[test] Exercise "soft" masks.

PDF has a concept of "soft" masks, for which it is able to construct a
mask out of PDF drawing operations. These tests exercise constructing
various masks using the high level drawing operations.

test/.gitignore

@@ -162,6 +162,13 @@ set-source
 show-glyphs-many
 show-text-current-point
 skew-extreme
+smask
+smask-fill
+smask-image-mask
+smask-mask
+smask-paint
+smask-stroke
+smask-text
 solid-pattern-cache-stress
 source-clip
 source-clip-scale

test/Makefile.am

@@ -120,6 +120,13 @@ self-intersecting$(EXEEXT)				\
 set-source$(EXEEXT)					\
 show-text-current-point$(EXEEXT)			\
 skew-extreme$(EXEEXT)					\
+smask$(EXEEXT)						\
+smask-fill$(EXEEXT)					\
+smask-image-mask$(EXEEXT)				\
+smask-mask$(EXEEXT)					\
+smask-paint$(EXEEXT)					\
+smask-stroke$(EXEEXT)					\
+smask-text$(EXEEXT)					\
 solid-pattern-cache-stress$(EXEEXT)			\
 source-clip$(EXEEXT)					\
 source-clip-scale$(EXEEXT)				\
@@ -579,6 +586,13 @@ REFERENCE_IMAGES = \
 	show-text-current-point-quartz-ref.png \
 	skew-extreme-ref.png \
 	skew-extreme-ps-ref.png \
+	smask-ref.png			\
+	smask-fill-ref.png		\
+	smask-image-mask-ref.png	\
+	smask-mask-ref.png		\
+	smask-paint-ref.png		\
+	smask-stroke-ref.png		\
+	smask-text-ref.png		\
 	stroke-image-ref.png \
 	stroke-image-pdf-ref.png \
 	stroke-image-ps-ref.png \

test/smask-fill.c

@@ -0,0 +1,83 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "smask-fill",
+    "Test the support of \"soft\" masks with fills",
+    60, 60,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *mask;
+    cairo_pattern_t *pattern;
+    cairo_t *cr2;
+
+    mask = cairo_surface_create_similar (cairo_get_group_target (cr),
+				         CAIRO_CONTENT_ALPHA,
+					 width, height);
+    cr2 = cairo_create (mask);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, width, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.75, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 0., 0., 0., 0.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_arc (cr2, 0.5 * width, 0.5 * height, 0.45 * height, 0, 2 * M_PI);
+    cairo_fill (cr2);
+    cairo_destroy (cr2);
+
+
+    cairo_set_source_rgb (cr, 0, 0, 1.0);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 1.0, 0, 0);
+    cairo_mask_surface (cr, mask, 0, 0);
+    cairo_surface_destroy (mask);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
+

test/smask-image-mask.c

@@ -0,0 +1,92 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "smask-image-mask",
+    "Test the support of \"soft\" masks with a secondary image mask",
+    60, 60,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    static uint32_t data[] = {
+	0xaa000000, 0x55000000,
+	0x55000000, 0xaa000000,
+    };
+
+    cairo_surface_t *mask, *mask2;
+    cairo_pattern_t *pattern;
+    cairo_t *cr2;
+
+    mask = cairo_surface_create_similar (cairo_get_group_target (cr),
+				         CAIRO_CONTENT_ALPHA,
+					 width, height);
+    cr2 = cairo_create (mask);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, width, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.75, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 0., 0., 0., 0.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    mask2 = cairo_image_surface_create_for_data ((unsigned char *) data,
+						CAIRO_FORMAT_ARGB32, 2, 2, 8);
+    pattern = cairo_pattern_create_for_surface (mask2);
+    cairo_surface_destroy (mask2);
+    cairo_pattern_set_extend (pattern, CAIRO_EXTEND_REPEAT);
+    cairo_mask (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+    cairo_destroy (cr2);
+
+    cairo_set_source_rgb (cr, 0, 0, 1.0);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 1.0, 0, 0);
+    cairo_mask_surface (cr, mask, 0, 0);
+    cairo_surface_destroy (mask);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
+

test/smask-mask.c

@@ -0,0 +1,107 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "smask-mask",
+    "Test the support of \"soft\" masks with a secondary mask",
+    60, 60,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *mask, *mask2;
+    cairo_pattern_t *pattern;
+    cairo_t *cr2;
+
+    mask = cairo_surface_create_similar (cairo_get_group_target (cr),
+				         CAIRO_CONTENT_ALPHA,
+					 width, height);
+
+    mask2 = cairo_surface_create_similar (mask,
+				          CAIRO_CONTENT_ALPHA,
+					  width, height);
+    cr2 = cairo_create (mask2);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, width, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.75, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 0., 0., 0., 0.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+    cairo_paint (cr2);
+    cairo_destroy (cr2);
+
+
+    cr2 = cairo_create (mask);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_radial (
+	    0.5 * width, 0.5 * height, 0,
+	    0.5 * width, 0.5 * height, 0.5 *height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 1., 1., 1., 1.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_mask_surface (cr2, mask2, 0, 0);
+    cairo_surface_destroy (mask2);
+    cairo_destroy (cr2);
+
+
+    cairo_set_source_rgb (cr, 0, 0, 1.0);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 1.0, 0, 0);
+    cairo_mask_surface (cr, mask, 0, 0);
+    cairo_surface_destroy (mask);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
+

test/smask-paint.c

@@ -0,0 +1,90 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "smask-paint",
+    "Test the support of \"soft\" masks with paints",
+    60, 60,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *mask;
+    cairo_pattern_t *pattern;
+    cairo_t *cr2;
+
+    mask = cairo_surface_create_similar (cairo_get_group_target (cr),
+				         CAIRO_CONTENT_ALPHA,
+					 width, height);
+    cr2 = cairo_create (mask);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, width, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.75, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 0., 0., 0., 0.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_paint (cr2);
+    cairo_destroy (cr2);
+
+    cairo_set_source_rgb (cr, 0, 0, 1.0);
+    cairo_paint (cr);
+
+    pattern = cairo_pattern_create_radial (
+	    0.5 * width, 0.5 * height, 0,
+	    0.5 * width, 0.5 * height, 0.5 *height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 0., 0., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 0., 0., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 1., 0., 0., 1.);
+    cairo_set_source (cr, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_mask_surface (cr, mask, 0, 0);
+    cairo_surface_destroy (mask);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
+

test/smask-stroke.c

@@ -0,0 +1,83 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "smask-stroke",
+    "Test the support of \"soft\" masks with strokes",
+    60, 60,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *mask;
+    cairo_pattern_t *pattern;
+    cairo_t *cr2;
+
+    mask = cairo_surface_create_similar (cairo_get_group_target (cr),
+				         CAIRO_CONTENT_ALPHA,
+					 width, height);
+    cr2 = cairo_create (mask);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, width, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.75, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 0., 0., 0., 0.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_arc (cr2, 0.5 * width, 0.5 * height, 0.4 * height, 0, 2 * M_PI);
+    cairo_stroke (cr2);
+    cairo_destroy (cr2);
+
+
+    cairo_set_source_rgb (cr, 0, 0, 1.0);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 1.0, 0, 0);
+    cairo_mask_surface (cr, mask, 0, 0);
+    cairo_surface_destroy (mask);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
+

test/smask-text.c

@@ -0,0 +1,92 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "smask-text",
+    "Test the support of \"soft\" masks with text",
+    120, 60,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *mask;
+    cairo_pattern_t *pattern;
+    cairo_t *cr2;
+    cairo_text_extents_t extents;
+
+    mask = cairo_surface_create_similar (cairo_get_group_target (cr),
+				         CAIRO_CONTENT_ALPHA,
+					 width, height);
+    cr2 = cairo_create (mask);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, width, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.75, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 0., 0., 0., 0.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_select_font_face (cr2,
+			    "Bitstream Vera Sans",
+			    CAIRO_FONT_SLANT_NORMAL,
+			    CAIRO_FONT_WEIGHT_NORMAL);
+    cairo_set_font_size (cr2, 0.5 * height);
+
+    cairo_text_extents (cr2, "cairo", &extents);
+    cairo_move_to (cr2,
+		   floor ((width - extents.width) / 2 + 0.5) - extents.x_bearing,
+		   floor ((height - extents.height) / 2 - 0.5) - extents.y_bearing);
+    cairo_show_text (cr2, "cairo");
+    cairo_destroy (cr2);
+
+    cairo_set_source_rgb (cr, 0, 0, 1.0);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 1.0, 0, 0);
+    cairo_mask_surface (cr, mask, 0, 0);
+    cairo_surface_destroy (mask);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
+

test/smask.c

@@ -0,0 +1,130 @@
+/*
+ * Copyright © 2008 Chris Wilson
+ *
+ * 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
+ * Chris Wilson not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Chris Wilson makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * CHRIS WILSON DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL CHRIS WILSON 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: Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#include "cairo-test.h"
+
+static cairo_test_draw_function_t draw;
+
+cairo_test_t test = {
+    "smask",
+    "Test the support of \"soft\" masks",
+    60, 60,
+    draw
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    static uint32_t data[] = {
+	0x80000000, 0x80000000,
+	0x80000000, 0x80000000,
+    };
+
+    cairo_surface_t *mask, *mask2;
+    cairo_pattern_t *pattern;
+    cairo_t *cr2;
+    cairo_text_extents_t extents;
+
+    mask = cairo_surface_create_similar (cairo_get_group_target (cr),
+				         CAIRO_CONTENT_ALPHA,
+					 width, height);
+    cr2 = cairo_create (mask);
+
+    cairo_save (cr2); {
+	cairo_set_operator (cr2, CAIRO_OPERATOR_CLEAR);
+	cairo_paint (cr2);
+    } cairo_restore (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, 0, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.0);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.80, 0., 0., 0., 0.0);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.90, 1., 1., 1., 0.25);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 1., 1., 1., 1.0);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_paint (cr2);
+
+    pattern = cairo_pattern_create_linear (0, 0, width, height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 1., 1., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.75, 1., 1., 1., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 0., 0., 0., 0.);
+    cairo_set_source (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    mask2 = cairo_image_surface_create_for_data ((unsigned char *) data,
+						CAIRO_FORMAT_ARGB32, 2, 2, 8);
+    pattern = cairo_pattern_create_for_surface (mask2);
+    cairo_surface_destroy (mask2);
+    cairo_pattern_set_extend (pattern, CAIRO_EXTEND_REPEAT);
+    cairo_mask (cr2, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_arc (cr2, 0.5 * width, 0.5 * height - 10, 0.2 * height, 0, 2 * M_PI);
+    cairo_fill (cr2);
+
+    cairo_arc (cr2, 0.5 * width, 0.5 * height - 10, 0.25 * height, 0, 2 * M_PI);
+    cairo_stroke (cr2);
+
+    cairo_select_font_face (cr2,
+			    "Bitstream Vera Sans",
+			    CAIRO_FONT_SLANT_NORMAL,
+			    CAIRO_FONT_WEIGHT_NORMAL);
+    cairo_set_font_size (cr2, 0.3 * height);
+
+    cairo_text_extents (cr2, "FG", &extents);
+    cairo_move_to (cr2,
+		   floor ((width - extents.width) / 2 + 0.5) - extents.x_bearing,
+		   floor (height - extents.height - 0.5) - extents.y_bearing - 5);
+    cairo_show_text (cr2, "FG");
+    cairo_destroy (cr2);
+
+    cairo_set_source_rgb (cr, 0, 0, 1.0);
+    cairo_paint (cr);
+
+    pattern = cairo_pattern_create_radial (
+	    0.5 * width, 0.5 * height, 0,
+	    0.5 * width, 0.5 * height, 0.5 *height);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.00, 0., 0., 0., 0.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.25, 1., 0., 0., 1.);
+    cairo_pattern_add_color_stop_rgba (pattern, 0.50, 1., 0., 0., .5);
+    cairo_pattern_add_color_stop_rgba (pattern, 1.00, 1., 0., 0., 1.);
+    cairo_set_source (cr, pattern);
+    cairo_pattern_destroy (pattern);
+
+    cairo_mask_surface (cr, mask, 0, 0);
+    cairo_surface_destroy (mask);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test);
+}
+