Struct ScrollView 

pub struct ScrollView {
    pub style: Style,
    pub show_scrollbar: bool,
    /* private fields */
}

Vertical scrolling viewport over taller content (REND-00 §6).

Children live in content space: a child with bounds y = 0 sits at the top of the content, which coincides with the top of the viewport only while scroll_y == 0.

Fields

style: Style

Visual style of the viewport background.

show_scrollbar: bool

Draw the optional built-in proportional scrollbar thumb (default false; the query seam is the supported contract for custom scrollbars).

Implementations

impl ScrollView

pub fn new(bounds: Rect, content_height: i32) -> Self

Create a viewport at bounds over content_height pixels of content. A content height ≤ the viewport height simply never scrolls.

pub fn add_child(&mut self, child: Rc<RefCell<dyn Widget>>)

Add a child widget positioned in content space.

pub fn set_content_height(&mut self, content_height: i32)

Replace the content extent (e.g. after adding rows). The current offset is re-clamped; a clamp that moves it marks the view dirty.

pub fn viewport(&self) -> Rect

The viewport rect (the widget’s own bounds, screen space).

pub fn content_height(&self) -> i32

Total content extent in pixels.

pub fn scroll_y(&self) -> i32

Current per-pixel scroll offset (0..=max_scroll).

pub fn max_scroll(&self) -> i32

Maximum reachable scroll offset.

pub fn scroll_to(&mut self, y: i32)

Scroll to an absolute offset, clamped to 0..=max_scroll. Marks the view dirty only when the effective offset changes.

pub fn scroll_by(&mut self, dy: i32)

Scroll by a signed per-pixel delta (clamped; see scroll_to).

pub fn take_dirty(&mut self) -> Option<Rect>

The region invalidated by scroll-offset changes since the last call: the viewport rect, once, then None until the next change (REND-00 §6.6 — a scrolled panel invalidates its viewport, not the whole frame).

Trait Implementations

impl Widget for ScrollView

fn bounds(&self) -> Rect

Return the area this widget occupies relative to its parent.

fn draw(&self, renderer: &mut dyn Renderer)

Render the widget using the provided Renderer.

fn handle_event(&mut self, event: &Event) -> bool

Handle an event and return true if it was consumed.

fn clear_region(&mut self) -> Option<Rect>

Return a region (in draw/landscape coordinates) that should be restored from the pristine background copy, or None.

fn set_bounds(&mut self, _bounds: Rect)

Called by the LPAR-10 layout pass to notify this widget of its layout-computed bounds.

fn widget_font_mut(&mut self) -> Option<&mut WidgetFont>

Expose this widget’s font slot for cascade-driven font resolution (FONT-05 §5.B).