test: Add tests covering more clip fast paths in groups.

The clip-group-shapes-* tests check that it doesn't
matter whether the clip path is set before or after
pushing a group using specific types of clip paths
(aligned/unaligned rectangles and general paths.)

test/Makefile.sources

@@ -25,6 +25,7 @@ test_sources = \
 	clip-fill-rule.c				\
 	clip-fill-rule-pixel-aligned.c			\
 	clip-fill-unbounded.c				\
+	clip-group-shapes.c				\
 	clip-image.c					\
 	clip-nesting.c					\
 	clip-operator.c					\

test/clip-group-shapes.c

@@ -0,0 +1,189 @@
+/*
+ * Copyright (c) 2010 M Joonas Pihlaja
+ *
+ * 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: M Joonas Pihlaja <jpihlaja@cc.helsinki.fi>
+ */
+#include "cairo-test.h"
+
+/* Tests specific clipping fast paths and their interaction with
+ * groups:  It shouldn't matter if the clip is set before or after
+ * pushing a group.
+ *
+ * There's some overlap with the following tests, but they test for
+ * different things:
+ *
+ *  group-clip.c (tests preserving paths), clipped-group.c (tests
+ *  clipping the same thing different ways), clip-push-group (tests
+ *  for a specific bug).
+ */
+
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+
+#define GENERATE_REF 0
+
+/* For determining whether we establish the clip path before or after
+ * pushing a group. */
+enum {
+    CLIP_OUTSIDE_GROUP,
+    CLIP_INSIDE_GROUP
+};
+
+typedef void (*clipper_t)(cairo_t *cr, int w, int h);
+
+static cairo_test_status_t
+clip_and_paint (cairo_t *cr,
+                int w, int h,
+                clipper_t do_clip,
+                int clip_where)
+{
+    cairo_save (cr); {
+        if (GENERATE_REF) {
+            do_clip (cr, w, h);
+            cairo_paint (cr);
+        }
+        else {
+            if (clip_where == CLIP_OUTSIDE_GROUP)
+                do_clip (cr, w, h);
+            cairo_push_group (cr); {
+                if (clip_where == CLIP_INSIDE_GROUP)
+                    do_clip (cr, w, h);
+                cairo_paint (cr);
+            }
+            cairo_pop_group_to_source (cr);
+            cairo_paint (cr);
+        }
+    }
+    cairo_restore (cr);
+    return CAIRO_TEST_SUCCESS;
+}
+
+static cairo_test_status_t
+run_clip_test (cairo_t *cr, int w, int h, clipper_t do_clip)
+{
+    cairo_set_source_rgb (cr, 1,1,1);
+    cairo_paint (cr);
+    cairo_set_source_rgb (cr, 1,0,0);
+
+    /* Left. */
+    clip_and_paint (cr, w/2, h, do_clip, CLIP_OUTSIDE_GROUP);
+
+    /* Right */
+    cairo_translate(cr, w/2, 0);
+    clip_and_paint (cr, w/2, h, do_clip, CLIP_INSIDE_GROUP);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+static void
+clip_aligned_rectangles (cairo_t *cr, int w, int h)
+{
+    int x1 = 0.2 * w;
+    int y1 = 0.2 * h;
+    int x2 = 0.8 * w;
+    int y2 = 0.8 * h;
+
+    cairo_rectangle (cr, x1, y1, w, h);
+    cairo_clip (cr);
+
+    cairo_rectangle (cr, x2, y2, -w, -h);
+    cairo_clip (cr);
+}
+
+static void
+clip_unaligned_rectangles (cairo_t *cr, int w, int h)
+{
+    /* This clip stresses the antialiased edges produced by an
+     * unaligned rectangular clip. The edges should be produced by
+     * compositing red on white with alpha = 0.5 on the sides, and with
+     * alpha = 0.25 in the corners. */
+    int x1 = 0.2 * w;
+    int y1 = 0.2 * h;
+    int x2 = 0.8 * w;
+    int y2 = 0.8 * h;
+
+    cairo_rectangle (cr, x1+0.5, y1+0.5, w, h);
+    cairo_clip (cr);
+
+    cairo_rectangle (cr, x2+0.5, y2+0.5, -w, -h);
+    w = x2 - x1;
+    h = y2 - y1;
+    cairo_rectangle (cr, x2, y1+1, -w+1, h-1);
+    cairo_clip (cr);
+}
+
+static void
+clip_circles (cairo_t *cr, int w, int h)
+{
+    int x1 = 0.5 * w;
+    int y1 = 0.5 * h;
+    int x2 = 0.75 * w;
+    int y2 = 0.75 * h;
+    int r = 0.4*MIN(w,h);
+
+    cairo_arc (cr, x1, y1, r, 0, 6.28);
+    cairo_close_path (cr);
+    cairo_clip (cr);
+
+    cairo_arc (cr, x2, y2, r, 0, 6.28);
+    cairo_close_path (cr);
+    cairo_clip (cr);
+}
+
+static cairo_test_status_t
+draw_aligned_rectangles (cairo_t *cr, int width, int height)
+{
+    return run_clip_test (cr, width, height, clip_aligned_rectangles);
+}
+
+static cairo_test_status_t
+draw_unaligned_rectangles (cairo_t *cr, int width, int height)
+{
+    return run_clip_test (cr, width, height, clip_unaligned_rectangles);
+}
+
+static cairo_test_status_t
+draw_circles (cairo_t *cr, int width, int height)
+{
+    return run_clip_test (cr, width, height, clip_circles);
+}
+
+CAIRO_TEST (clip_group_shapes_aligned_rectangles,
+	    "Test clip and group interaction with aligned rectangle clips",
+	    "clip", /* keywords */
+	    NULL, /* requirements */
+	    200, 100,
+	    NULL, draw_aligned_rectangles)
+
+CAIRO_TEST (clip_group_shapes_unaligned_rectangles,
+	    "Test clip and group interaction with unaligned rectangle clips",
+	    "clip", /* keywords */
+	    "target=raster", /* requirements */
+	    200, 100,
+	    NULL, draw_unaligned_rectangles)
+
+CAIRO_TEST (clip_group_shapes_circles,
+	    "Test clip and group interaction with circular clips",
+	    "clip", /* keywords */
+	    NULL, /* requirements */
+	    200, 100,
+	    NULL, draw_circles)