Property trigger bound to flag enum - wpf

Question

I have DependencyProperty State of Flags enum type. I want to change some element border color due to changing of the State property. For some reasons I can not operate with the element directly but only by setting its Style.
How can I change following code to make it possible not to check exact value of State but check whether it contains desired flag?
<Style.Triggers>
<Trigger Property="State" Value="None">
<Setter Property="StateBorderBrush" Value="Transparent"/>
</Trigger>
<Trigger Property="State" Value="Covered">
<Setter Property="StateBorderBrush" Value="Blue"/>
</Trigger>
<Trigger Property="State" Value="Selected">
<Setter Property="StateBorderBrush" Value="Red"/>
</Trigger>
<Trigger Property="State" Value="contains flag 'Controlled'">
<Setter Property="StateBorderBrush" Value="Orange"/>
</Trigger>
</Style.Triggers>

Answer 1

As far as I'm concerned, the only solution is converter:
public class EnumFlagConverter : ValueConverter
{
public string FlagValue { get; set; }
public override object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
Enum en = value as Enum;
var enumFlag = Enum.Parse((Type)parameter, FlagValue);
return en.HasFlag((Enum)enumFlag);
}
}
And the xaml binding:
<DataTrigger Binding="{Binding State,Converter={cnv:EnumFlagConverter FlagValue='Locked'}, ConverterParameter={x:Type viewModels:SourceControlState}}"
Value="True">
<Setter Property="Source"
TargetName="srcCtrlStatusIndicator"
Value="{StaticResource ImageSourceCheckedOutBySomeoneElse9x9}" />
</DataTrigger>

Answer 2

Check out Lars's generic answer to a similar question here: Using a generic converter
His solution works with enum flags that are not mutually exclusive. That allowed me to use this XAML.
<DataTrigger Binding="{Binding Path=State, Converter={StaticResource EnumBooleanConverter}, ConverterParameter={x:Static enums:MyStatesEnum.MyEnumFlagValue}}" Value="True">
<Setter Property="BorderBrush" Value="Red"/>
</DataTrigger>

Answer 3

Finally I achieved it by using DataTrigger with relative binding to Self:
<DataTrigger Binding="{Binding Path=State, RelativeSource={RelativeSource Self}}" Value="None">
<Setter Property="StateBorderBrush" Value="Transparent"/>
</DataTrigger>
Then it is possible to expand Binding element and apply appropriate converter

Answer 4

This is how you test for an enum in a trigger:
<ControlTemplate.Triggers>
<Trigger Property="ViewState"
Value="{x:Static constants:LicenseViewState.License}">
<Setter Property="Visibility"
Value="Collapsed"
TargetName="ProductComboBoxField">
</Setter>
</Trigger>
</ControlTemplate.Triggers>