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  • Your email address will not be published.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

  • You may already know about some of the benefits of Bluemix, IBM's open platform for developing and deploying mobile and web applications. Check out this webcast that focuses on building an Android application using the MobileData service, with a walk-through of the real process and workflow used to build and link the MobileData service within your application. Join IBM's subject matter experts as they show you the way to build a base application that will jumpstart you into building your own more complex app …

  • Not all enterprise applications are created equal. Sophisticated applications need developer support but other more basic apps do not. With the right tools, everyone is a potential app developer with ideas and a perspective to share. Trends such as low-code development and model driven development are fundamentally changing how and who creates applications. Is your organization ready? Read this report and learn: The seven personas of enterprise app delivery How application ownership is spreading to the …

Most Popular Programming Stories

More for Developers

Latest Developer Headlines

RSS Feeds