WPF convert boolean to colored string

Question

I stucked with "simple" converting. I have a method. It checks connection. If connection established it change boolean property of my viewmodel. What I want to do, is to display colored string on my form (red-colored "Connection failed" or green-colored "Connection established" depending on boolean property) but i don't have any idea how to do it.

Answer 1

Use below(change control type with what you are using):

<TextBox Text="content" >
    <TextBox.Style>
        <Style TargetType="TextBox">
            <Style.Triggers>
                <DataTrigger Binding="{Binding ConnectionStatus}" Value="true">
                    <Setter Property="Background" Value="Red"></Setter>
                </DataTrigger>
                <DataTrigger Binding="{Binding ConnectionStatus}" Value="false">
                    <Setter Property="Background" Value="Green"></Setter>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </TextBox.Style>
</TextBox>

Answer 2

You have two options here, for both of which I will simply provide some resources as you did not provide any specific code:

The first option is to update the property of the text using a trigger. This would be implemented in xaml and simply watched the bound property to take a specific value (in you case true or false) and updates the color accordingly. This is also what @Kylo-Ren did. Information about this can for example be found here:

http://www.wpf-tutorial.com/styles/trigger-datatrigger-event-trigger/

The other option is to use the IValueConverter interface and convert the boolean to a color. This is what @Stefan did. More info here:

http://www.codeproject.com/Tips/868163/IValueConverter-Example-and-Usage-in-WPF

I would recommend the first version if you only have a very limited range of values that the property can take and/or you want to update multiple visual properties at once.

The second version works better for more complex conversions (like converting a complete object to a formatted string) but can not be easily used to update multiple visual properties.

Rule of thumb:

I want to indicate a state => use Trigger

I want to display an objects value in a specific way (e.g. Text) => use IValueConverter

Answer 3

The best way is to use IValueConverter for binding. Just implement new class of converter:

public class BoolToColorConverter : IValueConverter
{
    object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var val = (bool) value;
        // your convertion logic here
        // return Brushes.Black;
    }

    object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotSupportedException();
    }
}

Next, add your converter to the resources in XAML:

<Window.Resources>
    <l:BoolToColorConverter x:Key="boolToColorConverter" />
</Window.Resources>

And use it in data binding:

<TextBox Background="{Binding YourBoolPropertyName, 
        Converter={StaticResource boolToColorConverter}}" />

You can read more about converters here.

Answer 4

Although a Converter was already posted I have created a BooleanToColorConverter which is more reusable. You can use it for different scenarios as shown below.

[ValueConversion(typeof(bool), typeof(SolidColorBrush))]
public class BooleanToColorConverter : IValueConverter
{
    public Brush TrueBrush { get; set; }

    public Brush FalseBrush { get; set; }

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var boolValue = value as bool? ?? true;
        if (parameter != null && parameter.ToString() == "!")
        {
            boolValue = !boolValue;
        }

        if (boolValue)
        {
            return TrueBrush;
        }
        return FalseBrush;
    }

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

Now in XAML in the Resource you can have something like this:

<ResourceDictionary>
    <converter:BooleanToColorConverter x:Key="BooleanToColorConverter" FalseBrush="#4CFF0000" TrueBrush="#4C00FF00" />
    <converter:BooleanToColorConverter x:Key="ReadOnlyToColorConverter" TrueBrush="LightGray"/>
</ResourceDictionary>

And now you can use it on the Background attribute like this (IsReadOnly is a property of Type bool):

Background="{Binding IsReadOnly, Converter={StaticResource ReadOnlyToColorConverter}}"

ps. this piece of code:

if (parameter != null && parameter.ToString() == "!")
    {
        boolValue = !boolValue;
    }

is just so you can invert easy your color if you need it. You can use it like this:

Background="{Binding IsReadOnly, Converter={StaticResource ReadOnlyToColorConverter}, ConverterParameter=!}"

Answer 5

1. Create a IValueConverter, which converts boolean value to Color if parameter is "Color" and bool to Text if parameter is "Text".
2. Imagine you have a TextBlock on the form, where you want to show text(it can be any control you like):

<TextBlock Text="{Binding MyBoolValue,Converter={StaticResource MyConverter,ConverterParameter=Text}}" Foreground="{Binding MyBoolValue,Converter={StaticResource MyConverter,ConverterParameter=Color}}"/>.

Solution above is incomplete and shows only basics. Feel free to ask additional questions in case you have difficulties.

Answer 6

You can either create SolidColorBrush property named for example ConnectionStatusColor. In its get you can do something like:

return connectionSuccess ? Brushes.Green : Brushes.Red

Don't forget to implement INotifyPropertyChanged so the binding gets applied.

Or you can create IValueConverter and use it in your binding.

 class BoolToBrushConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return (bool) value ? Brushes.Green : Brushes.Red;
        }

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