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Diffstat (limited to 'test/curve-to-as-line-to.c')
| -rw-r--r-- | test/curve-to-as-line-to.c | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/test/curve-to-as-line-to.c b/test/curve-to-as-line-to.c new file mode 100644 index 0000000..07eb005 --- /dev/null +++ b/test/curve-to-as-line-to.c @@ -0,0 +1,95 @@ +/* + * 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> + */ + +#include "cairo-test.h" + +#define SIZE 30 + +/* At one point, an optimization was proposed for cairo in which a + * curve_to would be optimized as a line_to. The initial (buggy) + * implementation verified that the slopes of several segments of the + * spline's control polygon were identical, but left open the + * possibility of an anti-parallel slope for one segment. + * + * For example, given a spline with collinear control points (A,B,C,D) + * positioned as follows: + * + * C--A--B--D + * + * The code verified identical slopes for AB, CD, and AD. The missing + * check for the BC segment allowed it to be anti-parallel to the + * others as above, and hence invalid to replace this spline with the + * AD line segment. + */ +static cairo_test_status_t +draw (cairo_t *cr, int width, int height) +{ + cairo_set_source_rgb (cr, 1.0, 1.0, 1.0); /* white */ + cairo_paint (cr); + + cairo_set_line_width (cr, 1.0); + cairo_set_line_cap (cr, CAIRO_LINE_CAP_BUTT); + cairo_set_line_join (cr, CAIRO_LINE_JOIN_BEVEL); + cairo_set_source_rgb (cr, 0.0, 0.0, 0.0); /* black */ + + cairo_translate (cr, 0, 1.0); + + /* The CABD spline as described above. We ensure that the spline + * folds over on itself outside the bounds of the image to avoid + * the reference image having the curved portion of that fold, + * (which would just be harder to match in all the backends than + * we really want). */ + cairo_move_to (cr, + 10.5, 0.5); + cairo_curve_to (cr, + 11.5, 0.5, + -25.0, 0.5, + 31.0, 0.5); + + cairo_stroke (cr); + + cairo_translate (cr, 0, 2.0); + + /* A reflected version: DBAC */ + cairo_move_to (cr, + 19.5, 0.5); + + cairo_curve_to (cr, + 18.5, 0.5, + 55.0, 0.5, + -1.0, 0.5); + + cairo_stroke (cr); + + return CAIRO_TEST_SUCCESS; +} + +CAIRO_TEST (curve_to_as_line_to, + "Test optimization treating curve_to as line_to", + "path", /* keywords */ + NULL, /* requirements */ + 30, + 5, + NULL, draw) |