以编程方式更改文本后保留文本框选择

我更喜欢在 Behavior 可以添加到XAML中;这需要 System.Windows.Interactivity.WPF NuGet Package .

如果你真的不想 另一方面,从中提取事件处理逻辑以用于您喜欢的任何方法应该是相当简单的。

public class KeepSelectionBehavior : Behavior<TextBox>
{
    private bool _wasAllTextSelected = false;
    private int inputKeysDown = 0;

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

        CheckSelection();
        AssociatedObject.TextChanged += TextBox_TextChanged;
        AssociatedObject.SelectionChanged += TextBox_SelectionChanged;
        AssociatedObject.PreviewKeyDown += TextBox_PreviewKeyDown;
        AssociatedObject.KeyUp += TextBox_KeyUp;
    }

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

        AssociatedObject.TextChanged -= TextBox_TextChanged;
        AssociatedObject.SelectionChanged -= TextBox_SelectionChanged;
        AssociatedObject.PreviewKeyDown -= TextBox_PreviewKeyDown;
        AssociatedObject.KeyUp -= TextBox_KeyUp;
    }

    private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
    {
        if (_wasAllTextSelected && inputKeysDown == 0)
        {
            AssociatedObject.SelectAll();
        }
        CheckSelection();
    }

    private void TextBox_SelectionChanged(object sender, RoutedEventArgs e)
    {
        CheckSelection();
    }

    private void TextBox_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        if (IsInputKey(e.Key))
        {
            inputKeysDown++;
        }
    }

    private void TextBox_KeyUp(object sender, KeyEventArgs e)
    {
        if (IsInputKey(e.Key))
        {
            inputKeysDown--;
        }
    }

    private bool IsInputKey(Key key)
    {
        return
            key == Key.Space ||
            key == Key.Delete ||
            key == Key.Back ||
            (key >= Key.D0 && key <= Key.Z) ||
            (key >= Key.Multiply && key <= Key.Divide) ||
            (key >= Key.Oem1 && key <= Key.OemBackslash);
    }

    private void CheckSelection()
    {
        _wasAllTextSelected = AssociatedObject.SelectionLength == AssociatedObject.Text.Length;
    }
}

你可以这样使用它:

<Window
    x:Class="ScriptyBot.Client.TestWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Title="TestWindow"
    Width="800"
    Height="450"
    mc:Ignorable="d">
    <StackPanel>
        <TextBox Name="TextBox1" Margin="20">
            <i:Interaction.Behaviors>
                <behaviors:KeepSelectionBehavior />
            </i:Interaction.Behaviors>
        </TextBox>
    </StackPanel>
</Window>

我正在用一个简单的 DispatchTimer 每秒钟更新一次文本:

public partial class TestWindow : Window
{
    private DispatcherTimer timer;

    public TestWindow()
    {
        InitializeComponent();

        timer = new DispatcherTimer(DispatcherPriority.Normal);
        timer.Interval = TimeSpan.FromSeconds(1);
        timer.Tick += (sender, e) => { TextBox1.Text = DateTime.Now.ToString(); };
        timer.Start();
    }
}

默认情况下 行为 ,您可以使用 Style app.xaml

public class AttachableForStyleBehavior<TComponent, TBehavior> : Behavior<TComponent>
    where TComponent : System.Windows.DependencyObject
    where TBehavior : AttachableForStyleBehavior<TComponent, TBehavior>, new()
{
    public static readonly DependencyProperty IsEnabledForStyleProperty =
        DependencyProperty.RegisterAttached(name: "IsEnabledForStyle",
                                            propertyType: typeof(bool),
                                            ownerType: typeof(AttachableForStyleBehavior<TComponent, TBehavior>),
                                            defaultMetadata: new FrameworkPropertyMetadata(false, OnIsEnabledForStyleChanged));

    public bool IsEnabledForStyle
    {
        get => (bool)GetValue(IsEnabledForStyleProperty);
        set => SetValue(IsEnabledForStyleProperty, value);
    }

    private static void OnIsEnabledForStyleChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (d is UIElement uiElement)
        {
            var behaviors = Interaction.GetBehaviors(uiElement);
            var existingBehavior = behaviors.FirstOrDefault(b => b.GetType() == typeof(TBehavior)) as TBehavior;

            if ((bool)e.NewValue == false && existingBehavior != null)
            {
                behaviors.Remove(existingBehavior);
            }
            else if ((bool)e.NewValue == true && existingBehavior == null)
            {
                behaviors.Add(new TBehavior());
            }
        }
    }
}

行为 类更改为如下所示:

public class KeepSelectionBehavior : AttachableForStyleBehavior<TextBox, KeepSelectionBehavior>

并且是这样应用的(它甚至可以绑定到 bool 动态开启和关闭!):

<Style TargetType="TextBox">
    <Setter Property="KeepSelectionBehavior.IsEnabledForStyle" Value="True" />
</Style>

就我个人而言,我更喜欢使用 风格 无论如何,即使将其添加到单个一次性控件中,也要使用基于方法的方法。它大大减少了输入,而且我不必记住如何定义 xmlns Interactions Behaviors 名称空间。

我想要收到的文本 TextBox B,以便用户在需要时更容易更改。

TextChanged 事件。每当 Text 属性已更改。Yoy可能需要添加一个延迟,以便用户可以在每个按键笔划上不选择文本的情况下进行键入:

private DateTime _last;
private void txt2_TextChanged(object sender, TextChangedEventArgs e)
{
    if (DateTime.Now.Subtract(_last) > TimeSpan.FromSeconds(3))
    {
        TextBox tb = (TextBox)sender;
        if (Keyboard.FocusedElement == tb)
            tb.SelectAll();
    }
    _last = DateTime.Now;
}