MultiMathExpressionConverter

The MultiMathExpressionConverter is a converter that allows users to perform various math operations with multiple values through using a MultiBinding.

The Convert calculates the expression string defined in the ConverterParameter with multiple variables and returns a double result.

The values that are passed in to the converter will be named x? where ? is the order in which it is defined in the MultiBinding, any other variable names in the expression will be ignored. For example to express the calculation of P = V * I (power = volts * amps) the following can be written:

<Label.Text>
    <MultiBinding Converter="{StaticResource MultiMathExpressionConverter}" ConverterParameter="x0 * x1">
        <Binding Path="Volts" />
        <Binding Path="Amps" />
    </MultiBinding>
</Label.Text>

Syntax

The following examples show how to add a Label that will show the result of x0 + x1 + x2 where the x values will be supplied in the order of the MultiBinding definitions.

XAML

Including the XAML namespace

In order to use the toolkit in XAML the following xmlns needs to be added into your page or view:

xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"

Therefore the following:

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

</ContentPage>

Would be modified to include the xmlns as follows:

<ContentPage
    x:Class="CommunityToolkit.Maui.Sample.Pages.MyPage"
    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">

</ContentPage>

Using the MultiMathExpressionConverter

The MultiMathExpressionConverter 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.MultiMathExpressionConverterPage">

    <ContentPage.Resources>
        <ResourceDictionary>
            <toolkit:MultiMathExpressionConverter x:Key="MultiMathExpressionConverter" />
        </ResourceDictionary>
    </ContentPage.Resources>

    <Label HorizontalOptions="Center">
        <Label.Text>
            <MultiBinding Converter="{StaticResource MultiMathExpressionConverter}" ConverterParameter="x0 + x1 + x2">
                <Binding Path="X0" />
                <Binding Path="X1" />
                <Binding Path="X2" />
            </MultiBinding>
        </Label.Text>
    </Label>

</ContentPage>

C#

The MultiMathExpressionConverter can be used as follows in C#:

class MultiMathExpressionConverterPage : ContentPage
{
    public MultiMathExpressionConverterPage()
    {
        var label = new Label
        {
            HorizontalOptions = LayoutOptions.Center
        };

        label.SetBinding(
            Label.TextProperty,
            new MultiBinding
            {
                Converter = new MultiMathExpressionConverter(),
                ConverterParameter = "x0 + x1 + x2",
                Bindings = new List<BindingBase>
                {
                    new Binding(nameof(ViewModel.X0)),
                    new Binding(nameof(ViewModel.X1)),
                    new Binding(nameof(ViewModel.X2))
                }
            });

        Content = label;
    }
}

C# Markup

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

class MultiMathExpressionConverterPage : ContentPage
{
    public MultiMathExpressionConverterPage()
    {
        Content = new Label()
            .CenterHorizontal()
            .Bind(
                Label.TextProperty,
                new List<BindingBase>
                {
                    new Binding(nameof(ViewModel.X0)),
                    new Binding(nameof(ViewModel.X1)),
                    new Binding(nameof(ViewModel.X2))
                },
                converter: new MultiMathExpressionConverter(),
                converterParameter: "x0 + x1 + x2");
    }
}

Supported operations

The following operations are supported:

• "+"
• "-"
• "*"
• "/"
• "%"
• "abs"
• "acos"
• "asin"
• "atan"
• "atan2"
• "ceiling"
• "cos"
• "cosh"
• "exp"
• "floor"
• "ieeeremainder"
• "log"
• "log10"
• "max"
• "min"
• "pow"
• "round"
• "sign"
• "sin"
• "sinh"
• "sqrt"
• "tan"
• "tanh"
• "truncate"
• "^"
• "pi"
• "e"

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 MultiMathExpressionConverter over on the .NET MAUI Community Toolkit GitHub repository.