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/////////////////////////////////////////////////////////////////////////////
// Name: wx/private/fileback.h
// Purpose: Back an input stream with memory or a file
// Author: Mike Wetherell
// Copyright: (c) 2006 Mike Wetherell
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
#ifndef _WX_FILEBACK_H__
#define _WX_FILEBACK_H__
#include "wx/defs.h"
#if wxUSE_FILESYSTEM
#include "wx/stream.h"
// ----------------------------------------------------------------------------
// Backs an input stream with memory or a file to make it seekable.
//
// One or more wxBackedInputStreams can be used to read it's data. The data is
// reference counted, so stays alive until the last wxBackingFile or
// wxBackedInputStream using it is destroyed.
// ----------------------------------------------------------------------------
class WXDLLIMPEXP_BASE wxBackingFile
{
public:
enum { DefaultBufSize = 16384 };
// Takes ownership of stream. If the stream is smaller than bufsize, the
// backing file is never created and the backing is done with memory.
wxBackingFile(wxInputStream *stream,
size_t bufsize = DefaultBufSize,
const wxString& prefix = wxT("wxbf"));
wxBackingFile() : m_impl(NULL) { }
~wxBackingFile();
wxBackingFile(const wxBackingFile& backer);
wxBackingFile& operator=(const wxBackingFile& backer);
operator bool() const { return m_impl != NULL; }
private:
class wxBackingFileImpl *m_impl;
friend class wxBackedInputStream;
};
// ----------------------------------------------------------------------------
// An input stream to read from a wxBackingFile.
// ----------------------------------------------------------------------------
class WXDLLIMPEXP_BASE wxBackedInputStream : public wxInputStream
{
public:
wxBackedInputStream(const wxBackingFile& backer);
// If the length of the backer's parent stream is unknown then GetLength()
// returns wxInvalidOffset until the parent has been read to the end.
wxFileOffset GetLength() const;
// Returns the length, reading the parent stream to the end if necessary.
wxFileOffset FindLength() const;
bool IsSeekable() const { return true; }
protected:
size_t OnSysRead(void *buffer, size_t size);
wxFileOffset OnSysSeek(wxFileOffset pos, wxSeekMode mode);
wxFileOffset OnSysTell() const;
private:
wxBackingFile m_backer;
wxFileOffset m_pos;
wxDECLARE_NO_COPY_CLASS(wxBackedInputStream);
};
#endif // wxUSE_FILESYSTEM
#endif // _WX_FILEBACK_H__
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