Yes, it's yet another splitter window class. So why I release a new class, when there are plenty of similar classes? The answer is simple. All splitter window classes at CodeProject can be IMHO divided into two parts:
- These derived from original MFC
CSplitterWnd. They look nice and give a lot of advantages to classical
CSplitterWnd, but deriving from
CSplitterWnd restrict you to use only
CView-derived windows in it.
- The others, which I can use in various windows - but when I compiled and tested them, they didn't look as pretty as the
In this article, I offer a class, which is not derived from
CSplitterWnd. It allows you to use simple
CWnd-derived windows. But it's combined with professional looking of the original
CSplitterWnd. Some routines I took from MFC source code. Please be forbearing while reading this article. It's my first article at CodeProject :).
My goal in
CSimpleSplitterWnd design was to simulate the basic features of
CSplitterWnd. With this class, you can make several panes arranged either horizontally or vertically. It doesn't offer automatic splitting, shared scroll bars and intersection trackers. I didn't find it very useful - but if there are enough people, who did, I can add some of these features. :) The idea of
CSimpleSplitter (compared to
CSplitterWnd) is that pane windows are independent of each other, hence they are also responsible for their scrolling and borders.
Using the Code
The layout of splitter is set in constructor:
CSimpleSplitter(int nPanes, UINT nOrientation = SSP_HORZ,
int nMinSize = 30, int nBarThickness = 3);
nPanes is number of the panes,
nOrientation should be either
nMinSize is the minimal height (or width) of any pane - it is important in recalculating layout algorithm, when you resize the splitter.
nBarThickness is height or width of bars between panes. All of these properties remain fixed during lifetime of the splitter instance. The creation of splitter and its panes is straightforward:
BOOL Create(CWnd* pParent, UINT nID = AFX_IDW_PANE_FIRST);
BOOL CreatePane(int nIndex, CWnd* pPaneWnd, DWORD dwStyle,
DWORD dwExStyle, LPCTSTR lpszClassName = NULL);
Panes are indexed from
nPanes - 1. The parameters
lpszClassName are passed to
pPaneWnd->CreateEx() (If you want to bind a created window with a pane, use
SetPane instead). You can specify for example the borders of panes there. In demo app, the "large" panes have a
WS_EX_CLIENTEDGE extended style, while the three "flat" panes have
WS_EX_STATICEDGE extended style. The splitter bar alone is only a gray rectangle, so if you don't specify any edge and set the gray background to pane windows, you can use the splitter in dialogs too.
The following five methods are analogous to
CSplitterWnd methods, so they don't require a special documentation.
int GetPaneCount() const;void SetPane(int nIndex, CWnd* pPaneWnd);
CWnd* GetPane(int nIndex) const;
virtual void SetActivePane(int nIndex);
CWnd* GetActivePane(int* pIndex) const;
However, setting the pane widths or heights uses different technique:
void SetPaneSizes(const int* sizes);
You pass an array of
nPanes integers. They specify relative sizes of panes. You can use any scale, the panes are resized proportionally to the sum of the array members. When you resize the whole splitter, the sizes of panes are changed proportionally to their actual sizes. If necessary, they're adjusted to
void GetPaneRect(int nIndex, CRect& rcPane) const;
void GetBarRect(int nIndex, CRect& rcBar) const;
With these functions, you can retrieve the position of panes in splitter client coordinates. Bars are indexed from
nPanes - 1.
And that's all. Look at the
SimpleSplitterApp demo, especially the
CMainFrame::OnCreate code, you will know everything!
Points of Interest
When I programmed the splitter, I was confused, how the framework redraws resized window. If you resize the top or left border, the framework first only move the window content in corresponding direction, and then it calls
OnPaint(). So the window was redrawn twice and in the splitter this looked ugly.
Fortunately, there is a message handler
CWnd::OnWindowPosChanging. You can avoid the initial moving of content, if you see
SWP_NOCOPYBITS as you see in
CChildWnd code. I think that this is useful in many other cases that splitters.
- 11. 2. 2004 - First version released
- 24. 3. 2004 - Some bugs fixed (see the messages below). In the
SetPaneSizes function, now you should pass only relative sizes, not absolute.
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