cairo/test/fill-missed-stop.c

   1 /*
   2  * Copyright © 2006 M Joonas Pihlaja
   3  *
   4  * Permission is hereby granted, free of charge, to any person
   5  * obtaining a copy of this software and associated documentation
   6  * files (the "Software"), to deal in the Software without
   7  * restriction, including without limitation the rights to use, copy,
   8  * modify, merge, publish, distribute, sublicense, and/or sell copies
   9  * of the Software, and to permit persons to whom the Software is
  10  * furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  19  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  20  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  *
  24  * Author: M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>
  25  */
  26
  27 /* Bug history
  28  *
  29  * 2006-12-05  M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>
  30  *
  31  *  The tessellator has a regression where a trapezoid may continue
  32  *  below the end of a polygon edge (i.e. the bottom of the trapezoid
  33  *  is miscomputed.)  This can only happen if the right edge of a
  34  *  trapezoid stops earlier than the left edge and there is no start
  35  *  event at the end point of the right edge.
  36  */
  37
  38 #include "cairo-test.h"
  39
  40 static cairo_test_draw_function_t draw;
  41 #define SIZE 50
  42
  43 static const cairo_test_t test = {
  44     "fill-missed-stop",
  45     "Tests that the tessellator doesn't miss stop events when generating trapezoids",
  46     SIZE+3, SIZE+3,
  47     draw
  48 };
  49
  50 static cairo_test_status_t
  51 draw (cairo_t *cr, int width, int height)
  52 {
  53     cairo_set_source_rgb (cr, 1, 0, 0);
  54
  55     cairo_translate (cr, 1, 1);
  56
  57     /* What it should look like, with # marking the filled areas:
  58      *
  59      * |\    |\
  60      * |#\   |#\
  61      * |##\__|##\
  62      *     \#|
  63      *      \|
  64      *
  65      * What it looke like with the bug, when the rightmost edge's end
  66      * is missed:
  67      *
  68      * |\    |\
  69      * |#\   |#\
  70      * |##\__|##\
  71      *     \#####|
  72      *      \####|
  73      */
  74
  75     cairo_move_to (cr, 0, 0);
  76     cairo_line_to (cr, SIZE/2, SIZE);
  77     cairo_line_to (cr, SIZE/2, 0);
  78     cairo_line_to (cr, SIZE, SIZE/2);
  79     cairo_line_to (cr, 0, SIZE/2);
  80     cairo_close_path (cr);
  81     cairo_fill (cr);
  82
  83     return CAIRO_TEST_SUCCESS;
  84 }
  85
  86 int
  87 main (void)
  88 {
  89     return cairo_test (&test);
  90 }