fix implementation of the creation of DrawingSurfaces

gfx/src/xlib/nsDeviceContextXlib.cpp

@@ -42,16 +42,16 @@ nsDeviceContextXlib::nsDeviceContextXlib()
   mPaletteInfo.numReserved = 0;
   mPaletteInfo.palette = NULL;
   mNumCells = 0;
+  mSurface = nsnull;
 }
 
 nsDeviceContextXlib::~nsDeviceContextXlib()
 {
+  nsDrawingSurfaceXlib *surf = (nsDrawingSurfaceXlib *)mSurface;
+  NS_IF_RELEASE(surf);
+  mSurface = nsnull;
 }
 
-NS_IMPL_QUERY_INTERFACE(nsDeviceContextXlib, kDeviceContextIID)
-NS_IMPL_ADDREF(nsDeviceContextXlib)
-NS_IMPL_RELEASE(nsDeviceContextXlib)
-
 NS_IMETHODIMP nsDeviceContextXlib::Init(nsNativeWidget aNativeWidget)
 {
   printf("nsDeviceContextXlib::Init()\n");
@@ -154,8 +154,11 @@ NS_IMETHODIMP nsDeviceContextXlib::GetSystemAttribute(nsSystemAttrID anID, Syste
 NS_IMETHODIMP nsDeviceContextXlib::GetDrawingSurface(nsIRenderingContext &aContext, nsDrawingSurface &aSurface)
 {
   printf("nsDeviceContextXlib::GetDrawingSurface()\n");
-  aContext.CreateDrawingSurface(nsnull, 0, aSurface);
-  return nsnull == aSurface ? NS_ERROR_OUT_OF_MEMORY : NS_OK;  
+  if (NULL == mSurface) {
+    aContext.CreateDrawingSurface(nsnull, 0, mSurface);
+  }
+  aSurface = mSurface;
+  return NS_OK;
 }
 
 NS_IMETHODIMP nsDeviceContextXlib::ConvertPixel(nscolor aColor, PRUint32 & aPixel)

gfx/src/xlib/nsDeviceContextXlib.h

@@ -25,9 +25,6 @@ class nsDeviceContextXlib : public DeviceContextImpl
 {
 public:
   nsDeviceContextXlib();
-  ~nsDeviceContextXlib();
-
-  NS_DECL_ISUPPORTS
 
   NS_IMETHOD  Init(nsNativeWidget aNativeWidget);
 
@@ -54,9 +51,11 @@ public:
   NS_IMETHOD EndPage(void);
 
 private:
-  nsPaletteInfo mPaletteInfo;
-  PRBool        mWriteable;
-  PRUint32 mNumCells;
+  virtual              ~nsDeviceContextXlib();
+  nsPaletteInfo        mPaletteInfo;
+  PRBool               mWriteable;
+  PRUint32             mNumCells;
+  nsDrawingSurface     mSurface;
 };
 
 #endif