Interface IndicatorDescriptor

Optionalcategory

id

inputs

name

placement

plots

Optionalattach

• attach(ctx: IndicatorAttachContext): void | () => void

• Optional per-instance lifecycle, for indicators whose data is not derived from the chart's bars (open interest, CVD, an external feed). Called once when the instance is created; return a teardown function.

  Fetch into ctx.store, then call ctx.requestRecompute() — calc runs again and reads what you stored.

  Parameters

  • ctx: IndicatorAttachContext

  Returns void | () => void

calc

• calc(
      bars: readonly Bar[],
      settings: Readonly<IndicatorSettings>,
      store: IndicatorStore,
  ): IndicatorValues

• Full recompute over every bar. Must return arrays the same length as bars (use null for warmup gaps — the line renderer breaks across them and autoscale skips them).

  Tier-1 indicators are pure functions of (bars, settings) and ignore store. Tier-2 indicators — the ones with their own data — read the external series their attach lifecycle put in store.

  Parameters

  • bars: readonly Bar[]
  • settings: Readonly<IndicatorSettings>
  • store: IndicatorStore

  Returns IndicatorValues

OptionalcalcTail

• calcTail(
      bars: readonly Bar[],
      settings: Readonly<IndicatorSettings>,
      fromIndex: number,
      previous: IndicatorValues,
      store: IndicatorStore,
  ): null | IndicatorValues

• Optional incremental path, called instead of calc when only the tail changed (a live tick). Return values for indices [fromIndex, bars.length) — the runtime splices them onto the previous result — or null to fall back to a full calc.

  Without it every tick costs a full recompute. That is a few hundred microseconds for one indicator over 50k bars, but it is O(n) per tick per indicator, so implement this for anything meant to run in a busy live pane.

  Parameters

  • bars: readonly Bar[]
  • settings: Readonly<IndicatorSettings>
  • fromIndex: number
  • previous: IndicatorValues
  • store: IndicatorStore

  Returns null | IndicatorValues

Optionallevels

• levels(settings: Readonly<IndicatorSettings>): readonly IndicatorLevel[]

• Optional horizontal reference levels drawn in the indicator's pane.

  Parameters

  • settings: Readonly<IndicatorSettings>

  Returns readonly IndicatorLevel[]

Optionalrange

• range(
      settings: Readonly<IndicatorSettings>,
  ): null | { max: number; min: number }

• Optional fixed price range for the indicator's own pane (RSI 0..100). Applied only when the indicator creates its pane — two indicators sharing a pane would otherwise fight over it.

  Parameters

  • settings: Readonly<IndicatorSettings>

  Returns null | { max: number; min: number }