Bugzilla Bug 95952 Waste of offscreen pixmaps

patch by Roland.Mainz@informatik.med.uni-giessen.de
r=kmcclusk@netscape.com, sr=attinasi

gfx/src/xlib/nsDrawingSurfaceXlib.cpp

@@ -53,7 +53,6 @@ nsDrawingSurfaceXlibImpl::nsDrawingSurfaceXlibImpl()
   NS_INIT_REFCNT();
   PR_LOG(DrawingSurfaceXlibLM, PR_LOG_DEBUG, ("nsDrawingSurfaceXlibImpl::nsDrawingSurfaceXlibImpl()\n"));
   mDrawable = 0;
-  mDestroyDrawable = PR_FALSE;
   mImage = nsnull;
   mXlibRgbHandle = nsnull;
   mDisplay = nsnull;
@@ -78,7 +77,7 @@ nsDrawingSurfaceXlibImpl::~nsDrawingSurfaceXlibImpl()
 {
   PR_LOG(DrawingSurfaceXlibLM, PR_LOG_DEBUG, ("nsDrawingSurfaceXlibImpl::~nsDrawingSurfaceXlibImpl()\n"));
   // if it's been labeled as destroy, it's a pixmap.
-  if (mDestroyDrawable) {
+  if (mDrawable!=None && mIsOffscreen) {
     XFreePixmap(mDisplay, mDrawable);
   }
   if (mImage) {

gfx/src/xlib/nsDrawingSurfaceXlib.h

@@ -123,7 +123,6 @@ private:
 
   // are we offscreen
   PRBool         mIsOffscreen;
-  PRBool         mDestroyDrawable;
 
 private:
   static PRUint8 ConvertMaskToCount(unsigned long val);

gfx/src/xlib/nsRenderingContextXlib.cpp

@@ -1590,6 +1590,22 @@ nsRenderingContextXlib::DrawImage(nsIImage *aImage, const nsRect& aSRect, const
                       dr.width, dr.height);
 }
 
+NS_IMETHODIMP nsRenderingContextXlib::GetBackbuffer(const nsRect &aRequestedSize, const nsRect &aMaxSize, nsDrawingSurface &aBackbuffer)
+{
+  PR_LOG(RenderingContextXlibLM, PR_LOG_DEBUG, ("nsRenderingContextXlib::GetBackbuffer()\n"));
+  /* Do not cache the backbuffer. On X11 it is more efficient to allocate
+   * the backbuffer as needed and it doesn't cause a performance hit. @see bug 95952 */
+  return AllocateBackbuffer(aRequestedSize, aMaxSize, aBackbuffer, PR_FALSE);
+}
+ 
+NS_IMETHODIMP nsRenderingContextXlib::ReleaseBackbuffer(void) 
+{
+  PR_LOG(RenderingContextXlibLM, PR_LOG_DEBUG, ("nsRenderingContextXlib::ReleaseBackbuffer()\n"));
+  /* Do not cache the backbuffer. On X11 it is more efficient to allocate
+   * the backbuffer as needed and it doesn't cause a performance hit. @see bug 95952 */
+  return DestroyCachedBackbuffer();
+}
+
 #if 0
 // in nsRenderingContextImpl
 /** ---------------------------------------------------

gfx/src/xlib/nsRenderingContextXlib.h

@@ -197,6 +197,9 @@ class nsRenderingContextXlib : public nsRenderingContextImpl
   NS_IMETHOD DrawImage(nsIImage *aImage, const nsRect& aRect);
   NS_IMETHOD DrawImage(nsIImage *aImage, const nsRect& aSRect, const nsRect& aDRect);
 
+  NS_IMETHOD GetBackbuffer(const nsRect &aRequestedSize, const nsRect &aMaxSize, nsDrawingSurface &aBackbuffer);
+  NS_IMETHOD ReleaseBackbuffer(void);
+
   NS_IMETHOD CopyOffScreenBits(nsDrawingSurface aSrcSurf, PRInt32 aSrcX, PRInt32 aSrcY,
                                const nsRect &aDestBounds, PRUint32 aCopyFlags);
   NS_IMETHOD RetrieveCurrentNativeGraphicData(PRUint32 * ngd);