Struct VirtualList 

pub struct VirtualList { /* private fields */ }

A list of any length that builds only the rows that show, with rows of any height. They are laid out and measured as they appear, and what was measured is kept by key, so going back finds them at the right size. It can jump to a row, stay at the end as a chat does, and keep what is on screen still when rows come in above it. With nothing to select, the arrows, Page Up, Page Down, Home and End scroll; with a selection or on_activate, they move between rows, and Enter or Space activates.

Rows of the same height, told with row_height, need no measuring.

use ravenrs_reactive::State;
use ravenrs_widgets::{Text, Ui, VirtualList};

let chosen = State::new(None::<usize>);
let list = VirtualList::new(10_000, |index| Text::new(format!("Row {index}")))
    .key(|index| index as u64)
    .selection(chosen.binding())
    .height(320.0);
let mut ui = Ui::new(list, ravenrs_style::Theme::raven_dark());
ui.update();

Implementations

impl VirtualList

pub fn new<V: View + 'static>( count: usize, item: impl Fn(usize) -> V + 'static, ) -> Self

A list of count rows, with item making the view of each one when it shows.

pub fn key(self, key: impl Fn(usize) -> u64 + 'static) -> Self

What identifies a row, which is its position by default. With it, a row keeps its measured height and what is on screen stays still when rows come in above. It is asked for every row on each build, so it should only read a value.

pub fn estimated_height(self, height: f32) -> Self

How tall a row probably is until it has been measured (40 by default).

pub fn row_height(self, height: f32) -> Self

Every row has this height, and nothing has to be measured.

pub fn row_heights(self, height: impl Fn(usize) -> f32 + 'static) -> Self

The height of each row is known, as with the pages of a document. It is asked for every row on each build.

pub fn spacing(self, spacing: f32) -> Self

Gap between rows, in logical pixels.

pub fn follow_end(self, follow: bool) -> Self

Starts at the end and stays there as rows arrive, as a chat does, until the user scrolls away; coming back to the end takes it up again.

pub fn scroll_to(self, index: Binding<Option<usize>>) -> Self

Set it to a row to bring that row to the start of the view. It goes back to None.

pub fn selection(self, selected: Binding<Option<usize>>) -> Self

Makes the rows selectable, one at a time, with the pointer and the arrows.

pub fn on_activate(self, handler: impl Fn(usize) + 'static) -> Self

Called with a row on a double click, or on Enter or Space.

pub fn on_visible(self, handler: impl Fn(Range<usize>) + 'static) -> Self

Called with the rows that show whenever they change, as for loading what comes next.

pub fn row_name(self, name: impl Fn(usize) -> String + 'static) -> Self

What screen readers call each row, for rows whose content does not say it.

pub fn label(self, label: impl Into<String>) -> Self

What screen readers call the list, instead of the name in Labels.

pub fn height(self, height: f32) -> Self

A fixed height. It takes the height its parent gives it by default.

pub fn horizontal(self) -> Self

Runs from left to right; the sizes above are then widths, and the height is across.

Trait Implementations

impl Debug for VirtualList

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

Formats the value using the given formatter.

impl View for VirtualList

fn build(&self, cx: &mut BuildCx<'_>) -> NodeId

Creates this view’s node for the current build.

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

The name the diagnostics panel shows this view’s cost under.