test: Test a1 clipping semantics

If I've written the tests correctly, these should produce identical
images as the a1 rasterisation tests.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

test/Makefile.refs

@@ -1,10 +1,14 @@
 # Note REFERENCE_IMAGES must be in lexicographical order.
-# Use generate_refs on a git checkout with updated images.
+# Use generate_refs.sh on a git checkout with updated images.
 REFERENCE_IMAGES = \
 	a1-bug.image16.ref.png \
 	a1-bug.quartz.xfail.png \
 	a1-bug.ref.png \
 	a1-bug.xlib.ref.png \
+	a1-clip-fill-equal.ref.png \
+	a1-clip-fill.ref.png \
+	a1-clip-paint.ref.png \
+	a1-clip-stroke.ref.png \
 	a1-image-sample.gl.xfail.png \
 	a1-image-sample.ref.png \
 	a1-mask-sample.ref.png \

test/Makefile.sources

@@ -1,5 +1,6 @@
 test_sources = \
 	a1-bug.c					\
+	a1-clip.c					\
 	a1-image-sample.c 				\
 	a1-mask.c					\
 	a1-mask-sample.c 				\

test/a1-clip.c

@@ -0,0 +1,175 @@
+/*
+ * 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.
+ *
+ * Author: Carl D. Worth <cworth@cworth.org>
+ */
+
+#include "cairo-test.h"
+
+#define POINTS	10
+#define STEP	(1.0 / POINTS)
+#define PAD	1
+#define WIDTH	(PAD + POINTS * 2 + PAD)
+#define HEIGHT	(WIDTH)
+
+static cairo_test_status_t
+paint (cairo_t *cr, int width, int height)
+{
+    int i, j;
+
+    /* Fill background white */
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_paint (cr);
+
+    /* Draw in black */
+    cairo_set_source_rgb (cr, 0, 0, 0);
+
+    cairo_translate (cr, PAD, PAD);
+    cairo_set_antialias (cr, CAIRO_ANTIALIAS_NONE);
+
+    for (i = 0; i < POINTS; i++)
+	for (j = 0; j < POINTS; j++) {
+	    cairo_save (cr);
+	    cairo_rectangle (cr, 2 * i + i * STEP, 2 * j + j * STEP, 1, 1);
+	    cairo_clip (cr);
+	    cairo_paint (cr);
+	    cairo_restore (cr);
+	}
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+static cairo_test_status_t
+fill_equal (cairo_t *cr, int width, int height)
+{
+    int i, j;
+
+    /* Fill background white */
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_paint (cr);
+
+    /* Draw in black */
+    cairo_set_source_rgb (cr, 0, 0, 0);
+
+    cairo_translate (cr, PAD, PAD);
+    cairo_set_antialias (cr, CAIRO_ANTIALIAS_NONE);
+
+    for (i = 0; i < POINTS; i++)
+	for (j = 0; j < POINTS; j++) {
+	    cairo_save (cr);
+	    cairo_rectangle (cr, 2 * i + i * STEP, 2 * j + j * STEP, 1, 1);
+	    cairo_clip_preserve (cr);
+	    cairo_fill (cr);
+	    cairo_restore (cr);
+	}
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+static cairo_test_status_t
+fill (cairo_t *cr, int width, int height)
+{
+    int i, j;
+
+    /* Fill background white */
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_paint (cr);
+
+    /* Draw in black */
+    cairo_set_source_rgb (cr, 0, 0, 0);
+
+    cairo_translate (cr, PAD, PAD);
+    cairo_set_antialias (cr, CAIRO_ANTIALIAS_NONE);
+
+    for (i = 0; i < POINTS; i++)
+	for (j = 0; j < POINTS; j++) {
+	    cairo_save (cr);
+	    cairo_rectangle (cr, 2 * i + i * STEP, 2 * j + j * STEP, 1, 1);
+	    cairo_clip (cr);
+	    cairo_rectangle (cr, 2 * i, 2 * j, 2, 2);
+	    cairo_fill (cr);
+	    cairo_restore (cr);
+	}
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+static cairo_test_status_t
+stroke (cairo_t *cr, int width, int height)
+{
+    int i, j;
+
+    /* Fill background white */
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_paint (cr);
+
+    /* Draw in black */
+    cairo_set_source_rgb (cr, 0, 0, 0);
+
+    cairo_translate (cr, PAD, PAD);
+    cairo_set_antialias (cr, CAIRO_ANTIALIAS_NONE);
+
+    cairo_set_line_width (cr, 2);
+    cairo_set_line_cap (cr, CAIRO_LINE_CAP_BUTT);
+
+    for (i = 0; i < POINTS; i++)
+	for (j = 0; j < POINTS; j++) {
+	    cairo_save (cr);
+	    cairo_rectangle (cr, 2 * i + i * STEP, 2 * j + j * STEP, 1, 1);
+	    cairo_clip (cr);
+	    cairo_move_to (cr, 2 * i, 2 * j + 1);
+	    cairo_line_to (cr, 2 * i + 2, 2 * j + 1);
+	    cairo_stroke (cr);
+	    cairo_restore (cr);
+	}
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (a1_clip_paint,
+	    "Test sample position when drawing trapezoids with ANTIALIAS_NONE",
+	    "alpha, clip", /* keywords */
+	    "target=raster", /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, paint)
+
+CAIRO_TEST (a1_clip_fill,
+	    "Test sample position when drawing trapezoids with ANTIALIAS_NONE",
+	    "alpha, clip", /* keywords */
+	    "target=raster", /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, fill)
+
+CAIRO_TEST (a1_clip_fill_equal,
+	    "Test sample position when drawing trapezoids with ANTIALIAS_NONE",
+	    "alpha, clip", /* keywords */
+	    "target=raster", /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, fill_equal)
+
+CAIRO_TEST (a1_clip_stroke,
+	    "Test sample position when drawing trapezoids with ANTIALIAS_NONE",
+	    "alpha, clip", /* keywords */
+	    "target=raster", /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, stroke)