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" />
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;
}
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。
哇!读完以上所有内容后，我发现自己不知所措。我从这篇文章中学到了一些东西，并尝试了一些完全不同的东西。当文本框获得焦点时，我使用这个来选择文本:
private void TextField_GotFocus(object sender, RoutedEventArgs e)
{
TextBox tb = (sender as Textbox);
if(tb != null)
{
e.Handled = true;
tb.Focus();
tb.SelectAll();
}
}
将文本框的GotFocus属性设置为该方法。
运行应用程序并在文本框中单击一次，将突出显示文本框中已经存在的所有内容。
如果目标确实是在用户单击文本框时选择文本，这看起来很简单，涉及的代码也少了很多。只是说……
