Add new filter-bilinear-extents test

This test exercises code that computes the extents of a surface
pattern with CAIRO_FILTER_BILINEAR, (where the filtering
effectively increases the extents of the pattern).

The original bug was reported by Owen Taylor here:

    bad clipping with EXTEND_NONE
    http://bugs.freedesktop.org/show_bug.cgi?id=15349

test/.gitignore

@@ -63,6 +63,7 @@ fill-and-stroke-alpha-add
 fill-degenerate-sort-order
 fill-missed-stop
 fill-rule
+filter-bilinear-extents
 filter-nearest-offset
 finer-grained-fallbacks
 ft-text-antialias-none

test/Makefile.am

@@ -51,6 +51,7 @@ fill-and-stroke-alpha-add$(EXEEXT)			\
 fill-degenerate-sort-order$(EXEEXT)			\
 fill-missed-stop$(EXEEXT)				\
 fill-rule$(EXEEXT)					\
+filter-bilinear-extents$(EXEEXT)			\
 filter-nearest-offset$(EXEEXT)				\
 finer-grained-fallbacks$(EXEEXT)			\
 font-face-get-type$(EXEEXT)				\
@@ -383,6 +384,7 @@ REFERENCE_IMAGES = \
 	fill-rule-ref.png	\
 	fill-rule-rgb24-ref.png	\
 	fill-rule-ps-rgb24-ref.png \
+	filter-bilinear-extents-ref.png \
 	filter-nearest-offset-ref.png	\
 	finer-grained-fallbacks-ref.png			\
 	finer-grained-fallbacks-rgb24-ref.png		\

test/filter-bilinear-extents.c

@@ -0,0 +1,91 @@
+/*
+ * Copyright © 2008 Red Hat, Inc.
+ *
+ * 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.
+ *
+ * Authors: Carl D. Worth <cworth@cworth.org>
+ *	    Owen Taylor <otaylor@redhat.com>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+/* This test exercises code that computes the extents of a surface
+ * pattern with CAIRO_FILTER_BILINEAR, (where the filtering
+ * effectively increases the extents of the pattern).
+ *
+ * The original bug was reported by Owen Taylor here:
+ *
+ *	bad clipping with EXTEND_NONE
+ *	http://bugs.freedesktop.org/show_bug.cgi?id=15349
+ */
+
+#define SCALE	10
+#define PAD 	3
+#define WIDTH	(PAD + 3 * SCALE + PAD)
+#define HEIGHT	WIDTH
+
+cairo_test_t test = {
+    "filter-bilinear-extents",
+    "Test that pattern extents are properly computed for CAIRO_FILTER_BILINEAR",
+    WIDTH, HEIGHT,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *checker;
+    cairo_t *cr2;
+
+    /* Create a 2x2 blue+red checker */
+    checker = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 2, 2);
+    cr2 = cairo_create (checker);
+
+    cairo_set_source_rgb (cr2, 1, 0 ,0); /* red */
+    cairo_paint (cr2);
+    cairo_set_source_rgb (cr2, 0, 0, 1); /* blue */
+    cairo_rectangle (cr2, 0, 1, 1, 1);
+    cairo_rectangle (cr2, 1, 0, 1, 1);
+    cairo_fill (cr2);
+    cairo_destroy (cr2);
+
+    /* Draw our surface scaled with EXTEND_NONE */
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_paint (cr);
+
+    cairo_save (cr);
+    cairo_translate (cr, PAD, PAD);
+    cairo_scale (cr, SCALE, SCALE);
+    cairo_translate (cr, 0.5, 0.5);
+    cairo_set_source_surface (cr, checker, 0, 0);
+    cairo_paint (cr);
+    cairo_restore (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}