Advanced MFC Programming

Chapter 3. Splitter Window
}
}
}
RecalcLayout();
Since the maximum number of rows that can be implemented in a dynamic split window is 2, we will
call the default implementation of this function (the corresponding function of the base class) if the number
of rows is not 2. Otherwise, we first obtain the size of upper pane (pane 0), enlarge its vertical size, and set
its current size. Then the current size of lower pane is reduced, if its ideal size is smaller than its minimum
size after change, we simply call function CSplitterWnd::DeleteRow(…) to delete this row. If the panes are
resized instead of being deleted, we call function CSplitterWnd::RecalcLayout() to update the new
layout.
Function MCSplitterWnd::DeleteColumn(int colDelete) is implemented in the same way, except
that here we call all the functions dealing with column instead of row.
Using the New Class
Using this new class is simple, we just need to include the header file containing class MCSplitterWnd
in file “MainFrm.h”, then use it to declare variable m_wndSpw in class CMainFrame as follows:
……
class CMainFrame : public CFrameWnd
{
protected:
CMainFrame();
DECLARE_DYNCREATE(CMainFrame)
MCSplitterWnd m_wndSp;
}
After these changes, by compiling and executing the application again, we will see that the split bar
behaves differently.
3.4 Customizing the Default Appearance
Drawing Functions
Class CSplitterWnd has two member functions that can be overridden to customize the appearance of
split bar, split box, split border, and split tracker. The functions are CSplitterWnd::OnDrawSplitter(…)
and CSplitter::OnInvertTracker(…) respectively, which have the following formats:
void CSplitterWnd::OnDrawSplitter(CDC *pDC, ESplitType nType, const CRect &rect);
void CSplitterWnd::OnInvertTracker(const CRect &rect);
Function CSplitterWnd::OnDrawSplitter(…) is called when either the split bar, split box or split
border needs to be painted. It has three parameters, the first of which is a pointer to the target device DC,
which will be used to draw the objects. The second parameter is an enumerate type, which indicates what
type of object is being drawn. This parameter could be either CSplitterWnd::splitBox, CSplitterWnd::
splitBar, or CSplitterWnd::splitBorder, which indicates different splitter window objects. The third
parameter specifies a rectangle region within which the object will be drawn.
Function CSplitterWnd::OnInvertTracker(…) is called when the user clicks the mouse on the split
bar and drags it to resize the panes contained in the splitter window. In this case, a tracker will appear on
the screen and move with the mouse. By default, the tracker is a grayed line. By overriding this function,
we could let the tracker have a different appearance.
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