Struct Padding 

pub struct Padding { /* private fields */ }

A layout container that adds padding (insets) around a single child.

See the module documentation for the full feature description and an example. Construct with Padding::new, Padding::uniform, or Padding::symmetric; attach a child with .child(widget) or .child_id(id).

Implementations

impl Padding

pub fn new( top: impl Into<Prop<f32>>, trailing: impl Into<Prop<f32>>, bottom: impl Into<Prop<f32>>, leading: impl Into<Prop<f32>>, ) -> Self

Create a padding with explicit per-side insets.

Argument order mirrors CSS shorthand: (top, trailing, bottom, leading). trailing and leading are logical — they map to physical right and left in LTR and are swapped in RTL.

pub fn uniform(amount: impl Into<Prop<f32>>) -> Self

Create a padding with the same inset on all four sides.

pub fn symmetric( vertical: impl Into<Prop<f32>>, horizontal: impl Into<Prop<f32>>, ) -> Self

Create a padding with equal top/bottom insets and equal leading/trailing insets.

vertical applies to both top and bottom; horizontal applies to both leading and trailing sides (logical, RTL-aware).

pub fn child_id(self, id: WidgetId) -> Self

Set child by pre-registered ID.

pub fn child(self, widget: impl Widget + 'static) -> Self

Set an inline child widget (deferred insertion).

Trait Implementations

impl Debug for Padding

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

Formats the value using the given formatter.

impl Widget for Padding

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 children(&self) -> Vec<WidgetId>

Return the child widget IDs that this widget manages.

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 context_menu_key_target(&self) -> Option<WidgetId>

Which descendant a keyboard request for a context menu should target.

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

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 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 clips_children(&self) -> bool

Whether this widget clips its children to its bounds.

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).

impl WidgetCatalog for Padding

fn id() -> &'static str

Stable, ASCII id (e.g. "button", "tag_chip"). Used in CLI args, navigator URLs, and persistence keys.

fn group() -> &'static str

Group label for navigator organisation ("Controls", "Containers", "Composites", …).

fn display_name() -> &'static str

Human-readable label shown in the navigator.

fn knobs() -> KnobSpec

Optional knob declarations. Empty by default — composite widgets that build via Scenario variants leave this empty.

fn variants() -> Vec<PreviewVariant>

Named variants. At least one is required — typically a “default”.

fn build(_variant: &str, knobs: &KnobValues) -> Box<dyn Widget>

Construct a fresh widget instance for the named variant, given runtime knob values. The implementation typically dispatches on the variant name to handle Scenario paths and otherwise builds via the knob values for Knobs variants.

fn icon() -> Option<Box<dyn Widget>>

An icon widget for the navigator palette and the designer’s outline tree. None (the default) leaves the consumer to substitute a generic fallback. Returns a Box<dyn Widget> (not an IconWidget) so this crate stays free of any widgets-crate dependency.

fn category() -> WidgetCategory

How this widget accepts children. The default, WidgetCategory::Leaf, is correct for every control; container widgets override it.

fn build_with_children( _variant: &str, knobs: &KnobValues, children: Vec<SlottedChild>, ) -> Box<dyn Widget>

Build with pre-registered children injected. ContainerA folds children as ordered bare children; ContainerB routes each by its slot name; Leaf ignores them. The default ignores children and delegates to build, so non-container widgets need no override.

fn slots() -> &'static [&'static str]

Named slots for a WidgetCategory::ContainerB widget (e.g. Card → ["header", "content", "footer"]). Empty for Leaf and ContainerA.