Remove clip handling from generic surface layer.

Handling clip as part of the surface state, as opposed to being part of
the operation state, is cumbersome and a hindrance to providing true proxy
surface support. For example, the clip must be copied from the surface
onto the fallback image, but this was forgotten causing undue hassle in
each backend. Another example is the contortion the meta surface
endures to ensure the clip is correctly recorded. By contrast passing the
clip along with the operation is quite simple and enables us to write
generic handlers for providing surface wrappers. (And in the future, we
should be able to write more esoteric wrappers, e.g. automatic 2x FSAA,
trivially.)

In brief, instead of the surface automatically applying the clip before
calling the backend, the backend can call into a generic helper to apply
clipping. For raster surfaces, clip regions are handled automatically as
part of the composite interface. For vector surfaces, a clip helper is
introduced to replay and callback into an intersect_clip_path() function
as necessary.

Whilst this is not primarily a performance related change (the change
should just move the computation of the clip from the moment it is applied
by the user to the moment it is required by the backend), it is important
to track any potential regression:

ppc:
Speedups
========
image-rgba         evolution-20090607-0    1026085.22 0.18% -> 672972.07 0.77%:  1.52x speedup
▌
image-rgba         evolution-20090618-0    680579.98 0.12% -> 573237.66  0.16%:  1.19x speedup
▎
image-rgba      swfdec-fill-rate-4xaa-0    460296.92 0.36% -> 407464.63  0.42%:  1.13x speedup
▏
image-rgba      swfdec-fill-rate-2xaa-0    128431.95 0.47% -> 115051.86  0.42%:  1.12x speedup
▏
Slowdowns
=========
image-rgba     firefox-periodic-table-0    56837.61 0.78% -> 66055.17    3.20%:  1.09x slowdown
▏

1 files changed, 129 insertions, 41 deletions

diff --git a/src/cairo-region.c b/src/cairo-region.c
index 6dfa9332d..d6fff7f7f 100644
--- a/src/cairo-region.c
+++ b/src/cairo-region.c
@@ -38,7 +38,13 @@
 
 #include "cairoint.h"
 
+#include "cairo-region-private.h"
+
+/* XXX need to update pixman headers to be const as appropriate */
+#define CONST_CAST (pixman_region32_t *)
+
 static const cairo_region_t _cairo_region_nil = {
+    CAIRO_REFERENCE_COUNT_INVALID,	/* ref_count */
     CAIRO_STATUS_NO_MEMORY,		/* status */
 };
 
@@ -82,6 +88,7 @@ _cairo_region_init (cairo_region_t *region)
     VG (VALGRIND_MAKE_MEM_UNDEFINED (region, sizeof (cairo_region_t)));
 
     region->status = CAIRO_STATUS_SUCCESS;
+    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 0);
     pixman_region32_init (&region->rgn);
 }
 
@@ -92,6 +99,7 @@ _cairo_region_init_rectangle (cairo_region_t *region,
     VG (VALGRIND_MAKE_MEM_UNDEFINED (region, sizeof (cairo_region_t)));
 
     region->status = CAIRO_STATUS_SUCCESS;
+    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 0);
     pixman_region32_init_rect (&region->rgn,
 			       rectangle->x, rectangle->y,
 			       rectangle->width, rectangle->height);
@@ -100,6 +108,7 @@ _cairo_region_init_rectangle (cairo_region_t *region,
 void
 _cairo_region_fini (cairo_region_t *region)
 {
+    assert (! CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&region->ref_count));
     pixman_region32_fini (&region->rgn);
     VG (VALGRIND_MAKE_MEM_NOACCESS (region, sizeof (cairo_region_t)));
 }
@@ -127,6 +136,7 @@ cairo_region_create (void)
 	return (cairo_region_t *) &_cairo_region_nil;
 
     region->status = CAIRO_STATUS_SUCCESS;
+    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);
 
     pixman_region32_init (&region->rgn);
 
@@ -134,29 +144,23 @@ cairo_region_create (void)
 }
 slim_hidden_def (cairo_region_create);
 
-cairo_region_t *
-cairo_region_create_rectangles (cairo_rectangle_int_t *rects,
-				int count)
+cairo_status_t
+_cairo_region_init_rectangles (cairo_region_t *region,
+			       const cairo_rectangle_int_t *rects,
+			       int count)
 {
     pixman_box32_t stack_pboxes[CAIRO_STACK_ARRAY_LENGTH (pixman_box32_t)];
     pixman_box32_t *pboxes = stack_pboxes;
-    cairo_region_t *region;
+    cairo_status_t status;
     int i;
 
-    region = _cairo_malloc (sizeof (cairo_region_t));
-
-    if (!region)
-	return (cairo_region_t *)&_cairo_region_nil;
-
-    region->status = CAIRO_STATUS_SUCCESS;
+    status = CAIRO_STATUS_SUCCESS;
+    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 0);
 
     if (count > ARRAY_LENGTH (stack_pboxes)) {
 	pboxes = _cairo_malloc_ab (count, sizeof (pixman_box32_t));
-
-	if (unlikely (pboxes == NULL)) {
-	    free (region);
-	    return (cairo_region_t *)&_cairo_region_nil;
-	}
+	if (unlikely (pboxes == NULL))
+	    return _cairo_error (CAIRO_STATUS_NO_MEMORY);
     }
 
     for (i = 0; i < count; i++) {
@@ -166,15 +170,35 @@ cairo_region_create_rectangles (cairo_rectangle_int_t *rects,
 	pboxes[i].y2 = rects[i].y + rects[i].height;
     }
 
-    if (! pixman_region32_init_rects (&region->rgn, pboxes, count)) {
-	free (region);
-
-	region = (cairo_region_t *)&_cairo_region_nil;
-    }
+    if (! pixman_region32_init_rects (&region->rgn, pboxes, count))
+	status = _cairo_error (CAIRO_STATUS_NO_MEMORY);
 
     if (pboxes != stack_pboxes)
 	free (pboxes);
 
+    return region->status = status;
+}
+
+cairo_region_t *
+cairo_region_create_rectangles (const cairo_rectangle_int_t *rects,
+				int count)
+{
+    cairo_region_t *region;
+    cairo_status_t status;
+
+    region = _cairo_malloc (sizeof (cairo_region_t));
+    if (unlikely (region == NULL)) {
+	_cairo_error_throw (CAIRO_STATUS_NO_MEMORY);
+	return (cairo_region_t *) &_cairo_region_nil;
+    }
+
+    status = _cairo_region_init_rectangles (region, rects, count);
+    if (unlikely (status)) {
+	cairo_region_destroy (region);
+	return (cairo_region_t *) &_cairo_region_nil;
+    }
+
+    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);
     return region;
 }
 slim_hidden_def (cairo_region_create_rectangles);
@@ -199,10 +223,11 @@ cairo_region_create_rectangle (const cairo_rectangle_int_t *rectangle)
     cairo_region_t *region;
 
     region = _cairo_malloc (sizeof (cairo_region_t));
-    if (region == NULL)
+    if (unlikely (region == NULL))
 	return (cairo_region_t *) &_cairo_region_nil;
 
     region->status = CAIRO_STATUS_SUCCESS;
+    CAIRO_REFERENCE_COUNT_INIT (&region->ref_count, 1);
 
     pixman_region32_init_rect (&region->rgn,
 			       rectangle->x, rectangle->y,
@@ -227,18 +252,20 @@ slim_hidden_def (cairo_region_create_rectangle);
  * Since: 1.10
  **/
 cairo_region_t *
-cairo_region_copy (cairo_region_t *original)
+cairo_region_copy (const cairo_region_t *original)
 {
     cairo_region_t *copy;
 
-    if (original->status)
+    if (original != NULL && original->status)
 	return (cairo_region_t *) &_cairo_region_nil;
 
     copy = cairo_region_create ();
-    if (copy->status)
+    if (unlikely (copy->status))
 	return copy;
 
-    if (! pixman_region32_copy (&copy->rgn, &original->rgn)) {
+    if (original != NULL &&
+	! pixman_region32_copy (&copy->rgn, CONST_CAST &original->rgn))
+    {
 	cairo_region_destroy (copy);
 	return (cairo_region_t *) &_cairo_region_nil;
     }
@@ -248,6 +275,31 @@ cairo_region_copy (cairo_region_t *original)
 slim_hidden_def (cairo_region_copy);
 
 /**
+ * cairo_region_reference:
+ * @region: a #cairo_region_t
+ *
+ * Increases the reference count on @region by one. This prevents
+ * @region from being destroyed until a matching call to
+ * cairo_region_destroy() is made.
+ *
+ * Return value: the referenced #cairo_region_t.
+ *
+ * Since: 1.10
+ **/
+cairo_region_t *
+cairo_region_reference (cairo_region_t *region)
+{
+    if (region == NULL || CAIRO_REFERENCE_COUNT_IS_INVALID (&region->ref_count))
+	return NULL;
+
+    assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&region->ref_count));
+
+    _cairo_reference_count_inc (&region->ref_count);
+    return region;
+}
+slim_hidden_def (cairo_region_reference);
+
+/**
  * cairo_region_destroy:
  * @region: a #cairo_region_t
  *
@@ -260,10 +312,15 @@ slim_hidden_def (cairo_region_copy);
 void
 cairo_region_destroy (cairo_region_t *region)
 {
-    if (region == (cairo_region_t *) &_cairo_region_nil)
+    if (region == NULL || CAIRO_REFERENCE_COUNT_IS_INVALID (&region->ref_count))
 	return;
 
-    pixman_region32_fini (&region->rgn);
+    assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&region->ref_count));
+
+    if (! _cairo_reference_count_dec_and_test (&region->ref_count))
+	return;
+
+    _cairo_region_fini (region);
     free (region);
 }
 slim_hidden_def (cairo_region_destroy);
@@ -279,12 +336,12 @@ slim_hidden_def (cairo_region_destroy);
  * Since: 1.10
  **/
 int
-cairo_region_num_rectangles (cairo_region_t *region)
+cairo_region_num_rectangles (const cairo_region_t *region)
 {
     if (region->status)
 	return 0;
 
-    return pixman_region32_n_rects (&region->rgn);
+    return pixman_region32_n_rects (CONST_CAST &region->rgn);
 }
 slim_hidden_def (cairo_region_num_rectangles);
 
@@ -299,7 +356,7 @@ slim_hidden_def (cairo_region_num_rectangles);
  * Since: 1.10
  **/
 void
-cairo_region_get_rectangle (cairo_region_t *region,
+cairo_region_get_rectangle (const cairo_region_t *region,
 			    int nth,
 			    cairo_rectangle_int_t *rectangle)
 {
@@ -311,7 +368,7 @@ cairo_region_get_rectangle (cairo_region_t *region,
 	return;
     }
 
-    pbox = pixman_region32_rectangles (&region->rgn, NULL) + nth;
+    pbox = pixman_region32_rectangles (CONST_CAST &region->rgn, NULL) + nth;
 
     rectangle->x = pbox->x1;
     rectangle->y = pbox->y1;
@@ -330,7 +387,7 @@ slim_hidden_def (cairo_region_get_rectangle);
  * Since: 1.10
  **/
 void
-cairo_region_get_extents (cairo_region_t *region,
+cairo_region_get_extents (const cairo_region_t *region,
 			  cairo_rectangle_int_t *extents)
 {
     pixman_box32_t *pextents;
@@ -341,7 +398,7 @@ cairo_region_get_extents (cairo_region_t *region,
 	return;
     }
 
-    pextents = pixman_region32_extents (&region->rgn);
+    pextents = pixman_region32_extents (CONST_CAST &region->rgn);
 
     extents->x = pextents->x1;
     extents->y = pextents->y1;
@@ -362,7 +419,7 @@ slim_hidden_def (cairo_region_get_extents);
  * Since: 1.10
  **/
 cairo_status_t
-cairo_region_status (cairo_region_t *region)
+cairo_region_status (const cairo_region_t *region)
 {
     return region->status;
 }
@@ -564,12 +621,12 @@ slim_hidden_def (cairo_region_union_rectangle);
  * Since: 1.10
  **/
 cairo_bool_t
-cairo_region_is_empty (cairo_region_t *region)
+cairo_region_is_empty (const cairo_region_t *region)
 {
     if (region->status)
 	return TRUE;
 
-    return ! pixman_region32_not_empty (&region->rgn);
+    return ! pixman_region32_not_empty (CONST_CAST &region->rgn);
 }
 slim_hidden_def (cairo_region_is_empty);
 
@@ -610,7 +667,7 @@ slim_hidden_def (cairo_region_translate);
  * Since: 1.10
  **/
 cairo_region_overlap_t
-cairo_region_contains_rectangle (cairo_region_t *region,
+cairo_region_contains_rectangle (const cairo_region_t *region,
 				 const cairo_rectangle_int_t *rectangle)
 {
     pixman_box32_t pbox;
@@ -624,7 +681,8 @@ cairo_region_contains_rectangle (cairo_region_t *region,
     pbox.x2 = rectangle->x + rectangle->width;
     pbox.y2 = rectangle->y + rectangle->height;
 
-    poverlap = pixman_region32_contains_rectangle (&region->rgn, &pbox);
+    poverlap = pixman_region32_contains_rectangle (CONST_CAST &region->rgn,
+						   &pbox);
     switch (poverlap) {
     default:
     case PIXMAN_REGION_OUT:  return CAIRO_REGION_OVERLAP_OUT;
@@ -647,14 +705,44 @@ slim_hidden_def (cairo_region_contains_rectangle);
  * Since: 1.10
  **/
 cairo_bool_t
-cairo_region_contains_point (cairo_region_t *region,
+cairo_region_contains_point (const cairo_region_t *region,
 			     int x, int y)
 {
     pixman_box32_t box;
-    
+
     if (region->status)
 	return FALSE;
 
-    return pixman_region32_contains_point (&region->rgn, x, y, &box);
+    return pixman_region32_contains_point (CONST_CAST &region->rgn, x, y, &box);
 }
 slim_hidden_def (cairo_region_contains_point);
+
+/**
+ * cairo_region_equal:
+ * @region_a: a #cairo_region_t
+ * @region_b: a #cairo_region_t
+ *
+ * Compares whether region_a is equivalent to region_b.
+ *
+ * Return value: %TRUE if both regions contained the same coverage,
+ * %FALSE if it is not.
+ *
+ * Since: 1.10
+ **/
+cairo_bool_t
+cairo_region_equal (const cairo_region_t *a,
+		    const cairo_region_t *b)
+{
+    /* error objects are never equal */
+    if ((a != NULL && a->status) || (b != NULL && b->status))
+	return FALSE;
+
+    if (a == b)
+	return TRUE;
+
+    if (a == NULL || b == NULL)
+	return FALSE;
+
+    return pixman_region32_equal (CONST_CAST &a->rgn, CONST_CAST &b->rgn);
+}
+slim_hidden_def (cairo_region_equal);