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

在谷歌搜索和测试之后,我找到了一个简单的解决方案。

你需要在容器窗口的Loaded事件中添加一个事件处理程序:

private void yourwindow_Loaded(object sender, RoutedEventArgs e)
{
    EventManager.RegisterClassHandler(typeof(TextBox),
        TextBox.PreviewMouseLeftButtonDownEvent,
        new RoutedEventHandler(SelectivelyIgnoreMouseButton));
}

接下来,你必须创建之前代码中引用的RoutedEventHandler的处理程序:

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

现在,你可以单独将GotFocus事件处理程序上的SelectAll()命令添加到任何TextBox控件:

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

您的文本现在被选中对焦!

改编自博士WPF解决方案,MSDN论坛

这个简单的实现非常适合我:

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

void TextBox_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
    var TextBox = (TextBox) sender;
    if (!TextBox.IsKeyboardFocusWithin)
    {
        TextBox.Focus();
        e.Handled = true;
    }
}

把它应用到所有的文本框,把下面的代码InitializeComponent();

EventManager.RegisterClassHandler(typeof(TextBox), TextBox.GotFocusEvent, new RoutedEventHandler(TextBox_GotFocus));
EventManager.RegisterClassHandler(typeof(TextBox), TextBox.PreviewMouseDownEvent, new MouseButtonEventHandler(TextBox_PreviewMouseDown));

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();
}

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;
}

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();
                }
            );
        });
    }
}