mouse button down

[Philip Nicoletti]

Actually I had a client that wanted something similar. In my
case, basically simulating a thumbwheel with a slider control.

Here is how I did it (there are probably better ways -
my MFC use is minimal and knowledge limitted). Maybe
you can adapt it to do what you want. (at any rate, with
you move the slider windows sends WM_H_SCROLL message (or
WM_V_SCROLL if vertical). Look up OnHScroll for more info.

• associate a CSliderCtrl variable with your slider control.
  (in sample code below I named it : m_xTranslation_slider)
  
• process WM_H_SCROLL for the dialog (if a horizontal slider)
  
• add additional member variables to the dialog :
  

  int m_xTranslation_old_position;  // saved position of slider control
  int m_xTranslation;               // current value of variable you are tracking

• Initialize everything in dialog's OnInitDialog()
  

  int minRange =   0;
  int maxRange = 100;
  int avgRange = (minRange+maxRange)/2;
  
  m_xTranslation_slider.SetRange(minRange,maxRange);
  m_xTranslation_slider.SetPos( avgRange );
  m_xTranslation_old_position = avgRange;
  
  m_xTranslation = 0;

• process WM_H_SCROLL for the dialog (see where I have
  the TRACE() for the updated value)
  

  void CNozzleEditorDlg::OnHScroll(UINT nSBCode, UINT nPos, CScrollBar* pScrollBar) 
  {
  
      if (pScrollBar->GetSafeHwnd() == m_xTranslation_slider.GetSafeHwnd())
      {
          int minRange , maxRange , avgRange;
          m_xTranslation_slider.GetRange(minRange,maxRange);
          avgRange = (minRange + maxRange)/2;
  
          int xTranslation_new_position = m_xTranslation_slider.GetPos();
  
          if (xTranslation_new_position != avgRange)
          {
              if (xTranslation_new_position == m_xTranslation_old_position)
              {
                  m_xTranslation_old_position = avgRange;
                  m_xTranslation_slider.SetPos(avgRange);
              }
              else
              {
                  m_xTranslation += (xTranslation_new_position - m_xTranslation_old_position);
                  m_xTranslation_old_position = xTranslation_new_position;
                  TRACE("new value for xTranslation = %d\n",m_xTranslation);
              }
          }
      }
  	
      CDialog::OnHScroll(nSBCode, nPos, pScrollBar);
  }