test: Add shape-general-concave

A discussion that we've been having is the use of contours in filling,
and for optimizing for convex contours in particular. A devious mind
quickly generates a shape using a convex "contour" whose hull is larger
than its area. This is due to the self-intersection of the "contour"
which if properly excised causes the contour to be classed as concave.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

test/Makefile.refs

@@ -1146,6 +1146,7 @@ REFERENCE_IMAGES = \
 	self-intersecting.xlib.ref.png \
 	set-source.ref.png \
 	set-source.rgb24.ref.png \
+	shape-general-concave.ref.png \
 	show-glyphs-advance.image16.ref.png \
 	show-glyphs-advance.ps.ref.png \
 	show-glyphs-advance.quartz.ref.png \
@@ -1290,9 +1291,6 @@ REFERENCE_IMAGES = \
 	svg-surface-source.rgb24.ref.png \
 	svg-surface-source.svg12.argb32.xfail.png \
 	svg-surface-source.svg12.rgb24.xfail.png \
-	test-fallback16-surface-source.ps.ref.png \
-	test-fallback16-surface-source.svg12.argb32.xfail.png \
-	test-fallback16-surface-source.svg12.rgb24.xfail.png \
 	text-antialias-gray.image16.ref.png \
 	text-antialias-gray.quartz.ref.png \
 	text-antialias-gray.ref.png \

test/Makefile.sources

@@ -267,6 +267,7 @@ test_sources = \
 	show-glyphs-advance.c				\
 	show-glyphs-many.c				\
 	show-text-current-point.c			\
+	shape-general-convex.c				\
 	skew-extreme.c					\
 	smask.c						\
 	smask-fill.c					\

test/shape-general-convex.c

@@ -0,0 +1,88 @@
+/*
+ * Copyright © 2011 Intel Corporation
+ *
+ * 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+/* A general convex shape with a twist. */
+
+#include "cairo-test.h"
+
+#define SIZE		(100)
+#define PAD 4
+
+static void
+limacon (cairo_t *cr, double a, double b, double radius)
+{
+    int i;
+
+    cairo_save (cr);
+    cairo_translate (cr, PAD, 0);
+    for (i = 0; i < 360; i++) {
+	double theta = i * M_PI / 180;
+	double r = b + a * cos (theta);
+	double x = radius * r * cos (theta);
+	double y = radius * r * sin (theta);
+	cairo_line_to (cr, x, y);
+    }
+    cairo_close_path (cr);
+    cairo_restore (cr);
+}
+
+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_save (cr);
+    cairo_translate (cr, 2*PAD, PAD);
+
+    cairo_translate (cr, SIZE/2, SIZE/2);
+    limacon (cr, 1, .5, SIZE/3); /* trivia, this is a trisectrix */
+
+    cairo_set_source_rgb (cr, 1, 0, 0);
+    cairo_fill_preserve (cr);
+
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_stroke (cr);
+
+    cairo_scale (cr, -1, 1);
+
+    limacon (cr, 1, .5, SIZE/3); /* trivia, this is a trisectrix */
+
+    cairo_set_source_rgb (cr, 0, 0, 1);
+    cairo_fill_preserve (cr);
+
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_stroke (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (shape_general_convex,
+	    "A general shape that is not as convex as it first appears",
+	    "fill,stroke", /* keywords */
+	    NULL, /* requirements */
+	    SIZE+4*PAD, SIZE+4*PAD,
+	    NULL, draw)