Show WPF Tooltip if needed

Question

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.

I tried using a Converter to convert TextBlock width into Tooltip's Visibility.

<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:

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.

Answer 1

I figured it out, the Tooltip has PlacementTarget property that specifies the UI element that has the Tooltip. In case anyone needs it:

<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).