Zoom Helpers

(no submodules)

Purpose

The zoom.ts module provides a discrete zoom table and navigation helpers for the timeline view. Zoom levels are expressed as samplesPerPixel; larger values show more timeline in fewer pixels. The module is pure and side-effect free, making it safe to use in reducers, audio-thread code, and React memoization.

Features

Predefined DEFAULT_ZOOM_TABLE with 14 powers-of-two entries (1 to 8192)
zoomIn / zoomOut index arithmetic with boundary capping
setZoomLevel to snap arbitrary samplesPerPixel values to the nearest table entry
canZoomIn / canZoomOut boolean predicates for UI button disabled states

Usage

Basic

import { zoomIn, zoomOut, DEFAULT_ZOOM_TABLE } from "@suaveplan/audio-timeline/zoom";

let index = 0;
index = zoomIn(DEFAULT_ZOOM_TABLE, index); // 1
index = zoomOut(DEFAULT_ZOOM_TABLE, index); // 0

Advanced

import { setZoomLevel, canZoomIn } from "@suaveplan/audio-timeline/zoom";

const result = setZoomLevel(DEFAULT_ZOOM_TABLE, 150); // snaps to 128
const canGoFiner = canZoomIn(DEFAULT_ZOOM_TABLE, result.zoomIndex);

API Reference

Export	Signature	Description
`DEFAULT_ZOOM_TABLE`	`readonly number[]`	Default discrete zoom table
`zoomIn`	`(table, index) => number`	Increment zoom index, capped at max
`zoomOut`	`(table, index) => number`	Decrement zoom index, floored at 0
`setZoomLevel`	`(table, spp) => { zoomIndex, samplesPerPixel }`	Snap to nearest table entry
`canZoomIn`	`(table, index) => boolean`	True if index < max
`canZoomOut`	`(table, index) => boolean`	True if index > 0

Implementation Notes

Using a discrete table instead of a continuous float keeps zoom states comparable by simple index equality. This is useful for React memoization and for persisting user preferences. All helpers are pure and operate only on the table and index, so they can be used in reducers, tests, and even audio-thread code without side effects.

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