Binding fails when using SolidColorBrush resource on Stroke property

Question

I have created a UserControl and have quite a few bindings to several custom DependencyProperties in the control. For some reason though, one of these is failing with the error:

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=YearSelectorControl'. BindingExpression:Path=SelectedBorderColor; DataItem=null; target element is 'SolidColorBrush' (HashCode=45568629); target property is 'Color' (type 'Color')

The control includes a ToggleButton and Popup. The error occurs when the Popup is opened by clicking on the ToggleButton.

Here is the xaml:

<UserControl x:Class="MyProject.Views.YearSelector"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:MyProject.Views"
             mc:Ignorable="d" 
             d:DesignHeight="23" d:DesignWidth="181"
             x:Name="YearSelectorControl">
    <UserControl.Resources>
        <SolidColorBrush x:Key="HoverColorBrush" Color="{Binding ElementName=YearSelectorControl, Path=HoverColor}"/> <!--This binding is virtually identical, but works fine-->
        <SolidColorBrush x:Key="SelectedBorderColorBrush" Color="{Binding ElementName=YearSelectorControl, Path=SelectedBorderColor}"/> <!--This is the binding that fails-->
        <local:YearToBackColorConverter x:Key="YearToBackColorConverter"/>
        <local:YearToBorderThicknessConverter x:Key="YearToBorderThicknessConverter"/>

        <Style x:Key="ForwardBackButtons" TargetType="{x:Type Button}" >
            <Setter Property="Background" Value="Transparent" />
            <Setter Property="BorderThickness" Value="0" />
            <Setter Property="FontFamily" Value="Arial" />
        </Style>
        <ControlTemplate x:Key="YearButton" TargetType="{x:Type Button}">
            <Grid Width="55" Height="30" Margin="2">
                <Rectangle x:Name="ButtonRectangle" Stroke="{StaticResource SelectedBorderColorBrush}"> <!--Use of the failing brush-->
                   <!--Removed code that determines StrokeThickness. Works correctly if Stroke set to a specific color rather than a Static Resource-->
                </Rectangle>
                <ContentPresenter VerticalAlignment="Center" HorizontalAlignment="Center"/>
            </Grid>
            <ControlTemplate.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter TargetName="ButtonRectangle" Property="Fill" Value="{StaticResource HoverColorBrush}"/> <!--Use of the properly binding brush-->
                </Trigger>
            </ControlTemplate.Triggers>
        </ControlTemplate>
    </UserControl.Resources>

    <Grid>
        <!--Layout here-->
    </Grid>
</UserControl>

Here is an excerpt from the code-behind for the two DependencyProperties that are bound to SolidColorBrush resources:

public Color HoverColor
{
    get { return (Color)GetValue(HoverColorProperty); }
    set { SetValue(HoverColorProperty, value); }
}
public static readonly DependencyProperty HoverColorProperty = 
    DependencyProperty.Register("HoverColor", typeof(Color), typeof(YearSelector), new PropertyMetadata(Color.FromArgb(255,190,230,253)));

public Color SelectedBorderColor
{
    get { return (Color)GetValue(SelectedBorderColorProperty); }
    set { SetValue(SelectedBorderColorProperty, value); }
}
public static readonly DependencyProperty SelectedBorderColorProperty = 
    DependencyProperty.Register("SelectedBorderColor", typeof(Color), typeof(YearSelector), new PropertyMetadata(Color.FromArgb(255,126,0,234)));

I think you have to use path: `DataContext.SelectedBorderColor`. — Sinatr, May 19 '16 at 14:11
It's because popup is in different visual tree of all the other element. [Check this for solution](http://stackoverflow.com/a/14941105/352101) — Bolu, May 19 '16 at 14:11
Does `PopUp `just have one button? Cannot understand the reason why error occurs — StepUp, May 19 '16 at 14:17
@Bolu: I looked at the that solution, but I'm not sure how to implement it here. The binding doesn't occur in the `Popup`, but in the `UserControl.Resources`. — matthew_b, May 19 '16 at 14:22
@StepUp: There are 10 buttons, actually. I just removed the other 9 because they're essentially identical (they each have different names, click events and the Content is bound to a different CLR property, but use the same `Template`). — matthew_b, May 19 '16 at 14:24

score 0 · Accepted Answer · answered Aug 19 '16 at 15:04

I went away from this for a few months to focus on more important elements of my application and have finally come back to it. I discovered the solution, though I'm not sure why it was a problem in the first place.

For whatever reason, binding a SolidColorBrush resource to the Stroke property doesn't work. What I did instead, is I bound the Color DependencyProperty directly to Stroke and used an IValueConverter to convert it to a SolidColorBrush.

XAML:

<Rectangle x:Name="ButtonRectangle" Stroke="{Binding ElementName=YearSelectorControl, Path=SelectedBorderColor, Converter={StaticResource ColorToSolidColorBrushConverter}}">

Code-behind:

public class ColorToSolidColorBrushConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        try
        {
            Color c = (Color)value;
            return new SolidColorBrush(c);
        }
        catch
        {
            return new SolidColorBrush(Color.FromRgb(0,0,0));
        }
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

Binding fails when using SolidColorBrush resource on Stroke property

1 Answers1