下面的文本块如预期一样换行并裁剪。当文本被裁剪时，显示省略号"..."。
<TextBlock
MaxWidth="60"
MaxHeight="60"
Text="This is some long text which I would like to wrap."
TextWrapping="Wrap"
TextTrimming="CharacterEllipsis" />
我想在被截断的文本上方显示一个包含完整文本的工具提示，但只有在文本被截断时才显示。我不确定如何可靠地确定是否正在显示“…”。
如何确定文本是否被截断？
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace TextBlockService
{
//Based on the project from http://web.archive.org/web/20130316081653/http://tranxcoder.wordpress.com/2008/10/12/customizing-lookful-wpf-controls-take-2/
public static class TextBlockService
{
static TextBlockService()
{
// Register for the SizeChanged event on all TextBlocks, even if the event was handled.
EventManager.RegisterClassHandler(
typeof(TextBlock),
FrameworkElement.SizeChangedEvent,
new SizeChangedEventHandler(OnTextBlockSizeChanged),
true);
}
private static readonly DependencyPropertyKey IsTextTrimmedKey = DependencyProperty.RegisterAttachedReadOnly("IsTextTrimmed",
typeof(bool),
typeof(TextBlockService),
new PropertyMetadata(false));
public static readonly DependencyProperty IsTextTrimmedProperty = IsTextTrimmedKey.DependencyProperty;
[AttachedPropertyBrowsableForType(typeof(TextBlock))]
public static Boolean GetIsTextTrimmed(TextBlock target)
{
return (Boolean)target.GetValue(IsTextTrimmedProperty);
}
public static readonly DependencyProperty AutomaticToolTipEnabledProperty = DependencyProperty.RegisterAttached(
"AutomaticToolTipEnabled",
typeof(bool),
typeof(TextBlockService),
new FrameworkPropertyMetadata(true, FrameworkPropertyMetadataOptions.Inherits));
[AttachedPropertyBrowsableForType(typeof(DependencyObject))]
public static Boolean GetAutomaticToolTipEnabled(DependencyObject element)
{
if (null == element)
{
throw new ArgumentNullException("element");
}
return (bool)element.GetValue(AutomaticToolTipEnabledProperty);
}
public static void SetAutomaticToolTipEnabled(DependencyObject element, bool value)
{
if (null == element)
{
throw new ArgumentNullException("element");
}
element.SetValue(AutomaticToolTipEnabledProperty, value);
}
private static void OnTextBlockSizeChanged(object sender, SizeChangedEventArgs e)
{
TriggerTextRecalculation(sender);
}
private static void TriggerTextRecalculation(object sender)
{
var textBlock = sender as TextBlock;
if (null == textBlock)
{
return;
}
if (TextTrimming.None == textBlock.TextTrimming)
{
textBlock.SetValue(IsTextTrimmedKey, false);
}
else
{
//If this function is called before databinding has finished the tooltip will never show.
//This invoke defers the calculation of the text trimming till after all current pending databinding
//has completed.
var isTextTrimmed = textBlock.Dispatcher.Invoke(() => CalculateIsTextTrimmed(textBlock), DispatcherPriority.DataBind);
textBlock.SetValue(IsTextTrimmedKey, isTextTrimmed);
}
}
private static bool CalculateIsTextTrimmed(TextBlock textBlock)
{
if (!textBlock.IsArrangeValid)
{
return GetIsTextTrimmed(textBlock);
}
Typeface typeface = new Typeface(
textBlock.FontFamily,
textBlock.FontStyle,
textBlock.FontWeight,
textBlock.FontStretch);
// FormattedText is used to measure the whole width of the text held up by TextBlock container
FormattedText formattedText = new FormattedText(
textBlock.Text,
System.Threading.Thread.CurrentThread.CurrentCulture,
textBlock.FlowDirection,
typeface,
textBlock.FontSize,
textBlock.Foreground);
formattedText.MaxTextWidth = textBlock.ActualWidth;
// When the maximum text width of the FormattedText instance is set to the actual
// width of the textBlock, if the textBlock is being trimmed to fit then the formatted
// text will report a larger height than the textBlock. Should work whether the
// textBlock is single or multi-line.
// The "formattedText.MinWidth > formattedText.MaxTextWidth" check detects if any
// single line is too long to fit within the text area, this can only happen if there is a
// long span of text with no spaces.
return (formattedText.Height > textBlock.ActualHeight || formattedText.MinWidth > formattedText.MaxTextWidth);
}
}
}
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:tbs="clr-namespace:TextBlockService">
<!--
Rather than forcing *all* TextBlocks to adopt TextBlockService styles,
using x:Key allows a more friendly opt-in model.
-->
<Style TargetType="TextBlock" x:Key="TextBlockService">
<Style.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="tbs:TextBlockService.AutomaticToolTipEnabled" Value="True" />
<Condition Property="tbs:TextBlockService.IsTextTrimmed" Value="True"/>
</MultiTrigger.Conditions>
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=Text}" />
</MultiTrigger>
</Style.Triggers>
</Style>
</ResourceDictionary>
我最近没有做过太多WPF方面的工作，所以我不确定这是否是您要找的内容，但请看这篇文章：自定义“好看”的WPF控件 - 第二部分。它有点复杂，但似乎解决了您提出的同样问题。更新：该网站似乎已经不存在了，但您可以在档案中找到这篇文章。请参考Scott Chamberlain的答案和示例代码（感谢Scott）。
如果TextBlock是ListBoxItem DataTemplate的一部分，上面的解决方案对我无效。我提出另一个解决方案：
public class MyTextBlock : System.Windows.Controls.TextBlock
{
protected override void OnToolTipOpening(WinControls.ToolTipEventArgs e)
{
if (TextTrimming != TextTrimming.None)
{
e.Handled = !IsTextTrimmed();
}
}
private bool IsTextTrimmed()
{
Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
return ActualWidth < DesiredSize.Width;
}
}
<MyTextBlock Text="{Binding Text}" TextTrimming="CharacterEllipsis" ToolTip="{Binding Text}" />
在bidy的回答基础上进行扩展。这将创建一个只在未显示所有文本时显示工具提示的TextBlock。 工具提示将被调整大小以适应内容（与默认工具提示不同，后者将保持单行框并截断文本）。
using System;
using System.Windows;
using System.Windows.Controls;
namespace MyComponents
{
public class CustomTextBlock : TextBlock
{
protected override void OnInitialized(EventArgs e)
{
// we want a tooltip that resizes to the contents -- a textblock with TextWrapping.Wrap will do that
var toolTipTextBlock = new TextBlock();
toolTipTextBlock.TextWrapping = TextWrapping.Wrap;
// bind the tooltip text to the current textblock Text binding
var binding = GetBindingExpression(TextProperty);
if (binding != null)
{
toolTipTextBlock.SetBinding(TextProperty, binding.ParentBinding);
}
var toolTipPanel = new StackPanel();
toolTipPanel.Children.Add(toolTipTextBlock);
ToolTip = toolTipPanel;
base.OnInitialized(e);
}
protected override void OnToolTipOpening(ToolTipEventArgs e)
{
if (TextTrimming != TextTrimming.None)
{
e.Handled = !IsTextTrimmed();
}
}
private bool IsTextTrimmed()
{
Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
return ActualWidth < DesiredSize.Width;
}
}
}
XAML使用：
<Window ...
xmlns:components="clr-namespace:MyComponents"
... >
<components:CustomTextBlock Text="{Binding Details}" TextTrimming="CharacterEllipsis" />
我在使用Alex的答案时遇到了一些小问题，不得不稍微改变我的逻辑来澄清文本块中的文本是否被修剪。
var formattedText = new FormattedText(
Text, System.Threading.Thread.CurrentThread.CurrentCulture, FlowDirection, typeface, FontSize,
Foreground, VisualTreeHelper.GetDpi( this ).PixelsPerDip ) { MaxTextWidth = ActualWidth };
//Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
return ( Math.Floor(formattedText.Height ) > ActualHeight || Math.Floor( formattedText.MinWidth ) > ActualWidth;
这对我来说完美地运作。
我定义了一个启用省略号的 TextBlock 用户控件。然后，我为 OnMouseUp 和 OnMouseDown 定义了 2 个函数，以便当用户单击具有溢出的文本块时，它会显示一个带有完整值的工具提示。
这是 OnMouseDown 函数。
private void TextBlockWithToolTipView_OnMouseDown(
object sender,
MouseButtonEventArgs e )
{
var typeface = new Typeface(
FontFamily,
FontStyle,
FontWeight,
FontStretch);
var formattedText = new FormattedText(
Text, System.Threading.Thread.CurrentThread.CurrentCulture, FlowDirection, typeface, FontSize,
Foreground, VisualTreeHelper.GetDpi( this ).PixelsPerDip ) { MaxTextWidth = ActualWidth };
if (Math.Floor(formattedText.Height) > ActualHeight || Math.Floor(formattedText.MinWidth) > ActualWidth )
{
if( ToolTip is ToolTip tt )
{
{
if( tt.PlacementTarget == null )
{
tt.PlacementTarget = this;
}
tt.IsOpen = true;
e.Handled = true;
}
}
}
}
这是 Xaml 的部分
<TextBlock
ToolTipService.IsEnabled="True"
MouseDown="TextBlockWithToolTipView_OnMouseDown"
MouseLeave="TextBlockWithToolTipView_OnMouseLeave"
TextTrimming="CharacterEllipsis"
TextWrapping="WrapWithOverflow">
<TextBlock.ToolTip>
<ToolTip
DataContext="{Binding Path=PlacementTarget, RelativeSource={x:Static RelativeSource.Self}}">
<TextBlock Text="{Binding Path=Text, Mode=OneWay }"
TextWrapping="Wrap"/>
</ToolTip>
</TextBlock.ToolTip>
</TextBlock>
AutomaticToolTipEnabled启用它。（响应于代码注释“与其强制所有TextBlock采用TextBlockService样式， 使用x:Key可以采用更友好的选择模型。”） - Kelly EltonformattedText.Height始终比textBlock.ActualHeight大 0.04。换句话说，单行的formattedText.Height - textBlock.ActualHeight等于 0.04，两行时则为 0.08。 - huang