デフォルトで折りたたまれたスタックパネルに含まれるテキストボックスにキーボードフォーカスを設定しようとしています。スタックパネルが表示されると、デフォルトでテキストボックスがフォーカスされるようになります。
私はこのコードを試しました：
<StackPanel Orientation="Vertical" FocusManager.FocusedElement="{Binding ElementName=TxtB}">
<TextBox x:Name="TxtA" Text="A" />
<TextBox x:Name="TxtB" Text="B" />
</StackPanel>
しかし、うまくいきませんでした。文字カーソルは表示されましたが、点滅せず、書き込みができませんでした。
XAML のみを使用して問題を解決することはできますか? もしかしてトリガー？
true に設定すると、添付要素の Focus() メソッドを呼び出す添付プロパティ IsFocused を作成する必要があります。ちょっと待って、コードを追加します。
public static class FocusHelper
{
static FocusHelper()
{
var fpmd = new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, HandleAttachedIsFocusedChanged) { DefaultUpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged };
IsFocusedProperty = DependencyProperty.RegisterAttached("IsFocused", typeof(bool?), typeof(FocusHelper), fpmd);
}
public static readonly DependencyProperty IsFocusedProperty;
[Conditional("DEBUG")]
public static void StartFocusTracing()
{
FocusManager.FocusedElementProperty.OverrideMetadata(typeof(FrameworkElement), new PropertyMetadata(HandleFocusedElementChanged));
}
private static void HandleFocusedElementChanged(DependencyObject o, DependencyPropertyChangedEventArgs args)
{
var element = args.NewValue as FrameworkElement;
if (element == null)
{
Debug.WriteLine("Focus is lost");
return;
}
Debug.WriteLine("Focus moved to {0} type {1}", element.Name, element.GetType().Name);
var fs = FocusManager.GetFocusScope(element) as FrameworkElement;
if (fs == null)
return;
Debug.WriteLine("Focus scope {0} of type {1}", fs.Name, fs.GetType().Name);
}
public static bool? GetIsFocused(DependencyObject element)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
return (bool?)element.GetValue(IsFocusedProperty);
}
public static void SetIsFocused(DependencyObject element, bool? value)
{
if (element == null)
throw new ArgumentNullException("element");
element.SetValue(IsFocusedProperty, value);
}
private static void HandleAttachedIsFocusedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
WriteDependencyPropertyBindingInformation(d, IsFocusedProperty);
var fe = (UIElement)d;
// значение ранее было не задано
if (e.OldValue == null)
{
var pd = DependencyPropertyDescriptor.FromProperty(UIElement.IsFocusedProperty, typeof(UIElement));
pd.AddValueChanged(fe, HandleUIElementIsFocusedChanged);
}
if (e.NewValue == null)
{
var pd = DependencyPropertyDescriptor.FromProperty(UIElement.IsFocusedProperty, typeof(UIElement));
pd.RemoveValueChanged(fe, HandleUIElementIsFocusedChanged);
return;
}
if ((bool)e.NewValue)
{
Action setFocus = () =>
{
IInputElement elementToBeFocused = null;
IInputElement finalyFocusedElement = null;
// If current element is Focus Scope we try to restore logical focus
if (FocusManager.GetIsFocusScope(fe))
{
elementToBeFocused = FocusManager.GetFocusedElement(fe);
if (elementToBeFocused != null)
{
finalyFocusedElement = Keyboard.Focus(elementToBeFocused);
}
}
// If focus was not restored we try to focus
if (finalyFocusedElement == null
|| (elementToBeFocused != finalyFocusedElement))
{
fe.FocusThisOrChild();
}
};
if (ReflectionHelper.IsInMethod("MeasureOverride", typeof(FrameworkElement))) // hack of layout issue
Dispatcher.CurrentDispatcher.BeginInvoke(setFocus);
else
setFocus();
}
}
[Conditional("DEBUG")]
private static void WriteDependencyPropertyBindingInformation(DependencyObject d, DependencyProperty property)
{
var binding = BindingOperations.GetBindingBase(d, IsFocusedProperty);
if (binding == null)
{
Debug.WriteLine("Property {1} of object {0} has no bindings.", d, property.Name);
}
else
{
Debug.WriteLine("Property {1} of object {0} has binding.", d, property.Name);
Debug.WriteLine("Type {0}", binding.GetType());
var expressionBase = BindingOperations.GetBindingExpressionBase(d, IsFocusedProperty);
Debug.Assert(expressionBase != null);
Debug.WriteLine("Status {0}", expressionBase.Status);
var expression = expressionBase as BindingExpression;
if (expression != null)
{
Debug.WriteLine("Source type {0}", expression.DataItem.GetType());
Debug.WriteLine("Source {0}",expression.DataItem);
}
}
}
private static void HandleUIElementIsFocusedChanged(object sender, EventArgs e)
{
var uiElement = sender as UIElement;
var isFocused = uiElement.IsFocused;
((DependencyObject)sender).SetCurrentValue(IsFocusedProperty, isFocused);
}
/// <summary>
/// Tries to set focus to the element or any child element inside this one.
/// Tab index is respected
/// </summary>
public static bool FocusThisOrChild(this DependencyObject element)
{
if (element == null)
throw new ArgumentNullException("element");
var inputElement = element as IInputElement;
var wasFocused = inputElement != null && inputElement.Focus();
if (!wasFocused)
{
element.SetFocusWithin();
}
return true;
}
public static bool SetFocusWithin(this DependencyObject element)
{
if (element == null)
throw new ArgumentNullException("element");
var children = element.GetVisualChildrenSortedByTabIndex();
return children.Any(FocusThisOrChild);
}
}
およびヘルパー メソッド:
public static IEnumerable<DependencyObject> GetVisualChildrenSortedByTabIndex(this DependencyObject parent)
{
if (parent == null)
throw new ArgumentNullException("parent");
return parent.GetVisualChildren().OrderBy(KeyboardNavigation.GetTabIndex);
}
public static bool IsInMethod(string methodName, Type ownerType, bool isStatic = false)
{
if (string.IsNullOrWhiteSpace(methodName))
throw new ArgumentNullException("methodName");
if (ownerType == null)
throw new ArgumentNullException("ownerType");
var stackTrace = new StackTrace(false);
var isInMethod = stackTrace.GetFrames().Skip(1).Any(frame =>
{
var method = frame.GetMethod();
return method.Name == methodName
&& method.IsStatic == isStatic
&& ownerType.IsAssignableFrom(method.ReflectedType);
});
return isInMethod;
}