tdf#116646 Slideshows with transitions page swap rendering issues

regression from
    commit 5b75a169
    move cairo extract bitmap code from canvas to vcl

Change-Id: Ic8d7cd9d54010ae272073877da18a985e931e22a
Reviewed-on: https://gerrit.libreoffice.org/52005Tested-by: Jenkins <ci@libreoffice.org>
Tested-by: Xisco Faulí <xiscofauli@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

canvas/source/cairo/cairo_canvashelper.cxx

@@ -363,10 +363,10 @@ namespace cairocanvas
 
             if( !pSurface )
             {
-                vcl::bitmap::CanvasCairoExtractBitmapData(aBmpEx, aBitmap, data, bHasAlpha);
+                long nWidth;
+                long nHeight;
+                vcl::bitmap::CanvasCairoExtractBitmapData(aBmpEx, aBitmap, data, bHasAlpha, nWidth, nHeight);
 
-                const long nWidth = aBmpEx.GetPrefSize().Width();
-                const long nHeight = aBmpEx.GetPrefSize().Height();
                 SurfaceSharedPtr pImageSurface = rSurfaceProvider->getOutputDevice()->CreateSurface(
                     CairoSurfaceSharedPtr(
                         cairo_image_surface_create_for_data(

include/vcl/BitmapTools.hxx

@@ -102,7 +102,7 @@ VCL_DLLPUBLIC css::uno::Sequence< sal_Int8 > GetMaskDIB(BitmapEx const & aBmpEx)
  * @param data will be filled with alpha data, if xBitmap is alpha/transparent image
  * @param bHasAlpha will be set to true if resulting surface has alpha
  **/
-VCL_DLLPUBLIC void CanvasCairoExtractBitmapData( BitmapEx & rBmpEx, Bitmap & rBitmap, unsigned char*& data, bool& bHasAlpha );
+VCL_DLLPUBLIC void CanvasCairoExtractBitmapData( BitmapEx & rBmpEx, Bitmap & rBitmap, unsigned char*& data, bool& bHasAlpha, long& rnWidth, long& rnHeight );
 
 VCL_DLLPUBLIC css::uno::Sequence< sal_Int8 > CanvasExtractBitmapData(BitmapEx & rBitmapEx, const css::geometry::IntegerRectangle2D& rect);
 

vcl/source/bitmap/BitmapTools.cxx

@@ -719,14 +719,14 @@ static bool readAlpha( BitmapReadAccess const * pAlphaReadAcc, long nY, const lo
  * @param data will be filled with alpha data, if xBitmap is alpha/transparent image
  * @param bHasAlpha will be set to true if resulting surface has alpha
  **/
-void CanvasCairoExtractBitmapData( BitmapEx & aBmpEx, Bitmap & aBitmap, unsigned char*& data, bool& bHasAlpha )
+void CanvasCairoExtractBitmapData( BitmapEx & aBmpEx, Bitmap & aBitmap, unsigned char*& data, bool& bHasAlpha, long& rnWidth, long& rnHeight )
 {
     AlphaMask aAlpha = aBmpEx.GetAlpha();
 
     ::BitmapReadAccess* pBitmapReadAcc = aBitmap.AcquireReadAccess();
     ::BitmapReadAccess* pAlphaReadAcc = nullptr;
-    const long      nWidth = pBitmapReadAcc->Width();
-    const long      nHeight = pBitmapReadAcc->Height();
+    const long      nWidth = rnWidth = pBitmapReadAcc->Width();
+    const long      nHeight = rnHeight = pBitmapReadAcc->Height();
     long nX, nY;
     bool bIsAlpha = false;