include/wx/fileback.h

   1 /////////////////////////////////////////////////////////////////////////////
   2 // Name:        include/wx/fileback.h
   3 // Purpose:     Back an input stream with memory or a file
   4 // Author:      Mike Wetherell
   5 // RCS-ID:      $Id$
   6 // Copyright:   (c) 2006 Mike Wetherell
   7 // Licence:     wxWindows licence
   8 /////////////////////////////////////////////////////////////////////////////
   9
  10 #ifndef _WX_FILEBACK_H__
  11 #define _WX_FILEBACK_H__
  12
  13 #include "wx/defs.h"
  14
  15 #if wxUSE_BACKINGFILE
  16
  17 // ----------------------------------------------------------------------------
  18 // Backs an input stream with memory or a file to make it seekable.
  19 //
  20 // One or more wxBackedInputStreams can be used to read it's data. The data is
  21 // reference counted, so stays alive until the last wxBackingFile or
  22 // wxBackedInputStream using it is destroyed.
  23 // ----------------------------------------------------------------------------
  24
  25 class WXDLLIMPEXP_BASE wxBackingFile
  26 {
  27 public:
  28     enum { DefaultBufSize = 16384 };
  29
  30     // Takes ownership of stream. If the stream is smaller than bufsize, the
  31     // backing file is never created and the backing is done with memory.
  32     wxBackingFile(wxInputStream *stream,
  33                   size_t bufsize = DefaultBufSize,
  34                   const wxString& prefix = _T("wxbf"));
  35
  36     wxBackingFile() : m_impl(NULL) { }
  37     ~wxBackingFile();
  38
  39     wxBackingFile(const wxBackingFile& backer);
  40     wxBackingFile& operator=(const wxBackingFile& backer);
  41
  42     operator bool() const { return m_impl != NULL; }
  43
  44 private:
  45     class wxBackingFileImpl *m_impl;
  46     friend class wxBackedInputStream;
  47 };
  48
  49 // ----------------------------------------------------------------------------
  50 // An input stream to read from a wxBackingFile.
  51 // ----------------------------------------------------------------------------
  52
  53 class WXDLLIMPEXP_BASE wxBackedInputStream : public wxInputStream
  54 {
  55 public:
  56     wxBackedInputStream(const wxBackingFile& backer);
  57
  58     wxFileOffset GetLength() const;
  59     bool IsSeekable() const { return true; }
  60
  61 protected:
  62     size_t OnSysRead(void *buffer, size_t size);
  63     wxFileOffset OnSysSeek(wxFileOffset pos, wxSeekMode mode);
  64     wxFileOffset OnSysTell() const;
  65
  66 private:
  67     wxBackingFile m_backer;
  68     wxFileOffset m_pos;
  69
  70     DECLARE_NO_COPY_CLASS(wxBackedInputStream)
  71 };
  72
  73 #endif // wxUSE_BACKINGFILE
  74
  75 #endif // _WX_FILEBACK_H__