如果有一个事件，取消选择的文本在OnFocus鼠标向上，我通常只是延迟全部选择。

private void TextBox_GotFocus(object sender, RoutedEventArgs e)
{
    if (TextBox.Text != null)
    {
        _ = Task.Run(() =>
        {
            Dispatcher.Invoke(
                async () => {
                    await Task.Delay(100);
                    TextBox.SelectAll();
                }
            );
        });
    }
}

不知道为什么它在GotFocus事件中失去了选择。

但是一个解决方案是在GotKeyboardFocus和GotMouseCapture事件上进行选择。这样它就能一直工作。

——编辑——

在这里添加一个例子来告诉人们如何解决上面提到的一些缺点:

private void TextBox_GotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
    // Fixes issue when clicking cut/copy/paste in context menu
    if (textBox.SelectionLength == 0) 
        textBox.SelectAll();
}

private void TextBox_LostMouseCapture(object sender, MouseEventArgs e)
{
    // If user highlights some text, don't override it
    if (textBox.SelectionLength == 0) 
        textBox.SelectAll();

    // further clicks will not select all
    textBox.LostMouseCapture -= TextBox_LostMouseCapture; 
}

private void TextBox_LostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
    // once we've left the TextBox, return the select all behavior
    textBox.LostMouseCapture += TextBox_LostMouseCapture;
}

从这里开始:

在App.xaml.cs文件中注册全局事件处理程序:

protected override void OnStartup(StartupEventArgs e)
{
    EventManager.RegisterClassHandler(typeof(TextBox),TextBox.GotFocusEvent,
    new RoutedEventHandler(TextBox_GotFocus));

    base.OnStartup(e);
}

那么处理程序就像这样简单:

private void TextBox_GotFocus(object sender, RoutedEventArgs e)
{
    (sender as TextBox).SelectAll();
}

#region TextBoxIDCard selection
private bool textBoxIDCardGotFocus = false;
private void TextBoxIDCard_GotFocus(object sender, RoutedEventArgs e)
{
    this.TextBoxIDCard.SelectAll();
}

private void TextBoxIDCard_LostFocus(object sender, RoutedEventArgs e)
{
    textBoxIDCardGotFocus = false;
}

private void TextBoxIDCard_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
    if (textBoxIDCardGotFocus == false)
    {
        e.Handled = true;
        this.TextBoxIDCard.Focus();
        textBoxIDCardGotFocus = true;
    }
} 
#endregion

一个简单的方法来覆盖鼠标向下和选择所有双击后:

public class DoubleClickTextBox: TextBox
{

    public override void EndInit()
    {
        base.EndInit();            
    }

    protected override void OnMouseEnter(System.Windows.Input.MouseEventArgs e)
    {
        base.OnMouseEnter(e);
        this.Cursor = Cursors.Arrow;
    }
    protected override void OnMouseDown(System.Windows.Input.MouseButtonEventArgs e)
    {

    }

    protected override void OnMouseDoubleClick(System.Windows.Input.MouseButtonEventArgs e)
    {
        base.OnMouseDown(e);
        this.SelectAll();
    }
}

这似乎对我有用……

private bool TextBoxFocusBool;

private void TextBox_GotFocus(object sender, RoutedEventArgs e)
{
    TextBoxFocusBool = true;
}

private void TextBox_LostMouseCapture(object sender, MouseEventArgs e)
{
    if (TextBox.SelectionLength == 0 & TextBoxFocusBool == true)
    {
        TextBox.SelectAll();
        TextBoxFocusBool = false;
    }
}

private void TextBox_LostFocus(object sender, RoutedEventArgs e)
{
    TextBoxFocusBool = true;
}