ColorToCmykaStringConverter

Cikk
03/01/2023

The ColorToCmykaStringConverter is a one way converter that allows users to convert a Color value binding to its CMYKA string equivalent in the format: CMYKA(cyan,magenta,yellow,key,alpha) where cyan, magenta, yellow and key will be a value between 0% and 100%, and alpha will be a value between o and 1 (e.g. CMYKA(0%,100%,100%,0%,1) for Colors.Red.

The Convert method returns the supplied Color value converted to its CMYKA string equivalent.

The ConvertBack method is not supported.

BaseConverter Properties

The following properties are implemented in the base class, public abstract class BaseConverter:

Property	Description
`DefaultConvertReturnValue`	Default value to return when `IValueConverter.Convert(object?, Type, object?, CultureInfo?)` throws an `Exception`. This value is used when CommunityToolkit.Maui.Options`.ShouldSuppressExceptionsInConverters` is set to `true`.
`DefaultConvertBackReturnValue`	Default value to return when `IValueConverter.ConvertBack(object?, Type, object?, CultureInfo?)` throws an `Exception`. This value is used when CommunityToolkit.Maui.Options`.ShouldSuppressExceptionsInConverters` is set to `true`.

ICommunityToolkitValueConverter Properties

The following properties are implemented in the public interface ICommunityToolkitValueConverter:

Property	Type	Description
`DefaultConvertReturnValue`	`object?`	Default value to return when `IValueConverter.Convert(object?, Type, object?, CultureInfo?)` throws an `Exception`. This value is used when CommunityToolkit.Maui.Options`.ShouldSuppressExceptionsInConverters` is set to `true`.
`DefaultConvertBackReturnValue`	`object?`	Default value to return when `IValueConverter.ConvertBack(object?, Type, object?, CultureInfo?)` throws an `Exception`. This value is used when CommunityToolkit.Maui.Options`.ShouldSuppressExceptionsInConverters` is set to `true`.

Syntax

The following examples will show how to use the ColorToCmykaStringConverter to display the CMYKA equivalent string of a specific Color.

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 ColorToCmykaStringConverter

The ColorToCmykaStringConverter 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.ColorToCmykaStringConverterPage">

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

    <VerticalStackLayout>
        <Label Text="My favourite Color is:" />

        <Label Text="{Binding MyFavoriteColor, Converter={StaticResource ColorToCmykaStringConverter}}" />
    </VerticalStackLayout>

</ContentPage>

C#

The ColorToCmykaStringConverter can be used as follows in C#:

class ColorToCmykaStringConverterPage : ContentPage
{
    public ColorToCmykaStringConverterPage()
    {
        var label = new Label();

	label.SetBinding(
		Label.TextProperty,
		new Binding(
			nameof(ViewModel.MyFavoriteColor),
			converter: new ColorToCmykaStringConverter()));

	Content = new VerticalStackLayout
	{
		Children =
		{
			new Label { Text = "My favourite Color is:" },
			label
		}
	};
    }
}

C# Markup

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

using CommunityToolkit.Maui.Markup;

class ColorToCmykaStringConverterPage : ContentPage
{
    public ColorToCmykaStringConverterPage()
    {
        Content = new VerticalStackLayout
        {
            Children =
            {
                new Label()
                    .Text("My favourite Color is:"),
                new Label()
                    .Bind(
                        Label.TextProperty,
                        static (ViewModel vm) => vm.MyFavoriteColor,
                        converter: new ColorToCmykaStringConverter())
            }
        };
    }
}

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

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