test: Add tighten-bounds

In the spirit of the new big-{little,empty}-{box,triangle} tests, this test
combines various paths. However, these paths are not only filled but also used
for clipping, resulting in 120 different combinations.

No backend currently succeeds the test. The reference image is a gimp-ination of
the image and test-fallback results and thus certainly wrong. Feel free to fix.

Additionally, this makes the xcb backend die with an ugly failed assert.

Signed-off-by: Uli Schlachter <psychon@znc.in>

1 files changed, 172 insertions, 0 deletions

diff --git a/test/tighten-bounds.c b/test/tighten-bounds.c
new file mode 100644
index 000000000..02fc81aff
--- /dev/null
+++ b/test/tighten-bounds.c
@@ -0,0 +1,172 @@
+/*
+ * Copyright © 2011 Uli Schlachter
+ *
+ * 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: Uli Schlachter <psychon@znc.in>
+ */
+
+#include "cairo-test.h"
+
+static void path_none (cairo_t *cr, int size)
+{
+}
+
+static void path_box (cairo_t *cr, int size)
+{
+    cairo_rectangle (cr, 0, 0, size, size);
+}
+
+static void path_box_unaligned (cairo_t *cr, int size)
+{
+    cairo_rectangle (cr, 0.5, 0.5, size - 1, size - 1);
+}
+
+static void path_triangle (cairo_t *cr, int size)
+{
+    cairo_move_to (cr, 0, 0);
+    cairo_line_to (cr, size/2, size);
+    cairo_line_to (cr, size, 0);
+    cairo_close_path (cr);
+}
+
+static void path_circle (cairo_t *cr, int size)
+{
+    cairo_arc (cr, size / 2.0, size / 2.0, size / 2.0, 0, 2 * M_PI);
+}
+
+static void (* const path_funcs[])(cairo_t *cr, int size) = {
+    path_none,
+    path_box,
+    path_box_unaligned,
+    path_triangle,
+    path_circle
+};
+
+#define SIZE 20
+#define PAD 2
+#define TYPES 6
+/* All-clipped is boring, thus we skip path_none for clipping */
+#define CLIP_OFFSET 1
+#define IMAGE_WIDTH ((ARRAY_LENGTH (path_funcs) - CLIP_OFFSET) * TYPES * (SIZE + PAD) - PAD)
+#define IMAGE_HEIGHT (ARRAY_LENGTH (path_funcs) * (SIZE + PAD) - PAD)
+
+static void
+draw_idx (cairo_t *cr, int i, int j, int type)
+{
+    cairo_bool_t little_path = type & (1 << 0);
+    cairo_bool_t empty_clip;
+    cairo_bool_t little_clip;
+
+    /* The lowest bit controls the path, the rest the clip */
+    little_path = type & 1;
+
+    /* We don't want the combination "empty_clip = TRUE, little_clip = FALSE"
+     * (== all clipped).
+     */
+    switch (type >> 1)
+    {
+    case 0:
+	empty_clip = FALSE;
+	little_clip = FALSE;
+	break;
+    case 1:
+	empty_clip = FALSE;
+	little_clip = TRUE;
+	break;
+    case 2:
+	empty_clip = TRUE;
+	little_clip = TRUE;
+	break;
+    default:
+	return;
+    }
+
+    cairo_save (cr);
+
+    /* Thanks to the fill rule, drawing something twice removes it again */
+    cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);
+
+    path_funcs[i] (cr, SIZE);
+    if (empty_clip)
+	path_funcs[i] (cr, SIZE);
+    if (little_clip)
+    {
+	cairo_save (cr);
+	cairo_translate (cr, SIZE / 4, SIZE / 4);
+	path_funcs[i] (cr, SIZE / 2);
+	cairo_restore (cr);
+    }
+    cairo_clip (cr);
+
+    path_funcs[j] (cr, SIZE);
+    path_funcs[j] (cr, SIZE);
+    if (little_path)
+    {
+	/* Draw the object again in the center of itself */
+	cairo_save (cr);
+	cairo_translate (cr, SIZE / 4, SIZE / 4);
+	path_funcs[j] (cr, SIZE / 2);
+	cairo_restore (cr);
+    }
+    cairo_fill (cr);
+    cairo_restore (cr);
+}
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    size_t i, j, k;
+
+    cairo_set_source_rgb (cr, 0, 1, 0);
+    cairo_paint (cr);
+
+    /* Set an unbounded operator so that we can see how accurate the bounded
+     * extents were.
+     */
+    cairo_set_operator (cr, CAIRO_OPERATOR_IN);
+    cairo_set_source_rgb (cr, 1, 1, 1);
+
+    for (j = 0; j < ARRAY_LENGTH (path_funcs); j++) {
+	cairo_save (cr);
+	for (i = CLIP_OFFSET; i < ARRAY_LENGTH (path_funcs); i++) {
+	    for (k = 0; k < TYPES; k++) {
+		cairo_save (cr);
+		cairo_rectangle (cr, 0, 0, SIZE, SIZE);
+		cairo_clip (cr);
+		draw_idx (cr, i, j, k);
+		cairo_restore (cr);
+		cairo_translate (cr, SIZE + PAD, 0);
+	    }
+	}
+	cairo_restore (cr);
+	cairo_translate (cr, 0, SIZE + PAD);
+    }
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (tighten_bounds,
+	    "Tests that we tighten the bounds after tessellation.",
+	    "fill", /* keywords */
+	    NULL, /* requirements */
+	    IMAGE_WIDTH, IMAGE_HEIGHT,
+	    NULL, draw)