/// <summary>
/// Performs tab navigation while focus is within the drop down.
/// </summary>
private void PerformTabNavigation(Key key, ModifierKeys modifiers)
{
var shift = ((modifiers & ModifierKeys.Shift) == ModifierKeys.Shift);
var ctrl = ((modifiers & ModifierKeys.Control) == ModifierKeys.Control);
var focused = Keyboard.GetFocusedElement(View) as UIElement;
if (FocusNavigator.PerformNavigation(View, focused, shift ? FocusNavigationDirection.Previous : FocusNavigationDirection.Next, ctrl))
{
focused = Keyboard.GetFocusedElement(View) as UIElement;
var container = (focused == null) ? null : ItemsControlUtil.FindContainer <ComboBoxItem>(this, focused);
if (container != null)
{
ItemsControlUtil.ScrollItemIntoView <ComboBoxItem>(this, PART_ScrollViewer, container);
}
}
}
/// <summary>
/// Moves keyboard focus the specified number of steps away from the currently focused item.
/// </summary>
/// <param name="step">The number of steps by which to move focus.</param>
private void MoveItemFocus(Int32 step)
{
var selectedContainer = ItemsControlUtil.FindFocusedContainer <ComboBoxItem>(this);
var selectedIndex = (selectedContainer == null) ? -1 : ItemContainers.IndexOf(selectedContainer);
var targetIndex = selectedIndex + step;
if (targetIndex < 0 || targetIndex >= Items.Count)
{
return;
}
var targetContainer = ItemContainers[targetIndex] as UIElement;
if (targetContainer == null)
{
return;
}
targetContainer.Focus();
ItemsControlUtil.ScrollItemIntoView <ComboBoxItem>(this, PART_ScrollViewer, targetContainer);
}
/// <summary>
/// Selects the specified item and scrolls it into view.
/// </summary>
private void HandleItemClickedAndScrollIntoView(ListBoxItem item, Boolean buffer = true)
{
HandleItemClicked(item);
ItemsControlUtil.ScrollItemIntoView <ListBoxItem>(this, PART_ScrollViewer, item, buffer);
}
/// <summary>
/// Handles <see cref="Keyboard.KeyDownEvent"/> when the drop down is open.
/// </summary>
private void OnKeyDown_DropDownOpen(KeyboardDevice device, Key key, ModifierKeys modifiers, RoutedEventData data)
{
switch (key)
{
case Key.Tab:
PerformTabNavigation(key, modifiers);
data.Handled = true;
break;
case Key.Escape:
IsDropDownOpen = false;
data.Handled = true;
break;
case Key.Return:
SelectFocusedItem();
IsDropDownOpen = false;
data.Handled = true;
break;
case Key.Up:
MoveItemFocus(-1);
data.Handled = true;
break;
case Key.Down:
MoveItemFocus(1);
data.Handled = true;
break;
case Key.PageUp:
var pageUpTarget = ItemsControlUtil.GetPageUpNext <ComboBoxItem>(this, PART_ScrollViewer);
if (pageUpTarget != null && pageUpTarget.Focus())
{
ItemsControlUtil.ScrollItemIntoView <ComboBoxItem>(this, PART_ScrollViewer, pageUpTarget, false);
}
data.Handled = true;
break;
case Key.PageDown:
var pageDownTarget = ItemsControlUtil.GetPageDownNext <ComboBoxItem>(this, PART_ScrollViewer);
if (pageDownTarget != null && pageDownTarget.Focus())
{
ItemsControlUtil.ScrollItemIntoView <ComboBoxItem>(this, PART_ScrollViewer, pageDownTarget, false);
}
data.Handled = true;
break;
case Key.Home:
var firstItem = ItemsControlUtil.GetFirstItem <ComboBoxItem>(this, PART_ScrollViewer);
if (firstItem != null && firstItem.Focus())
{
ItemsControlUtil.ScrollItemIntoView <ComboBoxItem>(this, PART_ScrollViewer, firstItem);
}
data.Handled = true;
break;
case Key.End:
var lastItem = ItemsControlUtil.GetLastItem <ComboBoxItem>(this, PART_ScrollViewer);
if (lastItem != null && lastItem.Focus())
{
ItemsControlUtil.ScrollItemIntoView <ComboBoxItem>(this, PART_ScrollViewer, lastItem);
}
data.Handled = true;
break;
case Key.Left:
PART_ScrollViewer?.LineLeft();
data.Handled = true;
break;
case Key.Right:
PART_ScrollViewer?.LineRight();
data.Handled = true;
break;
}
}