如果我从GotFocus事件处理程序中调用SelectAll,它对鼠标不起作用——鼠标一释放,选择就消失了。

编辑:人们喜欢唐纳利的回答,我将试着解释为什么我不像公认的答案那样喜欢它。

It is more complex, while the accepted answer does the same thing in a simpler way. The usability of accepted answer is better. When you click in the middle of the text, text gets unselected when you release the mouse allowing you to start editing instantly, and if you still want to select all, just press the button again and this time it will not unselect on release. Following Donelle's recipe, if I click in the middle of text, I have to click second time to be able to edit. If I click somewhere within the text versus outside of the text, this most probably means I want to start editing instead of overwriting everything.


当前回答

我发现这里给出的答案都没有模仿标准的Windows文本框。例如,尝试在文本框的最后一个字符和文本框右侧之间的空白区域单击。这里的大多数解决方案总是选择整个内容,这使得将文本添加到文本框非常困难。

我在这里给出的答案在这方面表现得更好。它是一个行为(因此它需要来自Blend SDK的System.Windows.Interactivity程序集)。也可以使用附加属性重写。

public sealed class SelectAllTextOnFocusBehavior : Behavior<TextBox>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.PreviewMouseLeftButtonDown += AssociatedObject_PreviewMouseLeftButtonDown;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        AssociatedObject.PreviewMouseLeftButtonDown -= AssociatedObject_PreviewMouseLeftButtonDown;
    }

    void AssociatedObject_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        // Find the textbox
        DependencyObject parent = e.OriginalSource as UIElement;
        while (parent != null && !(parent is TextBox))
            parent = VisualTreeHelper.GetParent(parent);

        var textBox = parent as TextBox;
        Debug.Assert(textBox != null);

        if (textBox.IsFocused) return;

        textBox.SelectAll();
        Keyboard.Focus(textBox);
        e.Handled = true;
    }
}

这是基于我在这里找到的代码。

其他回答

这对我来说似乎很有效。它基本上是一些早期帖子的重述。我只是把它放到构造函数的MainWindow.xaml.cs文件中。我创建了两个处理程序,一个用于键盘,一个用于鼠标,并将两个事件导入同一个函数HandleGotFocusEvent,该函数定义在同一个文件的构造函数之后。

public MainWindow()
{
   InitializeComponent();

   EventManager.RegisterClassHandler(typeof(TextBox), 
      UIElement.GotKeyboardFocusEvent,
      new RoutedEventHandler(HandleGotFocusEvent), true);
   EventManager.RegisterClassHandler(typeof(TextBox),
      UIElement.GotMouseCaptureEvent,
      new RoutedEventHandler(HandleGotFocusEvent), true);   
}
private void HandleGotFocusEvent(object sender, RoutedEventArgs e)
{
   if (sender is TextBox)
      (sender as TextBox).SelectAll();
}

对于那些对Donnelle /Groky的方法感兴趣,但想要点击最后一个字符的右边(但仍然在TextBox内),以将插入符号放在输入文本的末尾,我想出了这个解决方案:

int GetRoundedCharacterIndexFromPoint(TextBox textBox, Point clickedPoint)
{
    int position = textBox.GetCharacterIndexFromPoint(clickedPoint, true);

    // Check if the clicked point is actually closer to the next character
    // or if it exceeds the righmost character in the textbox
    // (in this case return increase the position by 1)
    Rect charLeftEdge = textBox.GetRectFromCharacterIndex(position, false);
    Rect charRightEdge = textBox.GetRectFromCharacterIndex(position, true);
    double charWidth = charRightEdge.X - charLeftEdge.X;
    if (clickedPoint.X + charWidth / 2 > charLeftEdge.X + charWidth) position++;

    return position;
}

void SelectivelyIgnoreMouseButton(object sender, MouseButtonEventArgs e)
{
    // Find the TextBox
    DependencyObject parent = e.OriginalSource as UIElement;
    while (parent != null && !(parent is TextBox))
        parent = VisualTreeHelper.GetParent(parent);

    if (parent != null)
    {
        var textBox = (TextBox)parent;
        if (!textBox.IsKeyboardFocusWithin)
        {
            // If the text box is not yet focused, give it the focus and
            // stop further processing of this click event.
            textBox.Focus();
            e.Handled = true;
        }
        else
        {
            int pos = GetRoundedCharacterIndexFromPoint(textBox, e.GetPosition(textBox));
            textBox.CaretIndex = pos;
        }
    }
}

void SelectAllText(object sender, RoutedEventArgs e)
{
    var textBox = e.OriginalSource as TextBox;
    if (textBox != null)
        textBox.SelectAll();
}

GetRoundedCharacterIndexFromPoint方法取自这篇文章。

下面是为方便您实现答案解决方案的Blend行为:

一个用于附加到单个文本框:

public class SelectAllTextOnFocusBehavior : Behavior<TextBox>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.GotKeyboardFocus += AssociatedObjectGotKeyboardFocus;
        AssociatedObject.GotMouseCapture += AssociatedObjectGotMouseCapture;
        AssociatedObject.PreviewMouseLeftButtonDown += AssociatedObjectPreviewMouseLeftButtonDown;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        AssociatedObject.GotKeyboardFocus -= AssociatedObjectGotKeyboardFocus;
        AssociatedObject.GotMouseCapture -= AssociatedObjectGotMouseCapture;
        AssociatedObject.PreviewMouseLeftButtonDown -= AssociatedObjectPreviewMouseLeftButtonDown;
    }

    private void AssociatedObjectGotKeyboardFocus(object sender,
        System.Windows.Input.KeyboardFocusChangedEventArgs e)
    {
        AssociatedObject.SelectAll();
    }

    private void AssociatedObjectGotMouseCapture(object sender,
        System.Windows.Input.MouseEventArgs e)
    {
        AssociatedObject.SelectAll();   
    }

    private void AssociatedObjectPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if(!AssociatedObject.IsKeyboardFocusWithin)
        {
            AssociatedObject.Focus();
            e.Handled = true;
        }
    }
}

一个用于附加到包含多个文本框的容器的根:

public class SelectAllTextOnFocusMultiBehavior : Behavior<UIElement>
{
    protected override void OnAttached()
    {
        base.OnAttached();
        AssociatedObject.GotKeyboardFocus += HandleKeyboardFocus;
        AssociatedObject.GotMouseCapture += HandleMouseCapture;
    }

    protected override void OnDetaching()
    {
        base.OnDetaching();
        AssociatedObject.GotKeyboardFocus -= HandleKeyboardFocus;
        AssociatedObject.GotMouseCapture -= HandleMouseCapture;
    }

    private static void HandleKeyboardFocus(object sender,
        System.Windows.Input.KeyboardFocusChangedEventArgs e)
    {
        var txt = e.NewFocus as TextBox;
        if (txt != null)
            txt.SelectAll();
    }

    private static void HandleMouseCapture(object sender,
        System.Windows.Input.MouseEventArgs e)
    {
        var txt = e.OriginalSource as TextBox;
        if (txt != null)
            txt.SelectAll();
    }
}

我用附加行为解决了这个问题,而不是谢尔盖回答中的表达式行为。这意味着我不需要依赖Blend SDK中的System.Windows.Interactivity:

public class TextBoxBehavior
{
    public static bool GetSelectAllTextOnFocus(TextBox textBox)
    {
        return (bool)textBox.GetValue(SelectAllTextOnFocusProperty);
    }

    public static void SetSelectAllTextOnFocus(TextBox textBox, bool value)
    {
        textBox.SetValue(SelectAllTextOnFocusProperty, value);
    }

    public static readonly DependencyProperty SelectAllTextOnFocusProperty =
        DependencyProperty.RegisterAttached(
            "SelectAllTextOnFocus",
            typeof (bool),
            typeof (TextBoxBehavior),
            new UIPropertyMetadata(false, OnSelectAllTextOnFocusChanged));

    private static void OnSelectAllTextOnFocusChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var textBox = d as TextBox;
        if (textBox == null) return;

        if (e.NewValue is bool == false) return;

        if ((bool) e.NewValue)
        {
            textBox.GotFocus += SelectAll;
            textBox.PreviewMouseDown += IgnoreMouseButton;
        }
        else
        {
            textBox.GotFocus -= SelectAll;
            textBox.PreviewMouseDown -= IgnoreMouseButton;
        }
    }

    private static void SelectAll(object sender, RoutedEventArgs e)
    {
        var textBox = e.OriginalSource as TextBox;
        if (textBox == null) return;
        textBox.SelectAll();
    }

    private static void IgnoreMouseButton(object sender, System.Windows.Input.MouseButtonEventArgs e)
    {
        var textBox = sender as TextBox;
        if (textBox == null || (!textBox.IsReadOnly && textBox.IsKeyboardFocusWithin)) return;

        e.Handled = true;
        textBox.Focus();
    }
}

然后你可以像这样在XAML中使用它:

<TextBox Text="Some Text" behaviors:TextBoxBehavior.SelectAllTextOnFocus="True"/>

我在这里写过博客。

最简单和完美的解决方案,是在文本框获得焦点后使用计时器选择所有文本20ms:

Dim WithEvents Timer作为新的DispatcherTimer()

设置间隔: 计时器。Interval = timspan . frommilliseconds (20)

响应事件(我在这里继承了TextBox控件,所以我重写了它的事件:

Protected Overrides Sub OnGotFocus(e As RoutedEventArgs)
        Timer.Start()
        MyBase.OnGotFocus(e)
    End Sub


    Private Sub Timer_Tick(sender As Object, e As EventArgs) Handles Timer.Tick
        Timer.Stop()
        Me.SelectAll()
    End Sub

这就是全部!