Xamarin shared resources : Global Styles and Markup Extensions

Issue

Is there an advantage to using a XAML Markup Extension instead of a Style tag at the application (or page) level when setting global properties?

Context:

In the "XAML Basics" docs they give the following example:

ORIGINAL

 <Button Text="Do this!"
                HorizontalOptions="Center"
                VerticalOptions="CenterAndExpand"
                BorderWidth="3"
                Rotation="-15"
                TextColor="Red"
                FontSize="24" />

... OTHER SIMILAR BUTTONS ...

CLEAN

<ContentPage.Resources>
    <ResourceDictionary>
        <LayoutOptions x:Key="horzOptions"
                       Alignment="Center" />

        <LayoutOptions x:Key="vertOptions"
                       Alignment="Center"
                       Expands="True" />

         <x:Double x:Key="borderWidth">
            3
         </x:Double>

        <x:Double x:Key="rotationAngle">-15</x:Double>
    </ResourceDictionary>
</ContentPage.Resources>

<Button Text="Do this!"
        HorizontalOptions="{StaticResource horzOptions}"
        VerticalOptions="{StaticResource vertOptions}"
        BorderWidth="{StaticResource borderWidth}"
        Rotation="{StaticResource rotationAngle}"
        TextColor="{StaticResource textColor}"
        FontSize="{StaticResource fontSize}" />

and in the docs for Style they give the following example:

RESOURCE DICTIONARY CONTAINING BUTTON STYLE set in App.cs
<Application.Resources>
        <ResourceDictionary>
            <Style x:Key="buttonStyle" TargetType="Button">
                <Setter Property="HorizontalOptions" Value="Center" />
                <Setter Property="VerticalOptions" Value="CenterAndExpand" />
                <Setter Property="BorderColor" Value="Lime" />
                <Setter Property="BorderRadius" Value="5" />
                <Setter Property="BorderWidth" Value="5" />
                <Setter Property="WidthRequest" Value="200" />
                <Setter Property="TextColor" Value="Teal" />
            </Style>
        </ResourceDictionary>
    </Application.Resources>

BUTTON WITH STYLE APPLIED IN A ContentPage

<Button Text="These buttons" Style="{StaticResource buttonStyle}" />

Clearly they are syntactically similar but the second one is much less verbose, so what's the point of the first approach?

Solution

Obviously, they are different definitions according to the document.

XAML Markup Extensions

XAML markup extensions constitute an important feature in XAML that allow properties to be set to objects or values that are referenced indirectly from other sources. XAML markup extensions are particularly important for sharing objects, and referencing constants used throughout an application, but they find their greatest utility in data bindings.

Global Styles in Xamarin.Forms

Styles can be made available globally by adding them to the application's resource dictionary. This helps to avoid duplication of styles across pages or controls.

You will see that the range of XAML Markup Extensions is greater than Global Styles, however Global Styles is just a special use for Styles of Resource.

Answered By - Junior Jiang