From 680c0cb73c341c8e3c1db839293cdc787afd0f7d Mon Sep 17 00:00:00 2001
From: Timothy Nikkel <tnikkel@gmail.com>
Date: Tue, 30 Jul 2013 11:22:43 -0500
Subject: [PATCH] Bug 837242. Part 2. Add a function to calculate the area of
 an nsRegion. r=roc

---
 gfx/src/nsRegion.cpp          | 12 ++++++++++++
 gfx/src/nsRegion.h            |  1 +
 layout/base/nsDisplayList.cpp | 13 +------------
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/gfx/src/nsRegion.cpp b/gfx/src/nsRegion.cpp
index 4015c587f75d..5e8e3ec2b2a2 100644
--- a/gfx/src/nsRegion.cpp
+++ b/gfx/src/nsRegion.cpp
@@ -1275,6 +1275,18 @@ bool nsRegion::IsEqual (const nsRegion& aRegion) const
 }
 
 
+uint64_t nsRegion::Area () const
+{
+  uint64_t area = 0;
+  nsRegionRectIterator iter(*this);
+  const nsRect* r;
+  while ((r = iter.Next()) != nullptr) {
+    area += uint64_t(r->width)*r->height;
+  }
+  return area;
+}
+
+
 void nsRegion::MoveBy (nsPoint aPt)
 {
   if (aPt.x || aPt.y)
diff --git a/gfx/src/nsRegion.h b/gfx/src/nsRegion.h
index 2830cbe2290d..bd4de4139d97 100644
--- a/gfx/src/nsRegion.h
+++ b/gfx/src/nsRegion.h
@@ -147,6 +147,7 @@ public:
   bool IsEqual (const nsRegion& aRegion) const;
   uint32_t GetNumRects () const { return mRectCount; }
   const nsRect& GetBounds () const { return mBoundRect; }
+  uint64_t Area () const;
   // Converts this region from aFromAPP, an appunits per pixel ratio, to
   // aToAPP. This applies nsRect::ConvertAppUnitsRoundOut/In to each rect of
   // the region.
diff --git a/layout/base/nsDisplayList.cpp b/layout/base/nsDisplayList.cpp
index a778a0c07965..5464e1b675c5 100644
--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -718,17 +718,6 @@ nsDisplayListBuilder::GetBackgroundPaintFlags() {
   return flags;
 }
 
-static uint64_t RegionArea(const nsRegion& aRegion)
-{
-  uint64_t area = 0;
-  nsRegionRectIterator iter(aRegion);
-  const nsRect* r;
-  while ((r = iter.Next()) != nullptr) {
-    area += uint64_t(r->width)*r->height;
-  }
-  return area;
-}
-
 void
 nsDisplayListBuilder::SubtractFromVisibleRegion(nsRegion* aVisibleRegion,
                                                 const nsRegion& aRegion)
@@ -743,7 +732,7 @@ nsDisplayListBuilder::SubtractFromVisibleRegion(nsRegion* aVisibleRegion,
   // Do let aVisibleRegion get more complex if by doing so we reduce its
   // area by at least half.
   if (GetAccurateVisibleRegions() || tmp.GetNumRects() <= 15 ||
-      RegionArea(tmp) <= RegionArea(*aVisibleRegion)/2) {
+      tmp.Area() <= aVisibleRegion->Area()/2) {
     *aVisibleRegion = tmp;
   }
 }