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.
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。
我已经测试了所有的，但只有以下工作:
protected override void OnStartup(StartupEventArgs e)
{
EventManager.RegisterClassHandler(typeof(TextBox), UIElement.PreviewMouseLeftButtonDownEvent,
new MouseButtonEventHandler(SelectivelyHandleMouseButton), true);
EventManager.RegisterClassHandler(typeof(TextBox), UIElement.GotKeyboardFocusEvent,
new RoutedEventHandler(SelectAllText), true);
EventManager.RegisterClassHandler(typeof(TextBox), UIElement.GotFocusEvent,
new RoutedEventHandler(GotFocus), true);
}
private static void SelectivelyHandleMouseButton(object sender, MouseButtonEventArgs e)
{
var textbox = (sender as TextBox);
if (textbox != null)
{
int hc = textbox.GetHashCode();
if (hc == LastHashCode)
{
if (e.OriginalSource.GetType().Name == "TextBoxView")
{
e.Handled = true;
textbox.Focus();
LastHashCode = -1;
}
}
}
if (textbox != null) textbox.Focus();
}
private static void SelectAllText(object sender, RoutedEventArgs e)
{
var textBox = e.OriginalSource as TextBox;
if (textBox != null)
textBox.SelectAll();
}
private static int LastHashCode;
private static void GotFocus(object sender, RoutedEventArgs e)
{
var textBox = e.OriginalSource as TextBox;
if (textBox != null)
LastHashCode = textBox.GetHashCode();
}
我选择了部分Donnelle的答案(跳过双击)，因为我认为这更自然。然而，像grokies一样，我不喜欢创建派生类的需要。但我也不喜欢Grokys的OnStartup方法。我需要在“一般但不总是”的基础上这样做。
我已经实现了这作为一个附加的DependencyProperty，所以我可以设置local:SelectTextOnFocus。在xaml中Active =“True”。我觉得这种方式最令人愉快。
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
public class SelectTextOnFocus : DependencyObject
{
public static readonly DependencyProperty ActiveProperty = DependencyProperty.RegisterAttached(
"Active",
typeof(bool),
typeof(SelectTextOnFocus),
new PropertyMetadata(false, ActivePropertyChanged));
private static void ActivePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (d is TextBox)
{
TextBox textBox = d as TextBox;
if ((e.NewValue as bool?).GetValueOrDefault(false))
{
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 = (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 TextBox))
{
parent = VisualTreeHelper.GetParent(parent);
}
return parent;
}
private static void OnKeyboardFocusSelectText(object sender, KeyboardFocusChangedEventArgs e)
{
TextBox textBox = e.OriginalSource as TextBox;
if (textBox != null)
{
textBox.SelectAll();
}
}
[AttachedPropertyBrowsableForChildrenAttribute(IncludeDescendants = false)]
[AttachedPropertyBrowsableForType(typeof(TextBox))]
public static bool GetActive(DependencyObject @object)
{
return (bool) @object.GetValue(ActiveProperty);
}
public static void SetActive(DependencyObject @object, bool value)
{
@object.SetValue(ActiveProperty, value);
}
}
对于我的“一般但不总是”功能，我在(全局)文本框样式中将这个附件属性设置为True。这样，“选择文本”总是“打开”的，但我可以在每个文本框的基础上禁用它。
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();
}
}
