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Re: Scrollbar set up

From:
=?Utf-8?B?RXJha2lz?= <Erakis@discussions.microsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Mon, 15 Sep 2008 08:38:09 -0700
Message-ID:
<16ECC7A8-0A73-412E-B02D-560F205CCFDA@microsoft.com>
Yes... I finally found that nMax was the total number -1 of item available in
my list. -1 because we starting at zeo base index. And nPage it the (heigh of
client divied by height of one item).

This is not well explain on MSDN ! And their exemple of how scroll text
doesn't works.

But I thank you very much AliR :)

Regards,
Martin

"AliR (VC++ MVP)" wrote:

My Bad, I don't know why I was thinking that you have to subtract the number
of visible items from the nMax.

if ( m_iRowCount * rowRect.Height() > rectZoneVisible.Height() -
colRect.Height() )
{
   // Show vertical scroll bar
   SCROLLINFO si;
   si.cbSize = sizeof(SCROLLINFO);
   si.fMask = SIF_ALL;
   si.nPos = m_ScrollBarHiddenV.GetScrollPos();
   si.nMin = 0;
   int iVisibleItem = (rectZoneVisible.Height() - colRect.Height()) /
rowRect.Height();
   si.nMax = m_iRowCount;
   si.nPage = iVisibleItem;
   si.nTrackPos = 0;
   m_ScrollBarHiddenV.SetScrollInfo( &si, TRUE );
   ...
}

One more thing, I thought you are using MFC, you really shouldn't take over
WndProc in an MFC application, only under rare circumstances you would do
that. You should use the message map to catch your messages.

AliR.

"Erakis" <Erakis@discussions.microsoft.com> wrote in message
news:1BBDCB11-01C0-4A80-849B-018333072C87@microsoft.com...

For sure, here is the code of my WndProc :

SCROLLINFO si;
switch(message)
{
  case WM_VSCROLL :
  {
      m_ScrollBarHiddenV.GetScrollInfo(&si);

      switch( LOWORD(wParam) )
      {
          case SB_TOP :
               si.nPos = si.nMin;
          break;

          case SB_BOTTOM: //Scrolls to the lower right.
               si.nPos = si.nMax;
          break;

          case SB_ENDSCROLL: //Ends scroll.
          break;

          case SB_LINEDOWN: //Scrolls one line down.
               si.nPos = si.nPos + 1;
          break;

          case SB_LINEUP: //Scrolls one line up.
               si.nPos = si.nPos - 1;
          break;

          case SB_PAGEDOWN: //Scrolls one page down.
               si.nPos = si.nPos + si.nPage;
          break;

          case SB_PAGEUP: //Scrolls one page up.
               si.nPos = si.nPos - si.nPage;
          break;

          case SB_THUMBPOSITION:
          break;

          case SB_THUMBTRACK:
               si.nPos = si.nTrackPos;
          break;
       }

       m_ScrollBarHiddenV.SetScrollPos( si.nPos, TRUE );
   }
   break;

   case WM_HSCROLL :
   ...
   break;
}

return CWnd::WindowProc(message, wParam, lParam);

"AliR (VC++ MVP)" wrote:

Can you post your OnVScroll method?

AliR.

"Erakis" <Erakis@discussions.microsoft.com> wrote in message
news:756AC4FA-F244-4142-B15D-3B02A9C7451E@microsoft.com...

Hi,

When setting nPage value to number of item visible per page I got a
very
weird problem ! Here is the algo :

if ( m_iRowCount * rowRect.Height() > rectZoneVisible.Height() -
colRect.Height() )
{
  // Show vertical scroll bar
  SCROLLINFO si;
  si.cbSize = sizeof(SCROLLINFO);
  si.fMask = SIF_ALL;
  si.nPos = m_ScrollBarHiddenV.GetScrollPos();
  si.nMin = 0;
  int iVisibleItem = (rectZoneVisible.Height() - colRect.Height()) /
rowRect.Height();
  si.nMax = m_iRowCount - iVisibleItem;
  si.nPage = iVisibleItem;
  si.nTrackPos = 0;
  m_ScrollBarHiddenV.SetScrollInfo( &si, TRUE );
  ...
}

Number of item in the list (m_iRowCount) : 25
Visual client height (Zone visible) : 158px
Column height (colRect) : 19px
Row height (rowRect) : 17px

If a put break on WM_HSCROLL message and then I get scroll info of the
vertical scrollbar info here is what I get :

nMin = 0;
nMax = 17;

That make sens but when I click on the down button of the scrollbar
until
it
reach the max I get only 10 for nPos. Why I'm not able to go at 17 ???

Is there something I didn't understand ?

Regards,

"AliR (VC++ MVP)" wrote:

The number of visible items is the number of whole items that your
control
can display. Partial items need to be scrolled, so they don't count.
If
you have 8 items in your control, and it can only display 7.67 items
then
you still need to be able to scroll one item into view. So your number
of
visible items will simply be 7.

AliR.

"Erakis" <Erakis@discussions.microsoft.com> wrote in message
news:54575B87-1453-42DC-9972-02A4D18A6781@microsoft.com...

Do I have to minus the column height from my list height to
calculate
visible
item in the list ? Also tell me if it is necessary to check if a row
is
partially visible by doing modulo...

Here is what I think it could be ;

// Set nMin value
nMin = 0;

// Set nMax value
iVisibleItem = (rectZoneVisible.Height() - colRect.Height()) /
rowRect.Height();
if ((rectZoneVisible.Height() - colRect.Height()) % rowRect.Height()
!=
0)
  iVisibleItem++;
nMax = m_iRowCount - iVisibleItem;

// Set nPage value
nPage= iVisibleItem;

Best regards,
Martin

"AliR (VC++ MVP)" wrote:

nPage is the number that is passed to OnVScroll when the user pages
up
and
down, it can be anything you want, 5 is the typcial number of items
that
you
would scroll when the user pages up or down.

The list control will automatically show and hide its scrollbar
depending
on
the number of items in it, and it does it very cleanly. It sounds
like
that
is what you are trying to do. Is it not?

What the article was talking about was that if you disable the
scrollbar
of
a list control using the "No Scroll" option of the list control,
and
the
list control has enough items that would need scrolling you would
not
be
able to scroll these items. Which is true, for example if you have
a
listbox and you disable its scrollbar while there are enough items
to
scroll
up and down you can still scroll by using the keyboard or clicking
and
dragging inside the listbox. That is not the case with a list
control.
But
if you want to display a scrollbar when the user can scroll, and
hide
it
when there isn't enough items to scroll then it does that
automatically.

Now if you are doing this to get rid of the horizontal scrollbar
then
all
of
this changes, but there are ways around that, like making your last
column
be auto fit, so that it resizes itself in order to fit and not
cause a
horizontal scrollbar to show up.

AliR.

"Erakis" <Erakis@discussions.microsoft.com> wrote in message
news:29241AA6-AC8D-4D27-B7BC-22D0839677BC@microsoft.com...

I'm creating a list type control of my own, derived from CWnd.

I just wanted to confirm you that hiding scrollbar from a
CListCtrl
is
kind
of pain. Because we need to get and set rect of the list, cells
and
this
solution corrupt those information. Also we need to daw image on
specific
rows, custom headers drawing, transparent background, etc...

By the way, my own list is almost terminated and it is working. I
just
wanted to set up CORRECTLY my scrollbar and not doing it no
matter
how...

And what should be the value of nPage ?

Martin

"AliR (VC++ MVP)" wrote:

You would normally hide the scrollbar when the number of items
is
less
than
or equal to the number of visible items! What does that have to
do
with
anything.

I'm confused, your original message said that you want to setup
scrollbars
for your custom list control. Are you using a CListCtrl or are
you
creating
a list type control of your own?

The article you pointed me to shows how to cleanly remove
scrollbars
from
CListCtrl.

What does this solution does not work well with our project
really
mean?
What part of what does not work well?

m_iRowCount - 1 is not correct, m_iRowCount - NumVisible would
be
the

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