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Fast Ensure Visible for CGridCtrl

, 5 Mar 2012
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This tip shows a very fast algorithm (with some constraints enforced for it to work) to EnsureVisible a row in CGridCtrl by Chris Maunder

Introduction

 

In one of my projects, I had to load around 200000 rows in the CGridCtrl and then had to provide the functionalitiy of EnsureVisible to scroll to and highlight a row. So I had to come up with a reasonably fast algorithm. 

 

The code

 
// This function will only work if all the grid control rows are same in size

void GVEnsureVisible(CGridCtrl* pGridCtrl, int nRow)
{
	if(pGridCtrl== NULL)
		return;
 
	pGridCtrl->ResetScrollBars();
 
	int nItems = pGridCtrl->GetItemCount();
 
	int nPos = nRow;
 
	if(nItems > 0)
	{
		SCROLLINFO si;
 
		pGridCtrl->GetScrollInfo(SB_VERT, &si);
 
		double dx = (double)si.nMax / (double)nItems;
 
		si.cbSize = sizeof(SCROLLINFO);
 
		si.fMask = SIF_POS;
 
		si.nPos = (int)(dx * nPos) - si.nPage/2;
 
		pGridCtrl->SetScrollInfo(SB_VERT, &si, TRUE); 
		
	}
 
}
 

 

Points of Interest

 

This code will only work if all the rows of the Grid are of same size.

 

History

 

Article Uploaded : 5th March, 2012.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

About the Author

Mukit, Ataul
Chief Technology Officer Rational Technologies
Bangladesh Bangladesh
You don't learn patterns, you just code it.
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Comments and Discussions

 
QuestionCan you explain how this makes fast scroll? Also compare it with EnsureVisible, too. Pinmemberehaerim24-Oct-13 9:56 
AnswerRe: Can you explain how this makes fast scroll? Also compare it with EnsureVisible, too. PinmemberMukit, Ataul25-Oct-13 21:34 

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