close-path: New test case to demonstrate corner case discovered by Tim Rowley

The bug shows up when doing cairo_copy_path_flat for a path that has
a curve_to immediately after a close_path. When the curve is flattened
the flattener is using (0,0) as the initial point rather than the proper
close_to point.

This test also serves to ensure a similar bug doesn't crop up when
closing a path that begins with an implicit move_to, (as from cairo_arc).
In that bug the path state may have no last-move-point and the path
is closed to (0,0). This bug is not present currently, but did appear
during the development of a fix for the bug above.

test/.gitignore

@@ -15,6 +15,7 @@ clip-fill-rule-pixel-aligned
 clip-nesting
 clip-operator
 clip-twice
+close-path
 composite-integer-translate-source
 composite-integer-translate-over
 composite-integer-translate-over-repeat

test/Makefile.am

@@ -10,6 +10,7 @@ clip-fill-rule-pixel-aligned	\
 clip-nesting			\
 clip-operator			\
 clip-twice			\
+close-path			\
 composite-integer-translate-source \
 composite-integer-translate-over \
 composite-integer-translate-over-repeat \
@@ -174,6 +175,8 @@ clip-operator-rgb24-ref.png				\
 clip-twice-ref.png					\
 clip-twice-rgb24-ref.png				\
 clip-twice-ps-argb32-ref.png				\
+close-path-ref.png					\
+close-path-ps-argb32-ref.png				\
 composite-integer-translate-over-ref.png		\
 composite-integer-translate-over-pdf-argb32-ref.png	\
 composite-integer-translate-over-svg-ref.png		\

test/close-path.c

@@ -0,0 +1,84 @@
+/*
+ * Copyright © 2006 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>
+ */
+
+#include <stdlib.h>
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "close-path",
+    "Test some corner cases related to cairo_close_path",
+    32, 16,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_path_t *path;
+
+    /* We draw in the default black, so paint white first. */
+    cairo_save (cr);
+    cairo_set_source_rgb (cr, 1.0, 1.0, 1.0); /* white */
+    cairo_paint (cr);
+    cairo_restore (cr);
+
+    /* This curious approach for drawing a circle (starting with a
+     * closed arc) exercises a bug in which the "last move point" was
+     * not being set so the close_path closes to (0,0). */
+    cairo_arc (cr, 8, 8, 4, 0, M_PI);
+    cairo_close_path (cr);
+    cairo_arc (cr, 8, 8, 4, M_PI, 2 * M_PI);
+
+    cairo_fill (cr);
+
+    cairo_translate (cr, 16, 0);
+
+    /* Here a curve immediately after a close_to will begin from (0,0)
+     * when the path is obtained with cairo_copy_path_flat. */
+    cairo_move_to (cr, 8, 4);
+    cairo_arc_negative (cr, 8, 8, 4, 3 * M_PI / 2.0, M_PI / 2.0);
+    cairo_close_path (cr);
+    cairo_curve_to (cr,
+		    12, 4,
+		    12, 12,
+		    8, 12);
+
+    path = cairo_copy_path_flat (cr);
+    cairo_new_path (cr);
+    cairo_append_path (cr, path);
+    cairo_path_destroy (path);
+
+    cairo_fill (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}