VirtualList

VirtualList accepts a range and item factory, a State<Range>, or an item count and index factory.

Declare lazy items

VirtualList(items, [](const Item& item) {
  return ItemRow(item).Key(item.id);
})
    .EstimatedItemExtent(56.0F)
    .CacheExtent(240.0F)

Items are materialized on demand for the viewport plus cache extent. The factory must return a View; use stable keys for items whose state must follow semantic identity.

Tune extent and cache

.ItemExtent(...) enables fixed-extent positioning. Use .EstimatedItemExtent(...) for variable-height items so initial range and scroll corrections start from a useful estimate. .CacheExtent(...) keeps nearby content realized to reduce visible creation during scrolling.

Control axis and position

.ScrollAxis(Axis::Horizontal) changes the main axis. .Controller(...) connects a ScrollController, including ScrollToItem(index, alignment).

VirtualList emits collection and realized item semantics without materializing offscreen semantic-only nodes.

API

• Constructors inherited from VirtualLayout: range plus factory, state range plus factory, or count plus index factory.
• Fluent methods: .ScrollAxis, .ItemExtent, .EstimatedItemExtent, .CacheExtent, .Controller.
• Controller alignment: ScrollAlignment::Start, Center, or End.

Use ScrollView for a small heterogeneous document and VirtualGrid for multiple columns.