Struct ListView 

pub struct ListView<T: 'static> { /* private fields */ }

A virtualized scrollable list backed by a ListModel<T> or ListDataSource.

See the module-level documentation for the full feature overview.

Implementations

impl<T: 'static> ListView<T>

pub fn new( model: ListModel<T>, delegate: impl Fn(usize, &T, bool) -> Box<dyn Widget> + 'static, ) -> Self

Create a new ListView backed by a ListModel<T>.

The delegate closure receives (index, &item, selected) and returns a boxed widget for that item.

pub fn from_source<S: ListDataSource<Item = T>>( source: S, delegate: impl Fn(usize, &T, bool) -> Box<dyn Widget> + 'static, ) -> Self

Create a ListView backed by a custom ListDataSource.

Use this for large or external datasets that cannot fit in memory. The source must implement ListDataSource<Item = T>.

pub fn from_source_keyed<S: ListDataSource<Item = T>>( source: S, keyed: KeyedSelectionModel<S::Key>, delegate: impl Fn(usize, &T, bool) -> Box<dyn Widget> + 'static, ) -> Self

where S::Key: ItemKey,

Create a ListView backed by a custom ListDataSource with keyed selection. The KeyedSelectionModel<S::Key> tracks selection by source identity, so it survives reorders, filters, lazy window-slides, and stays consistent across two views of the same source. The view stays key-less (ListView<T>) — the index↔key mapping is captured from the concrete source here. Mutually exclusive with selection (the last one set wins).

pub fn enabled(self, enabled: impl Into<Prop<bool>>) -> Self

Enable or disable the whole view. A disabled view greys out and stops accepting focus / selection / keyboard input (arena-gated).

pub fn overscroll_behavior(self, behavior: OverscrollBehavior) -> Self

Set the scroll-chaining behavior at the boundary (default OverscrollBehavior::Chain; Contain disables chaining to an ancestor scrollable).

pub fn smooth_scrolling(self, enabled: bool) -> Self

Enable or disable animated wheel scrolling (enabled by default).

pub fn smooth_scroll_duration(self, duration: Duration) -> Self

Duration of the smooth scroll animation (default 150 ms).

pub fn scroll_bar_style(self, style: ScrollBarMode) -> Self

How the scroll bar is displayed (default Permanent). Overlay and Thin float the bar over the content instead of reserving a layout column, mirroring ScrollArea::scroll_bar_style.

pub fn item_height(self, height: f32) -> Self

Set the fixed height per item (default 32.0) — the uniform fast path. Mutually exclusive with item_height_fn and auto_item_height; the last mode setter wins.

pub fn item_height_fn(self, f: impl Fn(usize) -> f32 + 'static) -> Self

Per-item heights from a callback. The callback must be pure (same index + same data → same height); it is re-swept from the first changed index on every model change. No measurement pass runs — this is the deterministic variable-height path.

pub fn auto_item_height(self, estimated: f32) -> Self

Auto-measured item heights: each realized row is measured at the list’s content width (height-for-width), unrealized rows assume estimated. Scroll anchoring keeps content above the viewport stationary as estimates are corrected. estimated should be a typical row height — a wrong estimate only costs realization churn while measurements settle, never incorrect layout.

pub fn spacing(self, spacing: f32) -> Self

Set spacing between items (default 0.0).

pub fn selection(self, sel: SelectionModel) -> Self

Set the index-based selection model (positions). For identity-based selection that survives reorder / filter / window-slide, build the view with from_source_keyed instead.

pub fn realized_row_ids(&self) -> Rc<RefCell<Vec<(usize, WidgetId)>>>

A shared handle to the live (model index → row node id) map of the realized rows, rewritten at the end of every build.

The id is the row’s Role::ListItem wrapper — the node an active_descendant has to point at. Take the handle before moving the view into the tree; it is populated on the first build.

This exists for the ARIA combobox / listbox pattern, where keyboard focus stays on a text field while the arrow keys move a highlight through this list (a command palette, a type-ahead picker). The field’s AT node publishes active_descendant pointing here, so a screen reader announces each row as the highlight moves without focus ever leaving the input. A ListView that holds focus itself does not need this.

Only realized rows are present — a row scrolled outside the virtualization window has no widget, so look-ups for it return None. Callers should scroll_to_index the row they intend to announce.

pub fn reorderable(self, enabled: bool) -> Self

Enable intra-widget drag reordering.

When enabled, rows can be dragged within this ListView to reorder them. The move is routed through the source’s accept_drop — a ListModel reorders in place, an external source routes the move to its store. The hover indicator reflects the source’s can_accept verdict, so a forbidden drop shows no insertion line. Keyboard equivalent: Alt+ArrowUp/Down.

pub fn exportable(self, mode: DragTransferMode) -> Self

where T: Clone,

Make rows droppable outside this view — on a DropTarget, another data view, or the OS.

A dragged row (or the whole selection, when the pressed row is part of a multi-selection) carries clones of its items in a public RowDragData<T>, so a foreign receiver can pull them out with payload.get_typed::<RowDragData<T>>() / DropTarget::on_drop_typed::<RowDragData<T>>() — no serialization. This also makes rows a drag source even without reorderable.

mode chooses what happens to the origin rows once a foreign target accepts them: DragTransferMode::Move removes them (via the source’s on_drag_out, or on_rows_transferred_out), DragTransferMode::Copy leaves them. A same-view reorder is never a transfer, so mode never affects it. Requires T: Clone.

Move caveats. The row is removed only when the drop is accepted by an in-app target in the same window (DropOutcome::InApp { accepted: true }) or the OS reports a genuine move. Shipped OS backends advertise copy only, so a drag exported to another application — or to another window of the same app — is treated as a copy: the origin row is kept and the receiver must own its own copy semantics. Also, for a ListModel-backed view (whose key is the row index) the move-out removes by the indices captured at drag-start; if a shared handle to the same model is mutated while the drag is in flight, those indices can point at different rows — use a keyed source, or on_rows_transferred_out with your own stable identity, for models that change mid-drag.

pub fn export_external( self, f: impl Fn(&[T]) -> Vec<(String, Vec<u8>)> + 'static, ) -> Self

where T: Clone,

Additionally advertise the dragged rows as MIME data so they can be dropped on a DropZone or exported to another application / window via the OS. f maps the dragged items to (mime_type, bytes) pairs (e.g. text/plain, text/uri-list, an app-specific application/x-…). Implies exportable (defaulting to DragTransferMode::Move if not already set). Requires T: Clone.

pub fn on_rows_transferred_out( self, f: impl Fn(&[usize], &mut EventContext<'_>) + 'static, ) -> Self

Override how rows moved out to a foreign target are removed from this view. Receives the dragged rows’ indices (descending-safe) and the live context. Without this, an exportable Move drag removes them through the source’s on_drag_out (works out of the box for a ListModel).

pub fn accept_foreign_rows(self, accept: bool) -> Self

Accept exported rows dropped from a different view or source without writing a custom ListDataSource. Pair with on_rows_received, which is handed the dropped items and the insertion index. (Same-view reorder is reorderable; a custom ListDataSource can still accept foreign drops through its can_accept/accept_drop instead.)

pub fn on_rows_received( self, f: impl Fn(Vec<T>, usize, &mut EventContext<'_>) + 'static, ) -> Self

Handler for rows accepted via accept_foreign_rows: (items, insertion_index, ctx). Insert them into your model at the index.

pub fn on_activate( self, f: impl Fn(usize, &mut EventContext<'_>) + 'static, ) -> Self

Set the row-activation handler — invoked with the flat row index and the live EventContext on a click (per activate_on) or Enter on the focused row. The context lets the handler open a modal, toast, or dispatch an intent — matching TableView::on_row_activate / GridView::on_tile_activate. Distinct from selection: arrow-key navigation and Space move / toggle the selection but do not activate.

pub fn activate_on(self, mode: ActivateOn) -> Self

Choose single- vs double-click activation (default ActivateOn::DoubleClick). Enter activates in either mode.

pub fn row_tooltip_sticky(self, on: bool) -> Self

Enable type-ahead (“type to jump”): with this set, typing a printable character while the list has keyboard focus jumps the selection to the next row whose label starts with the accumulated search term, wrapping around (Qt keyboardSearch / macOS & Windows type-select). label(&item) yields the searchable text for a row; matching is ASCII-case-insensitive. A pause longer than the type_ahead_timeout starts a fresh term. Whether a composite row tooltip offers dwell-to-sticky promotion. Default true.

Turn it off for a read-only row card: with nothing to reach into there is nothing to pin, so the countdown indicator would promise an interaction that does not exist and the surface would outlive the pointer for no reason.

pub fn row_tooltip( self, f: impl Fn(usize, &T) -> Option<LocalizedString> + 'static, ) -> Self

Per-row plain tooltip: one line of text for the row under the pointer.

The resolver receives the row’s flat index and its item; returning None leaves that row without a tip. Mutually exclusive with row_rich_tooltip and row_composite_tooltip — last setter wins, matching the per-widget tooltip matrix.

Opens to the row’s trailing side, never below it: rows stack vertically, so a tip below would cover the next row.

pub fn row_rich_tooltip( self, f: impl Fn(usize, &T) -> Option<RichTooltipSource> + 'static, ) -> Self

Per-row rich tooltip — a registry key or inline TooltipContent. See row_tooltip for the shared semantics.

pub fn row_composite_tooltip( self, f: impl Fn(usize, &T) -> Option<Box<dyn Widget>> + 'static, ) -> Self

Per-row composite tooltip — an arbitrary widget tree describing the row.

The body is built for every realized row (the virtualization window) and rebuilt with it, so keep the resolver cheap and defer anything costly to the body’s own first paint, which only runs if the tip is actually shown. See row_tooltip for the rest.

pub fn type_ahead_label(self, label: impl Fn(&T) -> String + 'static) -> Self

pub fn type_ahead_timeout(self, timeout: Duration) -> Self

Reset window between keystrokes before the type-ahead search term clears (default 500 ms). A zero duration disables type-ahead.

pub fn show_scrollbar(self, show: bool) -> Self

Suppress the internal scroll bar. Use when the caller wants to mount its own ScrollBar outside the ListView (keeping it alive across rebuilds so a thumb drag isn’t torn down when the visible range shifts past the buffer). The caller is expected to wire the external bar up to the signals returned by scroll_y_signal, max_scroll_y_signal and viewport_ratio_y_signal.

pub fn scroll_y_signal(&self) -> &Signal<f32>

The current vertical scroll offset, in logical pixels. Drives the viewport position and the scroll bar thumb. Exposed so external logic (e.g. a parent widget implementing custom scroll-into-view) can read or drive the scroll directly — prefer scroll_to_index / ensure_index_visible when possible.

pub fn max_scroll_y_signal(&self) -> &Signal<f32>

The maximum scroll offset, content_height - viewport_height. Updated during layout. Exposed for callers that mount their own external scrollbar via show_scrollbar(false).

pub fn viewport_ratio_y_signal(&self) -> &Signal<f32>

The vertical viewport-to-content ratio (0.0..1.0). Drives the thumb size on any external scrollbar.

pub fn scroll_to_index(&self, index: usize)

Scroll so the given model index is aligned to the top of the viewport. Clamped to the valid scroll range. Safe to call before the ListView has been laid out — the clamp will kick in on the first layout pass.

pub fn ensure_index_visible(&self, index: usize)

Scroll the minimum distance needed to bring the given model index fully into the viewport. No-op if already visible.

Trait Implementations

impl<T: 'static> Debug for ListView<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: 'static> Widget for ListView<T>

fn build(&mut self, ctx: &mut BuildContext<'_>) -> Vec<WidgetId>

Compose child widgets. Called once after the widget is placed in the arena, and again on environment change (theme switch, locale switch). Takes &mut self — store child IDs, signal handles, any state needed later. Returns the list of root child IDs (empty for leaf widgets).

fn layout_response( &self, proposal: SizeProposal, _ctx: &LayoutContext<'_>, ) -> LayoutResponse

Respond to the parent’s size proposal with this widget’s wanted size, grow/shrink weights, and compression floor (see [LayoutResponse]).

fn place_children( &self, bounds: Rect, _proposal: SizeProposal, children: &mut [WidgetPlacement], _ctx: &LayoutContext<'_>, )

Position children within the allocated bounds.

fn paint(&self, bounds: Rect, canvas: &mut Canvas, ctx: &PaintContext<'_>)

Draw the widget’s visual representation.

fn accessibility(&self, builder: &mut AccessNodeBuilder)

Declare this widget’s accessibility identity.

fn as_any(&self) -> Option<&dyn Any>

Downcast hook. Default implementation returns None; concrete widgets override with Some(self) when they want to expose their concrete type to test-level introspection or reflection. The trait already bounds on std::any::Any so concrete types satisfy the 'static requirement.

fn children(&self) -> Vec<WidgetId>

Return the child widget IDs that this widget manages.

fn clips_children(&self) -> bool

Whether this widget clips its children to its bounds.

fn type_name(&self) -> &'static str

Concrete type name of this widget (e.g. "teksilo_widgets::button::Button"). The default implementation resolves at the impl site via std::any::type_name::<Self>(), so calls through &dyn Widget correctly dispatch to the monomorphized fn for the concrete type — getting the concrete name through the vtable without per-impl boilerplate.

fn cacheable_layout(&self) -> bool

Whether this widget’s layout_response may be memoized by the per-pass layout cache. Defaults to true.

fn wants_after_paint(&self) -> bool

Whether this widget wants its after_paint hook to fire each frame. Returning false (the default) saves a virtual call per widget per frame for the vast majority of widgets that don’t aggregate descendant geometry.

fn after_paint(&self, _view: &WidgetTreeView<'_>, _ctx: &PaintContext<'_>)

Called once per frame after this widget’s subtree has finished painting. Receives a read-only view of the layout-resolved arena so a parent can read its descendants’ final bounds — e.g. TitleBar aggregates its drag region and control-button rects into a single HitRegions payload for the Windows backend’s WM_NCHITTEST.

fn wants_post_paint(&self) -> bool

Whether this widget wants its post_paint hook to fire each frame. Returning false (the default) saves a virtual call per widget per frame for the vast majority of widgets that don’t draw a foreground over their children.

fn post_paint( &self, _bounds: Rect, _canvas: &mut Canvas, _ctx: &PaintContext<'_>, )

Draw a foreground layer over this widget’s children.

fn wants_descendant_redirects(&self) -> bool

Whether this widget wants the AT walker to consult its a11y_redirect_descendant hook for every descendant during AT tree emission, not just its direct arena children.

fn a11y_redirect_descendant( &self, _self_id: WidgetId, _descendant: WidgetId, ) -> Option<NodeId>

Optional redirection hook for AT-tree placement of a child.

fn accessible_title_hint(&self) -> Option<String>

Suggest an accessible title to an enclosing container that wraps this widget as content — typically a modal / dialog shell that wants to propagate the inner content’s visible title as the shell’s own accessible name.

fn initial_focus_hint(&self) -> Option<WidgetId>

Optional hint that directs initial focus to a specific descendant when this widget is the root of a deferred-built modal surface.

fn accessibility_children(&self) -> Option<Vec<WidgetId>>

Optional override for the child ORDER presented to assistive technology, when it must differ from the paint / z-order child order returned by children.

fn as_any_mut(&mut self) -> Option<&mut (dyn Any + 'static)>

Mutable counterpart of as_any. Default returns None; widgets that want to expose mutable state to tests (e.g. so a test can mutate a Scene inside a SceneView post-layout) override with Some(self). Should follow the same opt-in pattern as as_any: only widgets that opt into & introspection should opt into &mut.

fn focus_reveal_rect(&self, _bounds: Rect) -> Option<Rect>

The rectangle (in absolute tree coordinates) that best represents this widget when the framework reveals it into an ancestor scroll area on focus gain. Returning None (the default) reveals the widget’s whole bounds — correct for most controls.

fn hit_shape(&self, _local_point: Point, _bounds: Rect) -> bool

Whether the point lies inside this widget’s actual shape, not just its rectangular bounds. Consulted by hit-testing right after the bounds check: returning false for a point that is inside the bounding box makes the widget transparent to the click there, so it falls through to whatever sibling is painted underneath (the same machinery as a fully pass-through node, but shape-aware).

fn preserves_children_on_rebuild(&self) -> bool

How rebuild_single_widget treats this widget’s existing children when re-running its build().

fn tooltip_has_content(&self) -> bool

Whether this widget, used as tooltip content, currently has anything worth showing.

fn declare_shortcuts(&self) -> Vec<Shortcut>

Declare the rebindable keyboard shortcuts this widget exposes, without installing handlers. The framework calls this at arena insertion time (before build()) and at certain lazy boundaries (e.g. Switcher walks declarations on its not-yet-mounted Pending slots), so settings UIs and the ShortcutRegistry see the keystrokes the moment the owning container mounts — even if build() hasn’t run.

fn take_handler_set(&mut self) -> Option<HandlerSet>

Extract attached handler set from a WidgetWithHandlers wrapper. Called during arena insertion to transfer handlers to the WidgetNode. Default: returns None (no attached handlers).