Re: How to put limits on frame resizing when using splitter window?

"AliR \(VC++ MVP\)" <AliR@online.nospam>
Thu, 7 Aug 2008 14:13:50 -0500
Sorry I totally misunderstood the question. You explained it well, I just
didn't read it right.

Catch the WM_SIZING message and set the right panels size in response to
that message.

I believe there is even an example of doing that in the OnSizing methods

void CMainFrame::OnSizing(UINT fwSide, LPRECT pRect)
   CMDIChildWnd::OnSizing(fwSide, pRect);

   // Resize the splitter window in the frame. m_wndSplitter is of
   // type CSplitterWnd
   int nWidth = (pRect->right) - (pRect->left);
   m_wndSplitter.SetColumnInfo(0, nWidth / 2, 10);
   m_wndSplitter.SetColumnInfo(1, nWidth / 2, 10);


"Bogdan" <> wrote in message


Thanks for the reply. I don't think I was as clear as I should've been in
my original post. I'm OK with controlling pane sizes while splitter bar
is being dragged. The problem is that I do not know how to limit the size
of the right pane (and therefore the main frame) when the main frame is
being resized by a user (e.g. by dragging frame borders). In other words,
I'd like a user to resize the frame window only to a point where the right
pane (scroll view) of the splitter reaches its max size in either

I think I need two things to accomplish this:
1) find a way to cap the main frame size so a user cannot increase it
beyond a given max size
2) know how to calculate the main frame size based on the max size of the
right pane

Any thoughts?

"AliR (VC++ MVP)" <AliR@online.nospam> wrote in message

As far as I know, you will have to override the WM_MOUSEMOVE message and
do your limiting there.
Basically what you will have to do is copy the content of
CSplitterWnd::OnMouseMove into your CSplitterWnd::OnMouseMove method and
limit the size when the size is being set.

For example this code will limit the left hand panel of the splitter to
400 pixels. (this code is for demonstration purposes. There is no error
checking and It assumes that the pane's initial size is less than 400)

void CLockSplitterWnd::OnMouseMove(UINT nFlags, CPoint pt)
enum HitTestValue
noHit = 0,
vSplitterBox = 1,
hSplitterBox = 2,
bothSplitterBox = 3, // just for keyboard
vSplitterBar1 = 101,
vSplitterBar15 = 115,
hSplitterBar1 = 201,
hSplitterBar15 = 215,
splitterIntersection1 = 301,
splitterIntersection225 = 525

  if (GetCapture() != this)

if (m_bTracking)
 // move tracker to current cursor position

 pt.Offset(m_ptTrackOffset); // pt is the upper right of hit detect
 // limit the point to the valid split range
 if (pt.y <
  pt.y =;
 else if (pt.y > m_rectLimit.bottom)
  pt.y = m_rectLimit.bottom;
 if (pt.x < m_rectLimit.left)
  pt.x = m_rectLimit.left;
 else if (pt.x > m_rectLimit.right)
  pt.x = m_rectLimit.right;

 if (m_htTrack == vSplitterBox ||
  m_htTrack >= vSplitterBar1 && m_htTrack <= vSplitterBar15)
  if ( != pt.y)
   m_rectTracker.OffsetRect(0, pt.y -;
 else if (m_htTrack == hSplitterBox ||
  m_htTrack >= hSplitterBar1 && m_htTrack <= hSplitterBar15)
  if (m_rectTracker.left != pt.x)
   //if the pane is getting smaller or getting bigger and the size is
less then 400 then proceed
   if (m_rectTracker.left > pt.x || (m_rectTracker.left < pt.x && pt.x <
    m_rectTracker.OffsetRect(pt.x - m_rectTracker.left, 0);
 else if (m_htTrack == bothSplitterBox ||
    (m_htTrack >= splitterIntersection1 &&
  m_htTrack <= splitterIntersection225))
  if ( != pt.y)
   m_rectTracker.OffsetRect(0, pt.y -;
  if (m_rectTracker2.left != pt.x)
   m_rectTracker2.OffsetRect(pt.x - m_rectTracker2.left, 0);
 // simply hit-test and set appropriate cursor

 int ht = HitTest(pt);


"Bogdan" <> wrote in message


I have a static splitter window in SDI. The right pane of the splitter
is a CScrollView. The main frame is resizable.
How do I prevent a user from resizing the frame so the right pane does
not go beyond a given size?. The left pane's size is not important.

I keep the frame size in check on splitter bar drag by calling
ResizeParentToFit(TRUE) .


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