DataGrid Merging rowheaders

Question

i am creating a timeplan with drag function and am using datagrids for their amazing data binding and cell selection functionality. all works well, except now i want to have the row headers (time) only show the hours and not the half hour segments.

This is what i want:

And This is what i get:

Is there a way to merge the row headers without loosing the function of actual rows? I tried to just overlap the row header with another box, but this seems clunky

Answer 1

so i did the following: I created a grid on the side of the rowheaders, which i filled with half as many rows as the datagrid. the first row has a set height, so it matches the height of the Datagrid header, which i do not want to scale, as it contains the week day names

<Grid x:Name="Grid_Datagrid_Times_box" 
             Grid.Column="1"
             Grid.Row="1"
             Grid.RowSpan="2"
             Grid.ColumnSpan="2"
             HorizontalAlignment="Stretch"
             VerticalAlignment="Stretch">

     <Grid.ColumnDefinitions>
           <ColumnDefinition Width="0.3*"/>
           <ColumnDefinition Width="8*"/>
     </Grid.ColumnDefinitions>
     <Grid x:Name="Grid_Times"
           Grid.Column="0">

           <Grid.RowDefinitions>
                  <RowDefinition Height="30"/>
           </Grid.RowDefinitions>
     </Grid>
     <DataGrid x:Name="DataGrid_Timetable"
               Grid.Column="1"
               VerticalAlignment="Stretch"
               HorizontalAlignment="Stretch"
               ColumnHeaderHeight="30">
      ...
    </DataGrid>

in codebehind on Size Changed is set

private void Datagrid_Resize(object sender, SizeChangedEventArgs e)
    {
        DataGrid DG = new DataGrid();
        if ((sender) is DataGrid)
        {
            DG = (DataGrid)sender;
        }
        double test = DG.RowHeight;
        DataGridRow rowt = GetFirstVisualChild<DataGridRow>(DG, 1);
        double testR = rowt.ActualHeight; 


        DG.RowHeight = (Grid_Datagrid_Times_box.ActualHeight-30) /    (numberOfRows);
        
        for (int i = 0; i < (numberOfRows+2); i++)
        {
            DataGridRow row = GetFirstVisualChild<DataGridRow>(DG, i);
            if (row != null)
            {
                row.FontSize = DG.RowHeight / 2.3;
                row.Height = DG.RowHeight;
            }
            foreach (UIElement ele in Grid_Times.Children)
            {
                if (ele.GetType() == typeof(TextBlock))
                {
                    TextBlock txtb = (TextBlock)ele;
                    txtb.FontSize = DG.RowHeight;
                }
            }
          }
    }

and

public static T GetFirstVisualChild<T>(DependencyObject depObj, int index) where T : DependencyObject
    {
        if (depObj != null)
        {
            int counter = 0;
            for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
            {
                DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
                if (child != null && child is T )
                {
                    counter++;
                    if (counter==index)
                        return (T)child;
                }

                T childItem = GetFirstVisualChild<T>(child, index);
                if (childItem != null) return childItem;
            }
        }

        return null;
    }