Undo Manager

// undomgr_wtlView.h : interface of the CUndomgr_wtlView class
//
/////////////////////////////////////////////////////////////////////////////

#if !defined(AFX_UNDOMGR_WTLVIEW_H__7982DF86_1CC2_4DAD_9092_0B5422A44681__INCLUDED_)
#define AFX_UNDOMGR_WTLVIEW_H__7982DF86_1CC2_4DAD_9092_0B5422A44681__INCLUDED_

#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000

// included atlgdi and my sample gdi graphic objects
#include <atlgdi.h>
#include "gdigraph.h"

class CUndomgr_wtlView : public CWindowImpl<CUndomgr_wtlView>
{
public:
	CUndomgr_wtlView()
	{
		// Reset counter
		m_id = 0;

		// Intialize graphic context class, used for undo - redo operations
		GUIContext::Initialize(&m_displayMap, &m_deletedMap);
	}

	DECLARE_WND_CLASS(NULL)

	// Added IOleUndoManager as a member
	CComPtr<IOleUndoManager> m_spUndoMgr;

	// Added an object map for display objects and one for deleted objects
	GUIObjectMap	m_displayMap;
	GUIObjectMap	m_deletedMap;

	// Counter for unique identifiers
	long			m_id;

	BOOL PreTranslateMessage(MSG* pMsg)
	{
		pMsg;
		return FALSE;
	}

	BEGIN_MSG_MAP(CUndomgr_wtlView)
		MESSAGE_HANDLER(WM_PAINT, OnPaint)
		MESSAGE_HANDLER(WM_LBUTTONUP, OnLButtonUP)
	END_MSG_MAP()

	LRESULT OnPaint(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
	{
		CPaintDC dc(m_hWnd);

		// Draw each graphic object in the display map
		std::for_each(m_displayMap.begin(), m_displayMap.end(), DrawFunctor(dc));

		return 0;
	}

	LRESULT OnLButtonUP(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM lParam, BOOL& /*bHandled*/)
	{
		// Create different graphical objets with mouse clicks

		POINT pt = { GET_X_LPARAM(lParam), GET_Y_LPARAM(lParam) };

		switch (m_id % 4)
		{
			case 3:
			{
				// Creates a group of 2 boxes a round rect and an ellipse
				CreateGuiGroup(pt);
				break;
			}
			case 2:
			{
				// Creates an ellipse
				CreateGuiObject(2,pt);
				break;
			}
			case 1:
			{
				// Creates a round rect
				CreateGuiObject(1,pt);
				break;
			}
			default:
			{
				// Creates a box
				CreateGuiObject(0,pt);
				break;
			}
		}

		Invalidate();
		return 0;
	}


	void CreateGuiGroup(POINT pt)
	{
		//
		// Create parent undo unit to group units into one action
		//
		CComPtr<IOleParentUndoUnit> spPUU;
		HRESULT hr = CreateGroupUnit(&spPUU);
		if (SUCCEEDED(hr))
		{
			// Open the parent unit, following units added through the
			// manager will be added to this unit.
			hr = m_spUndoMgr->Open(spPUU);
			if (SUCCEEDED(hr))
			{
				POINT pt0, pt1, pt2, pt3;
				pt0.x = pt.x - 20; pt0.y = pt.y - 20;
				pt1.x = pt.x - 20; pt1.y = pt.y + 20;
				pt2.x = pt.x + 20; pt2.y = pt.y - 20;
				pt3.x = pt.x + 20; pt3.y = pt.y + 20;
				CreateGuiObject(0,pt0); // box
				CreateGuiObject(1,pt1); // round rect
				CreateGuiObject(2,pt2); // ellipse
				CreateGuiObject(0,pt3); // box

				// Commit to undo stack
				m_spUndoMgr->Close(spPUU, TRUE);
			}
		}

		// Increment counter, otherwise we will create only groups from now
		m_id++;
	}

	void CreateGuiObject(LONG type, POINT pt)
	{
		CGUIObject* p = NULL;

		switch (type)
		{
			case 0: 
				p = new CGUIBox(pt);
				break;
			case 1: 
				p = new CGUIRoundRect(pt);
				break;
			case 2: 
				p = new CGUIEllipse(pt);
				break;
		}

		if (p)
		{
			// Increment counter
			m_id++;

			// Insert the object in the display map by id
			m_displayMap.insert(GUIObjectMap::value_type(m_id, p));

			//
			// Add object to the undo stack
			//
			CComPtr<IOleUndoUnit> spUU;
			HRESULT hr = CreateUndoUnit(m_id, &spUU);
			if (SUCCEEDED(hr))
			{
				hr = m_spUndoMgr->Add(spUU);
			}
		}
	}

};


/////////////////////////////////////////////////////////////////////////////

//{{AFX_INSERT_LOCATION}}
// Microsoft Visual C++ will insert additional declarations immediately before the previous line.

#endif // !defined(AFX_UNDOMGR_WTLVIEW_H__7982DF86_1CC2_4DAD_9092_0B5422A44681__INCLUDED_)