cc: Create a Region class that wraps SkRegion, to replace use of WebCore::Region.

cc/region.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+
+#include "cc/region.h"
+
+namespace cc {
+
+// TODO(danakj) Use method from ui/gfx/skia_utils.h when it exists.
+static inline SkIRect ToSkIRect(const gfx::Rect& rect)
+{
+    return SkIRect::MakeXYWH(rect.x(), rect.y(), rect.width(), rect.height());
+}
+
+Region::Region() {
+}
+
+Region::Region(const Region& region)
+    : skregion_(region.skregion_) {
+}
+
+Region::Region(gfx::Rect rect)
+    : skregion_(ToSkIRect(rect)) {
+}
+
+Region::~Region() {
+}
+
+void Region::operator=(const Region& region) {
+  skregion_ = region.skregion_;
+}
+
+bool Region::IsEmpty() const {
+  return skregion_.isEmpty();
+}
+
+bool Region::Contains(const gfx::Point& point) const {
+  return skregion_.contains(point.x(), point.y());
+}
+
+bool Region::Contains(const gfx::Rect& rect) const {
+  return skregion_.contains(ToSkIRect(rect));
+}
+
+void Region::Subtract(const gfx::Rect& rect) {
+  skregion_.op(ToSkIRect(rect), SkRegion::kDifference_Op);
+}
+
+void Region::Subtract(const Region& region) {
+  skregion_.op(region.skregion_, SkRegion::kDifference_Op);
+}
+
+void Region::Union(const gfx::Rect& rect) {
+  skregion_.op(ToSkIRect(rect), SkRegion::kUnion_Op);
+}
+
+void Region::Union(const Region& region) {
+  skregion_.op(region.skregion_, SkRegion::kUnion_Op);
+}
+
+void Region::Intersect(const gfx::Rect& rect) {
+  skregion_.op(ToSkIRect(rect), SkRegion::kIntersect_Op);
+}
+
+void Region::Intersect(const Region& region) {
+  skregion_.op(region.skregion_, SkRegion::kIntersect_Op);
+}
+
+std::string Region::ToString() const {
+  if (IsEmpty())
+    return gfx::Rect().ToString();
+
+  std::string result;
+  for (Iterator it(*this); it.has_rect(); it.next()) {

[enne (OOO), 2012/11/05 21:15:21]

Is there any ordering constraint on the rects in region? In other words, if a
union a, b, c to and also union a, c, b, those should be logically identical,
but will the strings be the same?

[danakj, 2012/11/05 21:18:26]

My expectation is that that regardless of the order you add the rects, you get
the same state inside the region.

I tried this in a unit test:
        EXPECT_EQ(UnionRegions(gfx::Rect(30, 30, 60, 10), gfx::Rect(30, 40, 70,
60)).ToString(), occlusion.occlusionInScreenSpace().ToString());
        EXPECT_EQ(UnionRegions(gfx::Rect(30, 40, 70, 60), gfx::Rect(30, 30, 60,
10)).ToString(), occlusion.occlusionInScreenSpace().ToString());

And it passed as expected.

+    if (!result.empty())
+      result += " | ";
+    result += it.rect().ToString();
+  }
+  return result;
+}
+
+Region::Iterator::Iterator(const Region& region)
+    : it_(region.skregion_) {
+}
+
+Region::Iterator::~Iterator() {
+}
+
+}  // namespace cc