Module controls 

Stateful control behaviors for the <toggle> and <slider> markup tags.

Each control owns a single component holding its current value (Toggleable.checked, SliderValue.value). These systems map raw ClickEvent / DragStartEvent / DragMoveEvent messages into state mutations on the matching entity. Script-facing notifications (ToggleChanged / SliderChanged) fire on every state change so the Rhai host can forward them as on_toggle(id, checked) / on_slider(id, value).

Structs

ControlsPlugin

Plugin: registers the toggle + slider behavior systems and their outbound message types.

KnobGeometry

Knob and thumb geometry, resolved from CSS at spawn. Sits on the <toggle> / <switch> track entity (consulted via KnobGeometry::inset) and on the <slider> track entity (consulted via KnobGeometry::thumb_size). An entity without this component uses KnobGeometry::default, which reproduces today’s hardcoded geometry exactly.

SliderChanged

Emitted after a SliderValue is updated by user drag / click. Carries the entity and the new clamped value.

SliderDragOrigin

Pre-drag value snapshot for the Escape-cancel path. Inserted on the slider entity at DragStartEvent (whether the grab landed on the slider or its thumb child), consumed by cancel_slider_drag_on_escape, and cleared on normal DragEndEvent release.

SliderThumb

Marker for the thumb child entity spawned inside every <slider>. Absolute-positioned; sync_slider_thumb places it along the track at (value - min) / (max - min).

ToggleChanged

Emitted after a Toggleable flips its checked state in response to user input. Carries the entity and the new value.

ToggleKnob

Marker for the knob child entity spawned inside every <toggle>. Absolute-positioned; sync_toggle_visuals slides it left / right by the parent’s checked state.

TrackStyle

The full track palette of a <toggle> or <switch>, resolved at spawn from markup / CSS and refreshed by the restyle pass. sync_track_fill is the only thing that reads it, and TrackStyle::fill_for is the only place a state maps to a color.

Constants

KNOB_FILL

Fill for the toggle knob / slider thumb child tiles.

KNOB_INSET

Fallback gap between the toggle knob and the track edge, in logical pixels, used when the entity carries no KnobGeometry (e.g. no CSS knob-inset authored).

THUMB_SIZE

Fallback slider thumb diameter in logical pixels, used when the entity carries no KnobGeometry (e.g. no CSS thumb-size authored).

TOGGLE_CHECKED_BG

Track fill for a checked <toggle> when no :checked { bg: ... } rule supplied one. Accent teal so checked vs unchecked is visible with zero author CSS.

TOGGLE_UNCHECKED_BG

Track fill for an unchecked <toggle> when neither markup nor CSS supplied one. Matches the default skin’s #555555.

WHEEL_NOTCH_PX

One wheel line-notch in logical pixels. Must match the window backend’s LineDelta normalization (LINE_PX in lumen-window-winit), so one physical wheel detent maps to exactly one slider step; pixel-precise trackpad deltas scale proportionally.

Functions

adjust_slider_on_wheel

Wheel over a hovered <slider> (or its thumb child) nudges the value by SliderValue::step_size per notch - wheel-up (a negative delta, away from the user) increases, matching Qt’s QSlider::wheelEvent. The wheel is consumed by the slider: lumen_primitives::scroll::accumulate_wheel stands down whenever a slider sits on the hovered entity’s ancestor chain, so adjusting a slider never also scrolls an ancestor scroll container.

cancel_slider_drag_on_escape

Escape while a slider drag is in flight cancels it (Qt drag-cancel contract): the value snaps back to its SliderDragOrigin and the drag machinery is torn down - crate::drag::DragState and Pressed are removed, so the drag doesn’t resume while the button stays held and the eventual pointer release emits no ClickEvent (no release commit). Fires SliderChanged with the restored value so bound signals / scripts roll back too.

clear_slider_drag_origin_on_end

A drag that ends normally (pointer release) commits the dragged value: drop the snapshot so a later Escape doesn’t roll back a finished interaction.

flip_toggle_on_click

Flip Toggleable::checked every time the entity - or a child of it, such as the spawned ToggleKnob - receives a ClickEvent. Fires ToggleChanged so the script host can echo it to on_toggle(id, checked).

move_slider_on_keys

Keyboard control for a focused <slider>. Reads the raw KeyPressed bus directly rather than FocusedKey - the same pattern lumen_primitives::tabs::dispatch_tab_keys uses for its roving-tabindex nav - since a slider isn’t a TextInput and doesn’t need the extra dispatch_focused_keys routing hop.

set_slider_on_click

Click-anywhere-on-track: set SliderValue based on where in the track’s content rect the pointer landed. Clicks landing on the SliderThumb child resolve to the parent slider (see [resolve_control]). Coarse positioning; the drag handler refines from there.

set_slider_on_drag

While the user drags a slider, continuously update its value based on the cursor x within the track. Reuses DragMoveEvent, so the slider inherits all of lumen-input’s per-OS drag-threshold behavior for free. Drags that started on the SliderThumb child (the common grab) resolve to the parent slider (see [resolve_control]).

snapshot_slider_drag_origin

On DragStartEvent targeting a slider (or its thumb child), stash the current value so Escape can restore it. Ordered before set_slider_on_drag so the snapshot always precedes this tick’s moves.

sync_slider_thumb

Place the SliderThumb child along its track at (value - min) / (max - min), vertically centred. Runs every tick (the position depends on the track’s laid-out size, not just SliderValue); writes only when the target inset actually moved so change detection and relayout stay quiet on idle frames.

sync_toggle_visuals

Slide the ToggleKnob child of every <toggle> to the track end its Toggleable::checked state calls for, and size it from the laid-out track. The track fill itself belongs to sync_track_fill.

sync_track_fill

Paint every <toggle> / <switch> track with the fill its current state calls for. This is the single owner of a track’s Visuals::fill; the per-widget sync systems only move the knob.