private static void IsKeyboardFocusWithinAnchorChanged(object sender, DependencyPropertyChangedEventArgs e)
{
var element = sender as FrameworkElement;
if (element == null || DesignerProperties.GetIsInDesignMode(element))
{
return;
}
//如果元素内部还包含该装饰器，为防止重叠，则不处理
if (element.FirstVisualTreeChildren(x => AnchorAdorner.GetIsKeyboardFocusWithinAnchor(x)) != null)
{
return;
}
var flag = (bool)e.NewValue;
element.Dispatcher.BeginInvoke(new Action(() =>
{
//安装或卸载装饰器
var anchor = AnchorAdorner.GetKeyboardWithinAnchor(element);
//若flag为false，且anchor不存在，则直接退出
if (anchor == null && !flag)
{
return;
}
var adornerLayer = AdornerLayer.GetAdornerLayer(element);
if (adornerLayer == null)
{
return;
}
if (anchor == null)
{
anchor = new AnchorAdorner(element);
AnchorAdorner.SetKeyboardWithinAnchor(element, anchor);
//装饰器Visibility与依附元素的IsVisible绑定
anchor.SetBinding(FrameworkElement.VisibilityProperty,
new System.Windows.Data.Binding()
{
Source = element,
Converter = ValueConverter.BoolToVisibility,
Path = new PropertyPath(IsVisibleProperty)
});
}
adornerLayer.Remove(anchor);
if (flag)
{
adornerLayer.Add(anchor);
}
}), System.Windows.Threading.DispatcherPriority.Loaded);
}
private static void SetKeyboardWithinAnchor(DependencyObject obj, AnchorAdorner value)
{
obj.SetValue(KeyboardWithinAnchorProperty, value);
}