diff -r 000000000000 -r 6474c204b198 gfx/skia/trunk/src/images/SkPageFlipper.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/skia/trunk/src/images/SkPageFlipper.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,76 @@
+
+/*
+ * Copyright 2008 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#include "SkPageFlipper.h"
+
+SkPageFlipper::SkPageFlipper() {
+    fWidth = 0;
+    fHeight = 0;
+    fDirty0 = &fDirty0Storage;
+    fDirty1 = &fDirty1Storage;
+
+    fDirty0->setEmpty();
+    fDirty1->setEmpty();
+}
+
+SkPageFlipper::SkPageFlipper(int width, int height) {
+    fWidth = width;
+    fHeight = height;
+    fDirty0 = &fDirty0Storage;
+    fDirty1 = &fDirty1Storage;
+
+    fDirty0->setRect(0, 0, width, height);
+    fDirty1->setEmpty();
+}
+
+void SkPageFlipper::resize(int width, int height) {
+    fWidth = width;
+    fHeight = height;
+
+    // this is the opposite of the constructors
+    fDirty1->setRect(0, 0, width, height);
+    fDirty0->setEmpty();
+}
+
+void SkPageFlipper::inval() {
+    fDirty1->setRect(0, 0, fWidth, fHeight);
+}
+
+void SkPageFlipper::inval(const SkIRect& rect) {
+    SkIRect r;
+    r.set(0, 0, fWidth, fHeight);
+    if (r.intersect(rect)) {
+        fDirty1->op(r, SkRegion::kUnion_Op);
+    }
+}
+
+void SkPageFlipper::inval(const SkRegion& rgn) {
+    SkRegion r;
+    r.setRect(0, 0, fWidth, fHeight);
+    if (r.op(rgn, SkRegion::kIntersect_Op)) {
+        fDirty1->op(r, SkRegion::kUnion_Op);
+    }
+}
+
+void SkPageFlipper::inval(const SkRect& rect, bool antialias) {
+    SkIRect r;
+    rect.round(&r);
+    if (antialias) {
+        r.inset(-1, -1);
+    }
+    this->inval(r);
+}
+
+const SkRegion& SkPageFlipper::update(SkRegion* copyBits) {
+    // Copy over anything new from page0 that isn't dirty in page1
+    copyBits->op(*fDirty0, *fDirty1, SkRegion::kDifference_Op);
+    SkTSwap<SkRegion*>(fDirty0, fDirty1);
+    fDirty1->setEmpty();
+    return *fDirty0;
+}