Struct VirtualListHandle 

pub struct VirtualListHandle { /* private fields */ }

The scroll and measurement state of one VirtualList. Cheap to clone; clones share the state. Keep one per list in the owning view.

Implementations

impl VirtualListHandle

pub fn new(item_count: usize) -> Self

A measured (variable-row-height) handle for a list of item_count rows, scrolled to the top.

pub fn uniform(item_count: usize) -> Self

A uniform (fixed-row-height) handle for a list of item_count rows, scrolled to the top. Every row is laid out at the height of the first, so rows should be built at one explicit height.

pub fn is_uniform(&self) -> bool

Whether this handle was made by uniform.

pub fn item_count(&self) -> usize

The number of rows the list renders.

pub fn set_item_count(&self, item_count: usize)

Replaces the collection: item_count rows, all remeasured, scrolled back to the top. For an append or a local edit, splice keeps the scroll position and the other rows’ measurements.

pub fn splice(&self, old_range: Range<usize>, count: usize)

Replaces the rows in old_range with count new rows, keeping every other row’s measured height and the scroll position (a uniform list clamps it when the content got shorter).

pub fn remeasure(&self)

Discards every measured height, for when row content changed size without the count changing (a font or density switch). A uniform list measures its first row every frame, so this does nothing there.

pub fn scroll_to_item(&self, ix: usize, strategy: VirtualListScroll)

Scrolls so row ix is visible, per strategy. An index past the end scrolls to the end. Takes effect on the next frame.

pub fn scroll_by(&self, distance: Pixels)

Scrolls by distance (positive moves the content up, towards later rows), clamped to the content.

pub fn first_visible_item(&self) -> usize

The index of the first row at the top of the viewport.

pub fn bounds_for_item(&self, ix: usize) -> Option<Bounds<Pixels>>

Row ix’s window-coordinate bounds from the last frame, when it was rendered.

pub fn viewport_bounds(&self) -> Bounds<Pixels>

The list’s viewport in window coordinates, as laid out in the last frame (zero-sized before the first). This is what PageUp/PageDown step over: it follows a bounded parent or a resized window, where a configured height would not.

pub fn remaining_below(&self) -> Option<Pixels>

How much content lies below the viewport’s bottom edge after the last frame, or None when that is not known. A uniform list knows it exactly once laid out: the row count times the measured row, less the scroll offset and the viewport. A measured list knows it only when its last row was laid out in the last frame, since the rows it has not built have no height yet.

pub fn is_scrolled_to_top(&self) -> bool

Whether the list is scrolled to its top (within half a pixel).

pub fn is_scrolled_to_end(&self) -> bool

Whether the list’s last row ends inside the viewport. An empty list answers true. A nonempty measured list answers false until its last row has been laid out; uniform mode defaults to true before GPUI reports its scroll extent.

Trait Implementations

impl Clone for VirtualListHandle

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for VirtualListHandle

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

Formats the value using the given formatter.