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Plug-In framework using DLLs

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25 Jun 200211 min read 311.4K   8.7K   226  
Explains how to develop applications that support plug-ins
 
// PlugInSelectDialog.cpp : implementation file
//

#include "stdafx.h"
#include "PlugSDI.h"
#include "PlugInSelectDialog.h"

#include "Mainfrm.h"

#include <io.h>

// CPlugInSelectDialog dialog

IMPLEMENT_DYNAMIC(CPlugInSelectDialog, CDialog)
CPlugInSelectDialog::CPlugInSelectDialog(CWnd* pParent /*=NULL*/)
	: CDialog(CPlugInSelectDialog::IDD, pParent)
	, m_pImageList(NULL)
	, m_pImageHdrSmall(NULL)
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::CPlugInSelectDialog() method\n");
#endif
}

CPlugInSelectDialog::~CPlugInSelectDialog()
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::~CPlugInSelectDialog() method\n");
#endif

	if( m_pImageList != NULL)
		delete m_pImageList;
	if( m_pImageHdrSmall != NULL)
		delete m_pImageHdrSmall;

	m_szListValidFilenames.RemoveAll();
	m_szPlugInName.RemoveAll();
}

void CPlugInSelectDialog::DoDataExchange(CDataExchange* pDX)
{
	CDialog::DoDataExchange(pDX);
	DDX_Control(pDX, IDC_LIST_PLUG_IN, m_PlugInList);
}


BEGIN_MESSAGE_MAP(CPlugInSelectDialog, CDialog)
	ON_BN_CLICKED(IDC_PLUG_IN_LOAD, OnBnClickedPlugInLoad)
END_MESSAGE_MAP()


// CPlugInSelectDialog message handlers

BOOL CPlugInSelectDialog::OnInitDialog()
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::OnInitDialog() method\n");
#endif

	CPlugSDIApp *pApp;

	CDialog::OnInitDialog();

	// Bring data from dialog
	UpdateData(TRUE);

	// TODO:  Add extra initialization here
	pApp = (CPlugSDIApp *) AfxGetApp();

	// create image list for header items
	m_pImageHdrSmall = new CImageList();
	ASSERT(m_pImageHdrSmall != NULL); // serious allocation failure checking
	m_pImageHdrSmall->Create(16, 16, ILC_MASK, 3, 3);
	m_pImageHdrSmall->Add(pApp->LoadIcon(IDI_HDRICON1));
	m_pImageHdrSmall->Add(pApp->LoadIcon(IDI_HDRICON2));
	m_pImageHdrSmall->Add(pApp->LoadIcon(IDI_HDRICON3));

	// fill in image lists
	m_pImageList = new CImageList();
	ASSERT(m_pImageList != NULL); // serious allocation failure checking
	m_pImageList->Create(16, 16, TRUE,  1, 1);
	m_pImageList->Add(pApp->LoadIcon(IDI_ICON_PLUG_IN));

	m_PlugInList.SetExtendedStyle(m_PlugInList.GetExtendedStyle()
		| LVS_EX_HEADERDRAGDROP
		| LVS_EX_GRIDLINES
		| 0x00004000 // LVS_EX_LABELTIP
		| LVS_EX_FULLROWSELECT
		| LVS_EX_FLATSB
		| LVS_EX_CHECKBOXES);

	FillPlugIns();

	m_PlugInList.SetFocus();
	if (m_PlugInList.GetItemCount() > 0)
        m_PlugInList.SetSelectionMark(0);
	else
	{
#ifdef DEBUG
		TRACE("ERROR: No Plug-Ins found in directory\n");
#endif
		AfxMessageBox("ERROR: No Plug-Ins found.\nPlease place *.PLX file in the program executable path\nand then try again!!!");
		m_PlugInList.EnableWindow(FALSE);
		((CButton *) GetDlgItem(IDC_PLUG_IN_LOAD))->EnableWindow(FALSE);
		((CButton *) GetDlgItem(IDOK))->SetFocus();
	}

	return FALSE;  // return TRUE unless you set the focus to a control
	// EXCEPTION: OCX Property Pages should return FALSE
}

// Used to fill the list control with available Plug Ins
void CPlugInSelectDialog::FillPlugIns(void)
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::FillPlugIns() method\n");
#endif

	CRect           rect;
	int             nActualItem = 0;
	LV_ITEM         lvitem;
	CString         strItem1= _T("S. No");
	CString         strItem2= _T("Plug-In Name");
	CString         strItem3= _T("Plug-In Path");
	CString         szSerialNo(""), szPlugInName(""), szPlugInPath("");
	LPTSTR          pStrTemp1 = NULL, pStrTemp2 = NULL, pStrTemp3 = NULL;
	CPlugSDIApp     *pApp = NULL;

	nActualItem = 0;
	pApp = (CPlugSDIApp *)AfxGetApp();

	int nNumDLLsFound = FindDLLs(pApp);

	m_PlugInList.SetImageList(m_pImageList, LVSIL_SMALL);

	// insert two columns (REPORT mode) and modify the new header items
	m_PlugInList.GetWindowRect(&rect);
	m_PlugInList.InsertColumn(0, strItem1, LVCFMT_LEFT, rect.Width() * 2/20, 0);
	m_PlugInList.InsertColumn(1, strItem2, LVCFMT_LEFT, rect.Width() * 4/20, 0);
	m_PlugInList.InsertColumn(2, strItem3, LVCFMT_LEFT, rect.Width() * 13/20, 1);

	ModifyHeaderItems();

	POSITION pos1 = m_szPlugInName.GetHeadPosition();
	POSITION pos2 = m_szListValidFilenames.GetHeadPosition();

	// insert the items and subitems into the list view.
	for (int nItem = 0; nItem < nNumDLLsFound; nItem++)
	{
		szPlugInName = m_szPlugInName.GetNext(pos1);
		szPlugInPath = m_szListValidFilenames.GetNext(pos2);
		szSerialNo.Format("%d", nItem);
		for (int nSubItem = 0; nSubItem < 3; nSubItem++)
		{
			lvitem.mask = LVIF_TEXT | (nSubItem == 0? LVIF_IMAGE : 0);
			lvitem.iItem = (nSubItem == 0)? nItem : nActualItem;
			lvitem.iSubItem = nSubItem;

			// calculate the main and sub-item strings for the current item
			pStrTemp1= szSerialNo.GetBuffer(szSerialNo.GetLength());
			pStrTemp2= szPlugInName.GetBuffer(szPlugInName.GetLength());
			pStrTemp3= szPlugInPath.GetBuffer(szPlugInPath.GetLength());
			switch(nSubItem)
			{
				case 0: lvitem.pszText = pStrTemp1;
					break;
				case 1: lvitem.pszText = pStrTemp2;
					break;
				case 2: lvitem.pszText = pStrTemp3;
					break;
			}
//			lvitem.pszText = nSubItem == 0? pStrTemp1 : pStrTemp2;

			lvitem.iImage = 0;
			if (nSubItem == 0)
				// insert new item
				nActualItem = m_PlugInList.InsertItem(&lvitem);
			else
				// modify existing item (the sub-item text)
				m_PlugInList.SetItem(&lvitem);
		}

		// Check whether this item (DLL) was loaded previously
		if (((CMainFrame *)pApp->m_pMainWnd)->m_szListDLLsCurrentlyLoaded.Find(szPlugInPath) != NULL)
		{
			ListView_SetCheckState(m_PlugInList.m_hWnd, nActualItem, TRUE);
		}
	}

	m_szPlugInName.RemoveAll();
	m_szListValidFilenames.RemoveAll();
}

// Used to find all available DLLs and store them in a list
int CPlugInSelectDialog::FindDLLs(CPlugSDIApp *pApp)
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::FindDLLs() method\n");
#endif

	long				lFile = 0L;
	struct _finddata_t	sFILE;
	DLLManager			tmpDLL; // for checking of functions
	CString				szSearchPath = "";
	CString				szCommandLine ;
	int					nNumDlls = 0 ;

	szCommandLine = GetCommandLine(); // so we know where to look for DLL's
	szCommandLine = szCommandLine.Left(szCommandLine.Find("PlugSDI.exe")); // lose exe name
	szCommandLine = szCommandLine.Right(szCommandLine.GetLength() - 1); // lose leading "

	szSearchPath = szCommandLine + "*.PLX";
	lFile = (long) _findfirst(szSearchPath, &sFILE);

	if (lFile != -1L)
	{
		do
		{
			tmpDLL.SetToolBarPointer(((CMainFrame *)pApp->m_pMainWnd)->GetToolBarObject());
			tmpDLL.SetDLLFileName(szCommandLine + sFILE.name);
			CString szName("");
			if (tmpDLL.GetDLLName(&szName) == true)
			{
				m_szPlugInName.AddTail(szName);
//				m_szPlugInName.AddTail(sFILE.name);
				m_szListValidFilenames.AddTail(tmpDLL.m_szDLLFileName);
				// Increment number of DLLs
				nNumDlls++;
//				tmpDLL.FreeDLL(); // release it
			}
		} while (_findnext(lFile, &sFILE) == 0);
		_findclose(lFile);
	}

	return nNumDlls;
}

// Used to modify list control's header items
void CPlugInSelectDialog::ModifyHeaderItems(void)
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::ModifyHeaderItems() method\n");
#endif

	HD_ITEM curItem;

	// retrieve embedded header control
	CHeaderCtrl* pHdrCtrl= NULL;
	pHdrCtrl= m_PlugInList.GetHeaderCtrl();

	pHdrCtrl->SetImageList(m_pImageHdrSmall);

	// add bitmaps to each header item
	pHdrCtrl->GetItem(0, &curItem);
	curItem.mask= HDI_IMAGE | HDI_FORMAT;
	curItem.iImage= 0;
	curItem.fmt= HDF_LEFT | HDF_IMAGE | HDF_STRING;
	pHdrCtrl->SetItem(0, &curItem);

	pHdrCtrl->GetItem(1, &curItem);
	curItem.mask= HDI_IMAGE | HDI_FORMAT;
	curItem.iImage= 1;
	curItem.fmt= HDF_LEFT | HDF_IMAGE | HDF_STRING;
	pHdrCtrl->SetItem(1, &curItem);

	pHdrCtrl->GetItem(2, &curItem);
	curItem.mask= HDI_IMAGE | HDI_FORMAT;
	curItem.iImage= 2;
	curItem.fmt= HDF_LEFT | HDF_IMAGE | HDF_STRING;
	pHdrCtrl->SetItem(2, &curItem);
}

// Used to load all available DLLs
bool CPlugInSelectDialog::LoadDLLs(CPlugSDIApp *pApp, CStringList *szListSelectedDLLs)
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::LoadDLLs() method\n");
#endif

	// We now have a list of valid DLL's. Load all of them
	if (((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs > 0)
	{
		POSITION pos = szListSelectedDLLs->GetHeadPosition();
//		((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs = nNumDlls;
		((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs = new DLLManager[((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs];
		for (int nNumDlls = 0 ;	nNumDlls < ((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs ; nNumDlls++)
		{
			((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs[nNumDlls].SetToolBarPointer(((CMainFrame *)pApp->m_pMainWnd)->GetToolBarObject());
            if (((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs[nNumDlls].LoadDLL(szListSelectedDLLs->GetNext(pos)) != false)
			{
				// Call InitPLugIn() to initialize Plug-In and update toolbar
				if (((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs[nNumDlls].InitDLL() == false)
				{
					AfxMessageBox("ERROR: Could not initialize " + ((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs[nNumDlls].m_szDLLFileName + "\nInvalid or corrupt Plug-In\nPlease re-install it!!!");
	#ifdef DEBUG
					TRACE("ERROR: Could not call InitDLL(\"InitPlugIn\") method for \n\t" + ((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs[nNumDlls].m_szDLLFileName + "\n");
	#endif
					return false;
				}
			}
			else
			{
				AfxMessageBox("ERROR: Could not initialize " + ((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs[nNumDlls].m_szDLLFileName + "\nInvalid or corrupt Plug-In\nPlease re-install it!!!");
#ifdef DEBUG
				TRACE("ERROR: Could not call LoadDLL(\"GetPlugInName\") method for \n\t" + ((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs[nNumDlls].m_szDLLFileName + "\n");
#endif
				return false;
			}
		}
	}
	else
	{
#ifdef DEBUG
		TRACE("ERROR: No Plug-Ins currently selected\n");
#endif
		AfxMessageBox("ERROR: No Plug-Ins currently selected.\nSelect and then try again!!!");
		return false;
	}

	// Recalculate layout due to GUI changes
	((CMainFrame *)pApp->m_pMainWnd)->RecalcLayout();

	// Set flag to indicate that Plug-Ins are now loaded
	((CMainFrame *)pApp->m_pMainWnd)->m_bIsPlugInLoaded = TRUE;

	return true;
}

void CPlugInSelectDialog::OnBnClickedPlugInLoad()
{
#ifdef DEBUG
	TRACE("Called CPlugInSelectDialog::OnBnClickedPlugInLoad() method\n");
#endif

	// TODO: Add your control notification handler code here
	int nCount = m_PlugInList.GetItemCount();
	int nNumDLLsSelected = 0;

	if (nCount <= 0)
	{
#ifdef DEBUG
		TRACE("ERROR: No Plug-Ins found\n");
#endif
		AfxMessageBox("ERROR: No Plug-Ins found!!!");
		return;
	}

	CStringList szList;

	for (int i=0; i<m_PlugInList.GetItemCount(); i++)
	{
		if (ListView_GetCheckState(m_PlugInList.m_hWnd, i) != 0)
		{
#ifdef DEBUG
		TRACE1("Item %d selected\n", i);
#endif
			szList.AddTail(m_PlugInList.GetItemText(i, 2));
			++nNumDLLsSelected;
		}
	}

	if (nNumDLLsSelected == 0)
	{
#ifdef DEBUG
		TRACE("ERROR: No Plug-Ins currently selected\n");
#endif
		if (AfxMessageBox("ERROR: No Plug-Ins currently selected.\nDo you want to Un-Load previously loaded Plug-Ins?",MB_YESNO) == IDYES)
		{
			CPlugSDIApp *pApp = (CPlugSDIApp *) AfxGetApp();

			// If Previous number of DLLs > 0 then, Free/Un-Load all of them
			if (((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs > 0)
			{
				// free the previously loaded DLL's
				delete [] ((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs;
				((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs = NULL;
				((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs = 0;
				((CMainFrame *)pApp->m_pMainWnd)->m_szListDLLsCurrentlyLoaded.RemoveAll();

				// Recalculate layout due to GUI changes
				((CMainFrame *)pApp->m_pMainWnd)->RecalcLayout();
			}

			// Set the new number of DLLs selected
			((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs = 0;
		}
		return;
	}
	else
	{
		CPlugSDIApp *pApp = (CPlugSDIApp *) AfxGetApp();

#ifdef DEBUG
		POSITION pos = szList.GetHeadPosition();
		CString str;
		do
		{
			str = szList.GetNext(pos);
			TRACE("LIST ITEM: " + str + "\n");
		}while(pos != NULL);
#endif
		// If Previous number of DLLs > 0 then, Free/Un-Load all of them
		if (((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs > 0)
		{
			// free the previously loaded DLL's
			delete [] ((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs;
			((CMainFrame *)pApp->m_pMainWnd)->m_pLoadedDLLs = NULL;
			((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs = 0;

			// Recalculate layout due to GUI changes
			((CMainFrame *)pApp->m_pMainWnd)->RecalcLayout();
		}

		// Set the new number of DLLs selected
		((CMainFrame *)pApp->m_pMainWnd)->m_nNumberOfDLLs = nNumDLLsSelected;

		// Load new set of DLLs
		LoadDLLs(pApp, &szList);

		((CMainFrame *)pApp->m_pMainWnd)->m_szListDLLsCurrentlyLoaded.RemoveAll();
		((CMainFrame *)pApp->m_pMainWnd)->m_szListDLLsCurrentlyLoaded.AddTail(&szList);
		szList.RemoveAll();

#ifdef DEBUG
		pos = ((CMainFrame *)pApp->m_pMainWnd)->m_szListDLLsCurrentlyLoaded.GetHeadPosition();
		do
		{
			str = ((CMainFrame *)pApp->m_pMainWnd)->m_szListDLLsCurrentlyLoaded.GetNext(pos);
			TRACE("*************** LIST ITEM PREV: " + str + "\n");
		}while(pos != NULL);
#endif
	}
}

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Written By
Mohit Khanna
Web Developer
India India
Living in New Delhi (India). Did my Engg (Comp. Science) in 2000, and since then working on and off with VC++. It's my passion, and would really love to learn it to the very detail. Presently working as a software engg in a Telecom based firm. I've got around 3yrs experience in NMS (network management systems). Well thats all about me for now. Feel free to contact me...

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Posted 25 Jun 2002

Article Copyright 2002 by Mohit Khanna
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