Mouse scroll not working in a scroll viewer with a wpf datagrid and additional UI elements

Question

I am trying to figure out how to get the mouse scroll working on a wpf window with a scrollviewer and a datagrid within it. The WPF and C# code is below

<ScrollViewer HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Auto">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid Grid.Row="0">

            <Border Name="DataGridBorder" BorderThickness="2"  Margin="1" CornerRadius="4" BorderBrush="#FF080757">
                <dg:DataGrid AutoGenerateColumns="False" Name="ValuesDataGrid" 
                         BorderThickness="0" CanUserResizeColumns="True" FontWeight="Bold" HorizontalScrollBarVisibility="Auto" 
                         CanUserReorderColumns="False" IsReadOnly="True" IsTextSearchEnabled="True" AlternationCount="2"
                         SelectionMode="Extended" GridLinesVisibility="All"                
                         HeadersVisibility="Column" CanUserAddRows="False" CanUserDeleteRows="False" CanUserResizeRows="False" CanUserSortColumns="False"
                         RowDetailsVisibilityMode="Collapsed"  SelectedIndex="0"
                         RowStyle="{StaticResource CognitiDataGridRowStyle}"
                         >

                    <dg:DataGrid.Columns>
                        <dg:DataGridTemplateColumn Header="Title" >
                            <dg:DataGridTemplateColumn.CellTemplate>
                                <DataTemplate>
                                    <StackPanel Orientation="Horizontal" >
                                        <TextBlock HorizontalAlignment="Left" VerticalAlignment="Center" Text="{Binding Path=Name}" FontWeight="Normal"  />
                                    </StackPanel>
                                </DataTemplate>
                            </dg:DataGridTemplateColumn.CellTemplate>
                        </dg:DataGridTemplateColumn>
                    </dg:DataGrid.Columns>
                </dg:DataGrid>
            </Border>
        </Grid>
        <Button Grid.Row="1" Height="90" >hello world</Button>
    </Grid>
</ScrollViewer>

and the C# code is as follows

 public partial class Window1 : Window
  {
     public Window1()
     {
        InitializeComponent();
        initialize();
      }

    public void initialize()
    {
        ObservableCollection<MyObject> testList = new ObservableCollection<MyObject>();

        for (int i = 0; i < 20; i++)
        {
            MyObject my = new MyObject("jack " + i);
            testList.Add(my);
        }

        ValuesDataGrid.ItemsSource = testList;



    }
}

public class MyObject
{
    public string Name { get; set; }



    public MyObject(string name)
    {
        Name = name;
    }
   }

The problem i am facing is that when using the mouse to scroll, it works fine when it is over the button but as soon as i move the mouse pointer over the grid and try to scroll, nothing happens. I am able to move the scrollbar of the scrollviewer directly though. I am still a wpf novice so any help on how to get the mouse scroll to work over the datagrid would be appreciated. I am guessing there should be a pretty easy solution for this but I havent been able to figure it out

Answer 1

I think Dave's solution is a good one. However, one recommendation I'd make is to catch the PreviewMouseWheel event on the scrollviewer instead of on the datagrid. If you don't, you might notice some minor differences based on whether you're scrolling over the datagrid or the scroll bar itself. The reasoning is that the scrollviewer will be handling scrolling when the mouse is hovered over the scrollbar, and the datagrid event will handle the scrolling when over the datagrid. For instance, one mouse wheel scroll over the datagrid might bring you farther down your list then it would when over the scroll bar. If you catch it on scrollviewer preview event, all will use the same measurement when scrolling. Also, if you catch it this way, you won't need to name the scrollviewer element, as you won't need a reference to the object since you can just type cast the sender object passed into the scrollviewer PreviewMouseWheel event. Lastly, I'd recommend marking the event handled at the end of the event, unless you need to catch it in an element further down the heirarchy for some reason. Example below:

private void ScrollViewer_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
    {
        ScrollViewer scv = (ScrollViewer)sender;
        scv.ScrollToVerticalOffset(scv.VerticalOffset - e.Delta);
        e.Handled = true;
    }