test: Add a1-rasterisation

Check the rounding criteria when rasterising.

test/Makefile.am

@@ -137,6 +137,8 @@ REFERENCE_IMAGES = \
 	a1-mask.ref.png \
 	a1-mask-sample.ref.png \
 	a1-mask-sample.quartz.xfail.png \
+	a1-rasterisation-rectangles.ref.png \
+	a1-rasterisation-triangles.ref.png \
 	a1-traps-sample.ref.png \
 	a1-traps-sample.quartz.xfail.png \
 	a8-mask.ref.png \

test/Makefile.sources

@@ -3,6 +3,7 @@ test_sources = \
 	a1-mask.c					\
 	a1-mask-sample.c 				\
 	a1-traps-sample.c				\
+	a1-rasterisation.c				\
 	a8-mask.c					\
 	aliasing.c					\
 	alpha-similar.c					\

test/a1-rasterisation.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright 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>
+ */
+
+#include "cairo-test.h"
+
+/*
+ * Test the fidelity of the rasterisation, paying careful attention to rounding.
+ */
+
+#include "../src/cairo-fixed-type-private.h"
+#define PRECISION (int)(1 << CAIRO_FIXED_FRAC_BITS)
+
+#define WIDTH ((PRECISION/2+1)*3)
+#define HEIGHT ((PRECISION/2+1)*3)
+
+#define SUBPIXEL(v) ((v)/(double)(PRECISION/2))
+
+static cairo_test_status_t
+rectangles (cairo_t *cr, int width, int height)
+{
+    int x, y;
+
+    cairo_set_source_rgb (cr, 1.0, 1.0, 1.0);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 0.0, 0.0, 0.0);
+    cairo_set_antialias (cr, CAIRO_ANTIALIAS_NONE);
+
+    for (x = 0; x < WIDTH; x += 3) {
+	for (y = 0; y < HEIGHT; y += 3) {
+	    cairo_rectangle (cr, x + SUBPIXEL (y/3) - .5, y + SUBPIXEL (x/3) - .5, .5, .5);
+	}
+    }
+    cairo_fill (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+static cairo_test_status_t
+triangles (cairo_t *cr, int width, int height)
+{
+    int x, y;
+
+    cairo_set_source_rgb (cr, 1.0, 1.0, 1.0);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 0.0, 0.0, 0.0);
+    cairo_set_antialias (cr, CAIRO_ANTIALIAS_NONE);
+
+    for (x = 0; x < WIDTH; x += 3) {
+	for (y = 0; y < HEIGHT; y += 3) {
+	    /* a rectangle with a diagonal to force tessellation */
+	    cairo_move_to (cr, x + SUBPIXEL (y/3) - .5, y + SUBPIXEL (x/3) - .5);
+	    cairo_rel_line_to (cr, .5, .5);
+	    cairo_rel_line_to (cr, 0, -.5);
+	    cairo_rel_line_to (cr, -.5, 0);
+	    cairo_rel_line_to (cr, 0, .5);
+	    cairo_rel_line_to (cr, .5, 0);
+	}
+    }
+    cairo_fill (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (a1_rasterisation_rectangles,
+	    "Check the fidelity of the rasterisation.",
+	    "rasterisation", /* keywords */
+	    "target=raster", /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, rectangles)
+
+CAIRO_TEST (a1_rasterisation_triangles,
+	    "Check the fidelity of the rasterisation.",
+	    "rasterisation", /* keywords */
+	    "target=raster", /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, triangles)