WPF Trigger when property value is greater than a certain amount

Question

I want to do something like this:

<ControlTemplate.Triggers>
    <Trigger Property="Width" Value=">25">
       <!-- Set values here -->
    </Trigger>
</ControlTemplate.Triggers>

Anyway to do something like this?

Answer 1

Something might have been added in SP1, but the way I've achieved this in the past is with a ValueConvertor that converts the value into a boolean.

In your example your convertor would return true if the value was > 25, false otherwise. If that doesn't make sense I can put an example up :-)

Answer 2

Not without code behind. Usual practice is:

• When working with UI elements, create an IValueConverter and bind to the property using the converter.
• When working with bound data, create a bool property on your data and trigger from that property.

Answer 3

You need a custom converter. Take a look at article

Answer 4

You can use a data trigger and set the binding RelativeSource to Self. Data Triggers allow binding and bindings lets you have converters.

Example:

   <Button Content="I change colour depending on my width for some reason">
        <Button.Triggers>
            <DataTrigger
                Binding="{Binding
                Path=Width,
                RelativeSource={RelativeSource Self},
                Converter={StaticResource isLessThanConverter},
                ConverterParameter=50}"
                Value="True">
                <Setter Property="Button.Background" Value="Red" />
            DataTrigger>
        Button.Triggers>
    Button>

Reference