memmapfile.cpp

一个国人自己实现图像库的程序（有参考价值）

#include "stdafx.h"
#include "..\Include\MemMapFile.h"

//===================================================================
void * FCMemMapFile::ReadFile (PCTSTR szFileName, DWORD dwShare)
{
	this->UnMap () ;
	m_hFile = ::CreateFile (szFileName, GENERIC_READ, dwShare, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL) ;
	if (m_hFile == INVALID_HANDLE_VALUE)
		return NULL ;

	m_hFileMap = ::CreateFileMapping (m_hFile, NULL, PAGE_READONLY, 0, 0, NULL) ;
	if (m_hFileMap == NULL)
	{
		::CloseHandle (m_hFile) ;
		m_hFile = INVALID_HANDLE_VALUE ;
		return NULL ;
	}
	m_pMapAddress = ::MapViewOfFile (m_hFileMap, FILE_MAP_READ, 0, 0, 0) ;
	if (m_pMapAddress == NULL)
		this->UnMap () ;
	return (void *)m_pMapAddress ;
}
//===================================================================
void * FCMemMapFile::CreateFile (PCTSTR szFileName, DWORD dwMaxFileSize, bool bOverWrite, DWORD dwShare)
{
	this->UnMap () ;
	m_hFile = ::CreateFile (szFileName, GENERIC_READ | GENERIC_WRITE, dwShare, NULL,
							bOverWrite ? CREATE_ALWAYS : CREATE_NEW,
							FILE_ATTRIBUTE_NORMAL | FILE_FLAG_SEQUENTIAL_SCAN, NULL) ;
	if (m_hFile == INVALID_HANDLE_VALUE)
		return NULL ;

	m_hFileMap = ::CreateFileMapping (m_hFile, NULL, PAGE_READWRITE, 0, dwMaxFileSize, NULL) ;
	if (m_hFileMap == NULL)
	{
		::CloseHandle (m_hFile) ;
		m_hFile = INVALID_HANDLE_VALUE ;
		return NULL ;
	}
	m_pMapAddress = ::MapViewOfFile (m_hFileMap, FILE_MAP_ALL_ACCESS, 0, 0, 0) ;
	if (m_pMapAddress == NULL)
		this->UnMap () ;
	return (void *)m_pMapAddress ;
}
//===================================================================
void * FCMemMapFile::ModifyFile (PCTSTR szFileName, DWORD dwMaxFileSize, DWORD dwShare)
{
	this->UnMap () ;
	m_hFile = ::CreateFile (szFileName, GENERIC_READ | GENERIC_WRITE, dwShare, NULL,
							OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL) ;
	if (m_hFile == INVALID_HANDLE_VALUE)
		return NULL ;

	m_hFileMap = ::CreateFileMapping (m_hFile, NULL, PAGE_READWRITE, 0, dwMaxFileSize, NULL) ;
	if (m_hFileMap == NULL)
	{
		::CloseHandle (m_hFile) ;
		m_hFile = INVALID_HANDLE_VALUE ;
		return NULL ;
	}
	m_pMapAddress = ::MapViewOfFile (m_hFileMap, FILE_MAP_ALL_ACCESS, 0, 0, 0) ;
	if (m_pMapAddress == NULL)
		this->UnMap () ;
	return (void *)m_pMapAddress ;
}
//===================================================================