test: random-intersections

The purpose of this test case is to help make
sure that changes to the trapezoid generation or
intersection computation in the tessellator
don't break it.

test/Makefile.am

@@ -69,6 +69,7 @@ paint-with-alpha		\
 pattern-get-type		\
 pattern-getters			\
 pixman-rotate			\
+random-intersections		\
 rectangle-rounding-error	\
 scale-source-surface-paint	\
 select-font-face		\
@@ -293,6 +294,9 @@ push-group-ref.png					\
 push-group-rgb24-ref.png				\
 push-group-svg-argb32-ref.png				\
 push-group-svg-rgb24-ref.png				\
+random-intersections-ref.png				\
+random-intersections-rgb24-ref.png			\
+random-intersections-ps-argb32-ref.png			\
 rectangle-rounding-error-ref.png			\
 rel-path-ref.png					\
 rel-path-rgb24-ref.png					\

test/random-intersections.c

@@ -0,0 +1,79 @@
+/*
+ * Copyright © 2006 M Joonas Pihlaja
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Author: M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>
+ */
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+#define SIZE 512
+#define NUM_SEGMENTS 128
+
+cairo_test_t test = {
+    "random-intersections",
+    "Tests the tessellator trapezoid generation and intersection computation",
+    SIZE+3, SIZE+3,
+    draw
+};
+
+static uint32_t state;
+static double
+uniform_random (double minval, double maxval)
+{
+    static uint32_t const poly = 0x9a795537U;
+    uint32_t n = 32;
+    while (n-->0)
+	state = 2*state < state ? (2*state ^ poly) : 2*state;
+    return minval + state * (maxval - minval) / 4294967296.0;
+}
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    int i;
+    state = 0x12345678;
+    cairo_translate (cr, 1, 1);
+    cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);
+
+    cairo_move_to (cr, 0, 0);
+    for (i = 0; i < NUM_SEGMENTS; i++) {
+	double x = uniform_random (0, width);
+	double y = uniform_random (0, height);
+	cairo_line_to (cr, x, y);
+    }
+    cairo_close_path (cr);
+
+    cairo_set_source_rgb (cr, 1, 0, 0);
+    cairo_fill_preserve (cr);
+    cairo_set_source_rgb (cr, 0, 1, 0);
+    cairo_set_line_width (cr, 0.5);
+    cairo_stroke (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}