I was developing an application that used the calendar control and needed to control the behavior of the splitter window that contained the calendar control so I thought I would create a splitter window that supported a snap-to behavior.
My original decision led me astray as I tried to reimplement the entire
CSplitterWindow as a new class, when it hit me, just override the
OnMouseMove method. So this is where we stand. Its a simple change to the code but I thought it would be an interesting contribution so I decided to wrap it up and submit it to CodeProject.
Using the code
The code is very easy and straightforward to use. You use it just like the
CSplitterWindow class but there is one additional method
SetSnapSize that controls how big a snap to perform. The code takes care of whether you are using a vertical splitter or a horizontal splitter.
The "biggest" change to the class was a few lines of code that were added to the
CSnapSplitterWindow class that derives from
CSplitterWindow. In the
OnSize method the following code was added to support the snap-to place. The variable
m_nSnapSize holds the size that the programmer wants the window to snap-to. During a mouse move I determine if the new position of the splitter is greater than 1/2 the snap size and if it is, I adjust the splitter to the next snap position. This is a simple operation but is really the "meat" of the code.
if( static_cast<UINT>(abs( xyNewSplitPos - m_xySplitterPos )) >
( m_nSnapSize / 2 ))
if( xyNewSplitPos < m_xySplitterPos )
xyNewSplitPos = m_xySplitterPos - m_nSnapSize;
xyNewSplitPos = m_xySplitterPos + m_nSnapSize;
xyNewSplitPos = m_xySplitterPos;
To use the code declare a variable of
CSnapSplitterWindow if you want a vertical splitter that snaps on left and right movements or use
CHorSnapSplitterWindow to create a horizontal splitter that snaps on up and down movements. The following code would be placed in your
CMainFrame class in the
class CMainFrame : public CFrameWindowImpl<CMainFrame>,
public CMessageFilter, public CIdleHandler
LRESULT OnCreate(UINT , WPARAM ,
LPARAM , BOOL& )
m_hWndClient = m_splitterContent.Create( m_hWnd, rcDefault,
NULL, WS_CHILD | WS_VISIBLE );
m_splitterContent.SetSnapSize( 75 );
Points of Interest
It wasn't very hard to write this class once I got over my initial attempt to try to rewrite the entire
CSplitterWindow class but the one problem that I had was using the
CMonthCalendarCtrl class. I made the call to
GetMinReqRect expecting to get the minimum size the control needs to display itself. Thinking that the minimum size would be all that is required to set the snap size for both horizontal and vertical I used it but I noticed that the control wouldn't display another month in the display. So I had to play around with some different height and width adjustments before I found some values that were the smallest possible and still allow the control to behave as expected when it snapped to a larger size.
|1.0 - 14 Feb 2003||First release version.|