Action History - Undo and Redo

// ActionDragBox.cpp: implementation file
//

#include "stdafx.h"
#include "ActionDragBox.h"

/***********************************************************************
class CActionDragBox : public IActionBase
	This class is designed to manage user action history. After an
	action has been handled the pointer to the original action should be
	stored in this class for undo and redo functionality.
***********************************************************************/

/***********************************************************************
	CActionDragBox - Constructor/Deconstructor
***********************************************************************/

// CActionDragBox - Constructor
//
CActionDragBox::CActionDragBox()
{
	// initialise the offset amounts
	m_ptOffset.x = m_ptOffset.y = 0;
	m_ptOldOffset.x = m_ptOldOffset.y = 0;
}

// CActionDragBox - Constructor
//
CActionDragBox::CActionDragBox(CRect* NewRect, CUndoRedoView* pParent /*=NULL*/)
	: m_pObject(NewRect), m_pParent(pParent)
{
	// initialise the offset amounts
	m_ptOffset.x = m_ptOffset.y = 0;
	m_ptOldOffset.x = m_ptOldOffset.y = 0;
}

// CActionDragBox - Deconstructor
//
CActionDragBox::~CActionDragBox()
{

}

/***********************************************************************
	CActionDragBox - Member Functions
***********************************************************************/

// void SetOffset(int left, int top)
//		Set the offset value of the drag box.
//
void CActionDragBox::SetOffset(int left, int top)
{
	// set the offset value of the drag box to that specified
	m_ptOffset.x = left;
	m_ptOffset.y = top;
}

// void IncOffset(int left, int top)
//		Increment the offset value of the drag box.
//
void CActionDragBox::IncOffset(int left, int top)
{
	// increment the offset value by the amount specified
	m_ptOffset.x += left;
	m_ptOffset.y += top;
}

/***********************************************************************
	CActionDragBox - Virtual Overrides
***********************************************************************/

// void Run()
//		Automatically runs when the action is to take place.
//
void CActionDragBox::Run()
{
	// create an instance of the client dc object
	CClientDC dc(m_pParent);

	// erase the old drag box
	m_pParent->DrawDragBox(&dc, true);
	// calculate the new rectangle
	m_pObject->left = m_pObject->left - m_ptOldOffset.x + m_ptOffset.x;
	m_pObject->top = m_pObject->top - m_ptOldOffset.y + m_ptOffset.y;
	m_pObject->right = m_pObject->right - m_ptOldOffset.x + m_ptOffset.x;
	m_pObject->bottom = m_pObject->bottom - m_ptOldOffset.y + m_ptOffset.y;
	// draw the new drag box
	m_pParent->DrawDragBox(&dc);

	// store the current offset value
	m_ptOldOffset = m_ptOffset;
}

// void Undo()
//		Automatically runs when the action is to be undone.
//
void CActionDragBox::Undo()
{
	// create an instance of the client dc object
	CClientDC dc(m_pParent);

	// erase the old drag box
	m_pParent->DrawDragBox(&dc, true);
	// calculate the new rectangle
	m_pObject->left = m_pObject->left - m_ptOldOffset.x;
	m_pObject->top = m_pObject->top - m_ptOldOffset.y;
	m_pObject->right = m_pObject->right - m_ptOldOffset.x;
	m_pObject->bottom = m_pObject->bottom - m_ptOldOffset.y;
	// draw the new drag box
	m_pParent->DrawDragBox(&dc);

	// store the current offset value
	m_ptOldOffset.x = m_ptOldOffset.y = 0;
}