Struct ScrollView 

pub struct ScrollView { /* private fields */ }

Implementations

impl ScrollView

pub fn new(content: Box<dyn Widget>) -> Self

pub fn with_fade_color(self, c: Color) -> Self

Override the edge-fade colour the scrollbar gutter blends to.

READ THIS BEFORE PLACING A ScrollView ON ANY CUSTOM BACKGROUND. The default fade colour is Visuals::window_fill (the colour behind a plain window). If the ScrollView sits inside a FlexColumn::with_panel_bg, a coloured Container, inside a tab body with a custom fill, or anywhere else where the pixels behind the scrollbar are NOT window_fill, the fade gradient will paint a bright halo of the WRONG colour because it blends to the default rather than what’s actually behind it.

Pass the visible ancestor background here so the fade dissolves invisibly into the panel. Common idioms:

// Sits on a panel:
ScrollView::new(child).with_fade_color(ctx.visuals().panel_fill)
// Sits on a coloured Container:
ScrollView::new(child).with_fade_color(my_container_bg)

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

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

pub fn scroll_offset(&self) -> f64

pub fn set_scroll_offset(&mut self, offset: f64)

pub fn max_scroll_value(&self) -> f64

pub fn with_offset_cell(self, cell: Rc<Cell<f64>>) -> Self

pub fn with_max_scroll_cell(self, cell: Rc<Cell<f64>>) -> Self

pub fn with_h_offset_cell(self, cell: Rc<Cell<f64>>) -> Self

pub fn with_h_max_scroll_cell(self, cell: Rc<Cell<f64>>) -> Self

pub fn with_stick_to_bottom(self, stick: bool) -> Self

pub fn with_bar_visibility(self, v: ScrollBarVisibility) -> Self

pub fn set_bar_visibility(&mut self, v: ScrollBarVisibility)

pub fn with_bar_visibility_cell( self, cell: Rc<Cell<ScrollBarVisibility>>, ) -> Self

pub fn with_style(self, s: ScrollBarStyle) -> Self

pub fn with_style_cell(self, cell: Rc<Cell<ScrollBarStyle>>) -> Self

pub fn with_viewport_cell(self, cell: Rc<Cell<Rect>>) -> Self

Bind a cell that receives the visible content-space viewport rect.

pub fn with_margin(self, m: Insets) -> Self

pub fn with_h_anchor(self, h: HAnchor) -> Self

pub fn with_v_anchor(self, v: VAnchor) -> Self

pub fn with_min_size(self, s: Size) -> Self

pub fn with_max_size(self, s: Size) -> Self

Trait Implementations

impl Widget for ScrollView

fn properties(&self) -> Vec<(&'static str, String)>

Surface the per-axis offsets and the maximum scroll distance as inspector / test properties. Tests use these to verify that a shrunken viewport actually exposes scrollable overflow.

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

A static name for this widget type, used by the inspector. Default: “Widget”.

fn bounds(&self) -> Rect

Bounding rectangle in parent-local Y-up coordinates.

fn set_bounds(&mut self, b: Rect)

Set the bounding rectangle. Called by the parent during layout.

fn children(&self) -> &[Box<dyn Widget>]

Immutable access to child widgets.

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

Mutable access to child widgets (required for event dispatch + layout).

fn needs_draw(&self) -> bool

Return true if this widget, or any visible descendant, has an ongoing draw need that should keep the host drawing.

fn margin(&self) -> Insets

Outer margin around this widget in logical units.

fn widget_base(&self) -> Option<&WidgetBase>

Direct read access to the widget’s embedded WidgetBase.

fn widget_base_mut(&mut self) -> Option<&mut WidgetBase>

Mutable counterpart of widget_base.

fn h_anchor(&self) -> HAnchor

Horizontal anchor: how this widget sizes/positions itself horizontally within the slot the parent assigns. Default: HAnchor::FIT (take natural content width).

fn v_anchor(&self) -> VAnchor

Vertical anchor: how this widget sizes/positions itself vertically within the slot the parent assigns. Default: VAnchor::FIT (take natural content height).

fn min_size(&self) -> Size

Minimum size constraint (logical units).

fn max_size(&self) -> Size

Maximum size constraint (logical units).

fn hit_test(&self, local_pos: Point) -> bool

Return true if local_pos (in this widget’s local coordinates) falls inside this widget’s interactive area. Default: axis-aligned rect test.

fn claims_pointer_exclusively(&self, local_pos: Point) -> bool

When true, hit_test_subtree stops recursing into this widget’s children and returns this widget as the hit target. Used for floating overlays (e.g. a scrollbar painted above its content) that must claim the pointer before children that happen to share the same pixels. Default: false.

fn layout(&mut self, available: Size) -> Size

Compute desired size given available space, and update internal layout.

fn paint(&mut self, _ctx: &mut dyn DrawCtx)

Paint this widget’s own content into ctx.

fn clip_children_rect(&self) -> Option<(f64, f64, f64, f64)>

Return a clip rectangle (in local coordinates) that constrains all child painting. paint_subtree applies this clip before recursing into children, then restores the previous clip state afterward. The clip does not affect paint_overlay, which runs after the clip is removed.

fn paint_overlay(&mut self, ctx: &mut dyn DrawCtx)

Paint decorations that must appear on top of all children.

fn on_event(&mut self, event: &Event) -> EventResult

Handle an event. The event’s positions are already in local Y-up coordinates. Return EventResult::Consumed to stop bubbling.

fn hit_test_global_overlay(&self, _local_pos: Point) -> bool

Return true when local_pos hits an app-level overlay owned by this widget. Unlike normal hit testing, ancestors may be missed because the overlay is painted outside their bounds.

fn has_active_modal(&self) -> bool

Whether this widget currently owns an app-modal interaction layer.

fn on_unconsumed_key( &mut self, _key: &Key, _modifiers: Modifiers, ) -> EventResult

Handle a key that was not consumed by the focused widget path.

fn is_focusable(&self) -> bool

Whether this widget can receive keyboard focus. Default: false.

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

Optional human-readable identifier for this widget instance.

fn is_visible(&self) -> bool

Return false to suppress painting this widget and all its children. The widget’s own paint() will not be called. Default: true.

fn set_label_color(&mut self, _color: Color)

If this widget is text-bearing (e.g. Label), update its foreground colour. Default is a no-op. Composite widgets call this on their children to retint labels without rebuilding them — used by Button when toggling between active (white text on accent) and inactive (theme text on subtle bg) appearances.

fn set_label_text(&mut self, _text: &str)

If this widget is text-bearing (e.g. Label), update its displayed text. Default is a no-op. Composite widgets that own a Label child use this to push live values (e.g. an FPS counter) into the child without bypassing the standard backbuffered glyph cache — calling this on a Label only invalidates the cache when the text actually changed.

fn as_reflect(&self) -> Option<&dyn Reflect>

Opt-in reflection accessor for the inspector’s typed property editors.

fn as_reflect_mut(&mut self) -> Option<&mut dyn Reflect>

Mutable counterpart of as_reflect. Used by the inspector to write edits back into the live widget.

fn has_backbuffer(&self) -> bool

Whether this widget renders into its own offscreen buffer before compositing into the parent.

fn compositing_layer(&mut self) -> Option<CompositingLayer>

Request that this widget subtree be painted into a transient transparent compositing layer before being blended into its parent.

fn backbuffer_spec(&mut self) -> BackbufferSpec

Unified widget-owned backbuffer request.

fn backbuffer_state_mut(&mut self) -> Option<&mut BackbufferState>

Mutable retained backbuffer state for widgets that request a BackbufferSpec other than BackbufferKind::None.

fn mark_dirty(&mut self)

Mark this widget’s own retained surface dirty, if it owns one.

fn backbuffer_cache_mut(&mut self) -> Option<&mut BackbufferCache>

Opt into per-widget CPU bitmap caching with a dirty flag.

fn backbuffer_mode(&self) -> BackbufferMode

Storage format for this widget’s backbuffer. Ignored unless [backbuffer_cache_mut] returns Some. Default BackbufferMode::Rgba — correct for any widget. Opt into BackbufferMode::LcdCoverage only when the widget paints opaque content covering its full bounds.

fn contributes_children_to_inspector(&self) -> bool

Whether the inspector should recurse into this widget’s children.

fn show_in_inspector(&self) -> bool

Return false to hide this widget (and its subtree) from the inspector node snapshot entirely. Intended for zero-size utility widgets such as layout-time watchers / tickers / invisible composers — they bloat the inspector tree without providing user-relevant information and, at scale, can make the inspector’s per-frame tree rebuild expensive.

fn lcd_preference(&self) -> Option<bool>

Per-widget LCD subpixel preference for backbuffered text rendering.

fn finish_paint(&mut self, _ctx: &mut dyn DrawCtx)

Called after paint, child painting, and optional overlay painting.

fn paint_global_overlay(&mut self, _ctx: &mut dyn DrawCtx)

Paint app-level overlays after the entire widget tree has been painted.

fn padding(&self) -> Insets

Inner padding — space the widget reserves between its own bounds and its child layout area. Only container widgets carry padding; leaf widgets default to Insets::ZERO.

fn enforce_integer_bounds(&self) -> bool

Whether paint_subtree should snap this widget’s incoming translation to the physical pixel grid.

fn measure_min_height(&self, _available_w: f64) -> f64

Report the minimum height this widget needs to fully render its content when given the supplied available_w for width.

fn take_raise_request(&mut self) -> bool

Container widgets (notably crate::widgets::Stack) call this on each child at the start of layout(). A widget that returns true is moved to the END of its parent’s child list — painted last, i.e. raised to the top of the z-order. take_ semantics: the call is also expected to clear the request so the child doesn’t keep getting raised every frame.

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

Return the earliest wall-clock instant at which this widget (or any visible descendant) wants the next draw. None = no scheduled wake. The host loop turns a Some(t) into ControlFlow::WaitUntil(t) so e.g. a cursor blink fires without continuous polling.