Using UWP VisualStateManager with varables

I can use VisualStateManager to change individual properties of controls. Something like this:

           <VisualStateManager.VisualStateGroups>
            <VisualStateGroup>
                <VisualState>
                    <VisualState.StateTriggers>
                        <!--small window-->
                        <AdaptiveTrigger MinWindowHeight="0" MinWindowWidth="0"/>
                    </VisualState.StateTriggers>
                    <VisualState.Setters>
                        <Setter Target="Control1.FontSize" Value="13"/>
                        <Setter Target="Control2.FontSize" Value="13"/>
                        <Setter Target="Control3.FontSize" Value="13"/>
                        <Setter Target="Control4.FontSize" Value="13"/>
                    </VisualState.Setters>
                </VisualState>
                <VisualState>
                    <VisualState.StateTriggers>
                        <!--large window-->
                        <AdaptiveTrigger MinWindowHeight="665" MinWindowWidth="1000"/>
                    </VisualState.StateTriggers>
                    <VisualState.Setters>
                        <Setter Target="Control1.FontSize" Value="24"/>
                        <Setter Target="Control2.FontSize" Value="24"/>
                        <Setter Target="Control3.FontSize" Value="24"/>
                        <Setter Target="Control4.FontSize" Value="24"/>
                    </VisualState.Setters>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>

This works but is soooo much typing!

Is it possible to use VisualStateManager to set a value for the font and than refer to this variable in XAML?

Something like this:

          <VisualStateManager.VisualStateGroups>
            <VisualStateGroup>
                <VisualState>
                    <VisualState.StateTriggers>
                        <!--small window-->
                        <AdaptiveTrigger MinWindowHeight="0" MinWindowWidth="0"/>
                    </VisualState.StateTriggers>
                    <VisualState.Setters>
                        <Setter Target="@MyFontSize" Value="13"/>
                    </VisualState.Setters>
                </VisualState>
                <VisualState>
                    <VisualState.StateTriggers>
                        <!--large window-->
                        <AdaptiveTrigger MinWindowHeight="665" MinWindowWidth="1000"/>
                    </VisualState.StateTriggers>
                    <VisualState.Setters>
                        <Setter Target="@MyFontSize" Value="24"/>
                    </VisualState.Setters>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>

I could then use @MyFontSize variable in XAML when designing controls and I could change it in one place.

<TextBlock x:Name="Control1" FontSize="@MyFontSize"/>
<TextBlock x:Name="Control2" FontSize="@MyFontSize"/>
<TextBlock x:Name="Control3" FontSize="@MyFontSize"/>

Is it possible to do something like this with UWP VisualStateManager?

Is it possible to use VisualStateManager to set a value for the font and than refer to this variable in XAML

I'm afraid you can't set variable within VisualStateManager, But for your scenario, we have a workaround that use Setting class as medium and effect other TextControl with MVVM bind.

For example

public class Setting : INotifyPropertyChanged
{
    private double _fontSize = 10;
    public double CFontSize
    {
        get { return _fontSize; }
        set { _fontSize = value; OnPropertyChanged(); }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Usage

<Page.Resources>
    <local:Setting x:Key="Setting" />
</Page.Resources>
<StackPanel>
    <TextBlock
        x:Name="BaseControl"
        VerticalAlignment="Center"
        FontSize="{Binding CFontSize, Source={StaticResource Setting}, Mode=TwoWay}"
        Text="Hello" />
    <TextBlock
        x:Name="Control1"
        VerticalAlignment="Center"
        FontSize="{Binding CFontSize, Source={StaticResource Setting}, Mode=TwoWay}"
        Text="How are you" />
    <TextBlock
        x:Name="Control2"
        VerticalAlignment="Center"
        FontSize="{Binding CFontSize, Source={StaticResource Setting}, Mode=TwoWay}"
        Text="Fine thank you, and you?" />

    <VisualStateManager.VisualStateGroups>
        <VisualStateGroup>
            <VisualState>
                <VisualState.StateTriggers>
                    <!--  small window  -->
                    <AdaptiveTrigger MinWindowHeight="0" MinWindowWidth="0" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="BaseControl.FontSize" Value="13" />
                </VisualState.Setters>
            </VisualState>
            <VisualState>
                <VisualState.StateTriggers>
                    <!--  large window  -->
                    <AdaptiveTrigger MinWindowHeight="665" MinWindowWidth="1000" />
                </VisualState.StateTriggers>
                <VisualState.Setters>
                    <Setter Target="BaseControl.FontSize" Value="24" />
                </VisualState.Setters>
            </VisualState>
        </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>
</StackPanel>