WaE: virtual functions but non-virtual destructor

sd/source/ui/slidesorter/cache/SlsBitmapCompressor.hxx

@@ -92,6 +92,7 @@ class NoBitmapCompression
 {
     class DummyReplacement;
 public:
+    virtual ~NoBitmapCompression() {}
     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rpBitmap) const;
     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData) const;
     virtual bool IsLossless (void) const;
@@ -109,6 +110,7 @@ class CompressionByDeletion
     : public BitmapCompressor
 {
 public:
+    virtual ~CompressionByDeletion() {}
     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rBitmap) const;
     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData) const;
     virtual bool IsLossless (void) const;
@@ -128,6 +130,7 @@ class ResolutionReduction
     class ResolutionReducedReplacement;
     static const sal_Int32 mnWidth = 100;
 public:
+    virtual ~ResolutionReduction() {}
     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rpBitmap) const;
     /** Scale the replacement bitmap up to the original size.
     */
@@ -146,6 +149,7 @@ class PngCompression
 {
     class PngReplacement;
 public:
+    virtual ~PngCompression() {}
     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rBitmap) const;
     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData) const;
     virtual bool IsLossless (void) const;