[test] Add a simple joins test case

Exercise joins between short (<LINE_WIDTH) lines - used in debugging
stroke-to-path.

test/Makefile.am

@@ -90,6 +90,7 @@ test_sources = \
 	in-fill-empty-trapezoid.c			\
 	in-fill-trapezoid.c				\
 	invalid-matrix.c				\
+	joins.c						\
 	large-clip.c					\
 	large-font.c					\
 	large-source.c					\
@@ -615,6 +616,8 @@ REFERENCE_IMAGES = \
 	infinite-join.ref.png	\
 	infinite-join.ps2.ref.png	\
 	infinite-join.ps3.ref.png	\
+	joins.ref.png		\
+	joins.ps.ref.png	\
 	large-clip.ref.png	\
 	large-font.ref.png	\
 	large-source.ref.png	\

test/joins.c

@@ -0,0 +1,109 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+#define LINE_WIDTH	12.
+#define SIZE		(5 * LINE_WIDTH)
+#define PAD		(2 * LINE_WIDTH)
+
+static void
+make_path (cairo_t *cr)
+{
+    const struct {
+	double x, y;
+    } scales[] = {
+	{  1,  1 },
+	{ -1,  1 },
+	{  1, -1 },
+	{ -1, -1 },
+    };
+    unsigned int i, j;
+
+    for (j = 0; j < sizeof (scales) / sizeof (scales[0]); j++) {
+	cairo_save (cr);
+	/* include reflections to flip the orientation of the join */
+	cairo_scale (cr, scales[j].x, scales[j].y);
+	for (i = 0; i < 3; i++) {
+	    cairo_new_sub_path (cr);
+	    cairo_move_to (cr, 0, -9*LINE_WIDTH/4 - 2);
+	    cairo_line_to (cr,  0, -2*LINE_WIDTH - 2);
+	    cairo_line_to (cr,  LINE_WIDTH/4, -2*LINE_WIDTH - 2);
+	    cairo_rotate (cr, M_PI / 4.);
+	}
+	cairo_restore (cr);
+    }
+}
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_line_join_t join;
+
+    cairo_save (cr);
+    cairo_set_source_rgb (cr, 1.0, 1.0, 1.0); /* white */
+    cairo_paint (cr);
+    cairo_restore (cr);
+
+    cairo_set_line_width (cr, LINE_WIDTH);
+    cairo_translate (cr, PAD + SIZE / 2., PAD + SIZE / 2.);
+
+    for (join = CAIRO_LINE_JOIN_MITER; join <= CAIRO_LINE_JOIN_BEVEL; join++) {
+	cairo_save (cr);
+
+	cairo_set_line_join (cr, join);
+
+	cairo_set_line_cap (cr, CAIRO_LINE_CAP_BUTT);
+	make_path (cr);
+	cairo_stroke (cr);
+
+	cairo_translate (cr, 0, SIZE + PAD);
+
+	cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
+	make_path (cr);
+	cairo_stroke (cr);
+
+	cairo_translate (cr, 0, SIZE + PAD);
+
+	cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
+	make_path (cr);
+	cairo_stroke (cr);
+
+	cairo_restore (cr);
+
+	cairo_translate (cr, SIZE + PAD, 0);
+    }
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (joins,
+	    "Test joins",
+	    "stroke joins", /* keywords */
+	    NULL, /* requirements */
+	    3 * (PAD + SIZE) + PAD,
+	    3 * (PAD + SIZE) + PAD,
+	    NULL, draw)
+