test: Add a test for various zero mask operations

test/Makefile.sources

@@ -269,7 +269,8 @@ test_sources = \
 	user-font-rescale.c				\
 	xcomposite-projection.c				\
 	xlib-expose-event.c 				\
-	zero-alpha.c
+	zero-alpha.c					\
+	zero-mask.c
 
 pthread_test_sources =					\
 	pthread-same-source.c				\

test/zero-mask.c

@@ -0,0 +1,199 @@
+/*
+ * Copyright © 2010 Red Hat, Inc.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of
+ * Red Hat, Inc. not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Red Hat, Inc. makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL RED HAT, INC. BE LIABLE FOR ANY SPECIAL,
+ * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+ * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Author: Benjamin Otte <otte@gnome.org>
+ */
+
+#include "cairo-test.h"
+
+#define RECT 10
+#define SPACE 5
+
+static void
+paint_with_alpha (cairo_t *cr)
+{
+    cairo_paint_with_alpha (cr, 0.0);
+}
+
+static void
+mask_with_solid (cairo_t *cr)
+{
+    cairo_pattern_t *pattern = cairo_pattern_create_rgba (1, 0, 0, 0);
+
+    cairo_mask (cr, pattern);
+    
+    cairo_pattern_destroy (pattern);
+}
+
+static void
+mask_with_empty_gradient (cairo_t *cr)
+{
+    cairo_pattern_t *pattern = cairo_pattern_create_linear (1, 2, 3, 4);
+
+    cairo_mask (cr, pattern);
+    
+    cairo_pattern_destroy (pattern);
+}
+
+static void
+mask_with_gradient (cairo_t *cr)
+{
+    cairo_pattern_t *pattern = cairo_pattern_create_radial (1, 2, 3, 4, 5, 6);
+
+    cairo_pattern_add_color_stop_rgba (pattern, 0, 1, 0, 0, 0);
+    cairo_pattern_add_color_stop_rgba (pattern, 0, 0, 0, 1, 0);
+
+    cairo_mask (cr, pattern);
+    
+    cairo_pattern_destroy (pattern);
+}
+
+static void
+mask_with_surface (cairo_t *cr)
+{
+    cairo_surface_t *surface = cairo_surface_create_similar (cairo_get_target (cr),
+                                                             CAIRO_CONTENT_COLOR_ALPHA,
+                                                             RECT,
+                                                             RECT);
+
+    cairo_mask_surface (cr, surface, 0, 0);
+    
+    cairo_surface_destroy (surface);
+}
+
+static void
+mask_with_alpha_surface (cairo_t *cr)
+{
+    cairo_surface_t *surface = cairo_surface_create_similar (cairo_get_target (cr),
+                                                             CAIRO_CONTENT_ALPHA,
+                                                             RECT / 2,
+                                                             RECT / 2);
+    cairo_pattern_t *pattern = cairo_pattern_create_for_surface (surface);
+    cairo_pattern_set_extend (pattern, CAIRO_EXTEND_REFLECT);
+
+    cairo_mask (cr, pattern);
+    
+    cairo_pattern_destroy (pattern);
+    cairo_surface_destroy (surface);
+}
+
+static void
+mask_with_nonclear_surface (cairo_t *cr)
+{
+    static unsigned char data[8 * 4] = { 0, };
+    cairo_surface_t *surface = cairo_image_surface_create_for_data (data,
+                                                                    CAIRO_FORMAT_A1,
+                                                                    16, 8, 4);
+
+    cairo_mask_surface (cr, surface, 0, 0);
+    
+    cairo_surface_destroy (surface);
+}
+
+static void
+mask_with_0x0_surface (cairo_t *cr)
+{
+    cairo_surface_t *surface = cairo_surface_create_similar (cairo_get_target (cr),
+                                                             CAIRO_CONTENT_COLOR_ALPHA,
+                                                             0, 0);
+
+    cairo_mask_surface (cr, surface, 0, 0);
+    
+    cairo_surface_destroy (surface);
+}
+
+static void
+mask_with_extend_none (cairo_t *cr)
+{
+    cairo_surface_t *surface = cairo_surface_create_similar (cairo_get_target (cr),
+                                                             CAIRO_CONTENT_COLOR_ALPHA,
+                                                             RECT,
+                                                             RECT);
+
+    cairo_mask_surface (cr, surface, 2 * RECT, 2 * RECT);
+    
+    cairo_surface_destroy (surface);
+}
+
+#define ARRAY_LENGTH(array) (sizeof (array) / sizeof ((array)[0]))
+
+typedef void (* mask_func_t) (cairo_t *);
+
+mask_func_t mask_funcs[] = {
+  paint_with_alpha,
+  mask_with_solid,
+  mask_with_empty_gradient,
+  mask_with_gradient,
+  mask_with_surface,
+  mask_with_alpha_surface,
+  mask_with_nonclear_surface,
+  mask_with_0x0_surface,
+  mask_with_extend_none
+};
+
+cairo_operator_t operators[] = {
+  CAIRO_OPERATOR_CLEAR,
+  CAIRO_OPERATOR_SOURCE,
+  CAIRO_OPERATOR_OVER,
+  CAIRO_OPERATOR_IN,
+  CAIRO_OPERATOR_DEST_ATOP,
+  CAIRO_OPERATOR_SATURATE,
+  CAIRO_OPERATOR_MULTIPLY
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    unsigned int i, op;
+
+    /* 565-compatible gray background */
+    cairo_set_source_rgb (cr, 0.51613, 0.55555, 0.51613);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 0.0, 1.0, 0.0); /* green */
+    /* mask with zero-alpha in several ways */
+
+    cairo_translate (cr, SPACE, SPACE);
+
+    for (op = 0; op < ARRAY_LENGTH (operators); op++) {
+        cairo_set_operator (cr, operators[op]);
+        
+        for (i = 0; i < ARRAY_LENGTH (mask_funcs); i++) {
+            cairo_save (cr);
+            cairo_translate (cr, i * (RECT + SPACE), op * (RECT + SPACE));
+            cairo_rectangle (cr, 0, 0, RECT, RECT);
+            cairo_clip (cr);
+            mask_funcs[i] (cr);
+            cairo_restore (cr);
+        }
+    }
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (zero_mask,
+	    "Testing that masking with zero alpha works",
+	    "alpha, mask", /* keywords */
+	    NULL, /* requirements */
+	    SPACE + (RECT + SPACE) * ARRAY_LENGTH (mask_funcs),
+	    SPACE + (RECT + SPACE) * ARRAY_LENGTH (operators),
+	    NULL, draw)