Automatic tooltip when text is trimmed in DataGrid

问题

My application runs with C# and WPF (.net framework 4.0). My goal is to have a DataGrid in which the text in the cells is trimmed with an ellipsis, and automatically has a tooltip with the full text displayed only if the text in the cell is actually trimmed.

Solution 1: I'm currently using this to know if the text is trimmed or not: http://tranxcoder.wordpress.com/2008/10/12/customizing-lookful-wpf-controls-take-2/ The problem is that it only works when I resize the columns. The tooltips don't show up when the DataGrid is first loaded, when the columns are sorted, or when the ItemSource of the DataGrid is updated.

Solution 2: I've also tried this:http://www.scottlogic.com/blog/2011/01/31/automatically-showing-tooltips-on-a-trimmed-textblock-silverlight-wpf.html But the tooltips never appear on my DataGrid cells, while it works fine with isolated textblocks.

I'm looking for simple ways to improve Solution 1 and make it work in my DataGrid in all cases, or maybe a different approach.

The style for Solution 1:

<UserControl.Resources>
    <Style x:Key="TextColumnElementStyle" TargetType="TextBlock" BasedOn="{StaticResource TextBlockService}">
        <Style.Setters>
            <Setter Property="TextWrapping" Value="NoWrap" />
            <Setter Property="TextTrimming" Value="WordEllipsis" />
        </Style.Setters>
    </Style>
</UserControl.Resources>

The source code of the TextBlockService

The DataGrid for Solution 1:

<DataGrid ItemsSource="{Binding IssueList}" tbs:TextBlockService.AutomaticToolTipEnabled="True">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Description" Binding="{Binding Description}" 
            ElementStyle="{StaticResource TextColumnElementStyle}">
    </DataGrid.Columns>
</DataGrid>

Thanks

回答1:

I've found the perfect solution, based on an answer by xr280xr. It works out of the box, in any condition, and without using additional code.

The style, that I put in <DataGrid.Resources> :

<Style TargetType="{x:Type DataGridCell}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type DataGridCell}">
                <TextBlock Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Content.Text}" TextTrimming="CharacterEllipsis">
                    <TextBlock.ToolTip>
                        <ToolTip Visibility="{Binding RelativeSource={RelativeSource Self}, Path=PlacementTarget, Converter={StaticResource TrimToVisConverter}}">
                            <ToolTip.Content>
                                <TextBlock Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Content.Text}"/>
                            </ToolTip.Content>
                        </ToolTip>
                    </TextBlock.ToolTip>
                 </TextBlock>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

The source of Converter={StaticResource TrimToVisConverter}:

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();
    }
}

来源：https://stackoverflow.com/questions/22709715/automatic-tooltip-when-text-is-trimmed-in-datagrid

标签

wpf

datagrid

tooltip

trim