Disable clicking on selected report view columns

I have developed a short piece of code to disable clicking column headers for columns than cannot be sorted-by.

This code simply uses the customization of header control as presented in "Indicating sort order" article. I just added slight more functionality to that header control.

1. I define a prototype and a variable in a class declaration body:


public:
	typedef BOOL (*ColumnCheckF)(void *,int,LPARAM);

	void SetCallback(ColumnCheckF checkf=NULL,void * cbdata=NULL)
	{
		m_fColumnCheck=checkf;
		m_pCBData=cbdata;
	}

private:
	ColumnCheckF m_fColumnCheck;
	void *m_pCBData;

After a click in a header, I find out the column (and I try to be wise and not disable clicking to resize columns) and ask the callback if the click is allowed (TRUE returned) or not.

It means, in the header (class declaration), I add


	// handlers
	afx_msg void OnLButtonDown(UINT,CPoint);
	DECLARE_MESSAGE_MAP()

and in the .CPP I add


BEGIN_MESSAGE_MAP(CCustHeaderCtrl,CHeaderCtrl)
	ON_WM_LBUTTONDOWN()
END_MESSAGE_MAP()

void CCustHeaderCtrl::OnLButtonDown(UINT flags,CPoint pt)
{
	if (m_fColumnCheck!=NULL)
	{
		HD_ITEM hditem;
		CClientDC dc(this);
		int offset=dc.GetTextExtent(_T(" "),1).cx*2;
		int x_coord=pt.x;

		int column=0;
		hditem.mask=HDI_WIDTH;
		while (x_coord>((column==0)?0:offset))
		{
			GetItem(column,&hditem);
			if (x_coord<hditem.cxy-offset)
			{
				// falls inside - query the func
				hditem.mask=HDI_LPARAM;
				GetItem(column,&hditem);
				if (!m_fColumnCheck(m_pCBData,column,hditem.lParam))
				{
					// don't forward the message!
					return;
				}
				break;
			}
			
			x_coord-=hditem.cxy;
			column++;
		}
	}

	CHeaderCtrl::OnLButtonDown(flags,pt);
}

The side effect of this code - it disables dragging the "disabled" columns. (That's because the header control never hears of LButtonDown message - I filter it of.)



Comments

  • Is any demo source is possible

    Posted by Legacy on 11/05/2001 12:00am

    Originally posted by: anup

    I need some demo code for this, if possible please send it to me.
    
    Thanks in advance.
    Anup

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  • Your email address will not be published.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

Top White Papers and Webcasts

  • Whether you're just now developing your first mobile app, refining an existing one, or deploying multiple apps, the process for doing so can be complicated. Utilizing a Rapid Mobile Application Development (RMAD) platform can help you not only make that process easier, but also help the business reach its goals in a timely, cost-efficient manner. This eBook outlines seven key factors to consider as you choose the right RMAD platform to meet your needs, and includes a quick-reference checklist.

  • Microsoft® Office 365 is a top choice for enterprises that want a cloud-based suite of productivity/ collaboration applications. With Office 365, you get access to Microsoft™ Office solutions practically anytime, anywhere, on virtually any device. It's a great option for current Microsoft users who can now build on their experience with Microsoft™ solutions while enjoying the flexibility of a cloud-based delivery. But even organizations with no previous investment in Microsoft will find that …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date