state-to-bool-converter.md

title	author	description	ms.date
StateToBooleanConverter - .NET MAUI Community Toolkit	bijington	The StateToBooleanConverter is a one way converter that returns a boolean result based on whether the supplied value is of a specific LayoutState.	05/17/2022

StateToBooleanConverter

The StateToBooleanConverter is a one way converter that returns a boolean result based on whether the supplied value is of a specific LayoutState.

The Convert method returns a boolean result based on whether the supplied value is of a specific LayoutState. The LayoutState enum is provided by the toolkit and offers the possible values:

• None
• Loading
• Saving
• Success
• Error
• Empty
• Custom

Note

Note that the expected LayoutState can be supplied in the following order of precedence:

1. as the ConverterParameter in the converter binding; this supersedes the StateToCompare property
2. as the StateToCompare property on the converter

The ConvertBack method is not supported.

[!INCLUDE common converter properties]

Syntax

The following example shows how to use the converter to change the visibility of a Label control based on the LayoutState property which is modified on a Button Command.

XAML

Including the XAML namespace

[!INCLUDE XAML usage guidance]

Using the StateToBooleanConverter

The StateToBooleanConverter can be used as follows in XAML:

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
             x:Class="CommunityToolkit.Maui.Sample.Pages.Converters.StateToBooleanConverterPage">

    <ContentPage.Resources>
        <ResourceDictionary>
            <toolkit:StateToBooleanConverter x:Key="StateToBooleanConverter" StateToCompare="Success" />
        </ResourceDictionary>
    </ContentPage.Resources>

    <VerticalStackLayout VerticalOptions="Center">
        <Label
            HorizontalOptions="Center"
            IsVisible="{Binding LayoutState, Converter={StaticResource StateToBooleanConverter}}"
            Text="The state is Success!"
            VerticalOptions="Center" />
        <Button Command="{Binding ChangeLayoutCommand}" Text="Change state" />
    </VerticalStackLayout>

</ContentPage>

C#

The StateToBooleanConverter can be used as follows in C#:

class StateToBooleanConverterPage : ContentPage
{
    public StateToBooleanConverterPage()
    {
        var label = new Label
        {
            HorizontalOptions = LayoutOptions.Center,
            Text = "The state is Success!",
            VerticalOptions = LayoutOptions.Center
        };

        label.SetBinding(
            Label.IsVisibleProperty,
            new Binding(
                nameof(ViewModel.LayoutState),
                converter: new StateToBooleanConverter { StateToCompare = LayoutState.Success }));

        var button = new Button
        {
            Text = "Change state"
        };
    
        button.SetBinding(
            Button.CommandProperty,
            nameof(ViewModel.ChangeLayoutCommand));

        Content = new VerticalStackLayout
        {
            Children = 
            {
                label,
                button
            }
        };
    }
}

C# Markup

Our CommunityToolkit.Maui.Markup package provides a much more concise way to use this converter in C#.

using CommunityToolkit.Maui.Markup;

class StateToBooleanConverterPage : ContentPage
{
    public StateToBooleanConverterPage()
    {
        Content = new VerticalStackLayout
        {
            Children = 
            {
                new Label()
                    .Text("The state is Success!")
                    .CenterHorizontal()
                    .CenterVertical()
                    .Bind(
                        Label.IsVisibleProperty,
                        static (ViewModel vm) => vm.LayoutState,
                        converter: new StateToBooleanConverter { StateToCompare = LayoutState.Success }),

                new Button()
                    .Text("Change state")
                    .BindCommand(static (ViewModel vm) => vm.ChangeLayoutCommand)
            }
        };
    }
}

Examples

You can find an example of this converter in action in the .NET MAUI Community Toolkit Sample Application.

API

You can find the source code for StateToBooleanConverter over on the .NET MAUI Community Toolkit GitHub repository.