Wednesday, May 06, 2009

WTL frames, toolbars and headers

The WTL CFrameWindowImpl class template uses a very simple approach to manage the client, toolbar and status bar windows. The preset arrangement for these windows is very simple:
  • a client view that occupies most of the frame's client area;
  • an optional toolbar window that is placed at the top of the frame's client area and above the client view;
  • an optional status bar placed at the bottom of the frame's client area and below the client view.
The frame window already knows how to handle the three child windows. Each frame contains three member variables for them:
  • m_hWndClient for the client view;
  • m_hWndToolBar for the top toolbar window and
  • m_hWndStatusBar for bottom status bar
To make the three child windows work together you must create them and assign them to the appropriate member variable. The top and bottom windows must implement a special handling of the WM_SIZE message because this is how the frame tells each window to place itself in its client area and thus calculate the remaining area for the client view. This special message is nothing but a WM_SIZE message with both parameters (wParam and lParam) set to zero. Here's a sample from my production code:

void OnSize(UINT nType, CSize size)
if( == 0 && == 0)
CWindow wndParent(GetParent());
CRect rc;

wndParent.GetClientRect(&rc); = rc.bottom - m_cyToolbar;

Easy, huh?

No comments: