[perf] Explicitly test rendering a path with lots of intersections.

We don't have one just for this purpose.  The only other
path with many intersections that gets actually rendered is zrusin-another,
but that might be sped up in the future (say by identifying
collinearities up front or something like that.)

perf/Makefile.am

@@ -43,7 +43,8 @@ cairo_perf_SOURCES =		\
 	zrusin-another.h	\
 	long-dashed-lines.c	\
 	dragon.c		\
-	pythagoras-tree.c
+	pythagoras-tree.c	\
+	intersections.c
 
 if CAIRO_HAS_WIN32_SURFACE
 cairo_perf_SOURCES += cairo-perf-win32.c

perf/cairo-perf.c

@@ -465,5 +465,6 @@ const cairo_perf_case_t perf_cases[] = {
     { twin, 800, 800},
     { dragon, 1024, 1024 },
     { pythagoras_tree, 768, 768 },
+    { intersections, 512, 512 },
     { NULL }
 };

perf/cairo-perf.h

@@ -175,5 +175,6 @@ CAIRO_PERF_DECL (composite_checker);
 CAIRO_PERF_DECL (twin);
 CAIRO_PERF_DECL (dragon);
 CAIRO_PERF_DECL (pythagoras_tree);
+CAIRO_PERF_DECL (intersections);
 
 #endif

perf/intersections.c

@@ -0,0 +1,97 @@
+/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
+/* cairo - a vector graphics library with display and print output
+ *
+ * Copyright (c) 2008  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.
+ */
+#include "cairo-perf.h"
+
+#define NUM_SEGMENTS 256
+
+static unsigned state;
+static double
+uniform_random (double minval, double maxval)
+{
+    static unsigned const poly = 0x9a795537U;
+    unsigned n = 32;
+    while (n-->0)
+	state = 2*state < state ? (2*state ^ poly) : 2*state;
+    return minval + state * (maxval - minval) / 4294967296.0;
+}
+
+static cairo_perf_ticks_t
+draw_random (cairo_t *cr, cairo_fill_rule_t fill_rule, int width, int height)
+{
+    int i;
+    double x[NUM_SEGMENTS];
+    double y[NUM_SEGMENTS];
+
+    cairo_save (cr);
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_paint (cr);
+
+    for (i = 0; i < NUM_SEGMENTS; i++) {
+         x[i] = uniform_random (0, width);
+         y[i] = uniform_random (0, height);
+    }
+
+    state = 0x12345678;
+    cairo_translate (cr, 1, 1);
+    cairo_set_fill_rule (cr, fill_rule);
+    cairo_set_source_rgb (cr, 1, 0, 0);
+
+    cairo_perf_timer_start (); {
+
+        cairo_move_to (cr, 0, 0);
+        for (i = 0; i < NUM_SEGMENTS; i++) {
+            cairo_line_to (cr, x[i], y[i]);
+        }
+        cairo_close_path (cr);
+
+        cairo_fill (cr);
+    }
+    cairo_perf_timer_stop ();
+
+    cairo_restore (cr);
+
+    return cairo_perf_timer_elapsed ();
+}
+
+static cairo_perf_ticks_t
+random_eo (cairo_t *cr, int width, int height)
+{
+    return draw_random (cr, CAIRO_FILL_RULE_EVEN_ODD, width, height);
+}
+
+static cairo_perf_ticks_t
+random_nz (cairo_t *cr, int width, int height)
+{
+    return draw_random (cr, CAIRO_FILL_RULE_WINDING, width, height);
+}
+
+void
+intersections (cairo_perf_t *perf, cairo_t *cr, int width, int height)
+{
+    cairo_perf_run (perf, "intersections-nz-fill", random_nz);
+    cairo_perf_run (perf, "intersections-eo-fill", random_eo);
+}