Added wxBackingFile and wxBackedInputStream.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42279 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Michael Wetherell
320
src/common/fileback.cpp
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320
src/common/fileback.cpp
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/////////////////////////////////////////////////////////////////////////////
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// Name: src/common/fileback.cpp
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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: $Id$
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// Copyright: (c) 2006 Mike Wetherell
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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// For compilers that support precompilation, includes "wx.h".
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#include "wx/wxprec.h"
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#ifdef __BORLANDC__
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#pragma hdrstop
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#endif
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#if wxUSE_BACKINGFILE
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#ifndef WX_PRECOMP
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#include "wx/stream.h"
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#include "wx/utils.h"
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#include "wx/log.h"
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#endif
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#include "wx/fileback.h"
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#include "wx/private/filename.h"
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// Prefer wxFFile unless wxFile has large file support but wxFFile does not.
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//
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#if wxUSE_FFILE && (defined WXFFILE_LARGEFILE || !defined WXFILE_LARGEFILE)
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typedef wxFFile wxBFFile;
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static const bool wxBadSeek = false;
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#else
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typedef wxFile wxBFFile;
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static const wxFileOffset wxBadSeek = wxInvalidOffset;
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#endif
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/////////////////////////////////////////////////////////////////////////////
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// Backing file implementation
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class wxBackingFileImpl
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{
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public:
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wxBackingFileImpl(wxInputStream *stream,
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size_t bufsize,
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const wxString& prefix);
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~wxBackingFileImpl();
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void Release() { if (--m_refcount == 0) delete this; }
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wxBackingFileImpl *AddRef() { m_refcount++; return this; }
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wxStreamError ReadAt(wxFileOffset pos, void *buffer, size_t *size);
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wxFileOffset GetLength() const;
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private:
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int m_refcount;
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wxInputStream *m_stream;
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wxStreamError m_parenterror;
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char *m_buf;
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size_t m_bufsize;
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size_t m_buflen;
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wxString m_prefix;
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wxString m_filename;
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wxBFFile m_file;
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wxFileOffset m_filelen;
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};
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wxBackingFileImpl::wxBackingFileImpl(wxInputStream *stream,
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size_t bufsize,
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const wxString& prefix)
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: m_refcount(1),
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m_stream(stream),
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m_parenterror(wxSTREAM_NO_ERROR),
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m_buf(NULL),
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m_bufsize(bufsize),
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m_buflen(0),
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m_prefix(prefix),
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m_filelen(0)
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{
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wxFileOffset len = m_stream->GetLength();
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if (len >= 0 && len + size_t(0) < m_bufsize)
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m_bufsize = len;
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if (m_bufsize)
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m_buf = new char[m_bufsize];
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}
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wxBackingFileImpl::~wxBackingFileImpl()
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{
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delete m_stream;
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delete [] m_buf;
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if (!m_filename.empty())
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wxRemoveFile(m_filename);
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}
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wxStreamError wxBackingFileImpl::ReadAt(wxFileOffset pos,
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void *buffer,
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size_t *size)
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{
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size_t reqestedSize = *size;
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*size = 0;
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// size1 is the number of bytes it will read directly from the backing
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// file. size2 is any remaining bytes not yet backed, these are returned
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// from the buffer or read from the parent stream.
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size_t size1, size2;
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if (pos + reqestedSize <= m_filelen + size_t(0)) {
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size1 = reqestedSize;
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size2 = 0;
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} else if (pos < m_filelen) {
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size1 = m_filelen - pos;
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size2 = reqestedSize - size1;
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} else {
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size1 = 0;
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size2 = reqestedSize;
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}
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if (pos < 0)
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return wxSTREAM_READ_ERROR;
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// read the backing file
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if (size1) {
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if (m_file.Seek(pos) == wxBadSeek)
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return wxSTREAM_READ_ERROR;
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ssize_t n = m_file.Read(buffer, size1);
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if (n > 0) {
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*size = n;
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pos += n;
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}
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if (*size < size1)
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return wxSTREAM_READ_ERROR;
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}
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// read from the buffer or parent stream
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if (size2)
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{
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while (*size < reqestedSize)
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{
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// if pos is further ahead than the parent has been read so far,
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// then read forward in the parent stream
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while (pos - m_filelen + size_t(0) >= m_buflen)
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{
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// if the parent is small enough, don't use a backing file
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// just the buffer memory
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if (!m_stream && m_filelen == 0)
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return m_parenterror;
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// before refilling the buffer write out the current buffer
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// to the backing file if there is anything in it
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if (m_buflen)
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{
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if (!m_file.IsOpened())
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if (!wxCreateTempFile(m_prefix, &m_file, &m_filename))
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return wxSTREAM_READ_ERROR;
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if (m_file.Seek(m_filelen) == wxBadSeek)
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return wxSTREAM_READ_ERROR;
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size_t count = m_file.Write(m_buf, m_buflen);
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m_filelen += count;
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if (count < m_buflen) {
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delete m_stream;
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m_stream = NULL;
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if (count > 0) {
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delete m_buf;
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m_buf = NULL;
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m_buflen = 0;
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}
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m_parenterror = wxSTREAM_READ_ERROR;
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return m_parenterror;
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}
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m_buflen = 0;
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if (!m_stream) {
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delete m_buf;
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m_buf = NULL;
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}
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}
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if (!m_stream)
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return m_parenterror;
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// refill buffer
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m_buflen = m_stream->Read(m_buf, m_bufsize).LastRead();
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if (m_buflen < m_bufsize) {
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m_parenterror = m_stream->GetLastError();
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if (m_parenterror == wxSTREAM_NO_ERROR)
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m_parenterror = wxSTREAM_EOF;
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delete m_stream;
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m_stream = NULL;
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}
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}
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// copy to the user's buffer
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size_t start = pos - m_filelen;
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size_t len = wxMin(m_buflen - start, reqestedSize - *size);
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memcpy((char*)buffer + *size, m_buf + start, len);
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*size += len;
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pos += len;
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}
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}
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return wxSTREAM_NO_ERROR;
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}
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wxFileOffset wxBackingFileImpl::GetLength() const
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{
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if (m_parenterror != wxSTREAM_EOF) {
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wxLogNull nolog;
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return m_stream->GetLength();
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}
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return m_filelen + m_buflen;
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}
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/////////////////////////////////////////////////////////////////////////////
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// Backing File, the handle part
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wxBackingFile::wxBackingFile(wxInputStream *stream,
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size_t bufsize,
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const wxString& prefix)
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: m_impl(new wxBackingFileImpl(stream, bufsize, prefix))
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{
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}
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wxBackingFile::wxBackingFile(const wxBackingFile& backer)
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: m_impl(backer.m_impl ? backer.m_impl->AddRef() : NULL)
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{
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}
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wxBackingFile& wxBackingFile::operator=(const wxBackingFile& backer)
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{
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if (backer.m_impl != m_impl) {
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if (m_impl)
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m_impl->Release();
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m_impl = backer.m_impl;
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if (m_impl)
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m_impl->AddRef();
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}
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return *this;
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}
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wxBackingFile::~wxBackingFile()
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{
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if (m_impl)
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m_impl->Release();
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}
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/////////////////////////////////////////////////////////////////////////////
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// Input stream
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wxBackedInputStream::wxBackedInputStream(const wxBackingFile& backer)
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: m_backer(backer),
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m_pos(0)
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{
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}
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size_t wxBackedInputStream::OnSysRead(void *buffer, size_t size)
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{
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if (!IsOk())
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return 0;
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m_lasterror = m_backer.m_impl->ReadAt(m_pos, buffer, &size);
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m_pos += size;
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return size;
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}
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wxFileOffset wxBackedInputStream::GetLength() const
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{
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return m_backer.m_impl->GetLength();
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}
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wxFileOffset wxBackedInputStream::OnSysSeek(wxFileOffset pos, wxSeekMode mode)
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{
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switch (mode) {
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case wxFromCurrent:
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{
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m_pos += pos;
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break;
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}
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case wxFromEnd:
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{
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wxFileOffset len = GetLength();
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if (len == wxInvalidOffset)
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return wxInvalidOffset;
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m_pos = len + pos;
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break;
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}
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default:
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{
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m_pos = pos;
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break;
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}
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}
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return m_pos;
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}
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wxFileOffset wxBackedInputStream::OnSysTell() const
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{
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return m_pos;
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}
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#endif // wxUSE_BACKINGFILE
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