Struct DataTable 

pub struct DataTable<Row> { /* private fields */ }

Implementations

impl<Row> DataTable<Row>

pub const MIN_COL_WIDTH: f32 = 40.0

Minimum column width in pixels — dragging below this clamps.

pub fn new(columns: Vec<ColumnDef<Row>>) -> DataTable<Row>

pub fn without_header(self) -> DataTable<Row>

Leave out the header band: for a table that continues one headed above it, or whose one column needs no name.

pub fn with_row_height(self, row_height_px: f32) -> DataTable<Row>

The estimated height of a row, for rows taller than one line of text (a title over its artist) in a table that sets no viewport.

pub fn host_scrolled(self) -> DataTable<Row>

The table stands in a page its host scrolls as a whole (a painted page with a hero above the table and more below it). The host keeps the table’s rect on the part of it in view and tells it which rows that is with Self::set_host_window; the table mounts and paints only those, keeps its header at the top of that part, draws no scroll bar of its own and leaves the wheel to the host.

pub fn set_host_window(&mut self, offset: f64, body_height: f64)

For a Self::host_scrolled table: body_height of rows is in view, offset below the first row’s top.

pub fn content_height(&self) -> f64

The height of the header and every row together: what a Self::host_scrolled table takes of its host’s page.

pub fn hovered_row(&self) -> Option<usize>

The row under the pointer, as an index into the rows the host set.

pub fn set_pointer_position(&mut self, point: Point) -> bool

Move the pointer in the table’s logical coordinate space. Embedded hosts can stage hover without constructing document state; window input uses this same pointer-tracking path.

pub fn compact(self) -> DataTable<Row>

Rows a small control tall (32 at the default scale) instead of 40: a dense grid (query results, logs).

pub fn drag_scroll(self) -> DataTable<Row>

Let a pointer drag on the body scroll it, as a finger does. Off by default for a mouse, so a press selects at once and a drag can begin a row drag (Self::on_row_drag_begin).

pub fn on_row_context_menu( self, f: impl FnMut(usize, Point, Rect) + 'static, ) -> DataTable<Row>

Run f(row, point, row_rect) when a row is right-clicked or asked for its menu by assistive technology. The row is selected first, unless it already is.

pub fn on_row_drag_begin( self, f: impl FnMut(usize, Point, Rect) + 'static, ) -> DataTable<Row>

Run f(row, point, row_rect) when a pointer drag starts on a row, to begin a drag and drop. Use Self::row_rect and Self::row_at_point to find drop targets.

pub fn fill_height(self) -> DataTable<Row>

Take the height the parent gives the table and scroll the rows inside it, with the shared scroll bar.

pub fn header_height(&self) -> f64

The header band’s height at the current text scale.

pub fn tree( self, depth: impl Fn(&Row) -> usize + 'static, has_children: impl Fn(&Row) -> bool + 'static, expanded: impl Fn(&Row) -> bool + 'static, on_toggle: impl FnMut(usize, bool) + 'static, ) -> DataTable<Row>

Show the rows as a flattened tree: each row indented by depth(row), with a chevron when has_children(row) that shows expanded(row). Pressing the chevron, or Right and Left on the selected row, calls on_toggle(row, expand); the host refolds its rows.

pub fn set_sort_indicator(&mut self, key: impl Into<String>, ascending: bool)

Show key’s header as sorted without reordering the rows: the host sorted them itself.

pub fn with_sort_state( self, state: &LocalState<Option<TableSort>>, ) -> DataTable<Row>

where Row: 'static,

Sort by the column state names, and keep the order a person picks from the headers in state, so it survives the view being built again. Rows and their callbacks keep the host’s indices.

pub fn with_add_row( self, label: impl Into<String>, on_add: impl FnMut() + 'static, ) -> DataTable<Row>

A blank row after the last one that adds a row when pressed (a new header, a new parameter); label is its placeholder.

pub fn on_check(self, f: impl FnMut(usize, bool) + 'static) -> DataTable<Row>

Run f(row, checked) when a checkbox column’s box is toggled.

pub fn rows_mut(&mut self) -> &mut Vec<Row>

The rows, for editing in place; follow with Self::apply_changes.

pub fn apply_changes(&mut self, changes: &[TableModelChange])

Reconcile edits made through Self::rows_mut: cell controls stay mounted by row key (so a field being typed into keeps its focus), and only the rows named in TableModelChange::RowsChanged rebuild theirs. Give the table a Self::with_row_key for keys that survive inserts and removals.

pub fn row_rect(&self, index: usize) -> Option<Rect>

The rect of display row index (the lift’s rect), for drop targets.

pub fn row_at_point(&self, point: Point) -> Option<usize>

The display row under point, if any.

pub fn reveal_row(&mut self, index: usize)

Scroll display row index into view, by the nearest edge.

pub fn ruled(self) -> DataTable<Row>

Draw a rule between columns, through the header and the body: for grids the eye reads by column (a query result, a spreadsheet).

pub fn from_model<M>(columns: Vec<ColumnDef<Row>>, model: M) -> DataTable<Row>

where M: TableModel<Row = Row> + 'static,

Construct a sparse table backed by an arbitrary model. Geometry and selection remain proportional to visible/measured rows rather than model.len().

pub fn with_id(self, id: impl Into<String>) -> DataTable<Row>

Give this table a stable app-test/inspection id. The historical default is data_table; set an explicit id when an app has more than one table.

pub fn with_accessible_name(self, name: impl Into<String>) -> DataTable<Row>

Give the table itself a localized screen-reader label. Column headers continue to label individual cells.

pub fn selectable(self, v: bool) -> DataTable<Row>

pub fn set_selection(&mut self, sel: SelectionModel)

pub fn selection(&self) -> &SelectionModel

pub fn selection_mut(&mut self) -> &mut SelectionModel

pub fn model_selection(&self) -> &KeySelection<u64>

Stable-key selection used by model-backed tables.

pub fn model_selection_mut(&mut self) -> &mut KeySelection<u64>

Mutable stable-key selection used by model-backed tables.

pub fn with_model_selection( self, selection: KeySelection<u64>, ) -> DataTable<Row>

Restore stable-key selection for a model-backed table, discarding keys absent from the current model.

pub fn with_selection(self, sel: SelectionModel) -> DataTable<Row>

pub fn on_row_click<F>(self, f: F) -> DataTable<Row>

where F: FnMut(usize, bool, bool) + 'static,

Run f(row, ctrl, shift) when a row is clicked. Every row callback names the row by its index in the rows the host set (Self::set_rows), however the table has sorted them.

pub fn on_activate<F>(self, f: F) -> DataTable<Row>

where F: FnMut(usize) + 'static,

pub fn on_header_click<F>(self, f: F) -> DataTable<Row>

where F: FnMut(usize) + 'static,

pub fn with_row_key<F>(self, key: F) -> DataTable<Row>

where F: Fn(&Row) -> u64 + Send + Sync + 'static,

Give rows stable model identity so scroll anchoring and cached measurements survive inserts, removals, and sorting. Duplicate values are disambiguated by occurrence order; unique keys provide the strongest continuity.

pub fn set_rows(&mut self, rows: Vec<Row>)

pub fn select_row(&mut self, row: usize)

Select only the host’s row row (an index into the rows set with Self::set_rows), wherever sorting shows it.

pub fn selected_rows(&self) -> Vec<usize>

The selected rows as indices into the rows the host set, in the order the table shows them.

pub fn columns(&self) -> &[ColumnDef<Row>]

pub fn view_rows(&self) -> Vec<&Row>

Rows in current sort order.

pub fn notify_model_changed(&mut self)

Reconcile an externally changed model. The first visible stable key, measured heights, and key selection survive moves and inserts.

pub fn notify_model_changes(&mut self, changes: &[TableModelChange])

Reconcile one already-applied model change batch. Structural changes retain visible cell controls whose stable keys still exist, while RowsChanged rebuilds controls only for the named keys.

pub fn sort_state(&self) -> Option<(&str, bool)>

pub fn sort_by_with<F>(&mut self, cmp: F, key: &str, ascending: bool)

where F: Fn(&Row, &Row) -> Ordering + Send + Sync + 'static,

Stores the comparator + key + direction so set_rows re-applies the same ordering automatically. Model-backed tables delegate sorting to TableModel::sort_by instead.

pub fn sort_by(&mut self, column_key: &str, ascending: bool) -> bool

Reuses the comparator already installed via Self::sort_by_with; returns false when none is installed for column_key. Per-column comparators can’t be encoded as pure (key, direction), so callers install one typed comparator, then header-click/keyboard handlers flip direction through this simpler entry point.

pub fn column_width_px(&self, key: &str) -> Option<f32>

Falls back to ColumnWidth::Fixed; Flex/Auto columns return None until resized since their pixel value depends on the layout pass.

pub fn begin_resize(&mut self, key: &str, pointer_x: f32)

Subsequent drag_resize calls compute the new width as origin_w + (pointer_x - origin_x).

pub fn drag_resize(&mut self, pointer_x: f32)

Clamps to MIN_COL_WIDTH.

pub fn end_resize(&mut self)

pub fn set_viewport(&mut self, height_px: f32, row_height_px: f32)

Enables the visible_row_range windowing so only rows intersecting the viewport (plus overscan) are rendered.

pub fn with_viewport(self, height_px: f32, row_height_px: f32) -> DataTable<Row>

Fluent form of Self::set_viewport for app constructors.

pub fn set_scroll_y(&mut self, y: f32)

pub fn scroll_y(&self) -> f32

pub fn set_row_height(&mut self, display_index: usize, height_px: f32) -> bool

Override one display row’s measured height while keeping the current stable anchor fixed. Returns false when display_index is absent or geometry did not change.

pub fn visible_row_range(&self) -> (usize, usize)

(start, end) row-index range (half-open), with two estimated row heights of pixel overscan on each side. With no viewport set, the entire row list is returned.

pub fn mounted_cell_count(&self) -> usize

Number of retained cell controls. This remains proportional to the visible window, not the logical model size.

pub fn max_scroll_y(&self) -> f32

content - viewport, floored at 0.

pub fn scroll_x(&self) -> f64

The horizontal scroll offset of the columns.

pub fn scrollbar_thumb(&self) -> Option<Rect>

None when the bar is inactive (no viewport set, or rows fit).

pub fn toggle_sort(&mut self, index: usize) -> Option<(String, bool)>

where Row: 'static,

Sort by column index, or flip the order when it already sorts by it; the column’s own comparator orders the rows (see ColumnDef::sorted_by). None if the column does not sort.

Trait Implementations

impl<Row> Widget for DataTable<Row>

where Row: 'static,

fn adjust_layout_style( &mut self, _taffy: &mut TaffyTree, _node: NodeId, text: &mut TextRenderer, ) -> bool

Measure ColumnWidth::Auto columns from their header and the visible cells, never narrower than four characters’ worth of line.

fn perform_action( &mut self, action: &Action, key_path: &[u64], _state: &mut Edits<'_>, _path: &(dyn Any + 'static), ) -> bool

Route an assistive technology’s action to the row it was aimed at.

The table paints its own rows and cells, so they reach an AT as synthetic nodes rather than as child widgets; without this, an AT could describe row 4 but activating it would land a click in the middle of the table. key_path is [row] for a row and [row, column] for a cell — the checkbox cells toggle their own checked value; other cells activate their row.

Rows carry no explicit key, so the path element is the row’s display index (its ordinal among the table’s synthetic children); the callbacks it reaches name the host’s row, as on_row_click does.

fn set_interaction_environment(&mut self, environment: InteractionEnvironment)

Receive the host’s current input capabilities. The default propagates through retained containers, so app code does not need device branches.

fn update( &mut self, state: &(dyn Any + 'static), path: &(dyn Any + 'static), ) -> bool

Notice, between frames, state that lives outside the document (a chrome revision, a momentum scroll still ticking) and report whether anything changed. The default updates every child Widget::children_mut returns, without short-circuiting, so a container never freezes its descendants at build-time state; a widget overrides it to check state of its own and then forward.

fn build_layout( &mut self, taffy: &mut TaffyTree, theme: &Theme, node_map: &mut HashMap<NodeId, *mut dyn Widget>, ) -> NodeId

fn apply_layout(&mut self, taffy: &TaffyTree, node: NodeId, origin: Point)

Take the geometry layout gave this node. The default keeps none, for widgets that neither draw nor hit-test.

fn draw( &mut self, scene: &mut Scene, transform: Affine, text_renderer: &mut TextRenderer, theme: &Theme, presence: &PresenceCtx, )

Paint into scene. The default paints nothing.

fn handle_event(&mut self, event: &WindowEvent, ctx: &mut EventCtx<'_>)

Handle one input event with the runtime services for this retained node.

fn wants_pointer_capture(&self) -> bool

fn needs_animation_frame(&self) -> bool

App polls this in Event::AboutToWait; without it a curve would freeze partway until an unrelated event woke it again.

fn children(&self) -> Vec<&dyn Widget>

fn for_each_child(&self, visitor: &mut dyn FnMut(&dyn Widget))

Allocation-free read-only child traversal. Existing custom containers inherit a compatibility adapter over Self::children; toolkit containers override this to walk their retained storage directly.

fn children_mut(&mut self) -> Vec<&mut dyn Widget>

fn accessibility_child_path(&self, child_index: usize) -> Option<Vec<usize>>

Reparent one retained children entry beneath a nested path of synthetic children returned by accessibility.

fn take_structure_dirty(&mut self) -> bool

True if this subtree’s structural composition (children inserted/removed) changed since the last frame; the App rebuilds the taffy tree when so. Reading clears it. The default drains every retained child (no short-circuit, so no child keeps a stale flag) and reports whether any was dirty; a leaf has no children and reports false. A container that changes its own child list sets its own flag and ORs it with this traversal.

fn is_layout_dirty(&self) -> bool

Default true; widgets with a fixed intrinsic size should override to false unless a size-affecting mutation landed. Containers MUST forward: layout-dirty iff any descendant is.

fn layout_needs_measure(&self) -> bool

Whether a layout_dirty frame needs taffy to re-solve sizes (compute_layout) rather than just reposition already-solved boxes. Scrollable is the motivating override: it translates its origin in apply_layout without changing any taffy size, so re-solving on every scroll frame is pure waste.

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

fn test_id(&self) -> Option<&str>

Stable id for the e2e test harness; None falls back to a path-based key. Must be unique across the live tree — the registry resolves on first match, so a duplicate shadows the second occurrence.

fn get_rect(&self) -> Rect

The rectangle this widget occupies. The default, for widgets that keep no geometry, is empty.

fn is_focusable(&self) -> bool

fn set_focus(&mut self, focused: bool)

fn is_focused(&self) -> bool

fn accessibility(&self) -> Option<AccessNode>

Role, name/description/value, and AccessState. Default None means presentational: the node is skipped and children reparent onto the parent. State must be derived, not stored so it can’t drift from draw; names must already be i18n!-resolved.

fn perform_semantic_action( &mut self, target: &str, action: &Action, _state: &mut Edits<'_>, _path: &(dyn Any + 'static), ) -> bool

Handle an action addressed to a synthetic accessibility child created by this widget. target is the opaque stable value supplied through AccessNode::with_action_target.

fn native_input_snapshot( &self, _state: &(dyn Any + 'static), _path: &(dyn Any + 'static), ) -> Option<Value>

Read-only state evidence for opt-in scheduled native input diagnostics. Called only around diagnostic inputs, never during ordinary input or paint. Keep this inexpensive and root-local; snapshots may be logged verbatim. This verifies widget state, not rendered pixels or display presentation.

fn view_only_scroll(&self, _event: &WindowEvent) -> bool

Opt in only when this wheel event changes scroll geometry and nothing else: no document edit, focus/selection, action availability, resource declaration, pending command or work that requires sync. The runner still lays out, paints and refreshes accessibility geometry. Unknown handlers stay on the full synchronization/publication path.

fn primary_vertical_scroll(&self) -> Option<PrimaryScrollRegion>

Explicit app-owned region; never search secondary children implicitly.

fn apply_primary_vertical_scroll( &mut self, _action: PrimaryScrollAction, ) -> PrimaryScrollResult

fn callback_binding(&self) -> Option<CallbackBinding>

Runtime binding inherited by descendants in a matching layout topology.

fn has_separate_document_owner(&self) -> bool

Whether this widget introduces a document owner distinct from the runner’s outer State. This is a compatibility check, never identity or authority for history access or restore.

fn history_owner(&self) -> Option<HistoryOwner>

Opaque actual custody for framework History source registration.

fn record_owners(&self) -> Vec<HistoryOwner>

Records this widget keeps open beside the document it shows, each synced on its own route: a framework app’s records in the person’s own room (crate::record::person). They take no part in this widget’s history or controls.

fn provide<'a>(&'a self, _request: &mut Request<'a, '_>)

Answer a request for a capability this widget takes part in (see capability). Declare capabilities with crate::provides!.

fn provide_mut<'a>(&'a mut self, _request: &mut RequestMut<'a, '_>)

Exclusive counterpart to Widget::provide.

fn mount_native_views(&mut self, host: &NativeViewHost<'_>)

Attach native child views through this owner’s retained lifecycle topology.

fn unmount_native_views(&mut self)

Tear native children down while their parent window still exists.

fn native_view_frame_start(&mut self)

Begin a native-view frame through this owner’s retained lifecycle topology.

fn set_platform_conventions(&mut self, conventions: PlatformConventions)

Receive host-selected platform conventions. The default propagates to retained children, keeping target-OS branches out of app code.

fn sync(&mut self, state: &(dyn Any + 'static), path: &(dyn Any + 'static))

Pull model state into this widget before layout. The default syncs the children Widget::children_mut returns; a widget overrides it only to read state of its own, or to sync children it does not expose there.

fn settle(&mut self, edits: &mut Edits<'_>, path: &ExId)

Apply, after the sync pass, what the widget took up there and must write: a worker’s answer, a chooser’s file, an event a child queued. Writes go only through typed actions on edits (a resource’s dispatcher); the host syncs again when the document changed. The default settles the children Widget::children_mut returns.

fn measure( &mut self, _known: Size<Option<f32>>, _available: Size<AvailableSpace>, _text_renderer: &mut TextRenderer, ) -> Size<f32>

fn layout_info(&self) -> Option<LayoutInfo>

Read-only resolved decisions for widgets with an explicit layout policy. None means the widget has no such policy; ordinary manual widgets remain valid. Values are available after build/settlement and carry real origins.

fn observe_physical_input(&mut self, _input: PhysicalInput)

Observe this app’s ordinary foreground physical input before framework shortcuts consume it. Keep feedback ephemeral; this is not an input grant.

fn local_resource_operation_handlers(&self) -> &'static [&'static str]

Effect/view operation type ids this widget can actually dispatch.

fn resource_operation_handlers(&self) -> HashSet<String>

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

Downcast to the concrete widget, for hosts and tests that reach a known widget through dyn Widget. Default None (a widget may borrow and so not be 'static); a widget opts in with Some(self), and a Decorator answers itself.

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

fn reveal_descendant(&mut self, target: *const dyn Widget) -> bool

Reveal a newly keyboard-focused descendant inside any enclosing viewport. Containers override this to scroll; ordinary widgets simply recurse toward the target and report whether it was found.

fn test_rects(&self) -> Vec<(String, Rect)>

Named hit rects for widgets that paint several affordances into one rect instead of composing children. Same space as Widget::get_rect; zero-area entries are dropped.

fn child_clip_rect(&self) -> Option<Rect>

Absolute logical clip applied to ordinary children during painting and pointer routing. Inspectors and enclosing scroll regions must respect this boundary instead of treating clipped descendants as visible extent.

fn take_action_palette_request(&mut self) -> Option<ActionAddress>

One-shot request to open the host’s action palette directly at a typed resource action. Parameter collection and permission checks remain host policy; widgets only name an address already present in resources().

fn take_search_request(&mut self) -> bool

One-shot request to open the host’s search palette, the same one the platform search shortcut opens. An app’s own search button latches it so search stays one shared host surface rather than an app overlay.

fn cursor_shape(&self, _point: Point) -> Option<CursorIcon>

point is logical coords, same space as Widget::get_rect; None defers to the default arrow. The host hit-tests the whole tree via node_map and picks the smallest-area claim, so containers need not override this.

fn claims_raw_touch(&self, _point: Point) -> bool

Opt out of touch-to-pointer emulation for contacts that begin at point (logical coords, same space as Widget::get_rect).

fn tooltip(&self) -> Option<&str>

Revealed after a dwell over the widget’s rect, via the toolkit’s one tooltip mechanism (crate::widget::tooltip::TooltipHost), hit-tested like cursor_shape so containers need not forward it. An icon-only control should also use this as its accessible name.

fn tooltip_side(&self) -> TooltipSide

Which side of the control its tooltip goes: below by default, beside it for a control in a vertical rail.

fn tooltip_target_at(&self, point: Point) -> Option<(Rect, String)>

fn is_default_keyboard_focus(&self) -> bool

Preferred control when its app is explicitly activated without a valid saved control. Hosts still enforce visibility, enabled state and scope.

fn keyboard_input_scope(&self) -> Option<u64>

Exact app instance whose non-text shortcuts this subtree owns when activation has no control target. Unbound desktop chrome may declare the active tab; component boundaries default to their captured owner.

fn set_invalid(&mut self, _invalid: bool)

The form’s validation verdict for this control, set by Field::with_error: an invalid control edges itself in danger ink and reports invalid to assistive technology. Controls without a field face ignore it.

fn focus_requested(&mut self, target: Option<NodeId>, tree: &TaffyTree)

An explicit runner focus request, after resolving the actual keyboard owner. Retained flags and layout restoration are not user gestures. Containers can observe this to reveal the owning viewport.

fn wants_tab_input(&self) -> bool

Whether a focused widget owns Tab instead of the host’s focus traversal. This is deliberately opt-in: ordinary form fields and controls retain platform-standard Tab/Shift+Tab navigation, while a code editor or terminal can receive the key for indentation or completion.

fn ime_cursor_rect(&self) -> Option<Rect>

Caret rectangle for the platform input method, in window-logical coordinates. Returning Some enables IME for the focused widget and positions its candidate window; non-text controls keep the default None and therefore disable IME.

fn traps_focus(&self) -> bool

While any widget answers true, the host restricts Tab/directional focus to this subtree (wrapping at the ends) and restores the prior focus once it goes back to false. Default false.

fn synthetic_accessibility_rect(&self, _path: &[usize]) -> Option<Rect>

Geometry for an immediate-mode semantic child from AccessNode::children. The path is its child-index path beneath this widget’s accessibility node. Returning a rect lets AccessKit activation inject the same click as pointer input.

fn focus_synthetic_accessibility(&mut self, _path: &[usize]) -> bool

Move this widget’s own immediate-mode focus to a synthetic semantic child. Retained widgets continue to use the ordinary taffy focus path.

fn accessibility_child_parent(&self, _child_index: usize) -> Option<usize>

Reparent one retained children entry beneath a synthetic child returned by accessibility. The returned index addresses AccessNode::children for this frame. Collections use this to place a real interactive row delegate inside its virtual ListItem/TreeItem instead of exporting a duplicate.

fn accessibility_represents_child(&self, _child_index: usize) -> bool

Whether one retained children entry is already represented in this widget’s own synthetic accessibility tree, so the bridge must not export it a second time. A host that publishes a child’s semantics itself (to add its own controls inside the same dialog) answers true for that child; assistive technology then sees one copy, not two.

fn is_enabled(&self) -> bool

A disabled (false) widget is excluded from focus traversal, must reject input in handle_event, and renders dimmed (see DISABLED_ALPHA).

fn ime_requires_deferred_ack(&self) -> bool

This field needs a host that consumes deferred receipts. Ordinary native Wayland windows must not advertise it until they have that delivery path.

fn start_deferred_text(&mut self) -> Option<Receipt>

Begin one bounded deferred session after explicit host consent, preserving the existing original-field fingerprint. This grants no microphone access.

fn commit_deferred_text(&mut self, text: &str) -> Option<Receipt>

A private asynchronous final. None leaves ordinary synchronous IME dispatch to the host. A receipt binds this original field and must be acknowledged before the host releases its private recovery transcript.

fn ime_purpose(&self) -> Option<ImePurpose>

The focused widget wants platform text input (Wayland text-input-v3, native IMEs elsewhere). None is intentionally the default: enabling an IME for buttons, canvas tools or games makes the compositor raise an on-screen keyboard over content that cannot accept the committed text.

fn ime_multiline(&self) -> bool

Whether the original focused editor accepts line feeds as text. This is field policy, never inferred from a multiline accessibility presentation. Wrappers inherit only one unambiguous child at their active IME caret.

fn ime_edit_fingerprint(&self, key: &[u8; 32]) -> Option<[u8; 32]>

Opaque local invalidation of deferred input, including selection edits that leave the caret rectangle unchanged. The host supplies an ephemeral secret key; no text or selection is retained in the resulting digest. The default shares the accessibility door and excludes protected or read-only controls. Text controls can override it to avoid cloning text.

fn presented(&self) -> bool

Default true; the exception is a widget standing in for a process that has started but not drawn. Must latch: once true, never false again for the same content, or an un-presenting widget would make a window vanish mid-resize. What shows meanwhile is decided by Widget::opening.

fn opening(&self) -> bool

True once waiting long enough, while not yet presented, that showing nothing would read as broken. Delayed so a fast open never flashes an indicator.

fn text_review(&self) -> Option<(usize, String)>

(caret_byte, text), byte offset on a char boundary. The host diffs this before/after an event so caret-only moves (arrows, Home/End) get announced, not just typing.

fn on_external_event( &mut self, _payload: &str, _state: &mut Edits<'_>, _root: &(dyn Any + 'static), )

Delivers an out-of-band string payload from crate::app::UserEvent::External (e.g. a worker thread streaming output into a status log). Default no-op; the App redraws and re-syncs after dispatch, so mutating state here is enough.

fn on_nav_gesture( &mut self, dir: NavDirection, state: &(dyn Any + 'static), path: &(dyn Any + 'static), ) -> bool

Global back/forward gesture (swipe/edge-pull), recognised by crate::gesture::NavGestureRecognizer and delivered to the whole tree; return true once consumed. Default forwards to children, so a widget that owns history becomes swipe-navigable for free.

fn nav_availability(&self) -> NavAvailability

Which directions Self::on_nav_gesture would consume now. A widget that owns history overrides this beside on_nav_gesture.

fn take_focus_reset(&mut self) -> bool

One-shot (reading MUST clear it) signal to move focus to this subtree’s first focusable widget after the next rebuild. Only consulted under crate::app::App::autofocus_on_structure_change; a wizard raises it on step transitions.

fn take_accessibility_request(&mut self) -> Option<AccessibilityRequest>

One-shot (reading MUST clear it) request to change the window’s accessibility preferences, raised by a control the person used. The host applies it before the next frame. Default forwards the first request found among the children.

fn dev_route(&self) -> Option<RouteSnapshot>

Route history when this widget, or one it contains, is a Router.

fn restore_dev_route(&mut self, route: &RouteSnapshot) -> bool

Put route back. Returns whether a router in this subtree accepted it.

fn appearance_intent(&self) -> Option<AppearanceIntent>

Theme/high-contrast/reduced-motion/scale, polled under crate::app::App::appearance_reconcile — how a settings pane re-themes the running app live without a back-channel. Level-triggered; the App recurses Self::children itself, so containers need not forward it. First Some wins.

fn set_motion_reduced(&mut self, reduced: bool)

Apply the effective reduced-motion preference before the host asks this subtree whether it needs another animation frame. The default forwards recursively, making the preference a framework policy instead of an optional convention that every container has to remember to implement.

fn needs_idle_sync(&self) -> bool

Whether sync still needs to run on idle frames without input or collab events — e.g. waiting out a document-adoption grace window.

fn take_committed_action(&mut self) -> Option<Vec<ChangeHash>>

The affordance-driven twin of the Ctrl+K palette: when a widget’s own control dispatches the same tilo_actions action its ActionSpec exports, it reports the document heads captured just before here, so the host can record one undo boundary the same way a palette dispatch does. Rising-edge: reading MUST clear it.

fn keeps_undo_step_open(&self) -> bool

Whether the undo step this widget’s last reported boundary opened stays open for the actions that continue it — the rest of a word typed a keystroke at a time. A hosted component then closes the step at the widget’s next boundary, or before an undo, a save or a merge, instead of after this event. Answered by the widget itself, never its children.

fn set_undo_status(&mut self, _status: &mut dyn FnMut() -> UndoStatus)

Host → widget: the live state of the undo history, published once per frame to every laid-out widget.

fn take_undo_request(&mut self) -> Option<UndoRequest>

Widget → host: an undo or redo the user asked for.

fn handle_local_undo_request(&mut self, request: UndoRequest) -> bool

Offer a host keyboard undo/redo shortcut to focused widget-local history before the application document consumes it.

fn apply_room_action( &mut self, _doc: &mut Edits<'_>, _type_id: &str, _payload: &[u8], ) -> bool

Apply an action another app in this room published, if this app owns the document — lets an app address a document it doesn’t hold by saying what should happen instead of writing bytes directly, keeping each document to one writer. An unrecognised type_id is silently declined, not an error.

fn start_operation( &mut self, op: &ResourceOperation<'_>, doc: &mut Edits<'_>, path: &ExId, ) -> Result<Option<ResourceOperationStart>, String>

Admit an exported effect or view operation: the one entry every handler implements. Document operations never enter it.

fn semantic_readers(&self) -> &'static [RegisteredSemanticReader]

Inert immutable-reader registrations owned by this actual widget. Registration alone supplies no qualified owner frame or disclosure.

fn poll_resource_operation( &mut self, invocation: InvocationId, cancellation_requested: bool, doc: &AutoCommit, path: &ExId, ) -> Option<InvocationUpdate>

Poll one admitted operation without blocking the UI thread.

fn next_wake_deadline(&self) -> Option<Instant>

Earliest wall-clock deadline at which this subtree needs a sync/redraw even if there is no input. Unlike needs_animation_frame, this keeps the event loop asleep until the requested instant and is appropriate for filesystem/status polling rather than animation.

fn modal_capture(&self) -> Option<Rect>

Some(rect) when this subtree holds an open modal, its panel box. While any widget reports Some, the host suppresses its own global focus shortcuts and swallows unhandled pointer presses so nothing behind the modal is clickable. Containers MUST forward (the default does, via first Some among children).

fn take_structure_change(&mut self) -> StructureChange

Self::take_structure_dirty, saying whether the frame’s damage can still describe the rebuild (StructureChange::Described). Reading clears what take_structure_dirty clears; the two must agree on whether there is a change. The default is the flag, as a StructureChange::Rebuild: only a widget that knows every pixel its change touches lands in its own damage says less, and a container forwards a child’s StructureChange::Described only by overriding this.

fn has_pending_visual_work(&self) -> bool

Work already requested by this view whose completion will replace a placeholder. Unlike animations, this can be awaited by still captures.

fn has_transient_feedback(&self) -> bool

Temporary feedback currently presented, such as a save acknowledgement. Captures may intentionally include it; scene-invariance checks can wait for it to disappear separately from unfinished placeholder work.

fn needs_redraw(&self) -> bool

Default true (dirty every frame). Opt into incremental redraw by tracking a dirty: bool, setting it in handle_event/sync, and clearing it in mark_drawn(). Containers MUST forward: dirty iff any descendant is.

fn collect_damage(&self, regions: &mut Vec<Rect>)

Logical-pixel bounds whose visual output differs from the last frame.

fn damage_covers_own_box(&self) -> bool

Whether, after this frame’s draw, this widget’s own Self::collect_damage covers every pixel a relayout changed by moving or resizing its layout box: a host that repaints where moved widgets were and are may then leave this widget’s box to it (its children’s boxes still count). A block editor that grew by a paragraph says where its blocks were and are; the default does not claim it.

fn mark_drawn(&mut self)

Called after this widget’s scene lands in the composed frame, to clear a dirty flag. Default forwards to children.

fn release_scene_cache(&mut self)

Release retained encoded-scene storage in this subtree without marking its visual/model state dirty. Outer caches call this after a successful reuse: while the outer display list is authoritative, keeping byte-for-byte descendant encodings only duplicates memory. A later outer rebuild causes descendants to record/cache normally.

fn paint_bounds(&self) -> Rect

Everything this widget paints, children included; draw_child skips the draw when it misses the viewport. Override for widgets that paint past their own rect.

fn draw_overlay( &mut self, scene: &mut Scene, transform: Affine, text_renderer: &mut TextRenderer, theme: &Theme, presence: &PresenceCtx, )

Top-layer pass, run once after the whole draw recursion, so anything emitted here composites above every sibling regardless of tree order — the toolkit’s overlay mechanism for content that escapes its layout box (an open Dropdown, a popover). Default recurses children_mut.