text: /* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
  /* cairo - a vector graphics library with display and print output
   *
   * Copyright © 2002 University of Southern California
   * Copyright © 2005 Red Hat, Inc.
   * Copyright © 2009 Chris Wilson
   *
   * This library is free software; you can redistribute it and/or
   * modify it either under the terms of the GNU Lesser General Public
   * License version 2.1 as published by the Free Software Foundation
   * (the "LGPL") or, at your option, under the terms of the Mozilla
   * Public License Version 1.1 (the "MPL"). If you do not alter this
   * notice, a recipient may use your version of this file under either
   * the MPL or the LGPL.
   *
   * You should have received a copy of the LGPL along with this library
   * in the file COPYING-LGPL-2.1; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
   * You should have received a copy of the MPL along with this library
   * in the file COPYING-MPL-1.1
   *
   * The contents of this file are subject to the Mozilla Public License
   * Version 1.1 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   * http://www.mozilla.org/MPL/
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
   * OF ANY KIND, either express or implied. See the LGPL or the MPL for
   * the specific language governing rights and limitations.
   *
   * The Original Code is the cairo graphics library.
   *
   * The Initial Developer of the Original Code is University of Southern
   * California.
   *
   * Contributor(s):
   *	Carl D. Worth <cworth@cworth.org>
   *	Kristian Høgsberg <krh@redhat.com>
   *	Chris Wilson <chris@chris-wilson.co.uk>
   */
  
  #include "cairoint.h"
  #include "cairo-clip-inline.h"
  #include "cairo-clip-private.h"
  #include "cairo-error-private.h"
  #include "cairo-freed-pool-private.h"
  #include "cairo-gstate-private.h"
  #include "cairo-path-fixed-private.h"
  #include "cairo-pattern-private.h"
  #include "cairo-composite-rectangles-private.h"
  #include "cairo-region-private.h"
  
  static freed_pool_t clip_path_pool;
  static freed_pool_t clip_pool;
  
  const cairo_clip_t __cairo_clip_all;
  
  static cairo_clip_path_t *
  _cairo_clip_path_create (cairo_clip_t *clip)
  {
      cairo_clip_path_t *clip_path;
  
      clip_path = _freed_pool_get (&clip_path_pool);
      if (unlikely (clip_path == NULL)) {
  	clip_path = malloc (sizeof (cairo_clip_path_t));
  	if (unlikely (clip_path == NULL))
  	    return NULL;
      }
  
      CAIRO_REFERENCE_COUNT_INIT (&clip_path->ref_count, 1);
  
      clip_path->prev = clip->path;
      clip->path = clip_path;
  
      return clip_path;
  }
  
  cairo_clip_path_t *
  _cairo_clip_path_reference (cairo_clip_path_t *clip_path)
  {
      assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&clip_path->ref_count));
  
      _cairo_reference_count_inc (&clip_path->ref_count);
  
      return clip_path;
  }
  
  void
  _cairo_clip_path_destroy (cairo_clip_path_t *clip_path)
  {
      assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&clip_path->ref_count));
  
      if (! _cairo_reference_count_dec_and_test (&clip_path->ref_count))
  	return;
  
      _cairo_path_fixed_fini (&clip_path->path);
  
      if (clip_path->prev != NULL)
  	_cairo_clip_path_destroy (clip_path->prev);
  
      _freed_pool_put (&clip_path_pool, clip_path);
  }
  
  cairo_clip_t *
  _cairo_clip_create (void)
  {
      cairo_clip_t *clip;
  
      clip = _freed_pool_get (&clip_pool);
      if (unlikely (clip == NULL)) {
  	clip = malloc (sizeof (cairo_clip_t));
  	if (unlikely (clip == NULL))
  	    return NULL;
      }
  
      clip->extents = _cairo_unbounded_rectangle;
  
      clip->path = NULL;
      clip->boxes = NULL;
      clip->num_boxes = 0;
      clip->region = NULL;
      clip->is_region = FALSE;
  
      return clip;
  }
  
  void
  _cairo_clip_destroy (cairo_clip_t *clip)
  {
      if (clip == NULL || _cairo_clip_is_all_clipped (clip))
  	return;
  
      if (clip->path != NULL)
  	_cairo_clip_path_destroy (clip->path);
  
      if (clip->boxes != &clip->embedded_box)
  	free (clip->boxes);
      cairo_region_destroy (clip->region);
  
      _freed_pool_put (&clip_pool, clip);
  }
  
  cairo_clip_t *
  _cairo_clip_copy (const cairo_clip_t *clip)
  {
      cairo_clip_t *copy;
  
      if (clip == NULL || _cairo_clip_is_all_clipped (clip))
  	return (cairo_clip_t *) clip;
  
      copy = _cairo_clip_create ();
  
      if (clip->path)
  	copy->path = _cairo_clip_path_reference (clip->path);
  
      if (clip->num_boxes) {
  	if (clip->num_boxes == 1) {
  	    copy->boxes = &copy->embedded_box;
  	} else {
  	    copy->boxes = _cairo_malloc_ab (clip->num_boxes, sizeof (cairo_box_t));
  	    if (unlikely (copy->boxes == NULL))
  		return _cairo_clip_set_all_clipped (copy);
  	}
  
  	memcpy (copy->boxes, clip->boxes,
  		clip->num_boxes * sizeof (cairo_box_t));
  	copy->num_boxes = clip->num_boxes;
      }
  
      copy->extents = clip->extents;
      copy->region = cairo_region_reference (clip->region);
      copy->is_region = clip->is_region;
  
      return copy;
  }
  
  cairo_clip_t *
  _cairo_clip_copy_path (const cairo_clip_t *clip)
  {
      cairo_clip_t *copy;
  
      if (clip == NULL || _cairo_clip_is_all_clipped (clip))
  	return (cairo_clip_t *) clip;
  
      assert (clip->num_boxes);
  
      copy = _cairo_clip_create ();
      copy->extents = clip->extents;
      if (clip->path)
  	copy->path = _cairo_clip_path_reference (clip->path);
  
      return copy;
  }
  
  cairo_clip_t *
  _cairo_clip_copy_region (const cairo_clip_t *clip)
  {
      cairo_clip_t *copy;
      int i;
  
      if (clip == NULL || _cairo_clip_is_all_clipped (clip))
  	return (cairo_clip_t *) clip;
  
      assert (clip->num_boxes);
  
      copy = _cairo_clip_create ();
      copy->extents = clip->extents;
  
      if (clip->num_boxes == 1) {
  	copy->boxes = &copy->embedded_box;
      } else {
  	copy->boxes = _cairo_malloc_ab (clip->num_boxes, sizeof (cairo_box_t));
  	if (unlikely (copy->boxes == NULL))
  	    return _cairo_clip_set_all_clipped (copy);
      }
  
      for (i = 0; i < clip->num_boxes; i++) {
  	copy->boxes[i].p1.x = _cairo_fixed_floor (clip->boxes[i].p1.x);
  	copy->boxes[i].p1.y = _cairo_fixed_floor (clip->boxes[i].p1.y);
  	copy->boxes[i].p2.x = _cairo_fixed_ceil (clip->boxes[i].p2.x);
  	copy->boxes[i].p2.y = _cairo_fixed_ceil (clip->boxes[i].p2.y);
      }
      copy->num_boxes = clip->num_boxes;
  
      copy->region = cairo_region_reference (clip->region);
      copy->is_region = TRUE;
  
      return copy;
  }
  
  cairo_clip_t *
  _cairo_clip_intersect_path (cairo_clip_t       *clip,
  			    const cairo_path_fixed_t *path,
  			    cairo_fill_rule_t   fill_rule,
  			    double              tolerance,
  			    cairo_antialias_t   antialias)
  {
      cairo_clip_path_t *clip_path;
      cairo_status_t status;
      cairo_rectangle_int_t extents;
      cairo_box_t box;
  
      if (_cairo_clip_is_all_clipped (clip))
  	return clip;
  
      /* catch the empty clip path */
      if (_cairo_path_fixed_fill_is_empty (path))
  	return _cairo_clip_set_all_clipped (clip);
  
      if (_cairo_path_fixed_is_box (path, &box)) {
  	if (antialias == CAIRO_ANTIALIAS_NONE) {
  	    box.p1.x = _cairo_fixed_round_down (box.p1.x);
  	    box.p1.y = _cairo_fixed_round_down (box.p1.y);
  	    box.p2.x = _cairo_fixed_round_down (box.p2.x);
  	    box.p2.y = _cairo_fixed_round_down (box.p2.y);
  	}
  
  	return _cairo_clip_intersect_box (clip, &box);
      }
      if (_cairo_path_fixed_fill_is_rectilinear (path))
  	return _cairo_clip_intersect_rectilinear_path (clip, path,
  						       fill_rule, antialias);
  
      _cairo_path_fixed_approximate_clip_extents (path, &extents);
      if (extents.width == 0 || extents.height == 0)
  	return _cairo_clip_set_all_clipped (clip);
  
      clip = _cairo_clip_intersect_rectangle (clip, &extents);
      if (_cairo_clip_is_all_clipped (clip))
  	return clip;
  
      clip_path = _cairo_clip_path_create (clip);
      if (unlikely (clip_path == NULL))
  	return _cairo_clip_set_all_clipped (clip);
  
      status = _cairo_path_fixed_init_copy (&clip_path->path, path);
      if (unlikely (status))
  	return _cairo_clip_set_all_clipped (clip);
  
      clip_path->fill_rule = fill_rule;
      clip_path->tolerance = tolerance;
      clip_path->antialias = antialias;
  
      if (clip->region) {
  	cairo_region_destroy (clip->region);
  	clip->region = NULL;
      }
  
      clip->is_region = FALSE;
      return clip;
  }
  
  static cairo_clip_t *
  _cairo_clip_intersect_clip_path (cairo_clip_t *clip,
  				 const cairo_clip_path_t *clip_path)
  {
      if (clip_path->prev)
  	clip = _cairo_clip_intersect_clip_path (clip, clip_path->prev);
  
      return _cairo_clip_intersect_path (clip,
  				       &clip_path->path,
  				       clip_path->fill_rule,
  				       clip_path->tolerance,
  				       clip_path->antialias);
  }
  
  cairo_clip_t *
  _cairo_clip_intersect_clip (cairo_clip_t *clip,
  			    const cairo_clip_t *other)
  {
      if (_cairo_clip_is_all_clipped (clip))
  	return clip;
  
      if (other == NULL)
  	return clip;
  
      if (clip == NULL)
  	return _cairo_clip_copy (other);
  
      if (_cairo_clip_is_all_clipped (other))
  	return _cairo_clip_set_all_clipped (clip);
  
      if (! _cairo_rectangle_intersect (&clip->extents, &other->extents))
  	return _cairo_clip_set_all_clipped (clip);
  
      if (other->num_boxes) {
  	cairo_boxes_t boxes;
  
  	_cairo_boxes_init_for_array (&boxes, other->boxes, other->num_boxes);
  	clip = _cairo_clip_intersect_boxes (clip, &boxes);
      }
  
      if (! _cairo_clip_is_all_clipped (clip)) {
  	if (other->path) {
  	    if (clip->path == NULL)
  		clip->path = _cairo_clip_path_reference (other->path);
  	    else
  		clip = _cairo_clip_intersect_clip_path (clip, other->path);
  	}
      }
  
      if (clip->region) {
  	cairo_region_destroy (clip->region);
  	clip->region = NULL;
      }
      clip->is_region = FALSE;
  
      return clip;
  }
  
  cairo_bool_t
  _cairo_clip_equal (const cairo_clip_t *clip_a,
  		   const cairo_clip_t *clip_b)
  {
      const cairo_clip_path_t *cp_a, *cp_b;
  
      /* are both all-clipped or no-clip? */
      if (clip_a == clip_b)
  	return TRUE;
  
      /* or just one of them? */
      if (clip_a == NULL || clip_b == NULL ||
  	_cairo_clip_is_all_clipped (clip_a) ||
  	_cairo_clip_is_all_clipped (clip_b))
      {
  	return FALSE;
      }
  
      /* We have a pair of normal clips, check their contents */
  
      if (clip_a->num_boxes != clip_b->num_boxes)
  	return FALSE;
  
      if (memcmp (clip_a->boxes, clip_b->boxes,
  		sizeof (cairo_box_t) * clip_a->num_boxes))
  	return FALSE;
  
      cp_a = clip_a->path;
      cp_b = clip_b->path;
      while (cp_a && cp_b) {
  	if (cp_a == cp_b)
  	    return TRUE;
  
  	/* XXX compare reduced polygons? */
  
  	if (cp_a->antialias != cp_b->antialias)
  	    return FALSE;
  
  	if (cp_a->tolerance != cp_b->tolerance)
  	    return FALSE;
  
  	if (cp_a->fill_rule != cp_b->fill_rule)
  	    return FALSE;
  
  	if (! _cairo_path_fixed_equal (&cp_a->path,
  				       &cp_b->path))
  	    return FALSE;
  
  	cp_a = cp_a->prev;
  	cp_b = cp_b->prev;
      }
  
      return cp_a == NULL && cp_b == NULL;
  }
  
  static cairo_clip_t *
  _cairo_clip_path_copy_with_translation (cairo_clip_t      *clip,
  					cairo_clip_path_t *other_path,
  					int fx, int fy)
  {
      cairo_status_t status;
      cairo_clip_path_t *clip_path;
  
      if (other_path->prev != NULL)
  	clip = _cairo_clip_path_copy_with_translation (clip, other_path->prev,
  						       fx, fy);
      if (_cairo_clip_is_all_clipped (clip))
  	return clip;
  
      clip_path = _cairo_clip_path_create (clip);
      if (unlikely (clip_path == NULL))
  	return _cairo_clip_set_all_clipped (clip);
  
      status = _cairo_path_fixed_init_copy (&clip_path->path,
  					  &other_path->path);
      if (unlikely (status))
  	return _cairo_clip_set_all_clipped (clip);
  
      _cairo_path_fixed_translate (&clip_path->path, fx, fy);
  
      clip_path->fill_rule = other_path->fill_rule;
      clip_path->tolerance = other_path->tolerance;
      clip_path->antialias = other_path->antialias;
  
      return clip;
  }
  
  cairo_clip_t *
  _cairo_clip_translate (cairo_clip_t *clip, int tx, int ty)
  {
      int fx, fy, i;
      cairo_clip_path_t *clip_path;
  
      if (clip == NULL || _cairo_clip_is_all_clipped (clip))
  	return clip;
  
      if (tx == 0 && ty == 0)
  	return clip;
  
      fx = _cairo_fixed_from_int (tx);
      fy = _cairo_fixed_from_int (ty);
  
      for (i = 0; i < clip->num_boxes; i++) {
  	clip->boxes[i].p1.x += fx;
  	clip->boxes[i].p2.x += fx;
  	clip->boxes[i].p1.y += fy;
  	clip->boxes[i].p2.y += fy;
      }
  
      clip->extents.x += tx;
      clip->extents.y += ty;
  
      if (clip->path == NULL)
  	return clip;
  
      clip_path = clip->path;
      clip->path = NULL;
      clip = _cairo_clip_path_copy_with_translation (clip, clip_path, fx, fy);
      _cairo_clip_path_destroy (clip_path);
  
      return clip;
  }
  
  static cairo_status_t
  _cairo_path_fixed_add_box (cairo_path_fixed_t *path,
  			   const cairo_box_t *box)
  {
      cairo_status_t status;
  
      status = _cairo_path_fixed_move_to (path, box->p1.x, box->p1.y);
      if (unlikely (status))
  	return status;
  
      status = _cairo_path_fixed_line_to (path, box->p2.x, box->p1.y);
      if (unlikely (status))
  	return status;
  
      status = _cairo_path_fixed_line_to (path, box->p2.x, box->p2.y);
      if (unlikely (status))
  	return status;
  
      status = _cairo_path_fixed_line_to (path, box->p1.x, box->p2.y);
      if (unlikely (status))
  	return status;
  
      return _cairo_path_fixed_close_path (path);
  }
  
  static cairo_status_t
  _cairo_path_fixed_init_from_boxes (cairo_path_fixed_t *path,
  				   const cairo_boxes_t *boxes)
  {
      cairo_status_t status;
      const struct _cairo_boxes_chunk *chunk;
      int i;
  
      _cairo_path_fixed_init (path);
      if (boxes->num_boxes == 0)
  	return CAIRO_STATUS_SUCCESS;
  
      for (chunk = &boxes->chunks; chunk; chunk = chunk->next) {
  	for (i = 0; i < chunk->count; i++) {
  	    status = _cairo_path_fixed_add_box (path, &chunk->base[i]);
  	    if (unlikely (status)) {
  		_cairo_path_fixed_fini (path);
  		return status;
  	    }
  	}
      }
  
      return CAIRO_STATUS_SUCCESS;
  }
  
  static cairo_clip_t *
  _cairo_clip_intersect_clip_path_transformed (cairo_clip_t *clip,
  					     const cairo_clip_path_t *clip_path,
  					     const cairo_matrix_t *m)
  {
      cairo_path_fixed_t path;
  
      if (clip_path->prev)
  	clip = _cairo_clip_intersect_clip_path_transformed (clip,
  							    clip_path->prev,
  							    m);
  
      if (_cairo_path_fixed_init_copy (&path, &clip_path->path))
  	return _cairo_clip_set_all_clipped (clip);
  
      _cairo_path_fixed_transform (&path, m);
  
      clip =  _cairo_clip_intersect_path (clip,
  				       &path,
  				       clip_path->fill_rule,
  				       clip_path->tolerance,
  				       clip_path->antialias);
      _cairo_path_fixed_fini (&path);
  
      return clip;
  }
  
  cairo_clip_t *
  _cairo_clip_transform (cairo_clip_t *clip, const cairo_matrix_t *m)
  {
      cairo_clip_t *copy;
  
      if (clip == NULL || _cairo_clip_is_all_clipped (clip))
  	return clip;
  
      if (_cairo_matrix_is_translation (m))
  	return _cairo_clip_translate (clip, m->x0, m->y0);
  
      copy = _cairo_clip_create ();
  
      if (clip->num_boxes) {
  	cairo_path_fixed_t path;
  	cairo_boxes_t boxes;
  
  	_cairo_boxes_init_for_array (&boxes, clip->boxes, clip->num_boxes);
  	_cairo_path_fixed_init_from_boxes (&path, &boxes);
  	_cairo_path_fixed_transform (&path, m);
  
  	copy = _cairo_clip_intersect_path (copy, &path,
  					   CAIRO_FILL_RULE_WINDING,
  					   0.1,
  					   CAIRO_ANTIALIAS_DEFAULT);
  
  	_cairo_path_fixed_fini (&path);
      }
  
      if (clip->path)
  	copy = _cairo_clip_intersect_clip_path_transformed (copy, clip->path,m);
  
      _cairo_clip_destroy (clip);
      return copy;
  }
  
  cairo_clip_t *
  _cairo_clip_copy_with_translation (const cairo_clip_t *clip, int tx, int ty)
  {
      cairo_clip_t *copy;
      int fx, fy, i;
  
      if (clip == NULL || _cairo_clip_is_all_clipped (clip))
  	return (cairo_clip_t *)clip;
  
      if (tx == 0 && ty == 0)
  	return _cairo_clip_copy (clip);
  
      copy = _cairo_clip_create ();
      if (copy == NULL)
  	    return _cairo_clip_set_all_clipped (copy);
  
      fx = _cairo_fixed_from_int (tx);
      fy = _cairo_fixed_from_int (ty);
  
      if (clip->num_boxes) {
  	if (clip->num_boxes == 1) {
  	    copy->boxes = &copy->embedded_box;
  	} else {
  	    copy->boxes = _cairo_malloc_ab (clip->num_boxes, sizeof (cairo_box_t));
  	    if (unlikely (copy->boxes == NULL))
  		return _cairo_clip_set_all_clipped (copy);
  	}
  
  	for (i = 0; i < clip->num_boxes; i++) {
  	    copy->boxes[i].p1.x = clip->boxes[i].p1.x + fx;
  	    copy->boxes[i].p2.x = clip->boxes[i].p2.x + fx;
  	    copy->boxes[i].p1.y = clip->boxes[i].p1.y + fy;
  	    copy->boxes[i].p2.y = clip->boxes[i].p2.y + fy;
  	}
  	copy->num_boxes = clip->num_boxes;
      }
  
      copy->extents = clip->extents;
      copy->extents.x += tx;
      copy->extents.y += ty;
  
      if (clip->path == NULL)
  	return copy;
  
      return _cairo_clip_path_copy_with_translation (copy, clip->path, fx, fy);
  }
  
  cairo_bool_t
  _cairo_clip_contains_extents (const cairo_clip_t *clip,
  			      const cairo_composite_rectangles_t *extents)
  {
      const cairo_rectangle_int_t *rect;
  
      rect = extents->is_bounded ? &extents->bounded : &extents->unbounded;
      return _cairo_clip_contains_rectangle (clip, rect);
  }
  
  void
  _cairo_debug_print_clip (FILE *stream, const cairo_clip_t *clip)
  {
      int i;
  
      if (clip == NULL) {
  	fprintf (stream, "no clip\n");
  	return;
      }
  
      if (_cairo_clip_is_all_clipped (clip)) {
  	fprintf (stream, "clip: all-clipped\n");
  	return;
      }
  
      fprintf (stream, "clip:\n");
      fprintf (stream, "  extents: (%d, %d) x (%d, %d), is-region? %d",
  	     clip->extents.x, clip->extents.y,
  	     clip->extents.width, clip->extents.height,
  	     clip->is_region);
  
      fprintf (stream, "  num_boxes = %d\n", clip->num_boxes);
      for (i = 0; i < clip->num_boxes; i++) {
  	fprintf (stream, "  [%d] = (%f, %f), (%f, %f)\n", i,
  		 _cairo_fixed_to_double (clip->boxes[i].p1.x),
  		 _cairo_fixed_to_double (clip->boxes[i].p1.y),
  		 _cairo_fixed_to_double (clip->boxes[i].p2.x),
  		 _cairo_fixed_to_double (clip->boxes[i].p2.y));
      }
  
      if (clip->path) {
  	cairo_clip_path_t *clip_path = clip->path;
  	do {
  	    fprintf (stream, "path: aa=%d, tolerance=%f, rule=%d: ",
  		     clip_path->antialias,
  		     clip_path->tolerance,
  		     clip_path->fill_rule);
  	    _cairo_debug_print_path (stream, &clip_path->path);
  	    fprintf (stream, "\n");
  	} while ((clip_path = clip_path->prev) != NULL);
      }
  }
  
  const cairo_rectangle_int_t *
  _cairo_clip_get_extents (const cairo_clip_t *clip)
  {
      if (clip == NULL)
  	return &_cairo_unbounded_rectangle;
  
      if (_cairo_clip_is_all_clipped (clip))
  	return &_cairo_empty_rectangle;
  
      return &clip->extents;
  }
  
  const cairo_rectangle_list_t _cairo_rectangles_nil =
    { CAIRO_STATUS_NO_MEMORY, NULL, 0 };
  static const cairo_rectangle_list_t _cairo_rectangles_not_representable =
    { CAIRO_STATUS_CLIP_NOT_REPRESENTABLE, NULL, 0 };
  
  static cairo_bool_t
  _cairo_clip_int_rect_to_user (cairo_gstate_t *gstate,
  			      cairo_rectangle_int_t *clip_rect,
  			      cairo_rectangle_t *user_rect)
  {
      cairo_bool_t is_tight;
  
      double x1 = clip_rect->x;
      double y1 = clip_rect->y;
      double x2 = clip_rect->x + (int) clip_rect->width;
      double y2 = clip_rect->y + (int) clip_rect->height;
  
      _cairo_gstate_backend_to_user_rectangle (gstate,
  					     &x1, &y1, &x2, &y2,
  					     &is_tight);
  
      user_rect->x = x1;
      user_rect->y = y1;
      user_rect->width  = x2 - x1;
      user_rect->height = y2 - y1;
  
      return is_tight;
  }
  
  cairo_rectangle_list_t *
  _cairo_rectangle_list_create_in_error (cairo_status_t status)
  {
      cairo_rectangle_list_t *list;
  
      if (status == CAIRO_STATUS_NO_MEMORY)
  	return (cairo_rectangle_list_t*) &_cairo_rectangles_nil;
      if (status == CAIRO_STATUS_CLIP_NOT_REPRESENTABLE)
  	return (cairo_rectangle_list_t*) &_cairo_rectangles_not_representable;
  
      list = malloc (sizeof (*list));
      if (unlikely (list == NULL)) {
  	status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
  	return (cairo_rectangle_list_t*) &_cairo_rectangles_nil;
      }
  
      list->status = status;
      list->rectangles = NULL;
      list->num_rectangles = 0;
  
      return list;
  }
  
  cairo_rectangle_list_t *
  _cairo_clip_copy_rectangle_list (cairo_clip_t *clip, cairo_gstate_t *gstate)
  {
  #define ERROR_LIST(S) _cairo_rectangle_list_create_in_error (_cairo_error (S))
  
      cairo_rectangle_list_t *list;
      cairo_rectangle_t *rectangles = NULL;
      cairo_region_t *region = NULL;
      int n_rects = 0;
      int i;
  
      if (clip == NULL)
  	return ERROR_LIST (CAIRO_STATUS_CLIP_NOT_REPRESENTABLE);
  
      if (_cairo_clip_is_all_clipped (clip))
  	goto DONE;
  
      if (! _cairo_clip_is_region (clip))
  	return ERROR_LIST (CAIRO_STATUS_CLIP_NOT_REPRESENTABLE);
  
      region = _cairo_clip_get_region (clip);
      if (region == NULL)
  	return ERROR_LIST (CAIRO_STATUS_NO_MEMORY);
  
      n_rects = cairo_region_num_rectangles (region);
      if (n_rects) {
  	rectangles = _cairo_malloc_ab (n_rects, sizeof (cairo_rectangle_t));
  	if (unlikely (rectangles == NULL)) {
  	    return ERROR_LIST (CAIRO_STATUS_NO_MEMORY);
  	}
  
  	for (i = 0; i < n_rects; ++i) {
  	    cairo_rectangle_int_t clip_rect;
  
  	    cairo_region_get_rectangle (region, i, &clip_rect);
  
  	    if (! _cairo_clip_int_rect_to_user (gstate,
  						&clip_rect,
  						&rectangles[i]))
  	    {
  		free (rectangles);
  		return ERROR_LIST (CAIRO_STATUS_CLIP_NOT_REPRESENTABLE);
  	    }
  	}
      }
  
   DONE:
      list = malloc (sizeof (cairo_rectangle_list_t));
      if (unlikely (list == NULL)) {
          free (rectangles);
  	return ERROR_LIST (CAIRO_STATUS_NO_MEMORY);
      }
  
      list->status = CAIRO_STATUS_SUCCESS;
      list->rectangles = rectangles;
      list->num_rectangles = n_rects;
      return list;
  
  #undef ERROR_LIST
  }
  
  /**
   * cairo_rectangle_list_destroy:
   * @rectangle_list: a rectangle list, as obtained from cairo_copy_clip_rectangle_list()
   *
   * Unconditionally frees @rectangle_list and all associated
   * references. After this call, the @rectangle_list pointer must not
   * be dereferenced.
   *
   * Since: 1.4
   **/
  void
  cairo_rectangle_list_destroy (cairo_rectangle_list_t *rectangle_list)
  {
      if (rectangle_list == NULL || rectangle_list == &_cairo_rectangles_nil ||
          rectangle_list == &_cairo_rectangles_not_representable)
          return;
  
      free (rectangle_list->rectangles);
      free (rectangle_list);
  }
  
  void
  _cairo_clip_reset_static_data (void)
  {
      _freed_pool_reset (&clip_path_pool);
      _freed_pool_reset (&clip_pool);
  }
  