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

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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  19
  20 #ifndef INCLUDED_SD_SOURCE_UI_SLIDESORTER_CACHE_SLSBITMAPCOMPRESSOR_HXX
  21 #define INCLUDED_SD_SOURCE_UI_SLIDESORTER_CACHE_SLSBITMAPCOMPRESSOR_HXX
  22
  23 #include <sal/types.h>
  24 #include <boost/shared_ptr.hpp>
  25
  26 class Bitmap;
  27
  28 namespace sd { namespace slidesorter { namespace cache {
  29
  30 class BitmapReplacement;
  31
  32 /** This interface class provides the minimal method set for classes that
  33     implement the compression and decompression of preview bitmaps.
  34 */
  35 class BitmapCompressor
  36 {
  37 public:
  38     /** Compress the given bitmap into a replacement format that is specific
  39         to the compressor class.
  40     */
  41     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rBitmap) const = 0;
  42
  43     /** Decompress the given replacement data into a preview bitmap.
  44         Depending on the compression technique the returned bitmap may
  45         differ from the original bitmap given to the Compress() method.  It
  46         may even of the wrong size or empty or the NULL pointer.  It is the
  47         task of the caller to create a new preview bitmap if the returned
  48         one is not as desired.
  49     */
  50     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData)const=0;
  51
  52     /** Return whether the compression and decompression is lossless.  This
  53         value is used by the caller of Decompress() to decide whether to use
  54         the returned bitmap as is or if a new preview has to be created.
  55     */
  56     virtual bool IsLossless() const = 0;
  57
  58 protected:
  59     ~BitmapCompressor() {}
  60 };
  61
  62 /** Interface for preview bitmap replacements.  Each bitmap
  63     compressor/decompressor has to provide an implementation that is
  64     suitable to store the compressed bitmaps.
  65 */
  66 class BitmapReplacement
  67 {
  68 public:
  69     virtual sal_Int32 GetMemorySize() const { return 0; }
  70
  71 protected:
  72     ~BitmapReplacement() {}
  73 };
  74
  75 /** This is one trivial bitmap compressor.  It stores bitmaps unmodified
  76     instead of compressing them.
  77     This compressor is lossless.
  78 */
  79 class NoBitmapCompression
  80     : public BitmapCompressor
  81 {
  82     class DummyReplacement;
  83 public:
  84     virtual ~NoBitmapCompression() {}
  85     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rpBitmap) const SAL_OVERRIDE;
  86     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData) const SAL_OVERRIDE;
  87     virtual bool IsLossless() const SAL_OVERRIDE;
  88 };
  89
  90 /** This is another trivial bitmap compressor.  Instead of compressing a
  91     bitmap, it throws the bitmap away.  Its Decompress() method returns a
  92     NULL pointer.  The caller has to create a new preview bitmap instead.
  93     This compressor clearly is not lossless.
  94 */
  95 class CompressionByDeletion
  96     : public BitmapCompressor
  97 {
  98 public:
  99     virtual ~CompressionByDeletion() {}
 100     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rBitmap) const SAL_OVERRIDE;
 101     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData) const SAL_OVERRIDE;
 102     virtual bool IsLossless() const SAL_OVERRIDE;
 103 };
 104
 105 /** Compress a preview bitmap by reducing its resolution.  While the aspect
 106     ratio is maintained the horizontal resolution is scaled down to 100
 107     pixels.
 108     This compressor is not lossless.
 109 */
 110 class ResolutionReduction
 111     : public BitmapCompressor
 112 {
 113     class ResolutionReducedReplacement;
 114     static const sal_Int32 mnWidth = 100;
 115 public:
 116     virtual ~ResolutionReduction() {}
 117     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rpBitmap) const SAL_OVERRIDE;
 118     /** Scale the replacement bitmap up to the original size.
 119     */
 120     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData) const SAL_OVERRIDE;
 121     virtual bool IsLossless() const SAL_OVERRIDE;
 122 };
 123
 124 /** Compress preview bitmaps using the PNG format.
 125     This compressor is lossless.
 126 */
 127 class PngCompression
 128     : public BitmapCompressor
 129 {
 130     class PngReplacement;
 131 public:
 132     virtual ~PngCompression() {}
 133     virtual ::boost::shared_ptr<BitmapReplacement> Compress (const Bitmap& rBitmap) const SAL_OVERRIDE;
 134     virtual Bitmap Decompress (const BitmapReplacement& rBitmapData) const SAL_OVERRIDE;
 135     virtual bool IsLossless() const SAL_OVERRIDE;
 136 };
 137
 138 } } } // end of namespace ::sd::slidesorter::cache
 139
 140 #endif
 141
 142 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */