From 245e23bf94eb70fdf4a028359fb266bea584721c Mon Sep 17 00:00:00 2001
From: "michaelp%netscape.com"
 <michaelp%netscape.com@18797224-902f-48f8-a5cc-f745e15eee43>
Date: Wed, 12 Aug 1998 21:17:52 +0000
Subject: [PATCH] we now allocate a single offscreen buffer.

git-svn-id: svn://10.0.0.236/trunk@7872 18797224-902f-48f8-a5cc-f745e15eee43
---
 mozilla/view/src/nsViewManager.cpp | 11 ++++++++++-
 mozilla/view/src/nsViewManager.h   |  8 +++++---
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/mozilla/view/src/nsViewManager.cpp b/mozilla/view/src/nsViewManager.cpp
index a836fe03c52..2f608a50d2a 100644
--- a/mozilla/view/src/nsViewManager.cpp
+++ b/mozilla/view/src/nsViewManager.cpp
@@ -46,10 +46,15 @@ static void vm_timer_callback(nsITimer *aTimer, void *aClosure)
   vm->Composite();
 }
 
+PRUint32 nsViewManager::mVMCount = 0;
+nsDrawingSurface nsViewManager::mDrawingSurface = nsnull;
+nsRect nsViewManager::mDSBounds = nsRect(0, 0, 0, 0);
+
 static NS_DEFINE_IID(knsViewManagerIID, NS_IVIEWMANAGER_IID);
 
 nsViewManager :: nsViewManager()
 {
+  mVMCount++;
 }
 
 nsViewManager :: ~nsViewManager()
@@ -63,7 +68,11 @@ nsViewManager :: ~nsViewManager()
   NS_IF_RELEASE(mRootWindow);
   NS_IF_RELEASE(mDirtyRegion);
 
-  if (nsnull != mDrawingSurface)
+  --mVMCount;
+
+  NS_ASSERTION(!(mVMCount < 0), "underflow of viewmanagers");
+
+  if ((0 == mVMCount) && (nsnull != mDrawingSurface))
   {
     nsIRenderingContext *rc;
 
diff --git a/mozilla/view/src/nsViewManager.h b/mozilla/view/src/nsViewManager.h
index 13aebd7326f..34b4594bf81 100644
--- a/mozilla/view/src/nsViewManager.h
+++ b/mozilla/view/src/nsViewManager.h
@@ -128,13 +128,15 @@ private:
 
   nsIPresContext    *mContext;
   nsIWidget         *mRootWindow;
-  nsRect            mDSBounds;
-  nsDrawingSurface  mDrawingSurface;
   PRTime            mLastRefresh;
   nsIRegion         *mDirtyRegion;
   PRInt32           mTransCnt;
   PRBool            mRefreshEnabled;
-                            
+
+  static PRUint32          mVMCount;        //number of viewmanagers
+  static nsDrawingSurface  mDrawingSurface; //single drawing surface
+  static nsRect            mDSBounds;       //for all VMs
+
 public:
   //these are public so that our timer callback can poke them.
   nsITimer          *mTimer;