FrameworkElement.PredictFocus(FocusNavigationDirection) メソッド

public:
 override System::Windows::DependencyObject ^ PredictFocus(System::Windows::Input::FocusNavigationDirection direction);

public override sealed System.Windows.DependencyObject PredictFocus(System.Windows.Input.FocusNavigationDirection direction);

override this.PredictFocus : System.Windows.Input.FocusNavigationDirection -> System.Windows.DependencyObject

Public Overrides NotOverridable Function PredictFocus (direction As FocusNavigationDirection) As DependencyObject

パラメーター

返品

フォーカスが実際に走査された場合にフォーカスが移動する次の要素。 指定した方向に対してこの要素を基準にしてフォーカスを移動できない場合は、 null 返されることがあります。

例外

例

次の例では、複数のボタン入力を処理するハンドラーを実装します。各ボタンは、考えられる FocusNavigationDirectionを表します。 ハンドラーは、現在のキーボード フォーカスを持つ要素を追跡し、その要素にPredictFocusを呼び出し、指定されたTraversalRequest型パラメーターの初期化として適切なFocusNavigationDirectionを指定します。 ハンドラーは、 MoveFocus のようにその要素に移動する代わりに、視覚化のために予測されたフォーカス先の物理的なディメンションを変更します。

    private void OnPredictFocus(object sender, RoutedEventArgs e)
    {
        DependencyObject predictionElement = null;

        UIElement elementWithFocus = Keyboard.FocusedElement as UIElement;

        if (elementWithFocus != null)
        {
            // Only these four directions are currently supported
            // by PredictFocus, so we need to filter on these only.
            if ((_focusMoveValue == FocusNavigationDirection.Up) ||
                (_focusMoveValue == FocusNavigationDirection.Down) ||
                (_focusMoveValue == FocusNavigationDirection.Left) ||
                (_focusMoveValue == FocusNavigationDirection.Right))
            {

                // Get the element which would receive focus if focus were changed.
                predictionElement = elementWithFocus.PredictFocus(_focusMoveValue);
               
                Control controlElement = predictionElement as Control;

                // If a ContentElement.
                if (controlElement != null)
                {
                    controlElement.Foreground = Brushes.DarkBlue;
                    controlElement.FontSize += 10;
                    controlElement.FontWeight = FontWeights.ExtraBold;

                    // Fields used to reset the UI when the mouse 
                    // button is released.
                    _focusPredicted = true;
                    _predictedControl = controlElement;
                }
            }
        }
    }

Private Sub OnPredictFocus(ByVal sender As Object, ByVal e As RoutedEventArgs)
    Dim predictionElement As DependencyObject = Nothing

    Dim elementWithFocus As UIElement = TryCast(Keyboard.FocusedElement, UIElement)

    If elementWithFocus IsNot Nothing Then
        ' Only these four directions are currently supported
        ' by PredictFocus, so we need to filter on these only.
        If (_focusMoveValue = FocusNavigationDirection.Up) OrElse (_focusMoveValue = FocusNavigationDirection.Down) OrElse (_focusMoveValue = FocusNavigationDirection.Left) OrElse (_focusMoveValue = FocusNavigationDirection.Right) Then

            ' Get the element which would receive focus if focus were changed.
            predictionElement = elementWithFocus.PredictFocus(_focusMoveValue)

            Dim controlElement As Control = TryCast(predictionElement, Control)

            ' If a ContentElement.
            If controlElement IsNot Nothing Then
                controlElement.Foreground = Brushes.DarkBlue
                controlElement.FontSize += 10
                controlElement.FontWeight = FontWeights.ExtraBold

                ' Fields used to reset the UI when the mouse 
                ' button is released.
                _focusPredicted = True
                _predictedControl = controlElement
            End If
        End If
    End If
End Sub

注釈

MoveFocus は、実際にフォーカスを移動する関連メソッドです。

こちらもご覧ください

• MoveFocus(TraversalRequest)
• PredictFocus(FocusNavigationDirection)