WPF datagrid.rowstyle binding

Question

I've got a known error

System.Windows.Data Error: 2 : Cannot find governing FrameworkElement or FrameworkContentElement for target element.BindingExpression:Path=Percent; DataItem=null; target element is 'GradientStop' (HashCode=81530); target property is 'Offset' (type 'Double')

on this part of code :

        <DataGrid.RowStyle>
            <Style TargetType="DataGridRow">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding State}" Value="Started">
                        <Setter Property="Background">
                            <Setter.Value>
                                <LinearGradientBrush EndPoint="1,0" StartPoint="0,0">
                                    <GradientStop Color="Green" Offset="0" />
                                    <GradientStop Color="#FF2D2D30" Offset="{Binding Percent}" />
                                </LinearGradientBrush>
                            </Setter.Value>
                        </Setter>
                    </DataTrigger>
                    <Trigger Property="Validation.HasError" Value="true">
                        <Setter Property="BorderThickness" Value="1"/>
                        <Setter Property="BorderBrush" Value="Red"/>
                    </Trigger>
                </Style.Triggers>
            </Style>
        </DataGrid.RowStyle>

I've tried to set the DataContext to a proxy but it did not work :

        <DataGrid.Resources>
            <app:BindingProxy x:Key="proxy" Data="{Binding}" />
        </DataGrid.Resources>

        [...]
        <GradientStop Color="#FF2D2D30" Offset="{Binding Data.Percent, Source={StaticResource proxyRow}}" />

System.Windows.Data Error: 40 : BindingExpression path error: 'Percent' property not found on 'object' ''ViewModel' (HashCode=37637549)'. BindingExpression:Path=Data.Percent; DataItem='BindingProxy' (HashCode=3342738); target element is 'GradientStop' (HashCode=64874797); target property is 'Offset' (type 'Double')

Which is obvious as the Data now contains the DataContext of the Control which is my ViewModel.

Any suggestion ? Thanks !

GuillaumeA GuillaumeA · Accepted Answer · 2015-09-26T03:55:48

As suggested in other posts, I thought it would not apply to my issue, but using a converter suits very well ! Here are some references:

Binding GradientStop works but reports error

How to bind GradientStop Colours or GradientStops Property in Silverlight?

    public object Convert(object value, Type targetType, object parameter,
        System.Globalization.CultureInfo culture)
    {
        Model.ListParameters parameters = (Model.ListParameters)value;
        if(parameters !=null)
        {
            var start = new GradientStop();
            start.Color = Colors.Green;
            start.Offset = 0;

            var stop = new GradientStop();
            stop.Color = (Color)ColorConverter.ConvertFromString("#FF2D2D30");
            stop.Offset = parameters .Percent;

            var result = new LinearGradientBrush();
            result.StartPoint = new Point(0, 0);
            result.EndPoint = new Point(1, 0);
            result.GradientStops.Add(start);
            result.GradientStops.Add(stop);

            return result;
        }
        return null;
    }

And the XAML

<UserControl.Resources>
   <app:GradientProgressConverter  x:Key="GradientProgressConverter" />
</UserControl.Resources>
<DataGrid>
   <DataGrid.RowStyle>
      <Style TargetType="DataGridRow">
         <Style.Triggers>
            <DataTrigger Binding="{Binding State}" Value="Started">
                <Setter Property="Background" Value="{Binding Converter={StaticResource GradientProgressConverter}}" />
            </DataTrigger>
         </Style.Triggers>
      </Style>
   </DataGrid.RowStyle>
</<DataGrid>

WPF datagrid.rowstyle binding

1 Answers