| /* |
| * Copyright © 2005 Red Hat, Inc. |
| * |
| * Permission to use, copy, modify, distribute, and sell this software |
| * and its documentation for any purpose is hereby granted without |
| * fee, provided that the above copyright notice appear in all copies |
| * and that both that copyright notice and this permission notice |
| * appear in supporting documentation, and that the name of |
| * Red Hat, Inc. not be used in advertising or publicity pertaining to |
| * distribution of the software without specific, written prior |
| * permission. Red Hat, Inc. makes no representations about the |
| * suitability of this software for any purpose. It is provided "as |
| * is" without express or implied warranty. |
| * |
| * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS |
| * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND |
| * FITNESS, IN NO EVENT SHALL RED HAT, INC. BE LIABLE FOR ANY SPECIAL, |
| * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER |
| * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION |
| * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR |
| * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| * |
| * Author: Carl D. Worth <cworth@cworth.org> |
| */ |
| |
| /* Bug history |
| * |
| * 2005-06-01 Carl Worth <cworth@cworth.org> |
| * |
| * There's a long-standing bug in that self-intersecting paths give |
| * an incorrect result when stroked. The problem is that the |
| * trapezoids are generated incrementally along the stroke and as |
| * such, are not disjoint. The errant intersections of these |
| * trapezoids then leads to overfilled pixels. |
| * |
| * The test belows first creates and fills a path. Then it creates a |
| * second path which has a stroked boundary identical to the first |
| * filled path. But the results of the two operations are |
| * different. The most obvious difference is in the central region |
| * where the entire path intersects itself. But notice that every |
| * time the path turns there are also errors on the inside of the |
| * turn, (since the subsequent trapezoids along the path intersect). |
| */ |
| |
| #include "cairo-test.h" |
| |
| static cairo_test_status_t |
| draw (cairo_t *cr, int width, int height) |
| { |
| cairo_set_source_rgb (cr, 1, 1, 1); |
| cairo_paint (cr); |
| |
| cairo_translate (cr, 1.0, 1.0); |
| |
| cairo_set_source_rgb (cr, 1, 0, 0); /* red */ |
| |
| /* First draw the desired shape with a fill */ |
| cairo_rectangle (cr, 0.5, 0.5, 4.0, 4.0); |
| cairo_rectangle (cr, 3.5, 3.5, 4.0, 4.0); |
| cairo_rectangle (cr, 3.5, 1.5, -2.0, 2.0); |
| cairo_rectangle (cr, 6.5, 4.5, -2.0, 2.0); |
| |
| cairo_fill (cr); |
| |
| /* Then try the same thing with a stroke */ |
| cairo_translate (cr, 0, 10); |
| cairo_move_to (cr, 1.0, 1.0); |
| cairo_rel_line_to (cr, 3.0, 0.0); |
| cairo_rel_line_to (cr, 0.0, 6.0); |
| cairo_rel_line_to (cr, 3.0, 0.0); |
| cairo_rel_line_to (cr, 0.0, -3.0); |
| cairo_rel_line_to (cr, -6.0, 0.0); |
| cairo_close_path (cr); |
| |
| cairo_set_line_width (cr, 1.0); |
| cairo_stroke (cr); |
| |
| return CAIRO_TEST_SUCCESS; |
| } |
| |
| CAIRO_TEST (self_intersecting, |
| "Test strokes of self-intersecting paths" |
| "\nSelf-intersecting strokes are wrong due to incremental trapezoidization.", |
| "stroke, trap", /* keywords */ |
| NULL, /* requirements */ |
| 10, 20, |
| NULL, draw) |