Augment tests to do better testing of paths/images with alpha.

Add a new cairo_test_paint_checkered function so that tests that draw
with alpha can easily put an easy-to-see checkered background in place
first.

Add new tests caps-joins-alpha and paint-source-alpha that do simple
tests of strokes and image painting with source pattern alpha.

Also, add the checkered background to paint-with-alpha for
consistency.

1 files changed, 94 insertions, 0 deletions

diff --git a/test/caps-joins-alpha.c b/test/caps-joins-alpha.c
new file mode 100644
index 000000000..c28482dac
--- /dev/null
+++ b/test/caps-joins-alpha.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright © 2005 Red Hat, Inc.
+ * 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 "cairo-test.h"
+
+#define LINE_WIDTH 	10.
+#define SIZE 		(5 * LINE_WIDTH)
+#define PAD		(2 * LINE_WIDTH)
+
+cairo_test_t test = {
+    "caps-joins-alpha",
+    "Test caps and joins with some source alpha",
+    3 * (PAD + SIZE) + PAD,
+    PAD + SIZE + PAD
+};
+
+static void
+make_path (cairo_t *cr)
+{
+    cairo_move_to (cr, 0., 0.);
+    cairo_rel_line_to (cr, 0., SIZE);
+    cairo_rel_line_to (cr, SIZE, 0.);
+    cairo_close_path (cr);
+
+    cairo_move_to (cr, 2 * LINE_WIDTH, 0.);
+    cairo_rel_line_to (cr, 3 * LINE_WIDTH, 0.);
+    cairo_rel_line_to (cr, 0., 3 * LINE_WIDTH);
+}
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    /* First draw a checkered background */
+    cairo_test_paint_checkered (cr);
+
+    /* Then draw the original caps-joins test but with a bit of alphs thrown in. */
+    cairo_set_line_width (cr, LINE_WIDTH);
+
+    cairo_set_source_rgba (cr, 1.0, 0.0, 0.0, 0.5); /* 50% red */
+    cairo_translate (cr, PAD, PAD);
+
+    make_path (cr);
+    cairo_set_line_cap (cr, CAIRO_LINE_CAP_BUTT);
+    cairo_set_line_join (cr, CAIRO_LINE_JOIN_BEVEL);
+    cairo_stroke (cr);
+
+    cairo_set_source_rgba (cr, 0.0, 1.0, 0.0, 0.5); /* 50% green */
+    cairo_translate (cr, SIZE + PAD, 0.);
+
+    make_path (cr);
+    cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
+    cairo_set_line_join (cr, CAIRO_LINE_JOIN_ROUND);
+    cairo_stroke (cr);
+
+    cairo_set_source_rgba (cr, 0.0, 0.0, 1.0, 0.5); /* 50% blue */
+
+    cairo_translate (cr, SIZE + PAD, 0.);
+
+    make_path (cr);
+    cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
+    cairo_set_line_join (cr, CAIRO_LINE_JOIN_MITER);
+    cairo_stroke (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test, draw);
+}