Struct ScrollbarState 

pub struct ScrollbarState {
    pub content_length: usize,
    pub position: usize,
    pub viewport_length: usize,
    pub drag_anchor: Option<usize>,
}

Mutable state for a Scrollbar widget.

Fields

content_length: usize

Total number of scrollable content units.

position: usize

Current scroll position within the content.

viewport_length: usize

Number of content units visible in the viewport.

drag_anchor: Option<usize>

Drag anchor point (offset from thumb top) to prevent jumping.

Implementations

impl ScrollbarState

pub fn new( content_length: usize, position: usize, viewport_length: usize, ) -> Self

Create a new scrollbar state with given content, position, and viewport sizes.

pub fn handle_mouse( &mut self, event: &MouseEvent, hit: Option<(HitId, HitRegion, u64)>, expected_id: HitId, ) -> MouseResult

Handle a mouse event for this scrollbar.

Hit data convention

The hit data (u64) is encoded as: [8: part] [28: track_len] [28: track_pos]

• part: One of SCROLLBAR_PART_*.
• track_len: The effective length of the track (excluding buttons).
• track_pos: The position within the effective track (0-based).

Arguments

• event — the mouse event from the terminal
• hit — result of frame.hit_test(event.x, event.y), if available
• expected_id — the HitId this scrollbar was rendered with

pub fn scroll_up(&mut self, lines: usize)

Scroll the content up by the given number of lines.

pub fn scroll_down(&mut self, lines: usize)

Scroll the content down by the given number of lines.

Clamps so that the viewport stays within content bounds.

Trait Implementations

impl Clone for ScrollbarState

fn clone(&self) -> ScrollbarState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ScrollbarState

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

Formats the value using the given formatter.

impl Default for ScrollbarState

fn default() -> ScrollbarState

Returns the “default value” for a type.