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

我对此有一个稍微简化的答案(只有PreviewMouseLeftButtonDown事件),这似乎模仿了浏览器的常用功能:

在XAML中,你有一个文本框说:

<TextBox Text="http://www.blabla.com" BorderThickness="2" BorderBrush="Green" VerticalAlignment="Center" Height="25"
                 PreviewMouseLeftButtonDown="SelectAll" />

在后台代码:

private void SelectAll(object sender, MouseButtonEventArgs e)
{
    TextBox tb = (sender as TextBox);

    if (tb == null)
    {
        return;
    }

    if (!tb.IsKeyboardFocusWithin)
    {
        tb.SelectAll();
        e.Handled = true;
        tb.Focus();
    }
}

其他回答

在MSDN上有一个非常好的非常简单的解决方案:

<TextBox
    MouseDoubleClick="SelectAddress"
    GotKeyboardFocus="SelectAddress"
    PreviewMouseLeftButtonDown="SelectivelyIgnoreMouseButton" />

下面是背后的代码:

private void SelectAddress(object sender, RoutedEventArgs e)
{
    TextBox tb = (sender as TextBox);
    if (tb != null)
    {
        tb.SelectAll();
    }
}

private void SelectivelyIgnoreMouseButton(object sender,
    MouseButtonEventArgs e)
{
    TextBox tb = (sender as TextBox);
    if (tb != null)
    {
        if (!tb.IsKeyboardFocusWithin)
        {
            e.Handled = true;
            tb.Focus();
        }
    }
}

以下是@Nasenbaer发布的答案的c#版本

private delegate void TextBoxSelectAllDelegate(object sender);

private void TextBoxSelectAll(object sender)
{
    (sender as System.Windows.Controls.TextBox).SelectAll();
}

private void MyTextBox_GotFocus(object sender, System.Windows.RoutedEventArgs e)
{
    TextBoxSelectAllDelegate d = TextBoxSelectAll;

    this.Dispatcher.BeginInvoke(d,
        System.Windows.Threading.DispatcherPriority.ApplicationIdle, sender);
}

而MyTextBox_GotFocus是分配给MyTextBox的GotFocus事件的事件处理程序。

我使用这个代码

  private void txtNav_GotFocus(object sender, RoutedEventArgs e)
            {
                e.Handled = true;
                var c = new DispatcherTimer();
                c.Interval = TimeSpan.FromMilliseconds(100);
                c.Tick += (a1, a2) =>
                {
                    c.IsEnabled = false;
                    txtNav.SelectAll();
                };
                c.IsEnabled = true;
    
            }

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;
}

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();
    }
}