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.
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();
}
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改编自博士WPF解决方案，MSDN论坛
Donnelle的答案是最好的，但是必须派生一个新的类来使用它是一种痛苦。
我没有这样做，而是在App.xaml.cs中为应用程序中的所有文本框注册处理程序。这允许我使用一个标准的文本框控件唐纳利的答案。
在App.xaml.cs中添加以下方法:
public partial class App : Application
{
protected override void OnStartup(StartupEventArgs e)
{
// Select the text in a TextBox when it receives focus.
EventManager.RegisterClassHandler(typeof(TextBox), TextBox.PreviewMouseLeftButtonDownEvent,
new MouseButtonEventHandler(SelectivelyIgnoreMouseButton));
EventManager.RegisterClassHandler(typeof(TextBox), TextBox.GotKeyboardFocusEvent,
new RoutedEventHandler(SelectAllText));
EventManager.RegisterClassHandler(typeof(TextBox), TextBox.MouseDoubleClickEvent,
new RoutedEventHandler(SelectAllText));
base.OnStartup(e);
}
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;
}
}
}
void SelectAllText(object sender, RoutedEventArgs e)
{
var textBox = e.OriginalSource as TextBox;
if (textBox != null)
textBox.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。
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;
}
