Explain Compile Binding in Xamarin Forms


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Explain_Compile_Binding_in_Xamarin_Forms

Table of Content

What is Compile Binding?

A constructed binding is a way of informing Xamarin to do what is required and forms the type of data that the binding will use at compilation time. This indicates that Xamarin Forms will not need to employ reflection to resolve data binding at runtime. A compiled binding can be enabled by using the x:DataType attribute on any VisualElement.

Compiled bindings resolve faster than traditional bindings, resulting in better data binding performance in Xamarin. Forms and submits applications. There are two major issues with data binding:

  1. Binding expressions are not validated at compile time. Bindings are resolved at runtime instead. As a result, any improper bindings aren't discovered until the application doesn't perform as planned or error messages arrive during runtime.
  2. They are inefficient in terms of cost. Bindings are resolved at runtime using general-purpose object inspection (reflection), with different overheads depending on the platform.

In Xamarin, compiled bindings improve data binding performance. Compile-time rather than run-time resolution of binding expressions is used to create applications. Furthermore, because erroneous binding expressions are communicated as build faults, this compile-time binding expression checking allows for better developer debugging.

XAML compilation must be enabled. XAML Compilation is a good place to start if you want to learn more about XAML.

Set the x:DataType attribute on a VisualElement to the type of object to which the VisualElement and its children will be bound.

The x:DataType attribute must be set to a string literal or a type using the x:Type markup extension to use compiled bindings. Any erroneous binding expressions will be notified as build errors throughout the XAML compilation process. The XAML compiler, on the other hand, will only raise a build problem if it encounters an erroneous binding expression for the first time. Regardless of whether the BindingContext is configured in XAML or code, any valid binding expressions declared on the VisualElement or its children will be compiled. When you compile a binding expression, you get compiled code that gets a value from a source property and sets it on the target property given in the markup.In addition, the created code may notice changes in the value of the source property and refresh the target property, as well as push changes from the target back to the source, based on the binding expression.

Benefits

Using these bindings has a number of significant advantages for you and your app:

  1. All binding expressions are validated at compile-time.
  2. As bindings are resolved at compile time, performance improves.
   

Enabling XAML Compilation

To use these bindings, you must first enable XAML Compilation in your project. This is the default in all new apps, and it dramatically improves XAML app speed. You can turn it on by including the following assembly flag in your shared code:

[assembly:XamlCompilation(XamlCompilationOptions.Compile)]

The XAML compiler can optionally compile XAML directly into the intermediate language (IL) (XAMLC).

The following are some of the advantages of XAML compilation:

  1. It checks XAML at build time and alerts the user if there are any issues.
  2. It speeds up the loading and instantiation of XAML elements.
  3. By removing.xaml files from the final assembly helps to minimize the file size.

By default, the framework disables XAML compilation. It is, however, enabled in the project templates for new projects. The XamlCompilation attribute can be used to directly activate or disable it (XamlCompilationOptions.Skip) at the assembly and class level.

The code example below shows how to enable XAML compiling at the assembly level:

using Xamarin.Forms.Xaml;
[assembly: XamlCompilation (XamlCompilationOptions.Compile)]
namespace PhotoApp
{
}

While the attribute can be inserted anywhere, AssemblyInfo.cs is a nice location to start.

In this example, all of the XAML in the assembly will be checked at compile time, with XAML issues being reported at compile time rather than run time. As a result, the XamlCompilation attribute's assembly prefix specifies that the attribute applies to the entire assembly.

The code example below shows how to enable XAML compilation at the class level:

using Xamarin.Forms.Xaml;
[XamlCompilation (XamlCompilationOptions.Compile)]
public class HomePage : ContentPage
{
}

Use Compile Binding

The Compiled Color Selector page shows how to use compiled bindings between Xamarin and other platforms. Viewmodel attributes and forms views:


<contentpage title="Compiled Color Selector" x:class="DataBindingDemos.CompiledColorSelectorPage" xmlns="http://xamarin.com/schemas/2014/forms" xmlns:local="clr-namespace:DataBindingDemos" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml">
    ...
    <stacklayout x:datatype="local:HslColorViewModel">
        <stacklayout.bindingcontext>
            <local:hslcolorviewmodel color="Sienna" />
        </stacklayout.bindingcontext>
        <boxview color="{Binding Color}" />
        <stacklayout margin="10, 0">
            <label text="{Binding Name}">
            <slider value="{Binding Hue}" />
            <label text="{Binding Hue, StringFormat='Hue = {0:F2}'}">
            <slider value="{Binding Saturation}" />
            <label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}">
            <slider value="{Binding Luminosity}" />
            <label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">
        </label></label></label></label></stacklayout><label text="{Binding Name}"><label text="{Binding Hue, StringFormat='Hue = {0:F2}'}"><label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}"><label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">
    </label></label></label></label></stacklayout><label text="{Binding Name}"><label text="{Binding Hue, StringFormat='Hue = {0:F2}'}"><label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}"><label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">    
</label></label></label></label></contentpage><label text="{Binding Name}"><label text="{Binding Hue, StringFormat='Hue = {0:F2}'}"><label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}"><label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">
</label></label></label></label>

 

 

Explain Compile Binding in Xamarin Forms

Explain_Compile_Binding_in_Xamarin_Forms

Table of Content

What is Compile Binding?

A constructed binding is a way of informing Xamarin to do what is required and forms the type of data that the binding will use at compilation time. This indicates that Xamarin Forms will not need to employ reflection to resolve data binding at runtime. A compiled binding can be enabled by using the x:DataType attribute on any VisualElement.

Compiled bindings resolve faster than traditional bindings, resulting in better data binding performance in Xamarin. Forms and submits applications. There are two major issues with data binding:

  1. Binding expressions are not validated at compile time. Bindings are resolved at runtime instead. As a result, any improper bindings aren't discovered until the application doesn't perform as planned or error messages arrive during runtime.
  2. They are inefficient in terms of cost. Bindings are resolved at runtime using general-purpose object inspection (reflection), with different overheads depending on the platform.

In Xamarin, compiled bindings improve data binding performance. Compile-time rather than run-time resolution of binding expressions is used to create applications. Furthermore, because erroneous binding expressions are communicated as build faults, this compile-time binding expression checking allows for better developer debugging.

XAML compilation must be enabled. XAML Compilation is a good place to start if you want to learn more about XAML.

Set the x:DataType attribute on a VisualElement to the type of object to which the VisualElement and its children will be bound.

The x:DataType attribute must be set to a string literal or a type using the x:Type markup extension to use compiled bindings. Any erroneous binding expressions will be notified as build errors throughout the XAML compilation process. The XAML compiler, on the other hand, will only raise a build problem if it encounters an erroneous binding expression for the first time. Regardless of whether the BindingContext is configured in XAML or code, any valid binding expressions declared on the VisualElement or its children will be compiled. When you compile a binding expression, you get compiled code that gets a value from a source property and sets it on the target property given in the markup.In addition, the created code may notice changes in the value of the source property and refresh the target property, as well as push changes from the target back to the source, based on the binding expression.

Benefits

Using these bindings has a number of significant advantages for you and your app:

  1. All binding expressions are validated at compile-time.
  2. As bindings are resolved at compile time, performance improves.
   

Enabling XAML Compilation

To use these bindings, you must first enable XAML Compilation in your project. This is the default in all new apps, and it dramatically improves XAML app speed. You can turn it on by including the following assembly flag in your shared code:

[assembly:XamlCompilation(XamlCompilationOptions.Compile)]

The XAML compiler can optionally compile XAML directly into the intermediate language (IL) (XAMLC).

The following are some of the advantages of XAML compilation:

  1. It checks XAML at build time and alerts the user if there are any issues.
  2. It speeds up the loading and instantiation of XAML elements.
  3. By removing.xaml files from the final assembly helps to minimize the file size.

By default, the framework disables XAML compilation. It is, however, enabled in the project templates for new projects. The XamlCompilation attribute can be used to directly activate or disable it (XamlCompilationOptions.Skip) at the assembly and class level.

The code example below shows how to enable XAML compiling at the assembly level:

using Xamarin.Forms.Xaml;
[assembly: XamlCompilation (XamlCompilationOptions.Compile)]
namespace PhotoApp
{
}

While the attribute can be inserted anywhere, AssemblyInfo.cs is a nice location to start.

In this example, all of the XAML in the assembly will be checked at compile time, with XAML issues being reported at compile time rather than run time. As a result, the XamlCompilation attribute's assembly prefix specifies that the attribute applies to the entire assembly.

The code example below shows how to enable XAML compilation at the class level:

using Xamarin.Forms.Xaml;
[XamlCompilation (XamlCompilationOptions.Compile)]
public class HomePage : ContentPage
{
}

Use Compile Binding

The Compiled Color Selector page shows how to use compiled bindings between Xamarin and other platforms. Viewmodel attributes and forms views:


<contentpage title="Compiled Color Selector" x:class="DataBindingDemos.CompiledColorSelectorPage" xmlns="http://xamarin.com/schemas/2014/forms" xmlns:local="clr-namespace:DataBindingDemos" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml">
    ...
    <stacklayout x:datatype="local:HslColorViewModel">
        <stacklayout.bindingcontext>
            <local:hslcolorviewmodel color="Sienna" />
        </stacklayout.bindingcontext>
        <boxview color="{Binding Color}" />
        <stacklayout margin="10, 0">
            <label text="{Binding Name}">
            <slider value="{Binding Hue}" />
            <label text="{Binding Hue, StringFormat='Hue = {0:F2}'}">
            <slider value="{Binding Saturation}" />
            <label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}">
            <slider value="{Binding Luminosity}" />
            <label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">
        </label></label></label></label></stacklayout><label text="{Binding Name}"><label text="{Binding Hue, StringFormat='Hue = {0:F2}'}"><label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}"><label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">
    </label></label></label></label></stacklayout><label text="{Binding Name}"><label text="{Binding Hue, StringFormat='Hue = {0:F2}'}"><label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}"><label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">    
</label></label></label></label></contentpage><label text="{Binding Name}"><label text="{Binding Hue, StringFormat='Hue = {0:F2}'}"><label text="{Binding Saturation, StringFormat='Saturation = {0:F2}'}"><label text="{Binding Luminosity, StringFormat='Luminosity= {0:F2}'}">
</label></label></label></label>