cairo_extend_t extend,
 				      float cx, float cy,
 				      float radius,
 				      float start_angle,
 				      float end_angle,
 				      cairo_pattern_t *pattern)
 {
   float angles_[PREALLOCATED_COLOR_STOPS];
   float *angles = angles_;
   hb_cairo_color_t colors_[PREALLOCATED_COLOR_STOPS];
   hb_cairo_color_t *colors = colors_;
   hb_cairo_color_t color0, color1;

   if (start_angle == end_angle)
   {
     if (extend == CAIRO_EXTEND_PAD)
     {
       hb_cairo_color_t c;
       if (start_angle > 0)
       {
 	c.r = hb_color_get_red (stops[0].color) / 255.;
 	c.g = hb_color_get_green (stops[0].color) / 255.;
 	c.b = hb_color_get_blue (stops[0].color) / 255.;
 	c.a = hb_color_get_alpha (stops[0].color) / 255.;
 	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 					       0.,          &c,
 					       start_angle, &c,
 					       pattern);
       }
       if (end_angle < _2_M_PIf)
       {
 	c.r = hb_color_get_red (stops[n_stops - 1].color) / 255.;
 	c.g = hb_color_get_green (stops[n_stops - 1].color) / 255.;
 	c.b = hb_color_get_blue (stops[n_stops - 1].color) / 255.;
 	c.a = hb_color_get_alpha (stops[n_stops - 1].color) / 255.;
 	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 					       end_angle, &c,
 					       _2_M_PIf,  &c,
 					       pattern);
       }
     }
     return;
   }

   assert (start_angle != end_angle);

   /* handle directions */
   if (end_angle < start_angle)
   {
     hb_swap (start_angle, end_angle);

     for (unsigned i = 0; i < n_stops - 1 - i; i++)
       hb_swap (stops[i], stops[n_stops - 1 - i]);
     for (unsigned i = 0; i < n_stops; i++)
       stops[i].offset = 1 - stops[i].offset;
   }

   if (n_stops > PREALLOCATED_COLOR_STOPS)
   {
     angles = (float *) hb_malloc (sizeof (float) * n_stops);
     colors = (hb_cairo_color_t *) hb_malloc (sizeof (hb_cairo_color_t) * n_stops);
   }

   for (unsigned i = 0; i < n_stops; i++)
   {
     angles[i] = start_angle + stops[i].offset * (end_angle - start_angle);
     colors[i].r = hb_color_get_red (stops[i].color) / 255.;
     colors[i].g = hb_color_get_green (stops[i].color) / 255.;
     colors[i].b = hb_color_get_blue (stops[i].color) / 255.;
     colors[i].a = hb_color_get_alpha (stops[i].color) / 255.;
   }

   if (extend == CAIRO_EXTEND_PAD)
   {
     unsigned pos;

     color0 = colors[0];
     for (pos = 0; pos < n_stops; pos++)
     {
       if (angles[pos] >= 0)
       {
 	if (pos > 0)
 	{
 	  float k = (0 - angles[pos - 1]) / (angles[pos] - angles[pos - 1]);
 	  _hb_cairo_interpolate_colors (&colors[pos-1], &colors[pos], k, &color0);
 	}
 	break;
       }
     }
     if (pos == n_stops)
     {
       /* everything is below 0 */
       color0 = colors[n_stops-1];
       _hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 					     0.,       &color0,
 					     _2_M_PIf, &color0,
 					     pattern);
       goto done;
     }

     _hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 					   0.,          &color0,
 					   angles[pos], &colors[pos],
 					   pattern);

     for (pos++; pos < n_stops; pos++)
     {
       if (angles[pos] <= _2_M_PIf)
       {
 	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 					       angles[pos - 1], &colors[pos-1],
 					       angles[pos],     &colors[pos],
 					       pattern);
       }
       else
       {
 	float k = (_2_M_PIf - angles[pos - 1]) / (angles[pos] - angles[pos - 1]);
 	_hb_cairo_interpolate_colors (&colors[pos - 1], &colors[pos], k, &color1);
 	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 					       angles[pos - 1], &colors[pos - 1],
 					       _2_M_PIf,        &color1,
 					       pattern);
 	break;
       }
     }

     if (pos == n_stops)
     {
       /* everything is below 2*M_PI */
       color0 = colors[n_stops - 1];
       _hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 					     angles[n_stops - 1], &color0,
 					     _2_M_PIf,            &color0,
 					     pattern);
       goto done;
     }
   }
   else
   {
     int k;
     float span;

     span = angles[n_stops - 1] - angles[0];
     k = 0;
     if (angles[0] >= 0)
     {
       float ss = angles[0];
       while (ss > 0)
       {
 	if (span > 0)
 	{
 	  ss -= span;
 	  k--;
 	}
 	else
 	{
 	  ss += span;
 	  k++;
 	}
       }
     }
     else if (angles[0] < 0)
     {
       float ee = angles[n_stops - 1];
       while (ee < 0)
       {
 	if (span > 0)
 	{
 	  ee += span;
 	  k++;
 	}
 	else
 	{
 	  ee -= span;
 	  k--;
 	}
       }
     }

     //assert (angles[0] + k * span <= 0 && 0 < angles[n_stops - 1] + k * span);
     span = fabs (span);

     for (signed l = k; l < 1000; l++)
     {
       for (unsigned i = 1; i < n_stops; i++)
       {
         float a0, a1;
 	hb_cairo_color_t *c0, *c1;

 	if ((l % 2 != 0) && (extend == CAIRO_EXTEND_REFLECT))
 	{
 	  a0 = angles[0] + angles[n_stops - 1] - angles[n_stops - 1 - (i-1)] + l * span;
 	  a1 = angles[0] + angles[n_stops - 1] - angles[n_stops - 1 - i] + l * span;
 	  c0 = &colors[n_stops - 1 - (i - 1)];
 	  c1 = &colors[n_stops - 1 - i];
 	}
 	else
 	{
 	  a0 = angles[i-1] + l * span;
 	  a1 = angles[i] + l * span;
 	  c0 = &colors[i-1];
 	  c1 = &colors[i];
 	}

 	if (a1 < 0)
 	  continue;
 	if (a0 < 0)
 	{
 	  hb_cairo_color_t color;
 	  float f = (0 - a0)/(a1 - a0);
 	  _hb_cairo_interpolate_colors (c0, c1, f, &color);
 	  _hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 						 0,  &color,
 						 a1, c1,
 						 pattern);
 	}
 	else if (a1 >= _2_M_PIf)
 	{
 	  hb_cairo_color_t color;
 	  float f = (_2_M_PIf - a0)/(a1 - a0);
 	  _hb_cairo_interpolate_colors (c0, c1, f, &color);
 	  _hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 						 a0,       c0,
 						 _2_M_PIf, &color,
 						 pattern);
 	  goto done;
 	}
 	else
 	{
 	  _hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
 						 a0, c0,
 						 a1, c1,
 						 pattern);
 	}
       }
     }
   }

 done:

   if (angles != angles_)
     hb_free (angles);
   if (colors != colors_)
     hb_free (colors);
 }

 void
 _hb_cairo_paint_sweep_gradient (hb_cairo_context_t *c,
 				hb_color_line_t *color_line,
 				float cx, float cy,
 				float start_angle,
 				float end_angle)
 {
   cairo_t *cr = c->cr;

   unsigned int len;
   hb_color_stop_t stops_[PREALLOCATED_COLOR_STOPS];
   hb_color_stop_t *stops = stops_;
   cairo_extend_t extend;
   double x1, y1, x2, y2;
   float max_x, max_y, radius;
   cairo_pattern_t *pattern;

   len = hb_color_line_get_color_stops (color_line, 0, nullptr, nullptr);
   if (len > PREALLOCATED_COLOR_STOPS)
     stops = (hb_color_stop_t *) hb_malloc (len * sizeof (hb_color_stop_t));
   hb_color_line_get_color_stops (color_line, 0, &len, stops);

   hb_qsort (stops, len, sizeof (hb_color_stop_t), _hb_cairo_cmp_color_stop);

   cairo_clip_extents (cr, &x1, &y1, &x2, &y2);
   max_x = (float) hb_max ((x1 - (double) cx) * (x1 - (double) cx), (x2 - (double) cx) * (x2 - (double) cx));
   max_y = (float) hb_max ((y1 - (double) cy) * (y1 - (double) cy), (y2 - (double) cy) * (y2 - (double) cy));
   radius = sqrtf (max_x + max_y);

   extend = hb_cairo_extend (hb_color_line_get_extend (color_line));
   pattern = cairo_pattern_create_mesh ();

   _hb_cairo_add_sweep_gradient_patches (stops, len, extend, cx, cy,
 					radius, start_angle, end_angle, pattern);

   cairo_set_source (cr, pattern);
   cairo_paint (cr);

   cairo_pattern_destroy (pattern);

   if (stops != stops_)
     hb_free (stops);
 }

 #endif
	/*
	* Copyright © 2022 Red Hat, Inc
	*
	* This is part of HarfBuzz, a text shaping library.
	*
	* Permission is hereby granted, without written agreement and without
	* license or royalty fees, to use, copy, modify, and distribute this
	* software and its documentation for any purpose, provided that the
	* above copyright notice and the following two paragraphs appear in
	* all copies of this software.
	*
	* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
	* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
	* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
	* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
	* DAMAGE.
	*
	* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
	* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
	* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
	* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
	* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
	*
	* Google Author(s): Matthias Clasen
	*/

	#include "hb.hh"

	#ifdef HAVE_CAIRO

	#include "hb-cairo-utils.hh"

	#include <cairo.h>

	#define PREALLOCATED_COLOR_STOPS 16

	#define _2_M_PIf (2.f * float (M_PI))

	typedef struct {
	float r, g, b, a;
	} hb_cairo_color_t;

	static inline cairo_extend_t
	hb_cairo_extend (hb_paint_extend_t extend)
	{
	switch (extend)
	{
	case HB_PAINT_EXTEND_PAD: return CAIRO_EXTEND_PAD;
	case HB_PAINT_EXTEND_REPEAT: return CAIRO_EXTEND_REPEAT;
	case HB_PAINT_EXTEND_REFLECT: return CAIRO_EXTEND_REFLECT;
	default: break;
	}

	return CAIRO_EXTEND_PAD;
	}

	#ifdef CAIRO_HAS_PNG_FUNCTIONS
	typedef struct
	{
	hb_blob_t *blob;
	unsigned int offset;
	} hb_cairo_read_blob_data_t;

	static cairo_status_t
	hb_cairo_read_blob (void *closure,
	unsigned char *data,
	unsigned int length)
	{
	hb_cairo_read_blob_data_t r = (hb_cairo_read_blob_data_t ) closure;
	const char *d;
	unsigned int size;

	d = hb_blob_get_data (r->blob, &size);

	if (r->offset + length > size)
	return CAIRO_STATUS_READ_ERROR;

	memcpy (data, d + r->offset, length);
	r->offset += length;

	return CAIRO_STATUS_SUCCESS;
	}
	#endif

	static const cairo_user_data_key_t *_hb_cairo_surface_blob_user_data_key = {0};

	static void
	_hb_cairo_destroy_blob (void *p)
	{
	hb_blob_destroy ((hb_blob_t *) p);
	}

	hb_bool_t
	_hb_cairo_paint_glyph_image (hb_cairo_context_t *c,
	hb_blob_t *blob,
	unsigned width,
	unsigned height,
	hb_tag_t format,
	float slant,
	hb_glyph_extents_t *extents)
	{
	cairo_t *cr = c->cr;

	if (!extents) /* SVG currently. */
	return false;

	cairo_surface_t *surface = nullptr;

	#ifdef CAIRO_HAS_PNG_FUNCTIONS
	if (format == HB_PAINT_IMAGE_FORMAT_PNG)
	{
	hb_cairo_read_blob_data_t r;
	r.blob = blob;
	r.offset = 0;
	surface = cairo_image_surface_create_from_png_stream (hb_cairo_read_blob, &r);

	/* For PNG, width,height can be unreliable, as is the case for NotoColorEmoji :(.
	* Just pull them out of the surface. */
	width = cairo_image_surface_get_width (surface);
	height = cairo_image_surface_get_width (surface);
	}
	else
	#endif
	if (format == HB_PAINT_IMAGE_FORMAT_BGRA)
	{
	/* Byte-endian conversion. */
	unsigned data_size = hb_blob_get_length (blob);
	if (data_size < width * height * 4)
	return false;

	unsigned char *data;
	#ifdef __BYTE_ORDER
	if (__BYTE_ORDER == __BIG_ENDIAN)
	{
	data = (unsigned char *) hb_blob_get_data_writable (blob, nullptr);
	if (!data)
	return false;

	unsigned count = width * height * 4;
	for (unsigned i = 0; i < count; i += 4)
	{
	unsigned char b;
	b = data[i];
	data[i] = data[i+3];
	data[i+3] = b;
	b = data[i+1];
	data[i+1] = data[i+2];
	data[i+2] = b;
	}
	}
	else
	#endif
	data = (unsigned char *) hb_blob_get_data (blob, nullptr);

	surface = cairo_image_surface_create_for_data (data,
	CAIRO_FORMAT_ARGB32,
	width, height,
	width * 4);

	cairo_surface_set_user_data (surface,
	_hb_cairo_surface_blob_user_data_key,
	hb_blob_reference (blob),
	_hb_cairo_destroy_blob);
	}

	if (!surface)
	return false;

	cairo_save (cr);
	/* this clip is here to work around recording surface limitations */
	cairo_rectangle (cr,
	extents->x_bearing,
	extents->y_bearing,
	extents->width,
	extents->height);
	cairo_clip (cr);

	cairo_pattern_t *pattern = cairo_pattern_create_for_surface (surface);
	cairo_pattern_set_extend (pattern, CAIRO_EXTEND_PAD);

	cairo_matrix_t matrix = {(double) width, 0, 0, (double) height, 0, 0};
	cairo_pattern_set_matrix (pattern, &matrix);

	/* Undo slant in the extents and apply it in the context. */
	extents->width -= extents->height * slant;
	extents->x_bearing -= extents->y_bearing * slant;
	cairo_matrix_t cairo_matrix = {1., 0., (double) slant, 1., 0., 0.};
	cairo_transform (cr, &cairo_matrix);

	cairo_translate (cr, extents->x_bearing, extents->y_bearing);
	cairo_scale (cr, extents->width, extents->height);
	cairo_set_source (cr, pattern);

	cairo_paint (cr);

	cairo_pattern_destroy (pattern);
	cairo_surface_destroy (surface);

	cairo_restore (cr);

	return true;
	}

	static void
	_hb_cairo_reduce_anchors (float x0, float y0,
	float x1, float y1,
	float x2, float y2,
	float xx0, float yy0,
	float xx1, float yy1)
	{
	float q1x, q1y, q2x, q2y;
	float s;
	float k;

	q2x = x2 - x0;
	q2y = y2 - y0;
	q1x = x1 - x0;
	q1y = y1 - y0;

	s = q2x * q2x + q2y * q2y;
	if (s < 0.000001f)
	{
	xx0 = x0; yy0 = y0;
	xx1 = x1; yy1 = y1;
	return;
	}

	k = (q2x * q1x + q2y * q1y) / s;
	*xx0 = x0;
	*yy0 = y0;
	xx1 = x1 - k q2x;
	yy1 = y1 - k q2y;
	}

	static int
	_hb_cairo_cmp_color_stop (const void *p1,
	const void *p2)
	{
	const hb_color_stop_t c1 = (const hb_color_stop_t ) p1;
	const hb_color_stop_t c2 = (const hb_color_stop_t ) p2;

	if (c1->offset < c2->offset)
	return -1;
	else if (c1->offset > c2->offset)
	return 1;
	else
	return 0;
	}

	static void
	_hb_cairo_normalize_color_line (hb_color_stop_t *stops,
	unsigned int len,
	float *omin,
	float *omax)
	{
	float min, max;

	hb_qsort (stops, len, sizeof (hb_color_stop_t), _hb_cairo_cmp_color_stop);

	min = max = stops[0].offset;
	for (unsigned int i = 0; i < len; i++)
	{
	min = hb_min (min, stops[i].offset);
	max = hb_max (max, stops[i].offset);
	}

	if (min != max)
	{
	for (unsigned int i = 0; i < len; i++)
	stops[i].offset = (stops[i].offset - min) / (max - min);
	}

	*omin = min;
	*omax = max;
	}

	void
	_hb_cairo_paint_linear_gradient (hb_cairo_context_t *c,
	hb_color_line_t *color_line,
	float x0, float y0,
	float x1, float y1,
	float x2, float y2)
	{
	cairo_t *cr = c->cr;

	hb_color_stop_t stops_[PREALLOCATED_COLOR_STOPS];
	hb_color_stop_t *stops = stops_;
	unsigned int len;
	float xx0, yy0, xx1, yy1;
	float xxx0, yyy0, xxx1, yyy1;
	float min, max;
	cairo_pattern_t *pattern;

	len = hb_color_line_get_color_stops (color_line, 0, nullptr, nullptr);
	if (len > PREALLOCATED_COLOR_STOPS)
	stops = (hb_color_stop_t ) hb_malloc (len sizeof (hb_color_stop_t));
	hb_color_line_get_color_stops (color_line, 0, &len, stops);

	_hb_cairo_reduce_anchors (x0, y0, x1, y1, x2, y2, &xx0, &yy0, &xx1, &yy1);
	_hb_cairo_normalize_color_line (stops, len, &min, &max);

	xxx0 = xx0 + min * (xx1 - xx0);
	yyy0 = yy0 + min * (yy1 - yy0);
	xxx1 = xx0 + max * (xx1 - xx0);
	yyy1 = yy0 + max * (yy1 - yy0);

	pattern = cairo_pattern_create_linear ((double) xxx0, (double) yyy0, (double) xxx1, (double) yyy1);
	cairo_pattern_set_extend (pattern, hb_cairo_extend (hb_color_line_get_extend (color_line)));
	for (unsigned int i = 0; i < len; i++)
	{
	double r, g, b, a;
	r = hb_color_get_red (stops[i].color) / 255.;
	g = hb_color_get_green (stops[i].color) / 255.;
	b = hb_color_get_blue (stops[i].color) / 255.;
	a = hb_color_get_alpha (stops[i].color) / 255.;
	cairo_pattern_add_color_stop_rgba (pattern, (double) stops[i].offset, r, g, b, a);
	}

	cairo_set_source (cr, pattern);
	cairo_paint (cr);

	cairo_pattern_destroy (pattern);

	if (stops != stops_)
	hb_free (stops);
	}

	void
	_hb_cairo_paint_radial_gradient (hb_cairo_context_t *c,
	hb_color_line_t *color_line,
	float x0, float y0, float r0,
	float x1, float y1, float r1)
	{
	cairo_t *cr = c->cr;

	hb_color_stop_t stops_[PREALLOCATED_COLOR_STOPS];
	hb_color_stop_t *stops = stops_;
	unsigned int len;
	float min, max;
	float xx0, yy0, xx1, yy1;
	float rr0, rr1;
	cairo_pattern_t *pattern;

	len = hb_color_line_get_color_stops (color_line, 0, nullptr, nullptr);
	if (len > PREALLOCATED_COLOR_STOPS)
	stops = (hb_color_stop_t ) hb_malloc (len sizeof (hb_color_stop_t));
	hb_color_line_get_color_stops (color_line, 0, &len, stops);

	_hb_cairo_normalize_color_line (stops, len, &min, &max);

	xx0 = x0 + min * (x1 - x0);
	yy0 = y0 + min * (y1 - y0);
	xx1 = x0 + max * (x1 - x0);
	yy1 = y0 + max * (y1 - y0);
	rr0 = r0 + min * (r1 - r0);
	rr1 = r0 + max * (r1 - r0);

	pattern = cairo_pattern_create_radial ((double) xx0, (double) yy0, (double) rr0, (double) xx1, (double) yy1, (double) rr1);
	cairo_pattern_set_extend (pattern, hb_cairo_extend (hb_color_line_get_extend (color_line)));

	for (unsigned int i = 0; i < len; i++)
	{
	double r, g, b, a;
	r = hb_color_get_red (stops[i].color) / 255.;
	g = hb_color_get_green (stops[i].color) / 255.;
	b = hb_color_get_blue (stops[i].color) / 255.;
	a = hb_color_get_alpha (stops[i].color) / 255.;
	cairo_pattern_add_color_stop_rgba (pattern, (double) stops[i].offset, r, g, b, a);
	}

	cairo_set_source (cr, pattern);
	cairo_paint (cr);

	cairo_pattern_destroy (pattern);

	if (stops != stops_)
	hb_free (stops);
	}

	typedef struct {
	float x, y;
	} hb_cairo_point_t;

	static inline float
	_hb_cairo_interpolate (float f0, float f1, float f)
	{
	return f0 + f * (f1 - f0);
	}

	static inline void
	_hb_cairo_premultiply (hb_cairo_color_t *c)
	{
	c->r *= c->a;
	c->g *= c->a;
	c->b *= c->a;
	}

	static inline void
	_hb_cairo_unpremultiply (hb_cairo_color_t *c)
	{
	if (c->a != 0.f)
	{
	c->r /= c->a;
	c->g /= c->a;
	c->b /= c->a;
	}
	}

	static void
	_hb_cairo_interpolate_colors (hb_cairo_color_t c0, hb_cairo_color_t c1, float k, hb_cairo_color_t *c)
	{
	// According to the COLR specification, gradients
	// should be interpolated in premultiplied form
	_hb_cairo_premultiply (c0);
	_hb_cairo_premultiply (c1);
	c->r = c0->r + k * (c1->r - c0->r);
	c->g = c0->g + k * (c1->g - c0->g);
	c->b = c0->b + k * (c1->b - c0->b);
	c->a = c0->a + k * (c1->a - c0->a);
	_hb_cairo_unpremultiply (c);
	}

	static inline float
	_hb_cairo_dot (hb_cairo_point_t p, hb_cairo_point_t q)
	{
	return p.x * q.x + p.y * q.y;
	}

	static inline hb_cairo_point_t
	_hb_cairo_normalize (hb_cairo_point_t p)
	{
	float len = sqrtf (_hb_cairo_dot (p, p));

	return hb_cairo_point_t { p.x / len, p.y / len };
	}

	static inline hb_cairo_point_t
	_hb_cairo_sum (hb_cairo_point_t p, hb_cairo_point_t q)
	{
	return hb_cairo_point_t { p.x + q.x, p.y + q.y };
	}

	static inline hb_cairo_point_t
	_hb_cairo_difference (hb_cairo_point_t p, hb_cairo_point_t q)
	{
	return hb_cairo_point_t { p.x - q.x, p.y - q.y };
	}

	static inline hb_cairo_point_t
	_hb_cairo_scale (hb_cairo_point_t p, float f)
	{
	return hb_cairo_point_t { p.x * f, p.y * f };
	}

	typedef struct {
	hb_cairo_point_t center, p0, c0, c1, p1;
	hb_cairo_color_t color0, color1;
	} hb_cairo_patch_t;

	static void
	_hb_cairo_add_patch (cairo_pattern_t pattern, hb_cairo_point_t center, hb_cairo_patch_t *p)
	{
	cairo_mesh_pattern_begin_patch (pattern);
	cairo_mesh_pattern_move_to (pattern, (double) center->x, (double) center->y);
	cairo_mesh_pattern_line_to (pattern, (double) p->p0.x, (double) p->p0.y);
	cairo_mesh_pattern_curve_to (pattern,
	(double) p->c0.x, (double) p->c0.y,
	(double) p->c1.x, (double) p->c1.y,
	(double) p->p1.x, (double) p->p1.y);
	cairo_mesh_pattern_line_to (pattern, (double) center->x, (double) center->y);
	cairo_mesh_pattern_set_corner_color_rgba (pattern, 0,
	(double) p->color0.r,
	(double) p->color0.g,
	(double) p->color0.b,
	(double) p->color0.a);
	cairo_mesh_pattern_set_corner_color_rgba (pattern, 1,
	(double) p->color0.r,
	(double) p->color0.g,
	(double) p->color0.b,
	(double) p->color0.a);
	cairo_mesh_pattern_set_corner_color_rgba (pattern, 2,
	(double) p->color1.r,
	(double) p->color1.g,
	(double) p->color1.b,
	(double) p->color1.a);
	cairo_mesh_pattern_set_corner_color_rgba (pattern, 3,
	(double) p->color1.r,
	(double) p->color1.g,
	(double) p->color1.b,
	(double) p->color1.a);
	cairo_mesh_pattern_end_patch (pattern);
	}

	#define MAX_ANGLE ((float) M_PI / 8.f)

	static void
	_hb_cairo_add_sweep_gradient_patches1 (float cx, float cy, float radius,
	float a0, hb_cairo_color_t *c0,
	float a1, hb_cairo_color_t *c1,
	cairo_pattern_t *pattern)
	{
	hb_cairo_point_t center = hb_cairo_point_t { cx, cy };
	int num_splits;
	hb_cairo_point_t p0;
	hb_cairo_color_t color0, color1;

	num_splits = ceilf (fabsf (a1 - a0) / MAX_ANGLE);
	p0 = hb_cairo_point_t { cosf (a0), sinf (a0) };
	color0 = *c0;

	for (int a = 0; a < num_splits; a++)
	{
	float k = (a + 1.) / num_splits;
	float angle1;
	hb_cairo_point_t p1;
	hb_cairo_point_t A, U;
	hb_cairo_point_t C0, C1;
	hb_cairo_patch_t patch;

	angle1 = _hb_cairo_interpolate (a0, a1, k);
	_hb_cairo_interpolate_colors (c0, c1, k, &color1);

	patch.color0 = color0;
	patch.color1 = color1;

	p1 = hb_cairo_point_t { cosf (angle1), sinf (angle1) };
	patch.p0 = _hb_cairo_sum (center, _hb_cairo_scale (p0, radius));
	patch.p1 = _hb_cairo_sum (center, _hb_cairo_scale (p1, radius));

	A = _hb_cairo_normalize (_hb_cairo_sum (p0, p1));
	U = hb_cairo_point_t { -A.y, A.x };
	C0 = _hb_cairo_sum (A, _hb_cairo_scale (U, _hb_cairo_dot (_hb_cairo_difference (p0, A), p0) / _hb_cairo_dot (U, p0)));
	C1 = _hb_cairo_sum (A, _hb_cairo_scale (U, _hb_cairo_dot (_hb_cairo_difference (p1, A), p1) / _hb_cairo_dot (U, p1)));

	patch.c0 = _hb_cairo_sum (center, _hb_cairo_scale (_hb_cairo_sum (C0, _hb_cairo_scale (_hb_cairo_difference (C0, p0), 0.33333f)), radius));
	patch.c1 = _hb_cairo_sum (center, _hb_cairo_scale (_hb_cairo_sum (C1, _hb_cairo_scale (_hb_cairo_difference (C1, p1), 0.33333f)), radius));

	_hb_cairo_add_patch (pattern, &center, &patch);

	p0 = p1;
	color0 = color1;
	}
	}

	static void
	_hb_cairo_add_sweep_gradient_patches (hb_color_stop_t *stops,
	unsigned int n_stops,
	cairo_extend_t extend,
	float cx, float cy,
	float radius,
	float start_angle,
	float end_angle,
	cairo_pattern_t *pattern)
	{
	float angles_[PREALLOCATED_COLOR_STOPS];
	float *angles = angles_;
	hb_cairo_color_t colors_[PREALLOCATED_COLOR_STOPS];
	hb_cairo_color_t *colors = colors_;
	hb_cairo_color_t color0, color1;

	if (start_angle == end_angle)
	{
	if (extend == CAIRO_EXTEND_PAD)
	{
	hb_cairo_color_t c;
	if (start_angle > 0)
	{
	c.r = hb_color_get_red (stops[0].color) / 255.;
	c.g = hb_color_get_green (stops[0].color) / 255.;
	c.b = hb_color_get_blue (stops[0].color) / 255.;
	c.a = hb_color_get_alpha (stops[0].color) / 255.;
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	0., &c,
	start_angle, &c,
	pattern);
	}
	if (end_angle < _2_M_PIf)
	{
	c.r = hb_color_get_red (stops[n_stops - 1].color) / 255.;
	c.g = hb_color_get_green (stops[n_stops - 1].color) / 255.;
	c.b = hb_color_get_blue (stops[n_stops - 1].color) / 255.;
	c.a = hb_color_get_alpha (stops[n_stops - 1].color) / 255.;
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	end_angle, &c,
	_2_M_PIf, &c,
	pattern);
	}
	}
	return;
	}

	assert (start_angle != end_angle);

	/* handle directions */
	if (end_angle < start_angle)
	{
	hb_swap (start_angle, end_angle);

	for (unsigned i = 0; i < n_stops - 1 - i; i++)
	hb_swap (stops[i], stops[n_stops - 1 - i]);
	for (unsigned i = 0; i < n_stops; i++)
	stops[i].offset = 1 - stops[i].offset;
	}

	if (n_stops > PREALLOCATED_COLOR_STOPS)
	{
	angles = (float ) hb_malloc (sizeof (float) n_stops);
	colors = (hb_cairo_color_t ) hb_malloc (sizeof (hb_cairo_color_t) n_stops);
	}

	for (unsigned i = 0; i < n_stops; i++)
	{
	angles[i] = start_angle + stops[i].offset * (end_angle - start_angle);
	colors[i].r = hb_color_get_red (stops[i].color) / 255.;
	colors[i].g = hb_color_get_green (stops[i].color) / 255.;
	colors[i].b = hb_color_get_blue (stops[i].color) / 255.;
	colors[i].a = hb_color_get_alpha (stops[i].color) / 255.;
	}

	if (extend == CAIRO_EXTEND_PAD)
	{
	unsigned pos;

	color0 = colors[0];
	for (pos = 0; pos < n_stops; pos++)
	{
	if (angles[pos] >= 0)
	{
	if (pos > 0)
	{
	float k = (0 - angles[pos - 1]) / (angles[pos] - angles[pos - 1]);
	_hb_cairo_interpolate_colors (&colors[pos-1], &colors[pos], k, &color0);
	}
	break;
	}
	}
	if (pos == n_stops)
	{
	/* everything is below 0 */
	color0 = colors[n_stops-1];
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	0., &color0,
	_2_M_PIf, &color0,
	pattern);
	goto done;
	}

	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	0., &color0,
	angles[pos], &colors[pos],
	pattern);

	for (pos++; pos < n_stops; pos++)
	{
	if (angles[pos] <= _2_M_PIf)
	{
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	angles[pos - 1], &colors[pos-1],
	angles[pos], &colors[pos],
	pattern);
	}
	else
	{
	float k = (_2_M_PIf - angles[pos - 1]) / (angles[pos] - angles[pos - 1]);
	_hb_cairo_interpolate_colors (&colors[pos - 1], &colors[pos], k, &color1);
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	angles[pos - 1], &colors[pos - 1],
	_2_M_PIf, &color1,
	pattern);
	break;
	}
	}

	if (pos == n_stops)
	{
	/* everything is below 2M_PI /
	color0 = colors[n_stops - 1];
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	angles[n_stops - 1], &color0,
	_2_M_PIf, &color0,
	pattern);
	goto done;
	}
	}
	else
	{
	int k;
	float span;

	span = angles[n_stops - 1] - angles[0];
	k = 0;
	if (angles[0] >= 0)
	{
	float ss = angles[0];
	while (ss > 0)
	{
	if (span > 0)
	{
	ss -= span;
	k--;
	}
	else
	{
	ss += span;
	k++;
	}
	}
	}
	else if (angles[0] < 0)
	{
	float ee = angles[n_stops - 1];
	while (ee < 0)
	{
	if (span > 0)
	{
	ee += span;
	k++;
	}
	else
	{
	ee -= span;
	k--;
	}
	}
	}

	//assert (angles[0] + k * span <= 0 && 0 < angles[n_stops - 1] + k * span);
	span = fabs (span);

	for (signed l = k; l < 1000; l++)
	{
	for (unsigned i = 1; i < n_stops; i++)
	{
	float a0, a1;
	hb_cairo_color_t c0, c1;

	if ((l % 2 != 0) && (extend == CAIRO_EXTEND_REFLECT))
	{
	a0 = angles[0] + angles[n_stops - 1] - angles[n_stops - 1 - (i-1)] + l * span;
	a1 = angles[0] + angles[n_stops - 1] - angles[n_stops - 1 - i] + l * span;
	c0 = &colors[n_stops - 1 - (i - 1)];
	c1 = &colors[n_stops - 1 - i];
	}
	else
	{
	a0 = angles[i-1] + l * span;
	a1 = angles[i] + l * span;
	c0 = &colors[i-1];
	c1 = &colors[i];
	}

	if (a1 < 0)
	continue;
	if (a0 < 0)
	{
	hb_cairo_color_t color;
	float f = (0 - a0)/(a1 - a0);
	_hb_cairo_interpolate_colors (c0, c1, f, &color);
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	0, &color,
	a1, c1,
	pattern);
	}
	else if (a1 >= _2_M_PIf)
	{
	hb_cairo_color_t color;
	float f = (_2_M_PIf - a0)/(a1 - a0);
	_hb_cairo_interpolate_colors (c0, c1, f, &color);
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	a0, c0,
	_2_M_PIf, &color,
	pattern);
	goto done;
	}
	else
	{
	_hb_cairo_add_sweep_gradient_patches1 (cx, cy, radius,
	a0, c0,
	a1, c1,
	pattern);
	}
	}
	}
	}

	done:

	if (angles != angles_)
	hb_free (angles);
	if (colors != colors_)
	hb_free (colors);
	}

	void
	_hb_cairo_paint_sweep_gradient (hb_cairo_context_t *c,
	hb_color_line_t *color_line,
	float cx, float cy,
	float start_angle,
	float end_angle)
	{
	cairo_t *cr = c->cr;

	unsigned int len;
	hb_color_stop_t stops_[PREALLOCATED_COLOR_STOPS];
	hb_color_stop_t *stops = stops_;
	cairo_extend_t extend;
	double x1, y1, x2, y2;
	float max_x, max_y, radius;
	cairo_pattern_t *pattern;

	len = hb_color_line_get_color_stops (color_line, 0, nullptr, nullptr);
	if (len > PREALLOCATED_COLOR_STOPS)
	stops = (hb_color_stop_t ) hb_malloc (len sizeof (hb_color_stop_t));
	hb_color_line_get_color_stops (color_line, 0, &len, stops);

	hb_qsort (stops, len, sizeof (hb_color_stop_t), _hb_cairo_cmp_color_stop);

	cairo_clip_extents (cr, &x1, &y1, &x2, &y2);
	max_x = (float) hb_max ((x1 - (double) cx) * (x1 - (double) cx), (x2 - (double) cx) * (x2 - (double) cx));
	max_y = (float) hb_max ((y1 - (double) cy) * (y1 - (double) cy), (y2 - (double) cy) * (y2 - (double) cy));
	radius = sqrtf (max_x + max_y);

	extend = hb_cairo_extend (hb_color_line_get_extend (color_line));
	pattern = cairo_pattern_create_mesh ();

	_hb_cairo_add_sweep_gradient_patches (stops, len, extend, cx, cy,
	radius, start_angle, end_angle, pattern);

	cairo_set_source (cr, pattern);
	cairo_paint (cr);

	cairo_pattern_destroy (pattern);

	if (stops != stops_)
	hb_free (stops);
	}

	#endif