Added new method to control whether ViewManager and ViewManager2 double-buffer when rendering. bug 49743 a=roc+moz@cs.cmu.edu r=peterl@netscape.com

view/public/nsIViewManager.h

@@ -497,6 +497,17 @@ public:
    */
   NS_IMETHOD CacheWidgetChanges(PRBool aCache)=0;
 
+  /**
+   * Control double buffering of the display. If double buffering
+   * is enabled the viewmanager is allowed to render to an offscreen
+   * drawing surface before copying to the display in order to prevent
+   * flicker. If it is disabled all rendering will appear directly on the
+   * the display. The display is double buffered by default.
+   * @param aDoubleBuffer PR_TRUE to enable double buffering
+   *                      PR_FALSE to disable double buffering
+   */
+  NS_IMETHOD AllowDoubleBuffering(PRBool aDoubleBuffer)=0;
+
 };
 
 //when the refresh happens, should it be double buffered?

view/src/nsViewManager.cpp

@@ -391,7 +391,7 @@ nsViewManager::nsViewManager()
   mX = 0;
   mY = 0;
   mCachingWidgetChanges = 0;
-  
+  mAllowDoubleBuffering = PR_TRUE; 
 }
 
 nsViewManager::~nsViewManager()
@@ -702,6 +702,11 @@ void nsViewManager::Refresh(nsIView *aView, nsIRenderingContext *aContext, nsIRe
     aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
 #endif
 
+  if (PR_FALSE == mAllowDoubleBuffering) {
+    // Turn off double-buffering of the display
+    aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
+  }
+
 	if (nsnull == aContext)
 		{
 			localcx = getter_AddRefs(CreateRenderingContext(*aView));
@@ -823,6 +828,11 @@ void nsViewManager::Refresh(nsIView *aView, nsIRenderingContext *aContext, const
     aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
 #endif
 
+  if (PR_FALSE == mAllowDoubleBuffering) {
+    // Turn off double-buffering of the display
+    aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
+  }
+
 	if (nsnull == aContext)
 		{
 			localcx = getter_AddRefs(CreateRenderingContext(*aView));
@@ -3619,6 +3629,13 @@ nsViewManager::CacheWidgetChanges(PRBool aCache)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsViewManager::AllowDoubleBuffering(PRBool aDoubleBuffer)
+{
+  mAllowDoubleBuffering = aDoubleBuffer;
+  return NS_OK;
+}
+
 nsresult
 nsViewManager::ProcessWidgetChanges(nsIView* aView)
 {

view/src/nsViewManager.h

@@ -159,6 +159,7 @@ public:
  
   NS_IMETHOD IsCachingWidgetChanges(PRBool* aCaching);
   NS_IMETHOD CacheWidgetChanges(PRBool aCache);
+  NS_IMETHOD AllowDoubleBuffering(PRBool aDoubleBuffer);
 protected:
   virtual ~nsViewManager();
 
@@ -371,6 +372,7 @@ public:
 protected:
   nscoord           mX;
   nscoord           mY;
+  PRBool            mAllowDoubleBuffering;
 
 #ifdef NS_VM_PERF_METRICS
   MOZ_TIMER_DECLARE(mWatch) //  Measures compositing+paint time for current document

view/src/nsViewManager2.cpp

@@ -156,7 +156,7 @@ nsViewManager2::nsViewManager2()
   mX = 0;
   mY = 0;
   mCachingWidgetChanges = 0;
-  
+  mAllowDoubleBuffering = PR_TRUE; 
 }
 
 nsViewManager2::~nsViewManager2()
@@ -490,6 +490,11 @@ void nsViewManager2::Refresh(nsIView *aView, nsIRenderingContext *aContext, nsIR
     aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
 #endif
 
+  if (PR_FALSE == mAllowDoubleBuffering) {
+    // Turn off double-buffering of the display
+    aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
+  }
+
 	if (nsnull == aContext)
 		{
 			localcx = getter_AddRefs(CreateRenderingContext(*aView));
@@ -611,6 +616,11 @@ void nsViewManager2::Refresh(nsIView *aView, nsIRenderingContext *aContext, cons
     aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
 #endif
 
+  if (PR_FALSE == mAllowDoubleBuffering) {
+    // Turn off double-buffering of the display
+    aUpdateFlags &= ~NS_VMREFRESH_DOUBLE_BUFFER;
+  }
+
 	if (nsnull == aContext)
 		{
 			localcx = getter_AddRefs(CreateRenderingContext(*aView));
@@ -2860,6 +2870,7 @@ nsViewManager2::IsCachingWidgetChanges(PRBool* aCaching)
   return NS_OK;
 }
 
+
 NS_IMETHODIMP
 nsViewManager2::CacheWidgetChanges(PRBool aCache)
 {
@@ -2880,6 +2891,13 @@ nsViewManager2::CacheWidgetChanges(PRBool aCache)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsViewManager2::AllowDoubleBuffering(PRBool aDoubleBuffer)
+{
+  mAllowDoubleBuffering = aDoubleBuffer;
+  return NS_OK;
+}
+
 nsresult
 nsViewManager2::ProcessWidgetChanges(nsIView* aView)
 {

view/src/nsViewManager2.h

@@ -157,6 +157,7 @@ public:
  
   NS_IMETHOD IsCachingWidgetChanges(PRBool* aCaching);
   NS_IMETHOD CacheWidgetChanges(PRBool aCache);
+  NS_IMETHOD AllowDoubleBuffering(PRBool aDoubleBuffer);
 protected:
   virtual ~nsViewManager2();
 
@@ -369,6 +370,7 @@ public:
 protected:
   nscoord           mX;
   nscoord           mY;
+  PRBool            mAllowDoubleBuffering;
 
 #ifdef NS_VM_PERF_METRICS
   MOZ_TIMER_DECLARE(mWatch) //  Measures compositing+paint time for current document