84 lines
2.6 KiB
C
84 lines
2.6 KiB
C
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/////////////////////////////////////////////////////////////////////////////
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// Name: wx/private/fileback.h
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// Purpose: Back an input stream with memory or a file
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// Author: Mike Wetherell
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// RCS-ID: $Id: fileback.h 64943 2010-07-13 13:29:58Z VZ $
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// Copyright: (c) 2006 Mike Wetherell
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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#ifndef _WX_FILEBACK_H__
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#define _WX_FILEBACK_H__
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#include "wx/defs.h"
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#if wxUSE_FILESYSTEM
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#include "wx/stream.h"
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// ----------------------------------------------------------------------------
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// Backs an input stream with memory or a file to make it seekable.
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//
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// One or more wxBackedInputStreams can be used to read it's data. The data is
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// reference counted, so stays alive until the last wxBackingFile or
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// wxBackedInputStream using it is destroyed.
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// ----------------------------------------------------------------------------
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class WXDLLIMPEXP_BASE wxBackingFile
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{
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public:
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enum { DefaultBufSize = 16384 };
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// Takes ownership of stream. If the stream is smaller than bufsize, the
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// backing file is never created and the backing is done with memory.
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wxBackingFile(wxInputStream *stream,
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size_t bufsize = DefaultBufSize,
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const wxString& prefix = wxT("wxbf"));
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wxBackingFile() : m_impl(NULL) { }
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~wxBackingFile();
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wxBackingFile(const wxBackingFile& backer);
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wxBackingFile& operator=(const wxBackingFile& backer);
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operator bool() const { return m_impl != NULL; }
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private:
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class wxBackingFileImpl *m_impl;
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friend class wxBackedInputStream;
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};
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// ----------------------------------------------------------------------------
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// An input stream to read from a wxBackingFile.
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// ----------------------------------------------------------------------------
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class WXDLLIMPEXP_BASE wxBackedInputStream : public wxInputStream
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{
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public:
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wxBackedInputStream(const wxBackingFile& backer);
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// If the length of the backer's parent stream is unknown then GetLength()
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// returns wxInvalidOffset until the parent has been read to the end.
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wxFileOffset GetLength() const;
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// Returns the length, reading the parent stream to the end if necessary.
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wxFileOffset FindLength() const;
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bool IsSeekable() const { return true; }
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protected:
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size_t OnSysRead(void *buffer, size_t size);
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wxFileOffset OnSysSeek(wxFileOffset pos, wxSeekMode mode);
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wxFileOffset OnSysTell() const;
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private:
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wxBackingFile m_backer;
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wxFileOffset m_pos;
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wxDECLARE_NO_COPY_CLASS(wxBackedInputStream);
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};
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#endif // wxUSE_FILESYSTEM
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#endif // _WX_FILEBACK_H__
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