cairo/src/cairo-polygon.c

   1 /* cairo - a vector graphics library with display and print output
   2  *
   3  * Copyright © 2002 University of Southern California
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it either under the terms of the GNU Lesser General Public
   7  * License version 2.1 as published by the Free Software Foundation
   8  * (the "LGPL") or, at your option, under the terms of the Mozilla
   9  * Public License Version 1.1 (the "MPL"). If you do not alter this
  10  * notice, a recipient may use your version of this file under either
  11  * the MPL or the LGPL.
  12  *
  13  * You should have received a copy of the LGPL along with this library
  14  * in the file COPYING-LGPL-2.1; if not, write to the Free Software
  15  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  16  * You should have received a copy of the MPL along with this library
  17  * in the file COPYING-MPL-1.1
  18  *
  19  * The contents of this file are subject to the Mozilla Public License
  20  * Version 1.1 (the "License"); you may not use this file except in
  21  * compliance with the License. You may obtain a copy of the License at
  22  * http://www.mozilla.org/MPL/
  23  *
  24  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
  25  * OF ANY KIND, either express or implied. See the LGPL or the MPL for
  26  * the specific language governing rights and limitations.
  27  *
  28  * The Original Code is the cairo graphics library.
  29  *
  30  * The Initial Developer of the Original Code is University of Southern
  31  * California.
  32  *
  33  * Contributor(s):
  34  *      Carl D. Worth <cworth@cworth.org>
  35  */
  36
  37 #include "cairoint.h"
  38
  39 void
  40 _cairo_polygon_init (cairo_polygon_t *polygon)
  41 {
  42     polygon->status = CAIRO_STATUS_SUCCESS;
  43
  44     polygon->num_edges = 0;
  45
  46     polygon->edges = polygon->edges_embedded;
  47     polygon->edges_size = ARRAY_LENGTH (polygon->edges_embedded);
  48
  49     polygon->has_current_point = FALSE;
  50 }
  51
  52 void
  53 _cairo_polygon_fini (cairo_polygon_t *polygon)
  54 {
  55     if (polygon->edges != polygon->edges_embedded)
  56         free (polygon->edges);
  57 }
  58
  59 /* make room for at least one more edge */
  60 static cairo_bool_t
  61 _cairo_polygon_grow (cairo_polygon_t *polygon)
  62 {
  63     cairo_edge_t *new_edges;
  64     int old_size = polygon->edges_size;
  65     int new_size = 4 * old_size;
  66
  67     if (polygon->edges == polygon->edges_embedded) {
  68         new_edges = _cairo_malloc_ab (new_size, sizeof (cairo_edge_t));
  69         if (new_edges != NULL)
  70             memcpy (new_edges, polygon->edges, old_size * sizeof (cairo_edge_t));
  71     } else {
  72         new_edges = _cairo_realloc_ab (polygon->edges,
  73                                        new_size, sizeof (cairo_edge_t));
  74     }
  75
  76     if (new_edges == NULL) {
  77         polygon->status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
  78         return FALSE;
  79     }
  80
  81     polygon->edges = new_edges;
  82     polygon->edges_size = new_size;
  83
  84     return TRUE;
  85 }
  86
  87 static void
  88 _cairo_polygon_add_edge (cairo_polygon_t *polygon,
  89                          const cairo_point_t *p1,
  90                          const cairo_point_t *p2)
  91 {
  92     cairo_edge_t *edge;
  93
  94     /* drop horizontal edges */
  95     if (p1->y == p2->y)
  96         goto DONE;
  97
  98     if (polygon->num_edges == polygon->edges_size) {
  99         if (! _cairo_polygon_grow (polygon))
 100             return;
 101     }
 102
 103     edge = &polygon->edges[polygon->num_edges++];
 104     if (p1->y < p2->y) {
 105         edge->edge.p1 = *p1;
 106         edge->edge.p2 = *p2;
 107         edge->clockWise = 1;
 108     } else {
 109         edge->edge.p1 = *p2;
 110         edge->edge.p2 = *p1;
 111         edge->clockWise = 0;
 112     }
 113
 114   DONE:
 115     _cairo_polygon_move_to (polygon, p2);
 116 }
 117
 118 void
 119 _cairo_polygon_move_to (cairo_polygon_t *polygon,
 120                         const cairo_point_t *point)
 121 {
 122     if (! polygon->has_current_point)
 123         polygon->first_point = *point;
 124
 125     polygon->current_point = *point;
 126     polygon->has_current_point = TRUE;
 127 }
 128
 129 void
 130 _cairo_polygon_line_to (cairo_polygon_t *polygon,
 131                         const cairo_point_t *point)
 132 {
 133     if (polygon->has_current_point)
 134         _cairo_polygon_add_edge (polygon, &polygon->current_point, point);
 135     else
 136         _cairo_polygon_move_to (polygon, point);
 137 }
 138
 139 void
 140 _cairo_polygon_close (cairo_polygon_t *polygon)
 141 {
 142     if (polygon->has_current_point) {
 143         _cairo_polygon_add_edge (polygon,
 144                                  &polygon->current_point,
 145                                  &polygon->first_point);
 146
 147         polygon->has_current_point = FALSE;
 148     }
 149 }