Xamarin Forms: How to change background color and textcolor when Expander is on or off?

Question

My Expander Header code:

<Expander.Header>
    <Frame 
        BackgroundColor="White"">

        <StackLayout>

            <Label 
                TextColor="Black"/>

            <Image />
        </StackLayout>
    </Frame>
</Expander.Header>

I need to change the background color(to blue) of the frame and text color(to white) of the label when the expander is on. When the expander is collapsing I need to revert to the initial colors. Using DataTrigger and IsExpanded properties I am able to change the image source, but don't know how to change the colors.

Answer 1

Soemthing like:

        <Frame BackgroundColor="White">
            <Frame.Triggers>
                <DataTrigger
                    Binding="{Binding Source={RelativeSource AncestorType={x:Type Expander}}, Path=IsExpanded}"
                    TargetType="Frame"
                    Value="True">
                    <Setter Property="BackgroundColor" Value="Black" />
                </DataTrigger>
            </Frame.Triggers>

            <StackLayout>

                <Label TextColor="Black">
                    <Label.Triggers>
                        <DataTrigger
                            Binding="{Binding Source={RelativeSource AncestorType={x:Type Expander}}, Path=IsExpanded}"
                            TargetType="Label"
                            Value="True">
                            <Setter Property="TextColor" Value="White" />
                        </DataTrigger>
                    </Label.Triggers>
                </Label>

                <Image />
            </StackLayout>
        </Frame>

Or you can also bind to another control's property, please check the docs.