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CWnd::SendMessage

Sends the specified message to this window.

LRESULT SendMessage(
   UINT message,
   WPARAM wParam = 0,
   LPARAM lParam = 0 
);

Parameters

message
Specifies the message to be sent.
wParam
Specifies additional message-dependent information.
lParam
Specifies additional message-dependent information.

Return Value

The result of the message processing; its value depends on the message sent.

Remarks

The SendMessage member function calls the window procedure directly and does not return until that window procedure has processed the message. This is in contrast to the PostMessage member function, which places the message into the window's message queue and returns immediately.

Example

// In a dialog-based app, if you add a minimize button to your 
// dialog, you will need the code below to draw the icon.
void CMyDlg::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 represented by handle m_hIcon
      dc.DrawIcon(x, y, m_hIcon);
   }
   else
   {
      CDialog::OnPaint();
   }
}

See Also

CWnd Overview | Class Members | Hierarchy Chart | InSendMessage | CWnd::PostMessage | CWnd::SendDlgItemMessage | SendMessage

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