test: Add clip-shape

cu found a bug when using clipping and fills with the image backend, but
it turns out to be the lost sign bug afflicting everything...

To trigger the bug requires evaluating the clip surface prior to using
in with _cairo_clip_combine_with_surface(). Which is taken along a
particular path when using a clip mask with non-pixel geometry on image,
but more easily hit by the fallback code.

Reported-by: <cairouser@yahoo.com>

test/Makefile.am

@@ -241,6 +241,10 @@ REFERENCE_IMAGES = \
 	clip-push-group.ref.png \
 	clip-push-group.svg.ref.png \
 	clip-push-group.xlib.ref.png \
+	clip-shape.ref.png \
+	clip-shape.ps.ref.png \
+	clip-shape.xlib.ref.png \
+	clip-shape.xlib-fallback.ref.png \
 	clip-stroke.ref.png \
 	clip-stroke.xlib.ref.png \
 	clip-stroke.xlib-fallback.ref.png \

test/Makefile.sources

@@ -33,6 +33,7 @@ test_sources = \
 	clip-nesting.c					\
 	clip-operator.c					\
 	clip-push-group.c				\
+	clip-shape.c					\
 	clip-stroke.c					\
 	clip-stroke-no-op.c				\
 	clip-stroke-unbounded.c				\

test/clip-shape.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2010 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>
+ */
+
+/* Adapted from a bug report by <cairouser@yahoo.com> */
+
+#include "cairo-test.h"
+
+static const struct xy {
+   double x;
+   double y;
+} gp[] = {
+    { 100, 250 },
+    { 100, 100 },
+    { 150, 230 },
+    { 239, 100 },
+    { 239, 250 },
+};
+
+static const double vp[3] = { 100, 144, 238.5 };
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    int i;
+
+    cairo_paint (cr); /* opaque background */
+
+    for (i = 0; i < 5; ++i)
+	cairo_line_to (cr, gp[i].x, gp[i].y);
+    cairo_close_path (cr);
+
+    cairo_set_source_rgb (cr, 1, 0, 0);
+    cairo_set_line_width (cr, 1.5);
+    cairo_stroke_preserve (cr);
+    cairo_clip (cr);
+
+    for (i = 1; i < 3; ++i) {
+	double x1 = vp[i - 1];
+	double x2 = vp[i];
+
+	cairo_move_to (cr, x1, 0);
+	cairo_line_to (cr, x1, height);
+	cairo_line_to (cr, x2, height);
+	cairo_line_to (cr, x2, 0);
+	cairo_close_path (cr);
+
+	if (i & 1)
+	    cairo_set_source_rgb (cr, 0, 1, 0);
+	else
+	    cairo_set_source_rgb (cr, 1, 1, 0);
+
+	cairo_fill (cr);
+    }
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (clip_shape,
+	    "Test handling of clipping with a non-aligned shape",
+	    "clip", /* keywords */
+	    NULL, /* requirements */
+	    400, 300,
+	    NULL, draw)