Windows NT Systems Programming

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List Boxes: Open Folder Dialog Window

Problem: How to identify which message folder to open?

Solution: Build a Dialog Window which displays available folders in a CListBox control

Code is here

CListBox

Object which displays a list of items which can be selected by the user.

Example for Message Folders:

• Assume a flat naming structure
• Use WIN32 APIs to enumerate all folders in a known directory
  (which is the current directory)
• Add each folder name to the listBox
  (default is to sort all the items in the listBox)

void CMainWindow::OnOpen()
{
	HANDLE folder;
	WIN32_FIND_DATA findData;
	
	CRect rect;
	GetClientRect(&rect);
	makeOpenFolderDialog(rect, this);

	folder = FindFirstFile("*", &findData);
	while( folder != INVALID_HANDLE_VALUE) {
		if(findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
			// assume all directories are folders
			m_lBoxFolders.AddString(findData.cFileName);
		}
		if(!FindNextFile(folder, &findData))
			break;
	}
	FindClose(folder);
}

Catching Selections from the listBox

1) Define a message handling member function for CMainWindow (or appropriate container window)

2) Add a MESSAGE_MAP entry for listBox Selection messages

ON_LBN_SELCHANGE(IDC_LISTBOX,OnFolderSelection)

3) Write the Message Handler

void CMainWindow::OnFolderSelection()
{
	CString selection;
	int nIndex = m_lBoxFolders.GetCurSel();
	if (nIndex != LB_ERR) {
		m_lBoxFolders.GetText(nIndex,selection);
		m_editSelection.SetWindowText(selection);
	}
}

Doubly Clicking Entries From ListBox

Double Click events are handled as another message type.

1) Define a message handling member function for CMainWindow (or appropriate container window)

2) Add a MESSAGE_MAP entry for listBox DBLCLK messages

ON_LBN_DBLCLK(IDC_LISTBOX,OnFolderDblClk)

3) Write the Message Handler

void CMainWindow::OnFolderDblClk()
{
	CString selection;

	int nIndex = m_lBoxFolders.GetCurSel();
	if (nIndex != LB_ERR) {
		m_lBoxFolders.GetText(nIndex,selection);
		m_editSelection.SetWindowText(selection);
		OnOpenFolder();
	}
}

void CMainWindow::OnOpenFolder()
{
	CString message;
	CString folder;
	
	m_editSelection.GetWindowText(folder);
	message = "Ok to open " + folder + "?"; // Cstring has nice concatenation operations
	int result = MessageBox(message,"Open",MB_YESNOCANCEL);
	if(result == IDYES) {
		MessageBox("need code to open here","open");
		cleanUpOpenFolder();
	}
	else if(result == IDNO) {
		MessageBox("no folder opened","no open");
		cleanUpOpenFolder();
	}
	else if(result == IDCANCEL) {
		
	}
}

void CMainWindow::cleanUpOpenFolder() // Here is how to get rid of open folder dialog window
{
	m_lBoxFolders.DestroyWindow();	// Destroys Window but not the object
	m_labelSelection.DestroyWindow();
	m_btnCancelFolder.DestroyWindow();
	m_btnOpenFolder.DestroyWindow();
	m_editSelection.DestroyWindow();
}

Summary on CListBox

• Arbitrary length list of Items
• Handles scrolling if necessary
• Can Automatically sort or can control exact position
• Allows single or multiple item selection
• Allows Selection and Double Click Events
• Has Focus Events

Copyright chris wild 1997.
For problems or questions regarding this web contact [Dr. Wild].
Last updated: September 24, 1997.