cairo_new_sub_path: Making cairo_arc easier to use and more.

This adds a new function which has as its only effect the elimination
of
the current point. This makes it much easier to use the various
cairo_arc calls when the initial line_to is not actually desired.

This function also unifies and generalizes the long-existing behavior
of cairo_line_to being treated as cairo_move_to when there is no
current point. With the addition of cairo_new_sub_path this becomes a
documented feature with similar behavior in cairo_curve_to as well.

1 files changed, 79 insertions, 0 deletions

diff --git a/test/new-sub-path.c b/test/new-sub-path.c
new file mode 100644
index 00000000..90e0c730
--- /dev/null
+++ b/test/new-sub-path.c
@@ -0,0 +1,79 @@
+/*
+ * 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>
+ */
+
+#include "cairo-test.h"
+
+#define SIZE 10
+
+cairo_test_t test = {
+    "new-sub-path",
+    "Test the cairo_new_sub_path call",
+    8 * SIZE,
+    3 * SIZE
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_set_source_rgb (cr, 0.0, 0.0, 1.0); /* blue */
+
+    /* Test cairo_new_sub_path followed by several different
+     * path-modification functions in turn...
+     */
+
+    /* ... cairo_move_to */
+    cairo_new_sub_path (cr);
+    cairo_move_to (cr, SIZE, SIZE);
+    cairo_line_to (cr, SIZE, 2 * SIZE);
+
+    /* ... cairo_line_to */
+    cairo_new_sub_path (cr);
+    cairo_line_to (cr, 2 * SIZE, 1.5 * SIZE);
+    cairo_line_to (cr, 3 * SIZE, 1.5 * SIZE);
+
+    /* ... cairo_curve_to */
+    cairo_new_sub_path (cr);
+    cairo_curve_to (cr,
+		    4.0 * SIZE, 1.5 * SIZE,
+		    4.5 * SIZE, 1.0 * SIZE,
+		    5.0 * SIZE, 1.5 * SIZE);
+
+    /* ... cairo_arc */
+    cairo_new_sub_path (cr);
+    cairo_arc (cr,
+	       6.5 * SIZE, 1.5 * SIZE,
+	       0.5 * SIZE,
+	       0.0, 2.0 * M_PI);
+
+    cairo_stroke (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test, draw);
+}