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I am practicing with datagrid, when I have many rows, the vertical scrollbar is activated. How to know that I am moving the scrollbar button from top to bottom with the left mouse button? Happy new year everybody.

What I have tried:

I'm new with WPF, I dont'n know how to do.
Posted
Updated 4-Jan-23 13:40pm
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[no name] 4-Jan-23 16:03pm    
https://stackoverflow.com/questions/7326656/adding-a-scroll-event-to-datagrid

1 solution

Further to Gerry's solution link, I am expecting you to ask how to get the visible Rows. Here is a solution from Wpf DataGrid: how to detect the set of visible cells?
[^]
Wire up the event:
XML
<DataGrid ScrollViewer.ScrollChanged="DataGrid_ScrollChanged">

Now the event handler:
C#
private static T GetChildOfType<T>(DependencyObject depObj)
	where T : DependencyObject
{
	if (depObj == null) return null;

	for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
	{
		var child = VisualTreeHelper.GetChild(depObj, i);

		var result = (child as T) ?? GetChildOfType<T>(child);
		if (result != null) return result;
	}
	return null;
}

private void DataGrid_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
	DataGrid datagrid = sender as DataGrid;
	var scroll = GetChildOfType<ScrollViewer>((DependencyObject)sender);

	int firstRow = (int)scroll.VerticalOffset;
	int lastRow = (int)scroll.VerticalOffset + (int)scroll.ViewportHeight + 1;

	for (int i = firstRow; i < lastRow; i++)
	{
		// do work here
	}
}
 
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Member 15639943 4-Jan-23 20:42pm    
Thanks a lot for your time and help. I'm going to do the corresponding tests, but I'm going to ask another question explaining the problem better (I hope)

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