Xamarin.Forms-Samples/Xamarin.Forms-Triggers/Xamarin Triggers/Xamarin_Triggers/Views/MainView.xaml

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
					   xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
					   x:Class="Xamarin_Triggers.Views.MainView"
             xmlns:triggers="clr-namespace:Xamarin_Triggers.Triggers;assembly=Xamarin_Triggers">
  <ContentPage.Resources>
    <ResourceDictionary>

      <Style
        x:Key="PropertyTriggerStyle"
        TargetType="Button">
        <Style.Triggers>
          <Trigger
              Property="Button.IsFocused"
              Value="True"
              TargetType="Button">
            <Setter
                Property="Button.TextColor"
                Value="Red" />
          </Trigger>
        </Style.Triggers>
      </Style>

    </ResourceDictionary>
  </ContentPage.Resources>
  <StackLayout Padding="20">
    <Label FontSize="32" Text="Property Triggers" />
    <Button Style="{StaticResource PropertyTriggerStyle}" Text="Property Triggers" />
    <Label FontSize="32" Text="Event Triggers" />
    <StackLayout>
      <Slider
        x:Name="SliderTriggers"
        Minimum="0"
        Maximum="100"
        Value="50">
        <Slider.Triggers>
          <EventTrigger
              Event="ValueChanged">
            <triggers:SliderColorTrigger />
          </EventTrigger>
        </Slider.Triggers>
      </Slider>
      <Label
       BindingContext="{x:Reference SliderTriggers}"
       Text="{Binding Value}"/>
    </StackLayout>
    <Label FontSize="32" Text="Data Triggers" />
      <StackLayout Spacing="12">
         <Label FontSize="24" Text="Recovery Password" />
        <Entry x:Name="EmailEntry"
               Placeholder="Enter Email" />
        <Button x:Name="ValidationButton" Text="Send"
                FontSize="Large"
                HorizontalOptions="Center">
            <Button.Triggers>
                <DataTrigger TargetType="Button"
                             Binding="{Binding Source={x:Reference EmailEntry},
                                               Path=Text.Length}"
                             Value="0">
                    <Setter Property="IsEnabled" Value="False" />
                </DataTrigger>
            </Button.Triggers>
        </Button>

    </StackLayout>
  </StackLayout>
</ContentPage>