xaml-csharp-development-skill-for-avalonia

WinUI Visual Tree / Logical Tree / NameScope to Avalonia

Table of Contents

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

Scope and APIs

Primary WinUI APIs:

• VisualTreeHelper.GetParent, GetChildrenCount, GetChild
• FrameworkElement.Parent, FindName, GetTemplateChild

Primary Avalonia APIs:

• VisualTree.VisualExtensions (GetVisualParent, GetVisualChildren, FindDescendantOfType)
• LogicalTree.LogicalExtensions (GetLogicalParent, GetLogicalChildren, GetLogicalAncestors)
• NameScope, NameScopeExtensions.Find / FindNameScope
• TemplateAppliedEventArgs.NameScope, StyledElement.TemplatedParent

Concept Mapping

WinUI idiom	Avalonia idiom
visual tree traversal via VisualTreeHelper	visual tree traversal via VisualExtensions
parent traversal from FrameworkElement.Parent	logical parent traversal via GetLogicalParent
GetTemplateChild("PART_...")	TemplateAppliedEventArgs.NameScope.Find<T>("PART_...")
template parent semantics	TemplatedParent

Conversion Example

WinUI XAML:

<ControlTemplate TargetType="local:StatusChip">
  <Border x:Name="PART_Indicator" />
</ControlTemplate>

WinUI C#:

protected override void OnApplyTemplate()
{
    base.OnApplyTemplate();
    _indicator = GetTemplateChild("PART_Indicator") as Border;

    var visualParent = VisualTreeHelper.GetParent(this);
    var logicalParent = Parent;
}

Avalonia XAML:

<ControlTheme TargetType="local:StatusChip">
  <Setter Property="Template">
    <ControlTemplate>
      <Border x:Name="PART_Indicator" />
    </ControlTemplate>
  </Setter>
</ControlTheme>

Avalonia C#:

protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
{
    base.OnApplyTemplate(e);
    _indicator = e.NameScope.Find<Border>("PART_Indicator");

    var visualParent = this.GetVisualParent();
    var logicalParent = this.GetLogicalParent();
    var templatedParent = TemplatedParent;
}

Migration Notes

1. Keep visual-tree and logical-tree concerns separate; they diverge in templated and item-generated UI.
2. Port template-part access to NameScope-based lookup inside OnApplyTemplate.
3. Avoid long-lived cached tree references when controls can be reparented or re-templated.

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