Dave's Brain

Browse - programming tips - mfc hidden window

Date: 2009may12
Platform: MFC
Language: C/C++

Q.  How do I make a hidden window with MFC?

A.  Hidden windows are handy for receiving messages and such.
Here's a class for you:

--- hiddenwnd.h 

class CHiddenWindow : public CWnd
{
public:
	CHiddenWindow(HWND hwndParent) { Init(hwndParent); }
	//{{AFX_DATA(CHiddenWindow)
	//}}AFX_DATA

protected:
	Init(HWND);

	//{{AFX_VIRTUAL(CHiddenWindow)
	protected:
	//}}AFX_VIRTUAL

	// Generated message map functions
	//{{AFX_MSG(CHiddenWindow)
	afx_msg void OnClose();
	//}}AFX_MSG
	DECLARE_MESSAGE_MAP()
};

--- hiddenwnd.cpp

#include "stdafx.h"
#include "resource.h"
#include "hiddenwnd.h"

BOOL CHiddenWindow::Init(const HWND hwndParent)
{
	LPCSTR	pszClass;
	BOOL	bResult;

	pszClass = AfxRegisterWndClass(
		CS_HREDRAW | CS_VREDRAW, // Style
		LoadCursor(NULL, IDC_ARROW), // Cursor
		(HBRUSH) GetStockObject(WHITE_BRUSH), // Brush
		LoadIcon(AfxGetInstanceHandle(), MAKEINTRESOURCE(IDR_MAINFRAME))); // Icon

	if (pszClass == NULL)
	{
		printf("CHiddenWindow::Init: could not make class\n");
		return FALSE;
	}

	bResult = CreateEx(WS_EX_OVERLAPPEDWINDOW,	// extended style
		pszClass,				// class name
		"CHiddenWindow",			// title
		WS_OVERLAPPEDWINDOW,			// style
		CW_USEDEFAULT,				// x position
		CW_USEDEFAULT,				// y position
		CW_USEDEFAULT,				// width
		CW_USEDEFAULT,				// height
		hwndParent,				// parent
		NULL,					// menu
		NULL);					// create param

	if (!bResult)
	{
		printf("CHiddenWindow::Init: CreateEx failed\n");
		return FALSE;
	}

	ShowWindow(SW_HIDE);
	UpdateWindow();

	return bResult;
}

void CHiddenWindow::OnClose()
{
	// Optionally, do something
}

BEGIN_MESSAGE_MAP(CHiddenWindow, CWnd)
	//{{AFX_MSG_MAP(CHiddenWindow)
	ON_WM_CLOSE()
	//}}AFX_MSG_MAP
END_MESSAGE_MAP()

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