How do I get an minimized icon for a dialog box in MFC?

Doran Kangwai -- dkangwai@cch.com.au
Thursday, October 24, 1996


Environment: NT 3.51, VC++ 1.52

I want to use a dialog box as a main window with MFC.
I can do this sucessfully by using:

class CT1Dlg: public CDialog
{
public:
	CT1Dlg();

protected:
	virtual void PostNcDestroy();

	afx_msg void OnQuitClicked();
	DECLARE_MESSAGE_MAP()
};	

BOOL CT1App::InitInstance()
{
	m_pMainWnd = new CT1Dlg;
	m_pMainWnd->ShowWindow( m_nCmdShow );
	m_pMainWnd->UpdateWindow();

	return TRUE;
}

to create the main window and the contructor:

CT1Dlg::CT1Dlg()
{
	Create( IDD_T1 );
}

and terminate the app with

void CT1Dlg::OnQuitClicked()
{
	TRACE( "In CT1Dlg::OnQuitClicked()\n" );
	DestroyWindow();
	::PostQuitMessage(0);
}

void  CT1Dlg::PostNcDestroy()
{
	TRACE( "In CT1Dlg::PostNcDestroy()\n" );
	delete this;
}

The problem is that I want the user to be able
to minimize the dialog. Unfortunately I cannot
get the dialog to use MY icon, it just uses
a default white box.

Now I can create a dialog box as a main window
that uses my icon with the WIN 3.1 SDK by using

static char szDlgName[] = "T2DLG";

int __pascal WinMain( HINSTANCE hCurrentInstance,
 HINSTANCE hinstPrevious, LPSTR lpszCmdLine, int nCmdShow )
{
 HWND hWnd;
 MSG msg;
 WNDCLASS t2WndClass ;

 if ( !hinstPrevious )
 {
  t2WndClass.style = CS_HREDRAW | CS_VREDRAW;
  t2WndClass.lpfnWndProc = t2WndProc;
  t2WndClass.cbClsExtra = 0;
  t2WndClass.cbWndExtra = DLGWINDOWEXTRA;
  t2WndClass.hInstance = hCurrentInstance;

  // Use my ICON
  t2WndClass.hIcon = LoadIcon( hCurrentInstance, MAKEINTRESOURCE( IDI_T2 ) );
  t2WndClass.hCursor = LoadCursor( NULL, IDC_ARROW );
  t2WndClass.hbrBackground = COLOR_WINDOW + 1;
  t2WndClass.lpszMenuName = NULL;
  t2WndClass.lpszClassName = szDlgName;

  RegisterClass( &t2WndClass );
 } // if

 hWnd = CreateDialog( hCurrentInstance, szDlgName, 0, NULL );

...
and

T2DLG DIALOG DISCARDABLE  0, 0, 185, 92
STYLE WS_POPUP | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX
CLASS "T2DLG"
CAPTION "Test Dialog"
FONT 8, "MS Sans Serif"
BEGIN
    PUSHBUTTON      "&Quit",IDC_QUIT,125,20,50,14
END

The t2WndClass.cbWndExtra = DLGWINDOWEXTRA;
and
CLASS "T2DLG" seem to be the important bits.

I need to somehow create a WNDCLASS and make
MFC use it to create the dialog box. I tried
overriding PreCreateWindow but it didn't seem
to be called when a dialog is created. I am
looking at CreateIndirect but still cannot
see how to tell MFC to use my WNDCLASS.
Oh how I wish WIN16 had the WIN32
WM_SETICON message so I could use SetIcon()!

Any ideas????

Sorry this turned out longer than I thought
it would but thanks if you got this far.

Doran Kangwai
CCH Australia Limited

---

Gordon Weakliem -- gweakl@metronet.com
Sunday, October 27, 1996

At 12:13 PM 10/24/96 +1000, you wrote:
>
>Environment: NT 3.51, VC++ 1.52
>
>I want to use a dialog box as a main window with MFC.
>I can do this sucessfully by using:
>
>class CT1Dlg: public CDialog
>{
>public:
>	CT1Dlg();
>
>protected:
>	virtual void PostNcDestroy();
>
>	afx_msg void OnQuitClicked();
>	DECLARE_MESSAGE_MAP()
>};	

>The problem is that I want the user to be able
>to minimize the dialog. Unfortunately I cannot
>get the dialog to use MY icon, it just uses
>a default white box.

You haven't overriden CDialog::OnPaint(), e.g.
void CT1Dlg::OnPaint() 
{
	if (IsIconic())
	{
		CPaintDC dc(this); // device context for painting

		SendMessage(WM_ICONERASEBKGND, (WPARAM) dc.GetSafeHdc(), 0);

		// Center icon in client rectangle
		int cxIcon = GetSystemMetrics(SM_CXICON);
		int cyIcon = GetSystemMetrics(SM_CYICON);
		CRect rect;
		GetClientRect(&rect);
		int x = (rect.Width() - cxIcon + 1) / 2;
		int y = (rect.Height() - cyIcon + 1) / 2;

		// Draw the icon
		dc.DrawIcon(x, y, m_hIcon);
	}
	else
	{
		CDialog::OnPaint();
	}
}
Gordon Weakliem
gweakl@metronet.com
http://www.metronet.com/~gweakl

---

Dong Chen -- d_chen@ix.netcom.com
Monday, October 28, 1996

[Mini-digest: 4 responses]

I wrote a dialog based application under NT 3.51 a while ago (VC++ 2.x),
what I did was slight different. I loaded the Icon in the constructor. In
OnPaint(), I checked if the app is iconic, if so, I draw the icon. Also, I
used OnQueryDragIcon() to handle the situation when the user drags the
iconic app.
Please post it if you got any better solution.
--
Dong

-----From: Ian Pepper 

Hi Doran,

You need to add the following to your ctor

	m_hIcon = AfxGetApp()->LoadIcon(IDR_MAINFRAME);
where m_hIcon is declared in your class as HICON and handle the WM_PAINT
and WM_QUERYDRAGICON messages thus:

void CT1Dlg::OnPaint()
{
	if (IsIconic())
	{
		CPaintDC dc(this); // device context for painting

		SendMessage(WM_ICONERASEBKGND, (WPARAM)dc.GetSafeHdc(), 0);

		// Center icon in client rectangle
		int cxIcon = GetSystemMetrics(SM_CXICON);
		int cyIcon = GetSystemMetrics(SM_CYICON);

		CRect rect;
		GetClientRect(&rect);

		// Draw the icon
		dc.DrawIcon((rect.Width() - cxIcon + 1) / 2, (rect.Height() - cyIcon +
1) / 2, m_hIcon);
	}
	else
		CDialog::OnPaint();
}

HCURSOR CT1Dlg::OnQueryDragIcon()
{
	return (HCURSOR)m_hIcon; // use the icon as cursor when dragging
minimized window
}

Ian
ian@flexicom.ie

-----From: tstewa00 

Hi Gordon,
 I had the same problem a while back.  I found the answer on the Stingray MFC 
FAQ.

They suggest the following:

// Create your Dialog
m_pMainWnd = new CMainDialog();


#if(_MFC_VER >= 0x0300)
    SetClassLong(m_pMainWnd->m_hWnd,GCL_HICON,
  (LONG)LoadIcon(IDC_ICONDIALOGAPP)); // Load your icon
#else
 SetClassWord(m_pMainWnd->m_hWnd,GCW_HICON,
  (WORD)LoadIcon(IDC_ICONDIALOGAPP)); // Load your icon
#endif

m_pMainWnd->ShowWindow(m_nCmdShow);


Short and sweet!

[Moderator's note: Short and sweet, but I think it's wrong.  It is
very dangerous to set the icon for a class - all windows in the
class, whether they are part of your thread or not, will get the same
icon.]

-----From: Dave_Rabbers@Quinton-Eng.CCMAIL.CompuServe.COM

     Refer to MS knowledge base article Q87976 for sample code.

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