The data model

The core types live in egui_charts::model. Keep market data in UTC and let the chart’s formatters and instrument calendar control its presentation.

Bars and series

Bar holds a UTC timestamp and f64 open, high, low, close and volume values. Its timestamp denotes the opening time. BarData owns a vector of bars; supply ordered history with unique opening times. BarData::from_bars is a container constructor, not an ingestion validator.

use chrono::{DateTime, TimeDelta};
use egui_charts::model::{Bar, BarData};

let time = DateTime::UNIX_EPOCH;
let first = Bar::new(time, 100.0, 104.0, 98.0, 103.0, 20.0);
let next = Bar::new(time + TimeDelta::minutes(1),
                    103.0, 105.0, 102.0, 104.0, 12.0);
let data = BarData::from_bars(vec![first, next]);
assert_eq!(data.len(), 2);

Use Bar::from_value for a single value and Bar::whitespace for a time-axis slot with no value. A bar may carry per-bar colours and an optional host JSON payload; the chart returns the payload through bar lookups and pointer/data events. Do not replace missing observations with invented OHLC values.

Instruments and intervals

Instrument describes the feed’s symbol, tick size, price precision and trading calendar. Resolve it consistently with the identifiers accepted by your feed. Timeframe describes time intervals and execution-based intervals. Tick-count, volume, range and delta bars need executions; OHLC history cannot reconstruct them. Range aggregation also needs the instrument tick size.

The bar clock applies the instrument’s session rules. A chart’s display time zone changes labels; it is not a reason to rewrite UTC timestamps. Named zones require timezones; UTC, system local time and explicit fixed offsets remain available without it.

Chart state belongs to the widget

Chart owns the view, configured series, studies and interactions. SeriesId::MAIN identifies its main series. Keep local bar indices inside their chart: synchronized charts exchange UTC positions because intervals and history lengths can differ. See scales and navigation and the builder guide.