Introduction

ProItemsRepeater brings the WinUI ItemsRepeater control to Avalonia. It is a hard fork of the retired Avalonia.Controls.ItemsRepeater and targets Avalonia 11+. The core idea is simple: a data-driven panel delegates measure/arrange to a layout while virtualizing and recycling item elements.

Why ItemsRepeater

ItemsRepeater is built for scenarios where you want:

• Full control over layout and virtualization behavior.
• High performance for large or fast-changing data sets.
• Reuse of visual elements across scrolls and collection updates.
• Selection behavior without the heavier ItemsControl templating pipeline.

Key Concepts

• Layout-first: you assign a layout (StackLayout, WrapLayout, UniformGridLayout, or a custom layout) that sizes and positions items.
• Virtualization: only items inside the realization window are created; cache length expands around the viewport.
• Recycling: templates can be backed by RecyclingElementFactory and RecyclePool to reuse elements efficiently.
• Selection: SelectingItemsRepeater layers selection on top of ItemsRepeater with SelectedItem, SelectedItems, and SelectionMode.
• Diagnostics: OpenTelemetry-friendly ActivitySource and Meter events expose measure/arrange/generate timing and realized counts.

Where It Fits

Use ItemsRepeater when you need a custom layout or high-performance virtualization. Use ItemsControl (or controls like ListBox) when you want built-in styling and behaviors with less manual layout configuration.