Automatically Center the Controls in CFormView



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Environment: VC6

For a CFormView application, when the form size is changed, the margins around the controls in the form may appear to be unbalanced. When the form application is used on very different monitor resolutions, the same problem also appear. To make the controls automatically centralize while the form is resizing, the following procedure can be used:

  1. Put an invisible group box around all the controls in the form (make sure the tab order of the group box is the last).
  2. Add the handler for the message WM_SIZE (using the class wizard) OnSize(UINT nType, int cx, int cy) to the form view.
  3. Use the following code to the OnSize function:
void myFormView::OnSize(UINT nType, int cx, int cy) 
{
  CFormView::OnSize(nType, cx, cy);
  
  // Don't adjust position when scrollbars appear.
  if ((GetScrollPos(SB_HORZ) != 0) || (GetScrollPos(SB_VERT) != 0))
  {
    return;
  }

  int   topMargin = 20, leftMargin = 20;
  CRect rectView, rectTotal;
  this  GetWindowRect(&rectView);

  for (CWnd *wnd = GetWindow(GW_CHILD); wnd != NULL;
    wnd = wnd->GetWindow(GW_HWNDNEXT))
  {
      CWnd *pWnd = GetDlgItem(IDC_TOTAL_RECT);
      pWnd->GetWindowRect(&rectTotal);

      CRect rect;
      int xPos, yPos;
      wnd->GetWindowRect(&rect);
      if(rectView.Width()>(rectTotal.Width() + 2*leftMargin))
      {
        xPos = (rectView.Width() - rectTotal.Width())/2;
      } 
      else 
      {
        xPos = leftMargin;
      }

      if(rectView.Height()>(rectTotal.Height() + 2*topMargin))
      {
        yPos = (rectView.Height() - rectTotal.Height())/2;
      }
      else 
      {
        yPos = topMargin;
      }
      wnd->MoveWindow(xPos + rect.left - rectTotal.left, 
        yPos + rect.top - rectTotal.top, 
        rect.Width(), rect.Height(), TRUE);
    }
}

Downloads

Download source & demo project - 50 Kb


Comments

  • Very nice! But the group box is not needed if you add this...

    Posted by Legacy on 12/16/2003 12:00am

    Originally posted by: Cristina Ca�ero

    I found your article very, very useful! Thank you so much!
    
    

    However, I had a lot of forms in my application, and I
    didn't wanted to add a group box to each of them, and fix
    the tab order (I am a very lazy person)

    Instead, I added this to your code:


    // Auto-detects the limits
    bool first = true;
    for (CWnd *pWnd = GetWindow(GW_CHILD); pWnd != NULL; pWnd = pWnd->GetWindow(GW_HWNDNEXT)) {
    CRect rect;

    pWnd->GetWindowRect(&rect);

    if (first) {
    rectTotal.bottom = rect.bottom;
    rectTotal.top = rect.top;
    rectTotal.right = rect.right;
    rectTotal.left = rect.left;
    first = false;
    } else {
    rectTotal.bottom = max(rectTotal.bottom,rect.bottom);
    rectTotal.top = min(rectTotal.top,rect.top);
    rectTotal.right = max(rectTotal.right,rect.right);
    rectTotal.left = min(rectTotal.left,rect.left);
    }
    }


    And hence, I commented this part of your code...


    for (CWnd *wnd = GetWindow(GW_CHILD); wnd != NULL;
    wnd = wnd->GetWindow(GW_HWNDNEXT)) {
    //CWnd *pWnd = GetDlgItem(IDC_TOTAL_RECT);
    //pWnd->GetWindowRect(&rectTotal);

    CRect rect;
    int xPos, yPos;

    Reply
  • Great idea! - Slight optimization

    Posted by Legacy on 09/26/2001 12:00am

    Originally posted by: Mike Petry

    The code would run faster (and be easier to understand)if the rectangle of IDC_TOTAL_RECT is obtained once, before entering the for loop.

    Reply
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