Event when a particular Slider is changed - visual-c++

Question

I am writing a C++ MFC Dialog based Application and my program has lots of sliders. I want the program to call a function depending on which Slider is being changed by the user. I tried using GetPos() but not much success so far. Any easier way of doing this?
Message Map:
BEGIN_MESSAGE_MAP(CSerialPortDlg, CDialog)
ON_WM_SYSCOMMAND()
ON_WM_PAINT()
ON_WM_QUERYDRAGICON()
//}}AFX_MSG_MAP
//ON_BN_CLICKED(IDC_BUTTON1, OnBnClickedButton1)
ON_BN_CLICKED(IDC_READ_COMM, OnBnClickedReadComm)
ON_WM_CLOSE()
ON_BN_CLICKED(IDC_WRITE, OnBnClickedWrite)
//ON_CBN_SELCHANGE(IDC_SENSORS, OnCbnSelchangeSensors)
//ON_CBN_SELCHANGE(IDC_SENSOR_LIST, OnCbnSelchangeSensorList)
ON_BN_CLICKED(IDC_GO, OnGo)
ON_WM_TIMER()
ON_BN_CLICKED(IDC_KILL_TIMER, OnBnClickedKillTimer)
ON_BN_CLICKED(IDC_READ_TIMER, OnBnClickedReadTimer)
ON_BN_CLICKED(IDC_WRITE_COMM, OnBnClickedWriteComm)
ON_BN_CLICKED(IDC_TERMINATE, OnBnClickedTerminate)
ON_BN_CLICKED(IDC_RUN, OnBnClickedRun)
ON_CONTROL(NM_CLICK,IDC_BOOM_SLIDER, Write_Boom)
ON_CONTROL(NM_CLICK,IDC_PITCH_SLIDER, Write_Pitch)
END_MESSAGE_MAP()
...

Answer 1

Slider controls send WM_HSCROLL or WM_VSCROLL notifications when they are scrolled, horizontally or vertically. Catch them in your dialog and there you can call your desired function, depending on who sent the notification.
BEGIN_MESSAGE_MAP(CMyDlg, CDialog)
//...
ON_WM_HSCROLL()
//...
END_MESSAGE_MAP()
//////////////////////////
// nSBCode: The operation performed on the slider
// nPos: New position of the slider
// pScrollBar: The scrollbar (slider ctrl in this case) that sent the notification
void CMyDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
CSliderCtrl* pSlider = reinterpret_cast<CSliderCtrl*>(pScrollBar);
// Check which slider sent the notification
if (pSlider == &c_Slider1)
{
}
else if (pSlider == &c_Slider2)
{
}
// Check what happened
switch(nSBCode)
{
case TB_LINEUP:
case TB_LINEDOWN:
case TB_PAGEUP:
case TB_PAGEDOWN:
case TB_THUMBPOSITION:
case TB_TOP:
case TB_BOTTOM:
case TB_THUMBTRACK:
case TB_ENDTRACK:
default:
break;
}
//...
}
`

Answer 2

BEGIN_MESSAGE_MAP(CMyDlg, CDialog)
//...
ON_WM_HSCROLL()
//...
END_MESSAGE_MAP()
void CMyDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar)
{
CSliderCtrl *ACSliderCtrl = (CSliderCtrl *)pScrollBar;
int nID = ACSliderCtrl->GetDlgCtrlID();
int NewPos = ((CSliderCtrl *)pScrollBar)->GetPos();
CWnd *ACWnd = GetDlgItem(nID);
switch (nID)
{
default:
break;
case IDC_SLIDER1:
m_edit1.Format( "%d", NewPos );
UpdateData(FALSE);
break;
}
CDialog::OnHScroll(nSBCode, nPos, pScrollBar);
}

Answer 3

I figured it out, I think. What you call a slider is commonly called a "Scrollbar". You're probably looking for the WM_VSCROLL message. As noted there, "lParam: If the message is sent by a scroll bar, this parameter is the handle to the scroll bar control."
See also CWnd::OnVScroll

Answer 4

You do have different ON_CONTROL macro's for the different controls? Because it's then just a matter of specifying different methods as the third argument to ON_CONTROL