C# 如果需要，显示 WPF 工具提示
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Show WPF Tooltip if needed
提问by Martin Konicek
I have a TextBlock inside a limited-size control. If the text is too long to fit into the control, I'd like to show a tooltip with full text. This is a classic behavior you surely know from many apps.
我在大小有限的控件中有一个 TextBlock。如果文本太长而不适合控件，我想显示带有全文的工具提示。这是您从许多应用程序中肯定知道的经典行为。
I tried using a Converter to convert TextBlock width into Tooltip's Visibility.
我尝试使用转换器将 TextBlock 宽度转换为工具提示的可见性。
<GridViewColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Text}">
<TextBlock.ToolTip>
<ToolTip
DataContext="{TemplateBinding Content}"
Visibility="{Binding Converter={StaticResource visConvert}}">
<TextBlock Text="{Binding Text}"></TextBlock>
</ToolTip>
</TextBlock.ToolTip>
</TextBlock>
</DataTemplate>
</GridViewColumn.CellTemplate>
The problem is that in the Converter:
问题是在转换器中：
public object Convert(object value, ...
'value' is the DataBound item. I'd like the 'value' to be the TextBlock, to observe its Width, and compare it to the GridViewColumn.Width.
'value' 是 DataBound 项。我希望“值”是 TextBlock，以观察其宽度，并将其与 GridViewColumn.Width 进行比较。
采纳答案by Martin Konicek
I figured it out, the Tooltip has PlacementTargetproperty that specifies the UI element that has the Tooltip. In case anyone needs it:
我想通了，工具提示具有PlacementTarget属性，该属性指定具有工具提示的 UI 元素。如果有人需要它：
<TextBlock Text="{Binding Text}">
<TextBlock.ToolTip>
<ToolTip
DataContext="{Binding Path=PlacementTarget, RelativeSource={x:Static RelativeSource.Self}}"
Visibility="{Binding Converter={StaticResource toolVisConverter}}">
<TextBlock Text="{Binding Text}"/> <!-- tooltip content -->
</ToolTip>
</TextBlock.ToolTip>
</TextBlock>
And then write a Converter that converts TextBlock to Visibility (based on TextBlock width).
然后编写一个转换器，将 TextBlock 转换为 Visibility（基于 TextBlock 宽度）。
回答by Zyphrax
I would think you have to look at a ControlTemplate trigger to solve this problem. Unfortunately ControlTemplate triggers always compare with a specific value, not less than or greater than. You can make it appear e.g. if the Width = 100, not Width < 100.
我认为您必须查看 ControlTemplate 触发器才能解决此问题。不幸的是 ControlTemplate 触发器总是与特定值进行比较，而不是小于或大于。你可以让它出现，例如如果宽度 = 100，而不是宽度 < 100。
回答by Martin Konicek
Ok, so why do it the hard XAML-only way? This works:
好的，那么为什么要采用仅 XAML 的硬方式呢？这有效：
<TextBlock Text="{Binding Text}"
IsMouseDirectlyOverChanged="TextBlock_IsMouseDirectlyOverChanged" >
<TextBlock.ToolTip>
<ToolTip Visibility="Collapsed">
<TextBlock Text="{Binding Text}"></TextBlock>
</ToolTip>
</TextBlock.ToolTip>
</TextBlock>
in Control.xaml.cs:
在 Control.xaml.cs 中：
private void TextBlock_IsMouseDirectlyOverChanged(object sender, DependencyPropertyChangedEventArgs e)
{
bool isMouseOver = (bool)e.NewValue;
if (!isMouseOver)
return;
TextBlock textBlock = (TextBlock)sender;
bool needed = textBlock.ActualWidth >
(this.listView.View as GridView).Columns[2].ActualWidth;
((ToolTip)textBlock.ToolTip).Visibility =
needed ? Visibility.Visible : Visibility.Collapsed;
}
