<TextBlock Width="100" Text="The quick brown fox jumps over the lazy dog" TextTrimming="WordEllipsis">
<TextBlock.ToolTip>
<ToolTip DataContext="{Binding Path=PlacementTarget, RelativeSource={x:Static RelativeSource.Self}}">
<TextBlock Text="{Binding Text}"/>
</ToolTip>
</TextBlock.ToolTip>
</TextBlock>
如何仅在修剪文字时显示ToolTip？就像windows desktp快捷方式图标一样。
答案 0 :(得分：15)
在Eyjafj工作......无论如何，我到达了一个工作的，主要是声明性的解决方案，至少不需要自定义控制。要克服的第一个障碍是进入TextBlock。因为ToolTip是在可视树之外呈现的，所以不能使用RelativeSource绑定或ElementName来获取TextBlock。幸运的是，ToolTip类通过PlacementTarget属性提供对其相关元素的引用。因此，您可以将ToolTip的Visibility属性绑定到ToolTip本身，并使用其PlacementTarget属性来访问TextBlock的属性：
<ToolTip Visibility="{Binding RelativeSource={RelativeSource Self}, Path=PlacementTarget, Converter={StaticResource trimmedVisibilityConverter}}">
下一步是使用转换器来查看我们必须确定的TextBlock是否应该可见。您可以使用ActualWidth和DesiredSize执行此操作。 ActualWidth正是它听起来的样子; TextBlock在屏幕上呈现的宽度。 DesiredSize是TextBlock更喜欢的宽度。唯一的问题是，DesiredSize似乎考虑了TextTrimming，并没有给你完整的，未修剪的文本的宽度。为了解决这个问题，我们可以重新调用通过Double.Positive infinity传递的Measure方法，实际上，如果TextBlock的宽度没有受到限制，它会询问TextBlock的宽度。这会更新DesiredSize属性，然后我们可以进行比较：
textBlock.Measure(new Size(Double.PositiveInfinity, Double.PositiveInfinity));
if (((FrameworkElement)value).ActualWidth < ((FrameworkElement)value).DesiredSize.Width)
return Visibility.Visible;
如果您想自动将其应用于TextBlocks，或者不想浪费资源来创建始终不可见的工具提示，则此方法实际上是here as an attached behavior。以下是我的示例的完整代码：
转换器：
public class TrimmedTextBlockVisibilityConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value == null) return Visibility.Collapsed;
FrameworkElement textBlock = (FrameworkElement)value;
textBlock.Measure(new System.Windows.Size(Double.PositiveInfinity, Double.PositiveInfinity));
if (((FrameworkElement)value).ActualWidth < ((FrameworkElement)value).DesiredSize.Width)
return Visibility.Visible;
else
return Visibility.Collapsed;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
XAML：
<UserControl.Resources>
<local:TrimmedTextBlockVisibilityConverter x:Key="trimmedVisibilityConverter" />
</UserControl.Resources>
....
<TextBlock TextTrimming="CharacterEllipsis" Text="{Binding SomeTextProperty}">
<TextBlock.ToolTip>
<ToolTip Visibility="{Binding RelativeSource={RelativeSource Self}, Path=PlacementTarget, Converter={StaticResource trimmedVisibilityConverter}}">
<ToolTip.Content>
<TextBlock Text="{Binding SomeTextProperty}"/>
</ToolTip.Content>
</ToolTip>
</TextBlock.ToolTip>
</TextBlock>
答案 1 :(得分：8)
基于此页面上的想法以及来自another answer的其他算法更正，我制作了非常便携的类，可以非常轻松地使用。它的目的是在修剪文本时启用修剪并在TextBlock上显示工具提示，就像许多应用程序中已知的一样。
在我的应用中，修剪检测已被证明是精确的。当显示修剪省略号时，工具提示会准确显示。
<!-- xmlns:ui="clr-namespace:Unclassified.UI" -->
<TextBlock Text="Demo" ui:TextBlockAutoToolTip.Enabled="True"/>
var textBlock = new TextBlock { Text = "Demo" };
TextBlockAutoToolTip.SetEnabled(textBlock, true);
using System;
using System.Globalization;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Media;
namespace Unclassified.UI
{
/// <summary>
/// Shows a ToolTip over a TextBlock when its text is trimmed.
/// </summary>
public class TextBlockAutoToolTip
{
/// <summary>
/// The Enabled attached property.
/// </summary>
public static readonly DependencyProperty EnabledProperty = DependencyProperty.RegisterAttached(
"Enabled",
typeof(bool),
typeof(TextBlockAutoToolTip),
new FrameworkPropertyMetadata(new PropertyChangedCallback(OnAutoToolTipEnabledChanged)));
/// <summary>
/// Sets the Enabled attached property on a TextBlock control.
/// </summary>
/// <param name="dependencyObject">The TextBlock control.</param>
/// <param name="enabled">The value.</param>
public static void SetEnabled(DependencyObject dependencyObject, bool enabled)
{
dependencyObject.SetValue(EnabledProperty, enabled);
}
private static readonly TrimmedTextBlockVisibilityConverter ttbvc = new TrimmedTextBlockVisibilityConverter();
private static void OnAutoToolTipEnabledChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs args)
{
TextBlock textBlock = dependencyObject as TextBlock;
if (textBlock != null)
{
bool enabled = (bool)args.NewValue;
if (enabled)
{
var toolTip = new ToolTip
{
Placement = System.Windows.Controls.Primitives.PlacementMode.Relative,
VerticalOffset = -3,
HorizontalOffset = -5,
Padding = new Thickness(4, 2, 4, 2),
Background = Brushes.White
};
toolTip.SetBinding(UIElement.VisibilityProperty, new System.Windows.Data.Binding
{
RelativeSource = new System.Windows.Data.RelativeSource(System.Windows.Data.RelativeSourceMode.Self),
Path = new PropertyPath("PlacementTarget"),
Converter = ttbvc
});
toolTip.SetBinding(ContentControl.ContentProperty, new System.Windows.Data.Binding
{
RelativeSource = new System.Windows.Data.RelativeSource(System.Windows.Data.RelativeSourceMode.Self),
Path = new PropertyPath("PlacementTarget.Text")
});
toolTip.SetBinding(Control.ForegroundProperty, new System.Windows.Data.Binding
{
RelativeSource = new System.Windows.Data.RelativeSource(System.Windows.Data.RelativeSourceMode.Self),
Path = new PropertyPath("PlacementTarget.Foreground")
});
textBlock.ToolTip = toolTip;
textBlock.TextTrimming = TextTrimming.CharacterEllipsis;
}
}
}
private class TrimmedTextBlockVisibilityConverter : IValueConverter
{
// Source 1: https://stackoverflow.com/a/21863054
// Source 2: https://stackoverflow.com/a/25436070
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var textBlock = value as TextBlock;
if (textBlock == null)
return Visibility.Collapsed;
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,
VisualTreeHelper.GetDpi(textBlock).PixelsPerDip);
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 width 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.
bool isTrimmed = formattedText.Height > textBlock.ActualHeight ||
formattedText.MinWidth > formattedText.MaxTextWidth;
return isTrimmed ? Visibility.Visible : Visibility.Collapsed;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
}
}
答案 2 :(得分：6)
我找到了最简单的解决方案来扩展TextBlock并比较文本长度以确定是否显示工具提示，即
public class ToolTipTextBlock : TextBlock
{
protected override void OnToolTipOpening(ToolTipEventArgs e)
{
if (TextTrimming != TextTrimming.None)
{
e.Handled = !IsTextTrimmed();
}
}
private bool IsTextTrimmed()
{
var typeface = new Typeface(FontFamily, FontStyle, FontWeight, FontStretch);
var formattedText = new FormattedText(Text, CultureInfo.CurrentCulture, FlowDirection, typeface, FontSize, Foreground);
return formattedText.Width > ActualWidth;
}
}
然后只需在xaml中使用此自定义文本块，如下所示：
<local:ToolTipTextBlock Text="This is some text that I'd like to show tooltip for!"
TextTrimming="CharacterEllipsis"
ToolTip="{Binding Text,RelativeSource={RelativeSource Self}}"
MaxWidth="10"/>
答案 3 :(得分：5)
行为就是爱，行为才是生命。
public class TextBlockAutoToolTipBehavior : Behavior<TextBlock>
{
private ToolTip _toolTip;
protected override void OnAttached()
{
base.OnAttached();
_toolTip = new ToolTip
{
Placement = PlacementMode.Relative,
VerticalOffset = 0,
HorizontalOffset = 0
};
ToolTipService.SetShowDuration(_toolTip, int.MaxValue);
_toolTip.SetBinding(ContentControl.ContentProperty, new Binding
{
Path = new PropertyPath("Text"),
Source = AssociatedObject
});
AssociatedObject.TextTrimming = TextTrimming.CharacterEllipsis;
AssociatedObject.AddValueChanged(TextBlock.TextProperty, TextBlockOnTextChanged);
AssociatedObject.SizeChanged += AssociatedObjectOnSizeChanged;
}
protected override void OnDetaching()
{
base.OnDetaching();
AssociatedObject.RemoveValueChanged(TextBlock.TextProperty, TextBlockOnTextChanged);
AssociatedObject.SizeChanged -= AssociatedObjectOnSizeChanged;
}
private void AssociatedObjectOnSizeChanged(object sender, SizeChangedEventArgs sizeChangedEventArgs)
{
CheckToolTipVisibility();
}
private void TextBlockOnTextChanged(object sender, EventArgs eventArgs)
{
CheckToolTipVisibility();
}
private void CheckToolTipVisibility()
{
if (AssociatedObject.ActualWidth == 0)
Dispatcher.BeginInvoke(
new Action(
() => AssociatedObject.ToolTip = CalculateIsTextTrimmed(AssociatedObject) ? _toolTip : null),
DispatcherPriority.Loaded);
else
AssociatedObject.ToolTip = CalculateIsTextTrimmed(AssociatedObject) ? _toolTip : null;
}
//Source: https://stackoverflow.com/questions/1041820/how-can-i-determine-if-my-textblock-text-is-being-trimmed
private static bool CalculateIsTextTrimmed(TextBlock 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) {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 width 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);
}
}
用法：
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:behavior="clr-namespace:MyWpfApplication.Behavior"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity">
<TextBlock Text="{Binding Text}">
<i:Interaction.Behaviors>
<behavior:TextBlockAutoToolTipBehavior />
</i:Interaction.Behaviors>
</TextBlock>
</Window>
所需的扩展方法：
public static class UITools
{
public static void AddValueChanged<T>(this T obj, DependencyProperty property, EventHandler handler)
where T : DependencyObject
{
var desc = DependencyPropertyDescriptor.FromProperty(property, typeof (T));
desc.AddValueChanged(obj, handler);
}
public static void RemoveValueChanged<T>(this T obj, DependencyProperty property, EventHandler handler)
where T : DependencyObject
{
var desc = DependencyPropertyDescriptor.FromProperty(property, typeof (T));
desc.RemoveValueChanged(obj, handler);
}
}
答案 4 :(得分：2)
我认为您可以创建一个转换器，在ActualWidth textblock和DesiredSize.Width之间进行比较，然后返回Visibility。
答案 5 :(得分：1)
发布附加属性here的替代答案，我认为这比使用转换器或派生的TextBlock控件更好。
答案 6 :(得分：0)
我使用了@pogosoma 的this，但是@snicker 的CalculateIsTextTrimmed 函数非常完美
private static void SetTooltipBasedOnTrimmingState(TextBlock tb)
{
Typeface typeface = new Typeface(tb.FontFamily, tb.FontStyle, tb.FontWeight, tb.FontStretch);
FormattedText formattedText = new FormattedText(tb.Text, System.Threading.Thread.CurrentThread.CurrentCulture, tb.FlowDirection, typeface, tb.FontSize, tb.Foreground)
{ MaxTextWidth = tb.ActualWidth };
bool isTextTrimmed = (formattedText.Height > tb.ActualHeight || formattedText.MinWidth > formattedText.MaxTextWidth);
ToolTipService.SetToolTip(tb, isTextTrimmed ? tb.ToolTip : null);
}