CP.Xaml.Converters.Avalonia

XamlConverters

Common value converters for WPF and Avalonia, published as separate packages.

A rich collection of ready-to-use value and multi-value converters for BCL values, collections, formatting, enums, colors, visibility, arithmetic, and layout.

Package	UI framework	Target frameworks
CP.Xaml.Converters	WPF	net462, net472, net48, net481, net8.0-windows, net9.0-windows, net10.0-windows, net11.0-windows
CP.Xaml.Converters.Avalonia	Avalonia	net8.0, net9.0, net10.0, net11.0

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Install

PM> Install-Package CP.Xaml.Converters
PM> Install-Package CP.Xaml.Converters.Avalonia

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WPF Quick Start (All Converters at Once)

<Application x:Class="App" ...
             xmlns:converters="https://github.com/ChrisPulman/XamlConverters">
    <Application.Resources>
        <converters:ConvertersDictionary />
    </Application.Resources>
</Application>

Use in bindings:

<TextBlock Text="{Binding Title, Converter={StaticResource ToUpperConverter}}"/>

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Lightweight Usage (Singletons)

Some frequently used stateless converters are exposed through ConvertersRegistry so you can avoid resource keys:

xmlns:c="clr-namespace:CP.Xaml.Converters"
<TextBlock Visibility="{Binding IsBusy, Converter={x:Static c:ConvertersRegistry.BoolToVisibility}}"/>

Available singletons (see ConvertersRegistry.cs) include boolean, visibility, arithmetic, comparison, formatting, BCL type conversion, Base64, GUID, URI, collection, and enum converters.

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Avalonia Quick Start

Merge the ready-made converter dictionary into Application.Resources:

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:converters="https://github.com/ChrisPulman/XamlConverters/Avalonia">
  <Application.Resources>
    <converters:ConvertersDictionary />
  </Application.Resources>
</Application>

The Avalonia package provides every public WPF converter class (except WPF-only numeric markup extensions), uses Avalonia binding sentinels, and adds Avalonia-focused helpers such as BclTypeConverter, ClampConverter, ComparisonToVisibilityConverter, RoundingConverter, and TrimConverter.

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Markup Numeric Extensions

Allow inline numeric objects in XAML without x:Static:

xmlns:c="clr-namespace:CP.Xaml.Converters"
<Setter Property="Tag" Value="{c:Int32 42}"/>
<Setter Property="Tag" Value="{c:Double 2.5}"/>

Available: Int16, Int32, Single (float), Double.

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Converter Catalogue

(Each listed as Resource Key = Class Name when using ConvertersDictionary)

Arithmetic & Math

• ArithmeticConverter – Parameter: simple expression "" e.g. "+5", "-2", "*3", "/10". Works with int/double.

  <TextBlock Text="{Binding Count, Converter={StaticResource ArithmeticConverter}, ConverterParameter='*2'}"/>
  

• MathConverter – Parameter: arithmetic expression over one or many bound values. Single binding uses value as {0}/x; MultiBinding supports {0},{1}… or a,b,c,d.

  <!-- Scale * Percentage example -->
  <TextBlock>
    <TextBlock.Text>
      <MultiBinding Converter="{StaticResource MathConverter}" ConverterParameter="({0} * {1}) / 100">
        <Binding Path="Base"/>
        <Binding Path="Percent"/>
      </MultiBinding>
    </TextBlock.Text>
  </TextBlock>
  

• PercentageConverter – Parameter: either "50%" or decimal factor "0.5" multiplies numeric value.

  <RowDefinition Height="{Binding ActualWidth, ElementName=Root, Converter={StaticResource PercentageConverter}, ConverterParameter=25%}" />
  

• MultiplierConverter – Parameter: numeric factor; ConvertBack divides.

  <Rectangle Width="{Binding BaseWidth, Converter={StaticResource MultiplierConverter}, ConverterParameter=1.5}"/>
  

• ValueGtXConverter – Rounds double to 1 decimal place if > parameter else 2.

  <TextBlock Text="{Binding Speed, Converter={StaticResource ValueGtXConverter}, ConverterParameter=40}"/>
  

• ValueGreaterThanXToBoolConverter / ValueLessThanXToBoolConverter – Parameter: threshold (default 0). Returns bool. ConvertBack adjusts relative to threshold.

  <CheckBox IsChecked="{Binding ItemsCount, Converter={StaticResource ValueGreaterThanXToBoolConverter}, ConverterParameter=5}" Content=">5?"/>
  

• IsGreaterThanOrEqualToConverter – (a) Single binding + parameter (b) MultiBinding with two inputs.

  <CheckBox IsChecked="{Binding Value, Converter={StaticResource IsGreaterThanOrEqualToConverter}, ConverterParameter=100}"/>
  

Boolean Logic / Aggregation

• BoolNegationConverter – Inverts bool.
• MultiBooleanAndConverter – MultiBinding; optional parameter "invert".
• MultiBooleanOrConverter – MultiBinding; optional parameter "invert".
• BooleanXorConverter – MultiBinding exclusive OR (true if odd number true).
• InverseValueToBoolConverter – True if numeric <= 0.
• NullToBoolConverter – Use NullToBoolConverter.IsNull or .NotNull static singletons; or set ReturnTrueIfNull property in XAML.
• ValueNotNullToBoolConverter – Parameter: "reverse" or "true" to invert.
• ObjectEqualsParameterConverter – Parameter: string to compare; prefix ! to invert.
• EqualityConverter – Parameter: value to compare; prefix ! to invert.
• ComparisonConverter – Parameter: comparison expression e.g. ">5", "<= 10", "!=X", "!>=3" (leading ! inverts result). Works with numeric or string.
• EnumToBooleanConverter – Parameter: enum member name; useful for RadioButtons.

  <RadioButton Content="Large" IsChecked="{Binding Size, Converter={StaticResource EnumToBooleanConverter}, ConverterParameter=Large}"/>
  

Visibility

• BoolToVisibilityConverter – Parameter: "reverse" or "true" to invert.
• BoolToVisibilityAdvancedConverter – Parameter tokens: ! (invert), H (Hidden instead of Collapsed). Examples: "!H", "H".
• BoolToVisibilityConverterNegate – Opposite of normal: true => Collapsed/Hidden, false => Visible. Parameter: "hidden" to use Hidden.
• InvertVisibilityConverter – Toggles Visible <-> Collapsed (parameter containing "hidden" toggles Visible <-> Hidden).
• IntToVisibilityConverter – Shows when int > 0. Parameter: "hidden" to hide instead of collapse.
• ValueNotNullToVisibilityConverter – Parameter: "reverse" or "true" to invert.
• NullToVisibilityConverter – Shows when null; parameter "inverse" reverses.
• StringNullOrEmptyToVisibilityConverter – Collapses when null/empty. Parameter: "invert", "hidden", or "hiddeninvert".
• CollectionSizeToVisibilityConverter – Parameter: either integer exact size OR "reverse" (see CollectionSizeToBoolConverter). Shows when size matches.
• CountToVisibilityConverter – Parameter: comparison expression like ">0", "==0", may append H to use Hidden (e.g. ">0H").
• ValueCompareVisibilityConverter – Shows when numeric > 0 (Hidden when <=0).
• VisibilityFromNumberConverter – Parameter: integer threshold; Visible when value >= threshold.
• VisibilityFromNumberEqualsConverter – Visible when value == parameter.
• ZeroToVisibilityConverter – Visible when value == 0.

Collection Size / Count

• CollectionSizeToBoolConverter – Parameter: integer required size OR "reverse". True when count equals size (default 0).
• CountToBooleanConverter – Parameter: comparison (>,>=,<,<=,==,!=) e.g. ">0" (default >0 if omitted).

  <CheckBox IsChecked="{Binding Items, Converter={StaticResource CountToBooleanConverter}, ConverterParameter='>5'}" Content=">5 Items"/>
  

BCL Types, Enums & Collections

• ChangeTypeConverter / BclTypeConverter (Avalonia) – Culture-aware conversion between compatible primitives, nullable values, enums, GUIDs, URIs, TimeSpan, DateTimeOffset, and other types supported by TypeConverter or Convert.ChangeType.
• ByteArrayToBase64Converter – Converts between byte[] and Base64 text.
• GuidConverter – Converts among Guid, common GUID text formats, and 16-byte arrays.
• UriConverter – Converts between URI text and relative, absolute, or relative-or-absolute Uri values.
• TypeMatchConverter – Tests assignability by Type, simple name, full name, or assembly-qualified name.
• EnumDescriptionConverter – Converts enum members to and from DescriptionAttribute text.
• EnumHasFlagConverter / EnumValuesConverter – Tests flags and provides enum item sources.
• CollectionContainsConverter / CollectionFirstOrDefaultConverter / CollectionItemConverter – Common collection binding operations.
• EnumerableToStringConverter – Joins culture-formatted enumerable items.
• DateTimeFormatConverter / TimeSpanFormatConverter / NumberFormatConverter / StringFormatConverter – Culture-aware formatting and supported reverse parsing.

Text & Formatting

• ToUpperConverter / ToLowerConverter – Case conversion.
• MultiStringFormatConverter – MultiBinding; parameter is composite format string: "{0} - {1:0.00} ({2})".

  <TextBlock>
    <TextBlock.Text>
      <MultiBinding Converter="{StaticResource MultiStringFormatConverter}" ConverterParameter="{0} - {1:0.0} ({2})">
        <Binding Path="Name"/>
        <Binding Path="Price"/>
        <Binding Path="Code"/>
      </MultiBinding>
    </TextBlock.Text>
  </TextBlock>
  

• NullCoalesceConverter – If bound value is null/empty string returns ConverterParameter (fallback).

  <TextBlock Text="{Binding Description, Converter={StaticResource NullCoalesceConverter}, ConverterParameter='(none)'}"/>
  

• BoolToStringTickCrossConverter – true => "P", false => "O" (style with a symbol font if desired).

Colors / Brushes

• BackgroundColorToBwForegroundConverter – Input background hex (#RRGGBB) -> White or Black foreground for readability.
• HexStringToColorConverter – Accepts #RRGGBB or RRGGBB returns Color.
• HexStringToSolidColorBrushConverter – Same but returns SolidColorBrush.
• ColorToBrushConverter – Hex/String Color -> SolidColorBrush.
• BrushToColorConverter – Brush/Color -> Color (or Red fallback).
• FallbackBrushConverter – Brush or Color; fallback is Red.
• ValueToBrushConverter – Parameter optional tokens: contains "BackPressure" or "Pressure" to choose palette; default DarkGreen if value>0 else LightYellow.
• ValueCompareVisibilityConverter (see Visibility) – also for numeric state color with Hidden.
• LineStrokeLevelConverter – Parameter: "low-high" (e.g. "50-80"). Returns Lime (<low), Yellow (>=low), Red (>=high).
• ValueGtXConverter – Rounds numeric (see above) – helpful for numeric UI formatting.

Numeric / Layout

• IntToThicknessConverter – Optionally sets specific sides via instance variants (BottomOnly, LeftOnly, etc.) when using registry or custom resource. Parameter may be a base Thickness.

  <Border Padding="{Binding Spacer, Converter={StaticResource IntToThicknessConverter}, ConverterParameter='4,2,4,2'}"/>
  

• ThicknessUniformConverter – Parameter tokens control sides: L,R,T,B or H (Left+Right), V (Top+Bottom). Empty => all sides.

  <Border Padding="{Binding Gap, Converter={StaticResource ThicknessUniformConverter}, ConverterParameter=HV}"/>
  

• MultiplierConverter / PercentageConverter – see Arithmetic section.
• InvertSignConverter / InvertValueConverter – Negate numeric; InvertSignConverter coerces to target type.
• DoubleToCurrencyStringConverter – Formats double/decimal to currency using current culture.
• ValueCompareVisibilityConverter – Numeric <=0 hidden else visible.
• InverseValueToBoolConverter – Numeric <=0 => true.

Type / Object Info

• ObjectToTypeNameConverter – Parameter: "full" for full type name.
• ObjectEqualsParameterConverter / EqualityConverter / ComparisonConverter – See Boolean section.
• EnumConverter – Parameter: Type (x:Type) to parse a string value to enum.

  <ComboBox SelectedValue="{Binding SelectedStatus}" SelectedValuePath="Tag">
    <ComboBoxItem Content="Open" Tag="{Binding 'Open', Converter={StaticResource EnumConverter}, ConverterParameter={x:Type local:TicketStatus}}"/>
  </ComboBox>
  

Chaining Converters

Use MultiConverter to pipe the output of one into the next:

<converters:MultiConverter x:Key="InvertVisibilityChain">
  <converters:BoolNegationConverter/>
  <converters:BoolToVisibilityConverter/>
</converters:MultiConverter>
<TextBlock Visibility="{Binding IsClosed, Converter={StaticResource InvertVisibilityChain}}"/>

MultiBinding Boolean Examples

<!-- Show only when all are true -->
<TextBlock Text="Ready" Visibility="{Binding Path=., Converter={x:Static c:ConvertersRegistry.BoolToVisibility}}">
  <TextBlock.Visibility>
    <MultiBinding Converter="{x:Static c:ConvertersRegistry.And}">
      <Binding Path="IsLoaded"/>
      <Binding Path="IsValid"/>
      <Binding Path="HasPermission"/>
    </MultiBinding>
  </TextBlock.Visibility>
</TextBlock>

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Error & Edge Notes

• Many converters throw if value types mismatch (fail fast). Ensure proper binding types.
• MathConverter caches parsed expressions internally.
• Comparison expressions (ComparisonConverter / CountToBooleanConverter) ignore malformed parameters and return default semantics.
• Some visibility converters support Hidden vs Collapsed selection via parameter tokens (H / hidden).

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Minimal Example Window

<Window ... xmlns:conv="https://github.com/ChrisPulman/XamlConverters">
  <Window.Resources>
    <conv:ConvertersDictionary />
  </Window.Resources>
  <StackPanel Margin="20" DataContext="{Binding SampleViewModelInstance}">
    <TextBlock Text="{Binding Title, Converter={StaticResource ToUpperConverter}}"/>
    <TextBlock Text="{Binding Amount, Converter={StaticResource DoubleToCurrencyStringConverter}}"/>
    <ProgressBar Value="{Binding Progress}" Maximum="100" Height="20"/>
    <TextBlock Text="{Binding Progress, Converter={StaticResource ArithmeticConverter}, ConverterParameter='*2'}"/>
    <TextBlock Foreground="{Binding HexColour, Converter={StaticResource BackgroundColorToBwForegroundConverter}}"
               Background="{Binding HexColour, Converter={StaticResource HexStringToSolidColorBrushConverter}}"
               Text="Contrast Demo" Padding="8"/>
    <CheckBox Content="Is Active" IsChecked="{Binding IsActive}"/>
    <TextBlock Text="Active" Visibility="{Binding IsActive, Converter={StaticResource BoolToVisibilityConverter}}"/>
  </StackPanel>
</Window>

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Contributing

PRs welcome. Please keep converters small, focused, documented and unit-tested.

Testing

Tests use TUnit on Microsoft.Testing.Platform. The repository global.json selects MTP, and the test projects are executable test applications without xUnit, VSTest, or coverlet dependencies.

dotnet test src/XamlConverters.sln -c Release

The .NET 11 targets require the preview SDK version pinned in global.json until .NET 11 reaches general availability.

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License

MIT

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XamlConverters - By Chris Pulman - Empowering Industrial Automation with Reactive Technology ⚡🏭