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.
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();
}
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;
}
我们有它，所以第一次点击选择所有，另一次点击光标(我们的应用程序是设计用于平板电脑与笔)。
你可能会发现它很有用。
public class ClickSelectTextBox : TextBox
{
public ClickSelectTextBox()
{
AddHandler(PreviewMouseLeftButtonDownEvent,
new MouseButtonEventHandler(SelectivelyIgnoreMouseButton), true);
AddHandler(GotKeyboardFocusEvent,
new RoutedEventHandler(SelectAllText), true);
AddHandler(MouseDoubleClickEvent,
new RoutedEventHandler(SelectAllText), true);
}
private static 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 focussed, give it the focus and
// stop further processing of this click event.
textBox.Focus();
e.Handled = true;
}
}
}
private static void SelectAllText(object sender, RoutedEventArgs e)
{
var textBox = e.OriginalSource as TextBox;
if (textBox != null)
textBox.SelectAll();
}
}
我使用了Nils的答案，但将其转换为更灵活的答案。
public enum SelectAllMode
{
/// <summary>
/// On first focus, it selects all then leave off textbox and doesn't check again
/// </summary>
OnFirstFocusThenLeaveOff = 0,
/// <summary>
/// On first focus, it selects all then never selects
/// </summary>
OnFirstFocusThenNever = 1,
/// <summary>
/// Selects all on every focus
/// </summary>
OnEveryFocus = 2,
/// <summary>
/// Never selects text (WPF's default attitude)
/// </summary>
Never = 4,
}
public partial class TextBox : DependencyObject
{
public static readonly DependencyProperty SelectAllModeProperty = DependencyProperty.RegisterAttached(
"SelectAllMode",
typeof(SelectAllMode?),
typeof(TextBox),
new PropertyMetadata(SelectAllModePropertyChanged));
private static void SelectAllModePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (d is System.Windows.Controls.TextBox)
{
var textBox = d as System.Windows.Controls.TextBox;
if (e.NewValue != null)
{
textBox.GotKeyboardFocus += OnKeyboardFocusSelectText;
textBox.PreviewMouseLeftButtonDown += OnMouseLeftButtonDown;
}
else
{
textBox.GotKeyboardFocus -= OnKeyboardFocusSelectText;
textBox.PreviewMouseLeftButtonDown -= OnMouseLeftButtonDown;
}
}
}
private static void OnMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
DependencyObject dependencyObject = GetParentFromVisualTree(e.OriginalSource);
if (dependencyObject == null)
return;
var textBox = (System.Windows.Controls.TextBox)dependencyObject;
if (!textBox.IsKeyboardFocusWithin)
{
textBox.Focus();
e.Handled = true;
}
}
private static DependencyObject GetParentFromVisualTree(object source)
{
DependencyObject parent = source as UIElement;
while (parent != null && !(parent is System.Windows.Controls.TextBox))
{
parent = VisualTreeHelper.GetParent(parent);
}
return parent;
}
private static void OnKeyboardFocusSelectText(object sender, KeyboardFocusChangedEventArgs e)
{
var textBox = e.OriginalSource as System.Windows.Controls.TextBox;
if (textBox == null) return;
var selectAllMode = GetSelectAllMode(textBox);
if (selectAllMode == SelectAllMode.Never)
{
textBox.SelectionStart = 0;
textBox.SelectionLength = 0;
}
else
textBox.SelectAll();
if (selectAllMode == SelectAllMode.OnFirstFocusThenNever)
SetSelectAllMode(textBox, SelectAllMode.Never);
else if (selectAllMode == SelectAllMode.OnFirstFocusThenLeaveOff)
SetSelectAllMode(textBox, null);
}
[AttachedPropertyBrowsableForChildrenAttribute(IncludeDescendants = false)]
[AttachedPropertyBrowsableForType(typeof(System.Windows.Controls.TextBox))]
public static SelectAllMode? GetSelectAllMode(DependencyObject @object)
{
return (SelectAllMode)@object.GetValue(SelectAllModeProperty);
}
public static void SetSelectAllMode(DependencyObject @object, SelectAllMode? value)
{
@object.SetValue(SelectAllModeProperty, value);
}
}
在XAML中，你可以这样使用:
<!-- On first focus, it selects all then leave off textbox and doesn't check again -->
<TextBox attprop:TextBox.SelectAllMode="OnFirstFocusThenLeaveOff" />
<!-- On first focus, it selects all then never selects -->
<TextBox attprop:TextBox.SelectAllMode="OnFirstFocusThenNever" />
<!-- Selects all on every focus -->
<TextBox attprop:TextBox.SelectAllMode="OnEveryFocus" />
<!-- Never selects text (WPF's default attitude) -->
<TextBox attprop:TextBox.SelectAllMode="Never" />
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();
}
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();
}
}
