/// <summary>
/// Updates the focused <see cref="DataGridColumnHeader"/>.
/// </summary>
private static void UpdateFocusedHeader(DataGridControl datagrid)
{
if (null == datagrid)
{
return;
}
// Get the list of headers
IList <DependencyObject> headers = VisualTreeHelperExtended.GetAllDescendants(datagrid, typeof(DataGridColumnHeader));
if (null == headers || 0 == headers.Count)
{
return;
}
// Update the focus based on the current tracking Modes
FocusTrackingModes trackingModes = GetTrackingModes(datagrid);
if (0 != (trackingModes & FocusTrackingModes.Headers))
{
// Get the focused cell, if any, and look for an ancestor cell when editing cell
DataGridCell cell = Keyboard.FocusedElement as DataGridCell;
if (cell == null)
{
cell = VisualTreeHelperExtended.GetAncestor(Keyboard.FocusedElement as FrameworkElement, typeof(DataGridCell)) as DataGridCell;
}
// Update header focus, if any
foreach (DataGridColumnHeader header in headers)
{
// Determine if the column associated with this header if focused
bool isFocused = (null != cell && cell.Column == header.Column);
// Update the focus for this header
if (isFocused != GetIsFocusedHeader(header))
{
if (isFocused)
{
header.SetValue(IsFocusedHeaderPropertyKey, true);
}
else
{
header.ClearValue(IsFocusedHeaderPropertyKey);
}
}
}
}
else
{
// Clear header focus, if any
foreach (DataGridColumnHeader header in headers)
{
if (GetIsFocusedHeader(header))
{
header.ClearValue(IsFocusedHeaderPropertyKey);
}
}
}
}
public static void SetTrackingModes(DataGridControl obj, FocusTrackingModes value)
{
if (null == obj)
{
throw new ArgumentNullException("obj");
}
obj.SetValue(FocusBehavior.TrackingModesProperty, value);
}
/// <summary>
/// Called when <see cref="TrackingModesProperty"/> is changed.
/// </summary>
/// <param name="d">The dependency object that was changed.</param>
/// <param name="e">The <see cref="DependencyPropertyChangedEventArgs"/> instance containing the event data.</param>
private static void OnTrackingModesPropertyValueChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
DataGridControl datagrid = d as DataGridControl;
if (null == datagrid)
{
return;
}
FocusTrackingModes trackingModes = (FocusTrackingModes)e.NewValue;
if (FocusTrackingModes.None != trackingModes)
{
datagrid.AddHandler(UIElement.GotFocusEvent, (RoutedEventHandler)OnDataGridGotFocus, true);
datagrid.AddHandler(UIElement.LostFocusEvent, (RoutedEventHandler)OnDataGridLostFocus, true);
}
else
{
datagrid.RemoveHandler(UIElement.GotFocusEvent, (RoutedEventHandler)OnDataGridGotFocus);
datagrid.RemoveHandler(UIElement.LostFocusEvent, (RoutedEventHandler)OnDataGridLostFocus);
}
UpdateFocusedHeader(datagrid);
}
