PageCounter Object for ScrollViews

Environment: The demo project was created with VC++ 6.0 SP1

When scrolling in a document that consists of quite a lot pages it might be helpful for the user to get an information which page of the document would be displayed if he/she >would release to slider of the scrollbar at a certain position.
Microsoft Word has such a feature. It's a tooltip-like window that displays the page number that corresponds to the current position of the slider during scrolling.

I implemented a class named CScrollViewPageCounter that displays such a page number in a window that looks like a tooltip-window. If you have a look at the source code you'll find out that it was quite easy to implement. The code itself is self-explanatory...

HOW TO USE

To use the ScrollViewPageCounter-Object you have to perform the following steps:

1. Add the files ScrollViewPageCounter.h and ScrollViewPageCounter.cpp to your project.

2. Add a new member m_pScrollViewPageCounter to your scroll view class.

 
CScrollViewPageCounter*
m_pScrollViewPageCounter;
Of course your have to include the corresponding header file here as well:

 #include "ScrollViewPageCounter.h"

3. Create the page counter object in CYourScrollView::OnInitialUpdate()

 
BOOL CYourScrollView::PreCreateWindow(CREATESTRUCT& cs)
{
 CScrollView::OnInitialUpdate();

 // Instantiate the counter object
 m_pScrollViewPageCounter = new CScrollViewPageCounter( this );
 }

4. Add a command handler for the message WM_VSCROLL:

 void CYourScrollView::OnVScroll(UINT SBCode, UINT nPos, CScrollBar* pScrollBar) 
{
 if ( nSBCode == SB_THUMBTRACK )
 {
  // calculate page number (insert your algorithm here)
 UINT uiPageNumber = (UINT) (nPos / 10) + 1;

  // display page number 
  m_pScrollViewPageCounter->DisplayPageNumber( uiPageNumber );
 }

 // when scrolling is finished we have to hide the page counter
 if ( nSBCode == SB_ENDSCROLL )
 m_pScrollViewPageCounter->Reset();
 
 CScrollView::OnVScroll(nSBCode, nPos, pScrollBar);
}
That's it.
Now compile and enjoy...

Download demo project - 33 KB

Download source - 3 KB

Date Last Updated: April 16, 1999



Comments

  • nPos only goes up to 32K

    Posted by wadigzon on 03/04/2004 10:00pm

    you've gotta use something like these in order to handle positions beyond 32K at ::OnVScroll(...) function.
    
    SCROLLINFO si;
    ZeroMemory(&si, sizeof(SCROLLINFO));
    si.cbSize = sizeof(SCROLLINFO);
    // Call GetScrollInfo to get current tracking 
    // position in si.nTrackPos
    if (!GetScrollInfo(SB_VERT, &si) )
    {
     return ; // GetScrollInfo failed
    }
    
    // this is the Page number
    UINT uiPageNumber = (UINT)(si.nTrackPos/10)+1;

    Reply
  • Thank you.

    Posted by Legacy on 12/08/2003 12:00am

    Originally posted by: NANA

    Great. This is exactly I was looking for. I had to integrate this to CListCtrl and it works great. Thank you.

    Reply
  • It looks nicer like this:

    Posted by Legacy on 06/21/1999 12:00am

    Originally posted by: Bruno Vais

    I think it looks nicer if the yellow thing moves aside the mouse. So delete the "s_bFirstCallDuringScrolling" member.
    Also, during scrolling the main view loses focus (of course). To avoid showing that dumb grey caption, at the end of your "DisplayPageNumber" function call
    "AfxGetMainWnd()->SendMessage(WM_NCACTIVATE,TRUE,0);".

    Reply
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