test: Add tests for mesh patterns

mesh-pattern tests a mesh pattern with non-opaque two overlapping
patches.

mesh-pattern-accuracy tests the accuracy of the color computed in each
point of a patch. It can point out defects in rasterizers which rely
on mesh subdivision only use the mesh shape instead of both shape and
color to decide when the tensor-product patches can be approximated
with Gouraud-shaded triangles.

mesh-pattern-conical is an example of how a conical gradient can be
approximated with a mesh pattern.

mesh-pattern-control-points tests a mesh pattern with control points
in non-default position to verify that their position affects the
color as expected.

mesh-pattern-fold tests a mesh pattern with a patch which folds along
both sides.

mesh-pattern-overlap tests a mesh pattern with a patch which folds
along just one side.

mesh-pattern-transformed tests a mesh pattern with non-identity
transform matrix.

1 files changed, 99 insertions, 0 deletions

diff --git a/test/mesh-pattern-accuracy.c b/test/mesh-pattern-accuracy.c
new file mode 100644
index 000000000..0f756c570
--- /dev/null
+++ b/test/mesh-pattern-accuracy.c
@@ -0,0 +1,99 @@
+/*
+ * Copyright © 2009 Adrian Johnson
+ *
+ * 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: Adrian Johnson <ajohnson@redneon.com>
+ */
+
+#include "cairo-test.h"
+#include <float.h>
+
+#define SIZE 256
+
+/* This test is designed to test the accuracy of the rendering of mesh
+ * patterns.
+ *
+ * Color accuracy is tested by a square patch covering the whole
+ * surface with black and white corners.
+ *
+ * Extents accuracy is checked by a small red square patch at the
+ * center of the surface which should measure 2x2 pixels.
+ */
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_pattern_t *pattern;
+    double offset;
+
+    cairo_test_paint_checkered (cr);
+
+    pattern = cairo_pattern_create_mesh ();
+
+    cairo_pattern_mesh_begin_patch (pattern);
+
+    cairo_pattern_mesh_move_to (pattern, 0, 0);
+    cairo_pattern_mesh_line_to (pattern, 1, 0);
+    cairo_pattern_mesh_line_to (pattern, 1, 1);
+    cairo_pattern_mesh_line_to (pattern, 0, 1);
+
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 0, 0, 0, 0);
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 1, 1, 1, 1);
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 2, 0, 0, 0);
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 3, 1, 1, 1);
+
+    cairo_pattern_mesh_end_patch (pattern);
+
+    cairo_pattern_mesh_begin_patch (pattern);
+
+    /* A small 1x1 red patch, that should be rendered as a 2x2 red
+     * square in the center of the image */
+
+    offset = 0.5 / SIZE;
+
+    cairo_pattern_mesh_move_to (pattern, 0.5 + offset, 0.5 + offset);
+    cairo_pattern_mesh_line_to (pattern, 0.5 + offset, 0.5 - offset);
+    cairo_pattern_mesh_line_to (pattern, 0.5 - offset, 0.5 - offset);
+    cairo_pattern_mesh_line_to (pattern, 0.5 - offset, 0.5 + offset);
+
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 0, 1, 0, 0);
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 1, 1, 0, 0);
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 2, 1, 0, 0);
+    cairo_pattern_mesh_set_corner_color_rgb (pattern, 3, 1, 0, 0);
+
+    cairo_pattern_mesh_end_patch (pattern);
+
+    cairo_scale (cr, SIZE, SIZE);
+
+    cairo_set_source (cr, pattern);
+    cairo_paint (cr);
+    cairo_pattern_destroy (pattern);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (mesh_pattern_accuracy,
+	    "Paint mesh pattern",
+	    "mesh,pattern", /* keywords */
+	    NULL, /* requirements */
+	    SIZE, SIZE,
+	    NULL, draw)