MFC - Slider Controls

A Slider Control (also known as a trackbar) is a window containing a slider and optional tick marks. When the user moves the slider, using either the mouse or the direction keys, the control sends notification messages to indicate the change. There are two types of sliders — horizontal and vertical. It is represented by CSliderCtrl class.

Here is the list of methods in CSliderCtrl class.

Sr.No.	Name & Description
1	ClearSel Clears the current selection in a slider control.
2	ClearTics Removes the current tick marks from a slider control.
3	Create Creates a slider control and attaches it to a CSliderCtrl object.
4	CreateEx Creates a slider control with the specified Windows extended styles and attaches it to a CSliderCtrl object.
5	GetBuddy Retrieves the handle to a slider control buddy window at a given location.
6	GetChannelRect Retrieves the size of the slider control's channel.
7	GetLineSize Retrieves the line size of a slider control.
8	GetNumTics Retrieves the number of tick marks in a slider control.
9	GetPageSize Retrieves the page size of a slider control.
10	GetPos Retrieves the current position of the slider.
11	GetRange Retrieves the minimum and maximum positions for a slider.
12	GetRangeMax Retrieves the maximum position for a slider.
13.	GetRangeMin Retrieves the minimum position for a slider.
14	GetSelection Retrieves the range of the current selection.
15	GetThumbLength Retrieves the length of the slider in the current trackbar control.
16	GetThumbRect Retrieves the size of the slider control's thumb.
17	GetTic Retrieves the position of the specified tick mark.
18	GetTicArray Retrieves the array of tick mark positions for a slider control.
19	GetTicPos Retrieves the position of the specified tick mark, in client coordinates.
20	GetToolTips Retrieves the handle to the tooltip control assigned to the slider control, if any.
21	SetBuddy Assigns a window as the buddy window for a slider control.
22	SetLineSize Sets the line size of a slider control.
23	SetPageSize Sets the page size of a slider control.
24	SetPos Sets the current position of the slider.
25	SetRange Sets the minimum and maximum positions for a slider.
26	SetRangeMax Sets the maximum position for a slider.
27	SetRangeMin Sets the minimum position for a slider.
28	SetSelection Sets the range of the current selection.
29	SetThumbLength Sets the length of the slider in the current trackbar control.
30	SetTic Sets the position of the specified tick mark.
31	SetTicFreq Sets the frequency of tick marks per slider control increment.
32	SetTipSide Positions a tooltip control used by a trackbar control.
33	SetToolTips Assigns a tooltip control to a slider control.

Let us look into a simple example by creating a new MFC dialog based project.

Step 1 − Once the project is created you will see the TODO line which is the Caption of Text Control. Remove the Caption and set its ID to IDC_STATIC_TXT.

Step 2 − Add a value variable m_strSliderVal for the Static Text control.

Step 3 − Drag the slider control from the Toolbox.

Step 4 − Add a control variable m_sliderCtrl for slider.

Step 5 − Go to the class view in solution.

Step 6 − Select the CMFCSliderControlDlg class.

Step 7 − In the Properties window, click Messages.

Step 8 − Scroll down to "WM_HSCROLL" and click on the drop-down menu. Click "<Add> OnHScroll".

Step 9 − Initialize the Slider and Static Text control inside the OnInitDialog() function.

BOOL CMFCSliderControlDlg::OnInitDialog() {
   CDialogEx::OnInitDialog();
  
   // Set the icon for this dialog. The framework does this automatically
   // when the application's main window is not a dialog
   SetIcon(m_hIcon, TRUE);            // Set big icon
   SetIcon(m_hIcon, FALSE);            // Set small icon

   // TODO: Add extra initialization here
   m_sliderCtrl.SetRange(0, 100, TRUE);
   m_sliderCtrl.SetPos(0);
   m_strSliderVal.Format(_T("%d"), 0);

   return TRUE; // return TRUE unless you set the focus to a control
}

Step 10 − Add the following code inside the function code block for OnVScroll()

void CMFCSliderControlDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar) {
   // TODO: Add your message handler code here and/or call default
   if (pScrollBar == (CScrollBar *)&m_sliderCtrl) {
      int value = m_sliderCtrl.GetPos();
      m_strSliderVal.Format(_T("%d"), value);
      UpdateData(FALSE);
   }else {
      CDialog::OnHScroll(nSBCode, nPos, pScrollBar);
   }
}

Step 11 − When the above code is compiled and executed, you will see the following output.

mfc_windows_controls.htm