Form Designer

// UndoRedoStorage.cpp: implementation of the CUndoRedoStorage class.
//
// Author : David Shepherd
//			Copyright (c) 2002, DaeDoe-Software
//
/////////////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "UndoRedoStorage.h"

// the base element name
#define BASE_ELEMENT_NAME	L""

/////////////////////////////////////////////////////////////////////////////
// CUndoRedoStorage

CUndoRedoStorage::CUndoRedoStorage()
{
	// initialise everthing
	m_Count=0;
}

CUndoRedoStorage::~CUndoRedoStorage()
{
	// clean up
}

std::wstring CUndoRedoStorage::ElementName(DWORD Ix) const
{
	// create an element name given the index
	std::wstringstream strm;
	strm << BASE_ELEMENT_NAME;
	strm << Ix;
	// return the element name
	return strm.str().c_str();
}

void CUndoRedoStorage::Create()
{
	// create the storage
	if(!SUCCEEDED(StgCreateDocfile(NULL,
		STGM_DIRECT|STGM_READWRITE|
		STGM_SHARE_EXCLUSIVE|STGM_CREATE|STGM_DELETEONRELEASE,
		0,&m_spStorage)))
	{
		throw std::exception();
	}
}

BOOL CUndoRedoStorage::IsCreated() const
{
	// determine if the storage has been created
	return (m_spStorage==NULL) ? FALSE : TRUE;
}

DWORD CUndoRedoStorage::GetElementCount() const
{
	// return the number of elements in the storage
	return m_Count;
}

CComPtr<IStream> CUndoRedoStorage::CreateNewElement()
{
	ATLASSERT(m_spStorage!=NULL);

	// create a new storage element
	CComPtr<IStream> spStream;
	if(!SUCCEEDED(m_spStorage->CreateStream(ElementName(m_Count).c_str(),
		STGM_DIRECT|STGM_WRITE|STGM_SHARE_EXCLUSIVE|STGM_CREATE,
		0,0,&spStream)))
	{
		throw std::exception();
	}
	// update the element count
	m_Count++;
	// return the element stream
	return spStream;
}

CComPtr<IStream> CUndoRedoStorage::GetStreamOnLastElement()
{
	ATLASSERT(m_spStorage!=NULL);
	ATLASSERT(m_Count > 0);

	// return a stream on the last storage element
	CComPtr<IStream> spStream;
	if(!SUCCEEDED(m_spStorage->OpenStream(ElementName(m_Count-1).c_str(),
		NULL,STGM_DIRECT|STGM_READ|STGM_SHARE_EXCLUSIVE,
		0,&spStream)))
	{
		throw std::exception();
	}
	// return the element stream
	return spStream;
}

void CUndoRedoStorage::RemoveLastElement()
{
	ATLASSERT(m_spStorage!=NULL);
	ATLASSERT(m_Count > 0);

	// remove the last storage element
	if(!SUCCEEDED(
		m_spStorage->DestroyElement(ElementName(m_Count-1).c_str())))
	{
		throw std::exception();
	}
	// update the element count
	m_Count--;
}

void CUndoRedoStorage::RemoveAllElements()
{
	ATLASSERT(m_spStorage!=NULL);

	// remove all storage elements
	while(m_Count > 0)
	{
		RemoveLastElement();
	}
}