Question

在我的视图中有一个ItemsControl，它绑定到ViewModel的ObservableCollection。该集合已被填充，之后将引发从VM到视图的事件（想想搜索结果和SearchFinished事件）。如何将键盘焦点移动到ItemsControl中的第一项？我正在使用MVVM模式

Answer 1

我在使用行为之前完成了这项工作：

public sealed class FocusBehavior : Behavior<FrameworkElement>
{
    protected override void OnAttached()
    {
        base.OnAttached();

        AssociatedObject.Loaded += OnLoaded;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();

        AssociatedObject.Loaded -= OnLoaded;
    }

    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        AssociatedObject.Focus();
    }
}

然后在XAML中使用它，如下所示：

<TextBox x:Name="UsernameTextBox"
         Text="{Binding Path=Username, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
         KeyboardNavigation.TabIndex="0">
    <i:Interaction.Behaviors>
        <b:FocusBehavior />
    </i:Interaction.Behaviors>
</TextBox>

您需要引用System.Windows.Interactivity程序集以引入Interaction名称空间。

Answer 2

我找到了解决方案..

private void VerifiValue_Loaded(object sender, RoutedEventArgs e)
    {
        if (verificationIC.Items.Count > 0)
        {
            UIElement uiElement = (UIElement)verificationIC.ItemContainerGenerator.ContainerFromIndex(0);

            TextBox t = GetChild<TextBox>(uiElement);
            t.Focus();
            t.SelectAll();
        }
    }

    public T GetChild<T>(DependencyObject obj) where T : DependencyObject
    {
        DependencyObject child = null;
        for (Int32 i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
        {
            child = VisualTreeHelper.GetChild(obj, i);
            if (child != null && child.GetType() == typeof(T))
            {
                break;
            }
            else if (child != null)
            {
                child = GetChild<T>(child);
                if (child != null && child.GetType() == typeof(T))
                {
                    break;
                }
            }
        }
        return child as T;
    }

WPF ItemsControl - 如何知道itemscontrol何时完成加载，以便我可以集中第一个？

2 个答案: