cairo/test/self-intersecting.c
Chris Wilson 436c0c8be2 [test] Preparatory work for running under memfault.
In order to run under memfault, the framework is first extended to handle
running concurrent tests - i.e. multi-threading. (Not that this is a
requirement for memfault, instead it shares a common goal of storing
per-test data).  To that end all the global data is moved into a per-test
context and the targets are adjusted to avoid overlap on shared, global
resources (such as output files and frame buffers). In order to preserve
the simplicity of the standard draw routines, the context is not passed
explicitly as a parameter to the routines, but is instead attached to the
cairo_t via the user_data.

For the masochist, to enable the tests to be run across multiple threads
simply set the environment variable CAIRO_TEST_NUM_THREADS to the desired
number.

In the long run, we can hope the need for memfault (runtime testing of
error paths) will be mitigated by static analysis. A promising candidate
for this task would appear to be http://hal.cs.berkeley.edu/cil/.
2008-08-13 21:54:59 +01:00

92 lines
3.2 KiB
C

/*
* 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_draw_function_t draw;
static const cairo_test_t test = {
"self-intersecting",
"Test strokes of self-intersecting paths"
"\nSelf-intersecting strokes are wrong due to incremental trapezoidization.",
10, 20,
draw
};
static cairo_test_status_t
draw (cairo_t *cr, int width, int height)
{
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;
}
int
main (void)
{
return cairo_test (&test);
}