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authorsanine <sanine.not@pm.me>2022-10-12 12:03:23 -0500
committersanine <sanine.not@pm.me>2022-10-12 12:03:23 -0500
commit530ffd0b7d3c39757b20f00716e486b5caf89aff (patch)
tree76b35fdf57317038acf6b828871f6ae25fce2ebe /libs/cairo-1.16.0/test/self-intersecting.c
parent3dbe9332e47c143a237db12440f134caebd1cfbe (diff)
add cairo
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diff --git a/libs/cairo-1.16.0/test/self-intersecting.c b/libs/cairo-1.16.0/test/self-intersecting.c
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+/*
+ * 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)