Augment tests to do better testing of paths/images with alpha.

Add a new cairo_test_paint_checkered function so that tests that draw
with alpha can easily put an easy-to-see checkered background in place
first.

Add new tests caps-joins-alpha and paint-source-alpha that do simple
tests of strokes and image painting with source pattern alpha.

Also, add the checkered background to paint-with-alpha for
consistency.

test/.gitignore

@@ -4,6 +4,7 @@ Makefile
 Makefile.in
 a8-mask
 caps-joins
+caps-joins-alpha
 caps-sub-paths
 clip-all
 clip-fill-rule
@@ -44,6 +45,7 @@ nil-surface
 operator-clear
 operator-source
 paint
+paint-source-alpha
 paint-with-alpha
 path-data
 pattern-get-type

test/Makefile.am

@@ -2,6 +2,7 @@
 TESTS = 			\
 a8-mask				\
 caps-joins			\
+caps-joins-alpha		\
 caps-sub-paths			\
 clip-all			\
 clip-fill-rule			\
@@ -36,6 +37,7 @@ nil-surface			\
 operator-clear			\
 operator-source			\
 paint				\
+paint-source-alpha		\
 paint-with-alpha		\
 path-data			\
 pattern-get-type		\
@@ -113,6 +115,8 @@ a8-mask-rgb24-ref.png					\
 caps-joins-ps-rgb24-ref.png				\
 caps-joins-ref.png					\
 caps-joins-rgb24-ref.png				\
+caps-joins-alpha-ref.png				\
+caps-joins-alpha-rgb24-ref.png				\
 caps-sub-paths-ref.png					\
 caps-sub-paths-rgb24-ref.png				\
 clip-all-ref.png					\
@@ -178,6 +182,8 @@ operator-source-ref.png					\
 operator-source-rgb24-ref.png				\
 paint-ref.png						\
 paint-rgb24-ref.png					\
+paint-source-alpha-ref.png				\
+paint-source-alpha-rgb24-ref.png			\
 paint-with-alpha-ref.png				\
 paint-with-alpha-rgb24-ref.png				\
 path-data-ref.png					\
@@ -309,6 +315,7 @@ endif
 # from autogen.sh. My, but this is painful...
 a8_mask_LDADD = $(LDADDS)
 caps_joins_LDADD = $(LDADDS)
+caps_joins_alpha_LDADD = $(LDADDS)
 caps_sub_paths_LDADD = $(LDADDS)
 clip_all_LDADD = $(LDADDS)
 clip_fill_rule_LDADD = $(LDADDS)
@@ -345,6 +352,7 @@ nil_surface_LDADD = $(LDADDS)
 operator_clear_LDADD = $(LDADDS)
 operator_source_LDADD = $(LDADDS)
 paint_LDADD = $(LDADDS)
+paint_source_alpha_LDADD = $(LDADDS)
 paint_with_alpha_LDADD = $(LDADDS)
 path_data_LDADD = $(LDADDS)
 pattern_get_type_LDADD = $(LDADDS)

test/cairo-test.c

@@ -1803,3 +1803,48 @@ cairo_test_create_pattern_from_png (const char *filename)
 
     return pattern;
 }
+
+static cairo_status_t
+_draw_check (cairo_surface_t *surface, int width, int height)
+{
+    cairo_t *cr;
+    cairo_status_t status;
+
+    cr = cairo_create (surface);
+    cairo_set_source_rgb (cr, 0.75, 0.75, 0.75); /* light gray */
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 0.25, 0.25, 0.25); /* dark gray */
+    cairo_rectangle (cr, width / 2,  0, width / 2, height / 2);
+    cairo_rectangle (cr, 0, height / 2, width / 2, height / 2);
+    cairo_fill (cr);
+
+    status = cairo_status (cr);
+
+    cairo_destroy (cr);
+
+    return status;
+}
+
+cairo_status_t
+cairo_test_paint_checkered (cairo_t *cr)
+{
+    cairo_status_t status;
+    cairo_surface_t *check;
+
+    check = cairo_image_surface_create (CAIRO_FORMAT_RGB24, 12, 12);
+    status = _draw_check (check, 12, 12);
+    if (status)
+	return status;
+
+    cairo_save (cr);
+    cairo_set_source_surface (cr, check, 0, 0);
+    cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);
+    cairo_pattern_set_extend (cairo_get_source (cr), CAIRO_EXTEND_REPEAT);
+    cairo_paint (cr);
+    cairo_restore (cr);
+
+    cairo_surface_destroy (check);
+
+    return CAIRO_STATUS_SUCCESS;
+}

test/cairo-test.h

@@ -138,6 +138,9 @@ cairo_test_create_surface_from_png (const char *filename);
 cairo_pattern_t *
 cairo_test_create_pattern_from_png (const char *filename);
 
+cairo_status_t
+cairo_test_paint_checkered (cairo_t *cr);
+
 void
 xasprintf (char **strp, const char *fmt, ...);
 

test/caps-joins-alpha.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright © 2005 Red Hat, Inc.
+ * Copyright © 2006 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: Carl D. Worth <cworth@cworth.org>
+ */
+
+#include "cairo-test.h"
+
+#define LINE_WIDTH 	10.
+#define SIZE 		(5 * LINE_WIDTH)
+#define PAD		(2 * LINE_WIDTH)
+
+cairo_test_t test = {
+    "caps-joins-alpha",
+    "Test caps and joins with some source alpha",
+    3 * (PAD + SIZE) + PAD,
+    PAD + SIZE + PAD
+};
+
+static void
+make_path (cairo_t *cr)
+{
+    cairo_move_to (cr, 0., 0.);
+    cairo_rel_line_to (cr, 0., SIZE);
+    cairo_rel_line_to (cr, SIZE, 0.);
+    cairo_close_path (cr);
+
+    cairo_move_to (cr, 2 * LINE_WIDTH, 0.);
+    cairo_rel_line_to (cr, 3 * LINE_WIDTH, 0.);
+    cairo_rel_line_to (cr, 0., 3 * LINE_WIDTH);
+}
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    /* First draw a checkered background */
+    cairo_test_paint_checkered (cr);
+
+    /* Then draw the original caps-joins test but with a bit of alphs thrown in. */
+    cairo_set_line_width (cr, LINE_WIDTH);
+
+    cairo_set_source_rgba (cr, 1.0, 0.0, 0.0, 0.5); /* 50% red */
+    cairo_translate (cr, PAD, PAD);
+
+    make_path (cr);
+    cairo_set_line_cap (cr, CAIRO_LINE_CAP_BUTT);
+    cairo_set_line_join (cr, CAIRO_LINE_JOIN_BEVEL);
+    cairo_stroke (cr);
+
+    cairo_set_source_rgba (cr, 0.0, 1.0, 0.0, 0.5); /* 50% green */
+    cairo_translate (cr, SIZE + PAD, 0.);
+
+    make_path (cr);
+    cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
+    cairo_set_line_join (cr, CAIRO_LINE_JOIN_ROUND);
+    cairo_stroke (cr);
+
+    cairo_set_source_rgba (cr, 0.0, 0.0, 1.0, 0.5); /* 50% blue */
+
+    cairo_translate (cr, SIZE + PAD, 0.);
+
+    make_path (cr);
+    cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
+    cairo_set_line_join (cr, CAIRO_LINE_JOIN_MITER);
+    cairo_stroke (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test, draw);
+}

test/paint-source-alpha.c

@@ -0,0 +1,67 @@
+/*
+ * Copyright © 2005 Red Hat, Inc.
+ * Copyright © 2006 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: Carl D. Worth <cworth@cworth.org>
+ */
+
+#include "cairo-test.h"
+
+cairo_test_t test = {
+    "paint-source-alpha",
+    "Simple test of cairo_paint with a source surface with non-opaque alpha",
+    32, 32
+};
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_surface_t *surface;
+    static uint32_t data[16] = {
+	0x80808080, 0x80808080,		0x80800000, 0x80800000,
+	0x80808080, 0x80808080,		0x80800000, 0x80800000,
+
+	0x80008000, 0x80008000,		0x80000080, 0x80000080,
+	0x80008000, 0x80008000,		0x80000080, 0x80000080
+    };
+
+    surface = cairo_image_surface_create_for_data ((unsigned char *) data,
+						   CAIRO_FORMAT_ARGB32, 4, 4, 16);
+
+    cairo_test_paint_checkered (cr);
+
+    cairo_scale (cr, 4, 4);
+
+    cairo_set_source_surface (cr, surface, 2 , 2);
+    cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);
+    cairo_paint (cr);
+
+    cairo_surface_destroy (surface);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+int
+main (void)
+{
+    return cairo_test (&test, draw);
+}

test/paint-with-alpha.c

@@ -1,5 +1,6 @@
 /*
  * Copyright © 2005 Red Hat, Inc.
+ * Copyright © 2006 Red Hat, Inc.
  *
  * Permission to use, copy, modify, distribute, and sell this software
  * and its documentation for any purpose is hereby granted without
@@ -28,7 +29,7 @@
 cairo_test_t test = {
     "paint-with-alpha",
     "Simple test of cairo_paint_with_alpha",
-    12, 12
+    32, 32
 };
 
 static cairo_test_status_t
@@ -46,9 +47,11 @@ draw (cairo_t *cr, int width, int height)
     surface = cairo_image_surface_create_for_data ((unsigned char *) data,
 						   CAIRO_FORMAT_RGB24, 4, 4, 16);
 
-    cairo_scale (cr, 2, 2);
+    cairo_test_paint_checkered (cr);
 
-    cairo_set_source_surface (cr, surface, 1 , 1);
+    cairo_scale (cr, 4, 4);
+
+    cairo_set_source_surface (cr, surface, 2 , 2);
     cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);
     cairo_paint_with_alpha (cr, 0.5);