Handling notifications for dynamically created control.

Contributed by d_arin100 On 7th October, 2009

This is an article on Handling notifications for dynamically created control. in MFC.

Introduction

This article is about how we can create controls dynamically without using wizard and how to handle notification for dynamically created control. Here I will try to explain it by the notification BN_CLICKED for a button.

Working

Following three things we need to do for creating the button control dynamically.

1. Need to define a button ID in the “resource.h” file and that should be given a unique integer value.

Code: Cpp

#define IDC_BUTTON1    4652

2. Defining handler with correct signature. For this we need to add the button ID as argument to the Create() method. Suppose we are creating it in OnInitDialog().

Code: Cpp

BOOL CMyDialog::OnInitDialog()
{
    CDialog::OnInitDialog();
    /// “m_wndPushButton” is a member variable of CButton class.
    m_wndPushButton.Create (_T ("Push Button"), 
        WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON, 
        CRect(100, 100, 150, 150), 
        this, IDC_BUTTON1);
    return TRUE;   
}

Here the “CMyDialog” is a dialog class and its declaration looks like...

Code: Cpp

class CMyDialog: public CDialog   
{     // Construction     
public:        
    CMyDialog (CWnd* pParent = NULL);     // standard constructor       
protected:        
    virtual void DoDataExchange(CDataExchange* pDX);         
    DECLARE_MESSAGE_MAP()   
};

Now we need to add handler function declaration of the event within the class declaration.

Code: Cpp

afx_msg void OnButton1Clicked();

And need to define the handler function in the corresponding source file (.cpp file).

Code: Cpp

void CMyDialog :: OnButton1Clicked()
{
/////////////
}

3. The last thing we need to add an entry to the message map of the class by specifying the ID of the control and the handler function of the notification.

Code: Cpp

BEGIN_MESSAGE_MAP(CMyDialog, CDialog)
//{{AFX_MSG_MAP(CMyDialog)        
ON_BN_CLICKED(IDC_BUTTON1, OnButton1Clicked)        
//}}AFX_MSG_MAPEND_MESSAGE_MAP()