PrintPreviewWindow dynamic preview Bitmap

The PrintDialog includes a preview (PrintPreviewWindow)
that currently used a fixed-pixel-size preview that takes
the aspect ratio into account (which may already explode
due to just growing vertically - try a much higher than
wide page). It is not dynamic and by using the high-quality
scale (BmpScaleFlag::BestQuality) for output it can get
rather slow in repainting. Also holds the VDev for creating
the preview all the time without need.
Made that process dynamic and responding to real resizing,
thus not using that huge number of pixels from the start.
Also use a VDev only temporary and use intelligent size
management.
Still keeping the high-quality scale due to ::DrawBitmap
with a target size not scaling well (still) and also
::DrawOutDev not good in quality. Those two should work
better nowadays, but adaption would be risky.

Change-Id: I211412a063def33a4e8f40c7442702770cd11a8e
Reviewed-on: https://gerrit.libreoffice.org/52150Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Armin Le Grand <Armin.Le.Grand@cib.de>

vcl/inc/printdlg.hxx

@@ -39,12 +39,11 @@ namespace vcl
     public:
         class PrintPreviewWindow : public vcl::Window
         {
-            static const sal_Int32 PREVIEW_BITMAP_WIDTH;
-
             GDIMetaFile         maMtf;
             Size                maOrigSize;
             Size                maPreviewSize;
-            VclPtr<VirtualDevice> maPageVDev;
+            sal_Int32           mnDPIX;
+            sal_Int32           mnDPIY;
             Bitmap              maPreviewBitmap;
             OUString            maReplacementString;
             OUString            maToolTipString;
@@ -62,7 +61,6 @@ namespace vcl
             virtual void Paint( vcl::RenderContext& rRenderContext, const tools::Rectangle& rRect ) override;
             virtual void Command( const CommandEvent& ) override;
             virtual void Resize() override;
-            virtual void DataChanged( const DataChangedEvent& ) override;
 
             void setPreview( const GDIMetaFile&, const Size& i_rPaperSize,
                              const OUString& i_rPaperName,