Is there is shareable QFloatArray1D?

[lni]

This QFloatArray1D should look like

class QFloatArray1D {
public:
  QFloatArray1D( float* valueArray, int length );
  ...
  const float* array( int* length ) const;
  void setArray( float* valueArray, int length );
  float valueAt( int idx ) const;
  ..
};

class QFloatArray1D {
public:
  QFloatArray1D( float* valueArray, int length );
  ...
  const float* array( int* length ) const;
  void setArray( float* valueArray, int length );
  float valueAt( int idx ) const;
  ..
};

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The reason is that I need to create a MyGraphicsTraceItem as

class MyGraphicsTraceItem : public QGraphicsItem
{
public:
 
  MyGraphicsTraceItem( float* traceData,
                                     int traceLength,
                                     float traceIndexFrom,
                                     float indexDelta,
                                      QGraphicsItem *parent = 0 );
 
private:
 
      float*              theTraceData;
      int                  theTraceLength;
      float               theTraceIndexFrom;
      float               theTraceIndexDelta;
 
};

class MyGraphicsTraceItem : public QGraphicsItem
{
public:

  MyGraphicsTraceItem( float* traceData,
                                     int traceLength,
                                     float traceIndexFrom,
                                     float indexDelta,
                                      QGraphicsItem *parent = 0 );

private:

      float*              theTraceData;
      int                  theTraceLength;
      float               theTraceIndexFrom;
      float               theTraceIndexDelta;

};

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But I feel something is wrong with this code, so I would wish to have a constructor like

public:
  MyGraphicsTraceItem( const QFloatArray1D& traceData,
                                     float traceIndexFrom,
                                     float indexDelta,
                                      QGraphicsItem *parent = 0 );
private:
 
      QFloatArray1D                  theTraceData; // <== explicitly shared
      float                                  theTraceIndexFrom;
      float                                  theTraceIndexDelta;

public:
  MyGraphicsTraceItem( const QFloatArray1D& traceData,
                                     float traceIndexFrom,
                                     float indexDelta,
                                      QGraphicsItem *parent = 0 );
private:

      QFloatArray1D                  theTraceData; // <== explicitly shared
      float                                  theTraceIndexFrom;
      float                                  theTraceIndexDelta;

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Also, what does Q_DECLARE_PRIVATE do, and how can I use it?

Thanks