xaml-csharp-development-skill-for-avalonia

WinUI Pointer Gestures, Touch/Pen, and InkCanvas to Avalonia

Table of Contents

1. Scope and APIs
2. Concept Mapping
3. Conversion Example
4. Migration Notes

Scope and APIs

Primary WinUI APIs:

• PointerPressed/PointerMoved/PointerReleased, GestureRecognizer, InkCanvas, InkPresenter

Primary Avalonia APIs:

• PointerPressed/PointerMoved/PointerReleased, Gestures (Tapped, Holding), GestureRecognizers, pointer type detection

Concept Mapping

WinUI idiom	Avalonia idiom
Pointer event handlers	Pointer event handlers
GestureRecognizer + taps/holds	Gestures events + recognizers
Pen input branching	e.Pointer.Type checks
InkCanvas strokes	custom drawing surface + pointer sampling

Conversion Example

WinUI XAML:

<Grid PointerPressed="OnPressed" PointerMoved="OnMoved" PointerReleased="OnReleased">
  <InkCanvas x:Name="InkSurface" />
</Grid>

WinUI C#:

void OnPressed(object sender, PointerRoutedEventArgs e)
{
    if (e.Pointer.PointerDeviceType == PointerDeviceType.Pen)
    {
        InkSurface.InkPresenter.InputDeviceTypes = CoreInputDeviceTypes.Pen;
    }
}

Avalonia XAML:

<Border xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        PointerPressed="OnPressed"
        PointerMoved="OnMoved"
        PointerReleased="OnReleased">
  <Canvas x:Name="InkSurface" Background="Transparent" />
</Border>

Avalonia C#:

void OnPressed(object? sender, PointerPressedEventArgs e)
{
    if (e.Pointer.Type == PointerType.Pen)
    {
        _activeStroke = new List<Point> { e.GetPosition(InkSurface) };
    }
}

void OnMoved(object? sender, PointerEventArgs e)
{
    if (_activeStroke is not null)
        _activeStroke.Add(e.GetPosition(InkSurface));
}

void OnReleased(object? sender, PointerReleasedEventArgs e)
{
    _activeStroke = null;
}

Migration Notes

1. Avalonia has no one-to-one InkCanvas; use custom pointer sampling + rendering.
2. Prefer routed gesture events (Tapped, Holding) for high-level interactions.
3. Keep pen/touch branching explicit via pointer type and modifiers.

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