Automatically Center the Controls in CFormView



Click here for larger image

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
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • The rapid evolution of enterprise storage technologies, combined with external forces, like the explosion of big data, can cause Linux® and server administrators to play catch-up when it comes to storage. Running a bunch of monolithic storage devices and proprietary, disconnected technologies forces administrators to spend valuable time creating and managing complex solutions. To reduce complexity and enable rapid deployment of new technologies and applications, server administrators need a single open …

  • When it comes to desktops – physical or virtual – it's all about the applications. Cloud-hosted virtual desktops are growing fast because you get local data center-class security and 24x7 access with the complete personalization and flexibility of your own desktop. Organizations make five common mistakes when it comes to planning and implementing their application management strategy. This eBook tells you what they are and how to avoid them, and offers real-life case studies on customers who didn't …

Most Popular Programming Stories

More for Developers

Latest Developer Headlines

RSS Feeds