Interpol 👮🏽‍

Interpol library interpolates a set of number values with a gsap's like API. This is the lowest level of animate machine. Interpol don't come with dom API, it only provides real time progress of the interpolations that can be use or bind on... mesh, dom element or anything else, for ~=3kB!

⚠️ Interpol still is in early development, the API can change until the first major release

Summary

• Summary
• Playground 🕹️
• Install
• Basic usage
  • Interpol
  • Timeline
• Props
  • Props types
  • Computed prop values
• Styles helper
• Easing
• API
  • interpol constructor
  • Interpol methods
  • Timeline constructor
  • Timeline methods
• Options
  • Ticker
    • Disable internal raf
    • Use the internal Ticker instance globally
  • Defaults properties
• Dev examples
• Credits
• About
• License

Playground 🕹️

The examples of this repo are available on codesandbox:

• Interpol basic
• Interpol colors
• Interpol dom onDrag
• Interpol ease
• Interpol graphic
• Interpol menu
• Interpol object el
• Interpol offsets
• Interpol particles
• Interpol timeline

Install

npm i @wbe/interpol

Basic usage

Interpol

Interpol instance usage:

import { Interpol } from "@wbe/interpol"

new Interpol({
  v: [0, 100],
  duration: 1000,
  ease: (t) => t,
  onUpdate: ({ v }, time, progress) => {
    // On each frame, get updated `v` value between 0 and 100
  },
  onComplete: ({ v }, time, progress) => {
    // Interpol is complete
  },
})

In this example:

• The Interpol will start automatically;
• v will be interpolated between 0 and 100 during 1 second
• time is the current time in millisecond
• progress is the current progress between 0 and 1

Timeline

Chaining interpol instancies with Timeline:

import { Interpol, Timeline } from "@wbe/interpol"

const tl = new Timeline({
  onUpdate: (time, progress) => {
    // Timeline is updating
  },
  onComplete: (time, progress) => {
    // Timeline is complete
  },
})

// Set an Interpol instance object constructor directly
tl.add({
  x: [0, 100],
  onComplete: ({ x }, time, progress) => {
    // itp 1 is complete
  },
})

// Or add interpol instance to the timeline
const itp = new Interpol({
  x: [100, 50],
  onComplete: ({ x }, time, progress) => {
    // itp 2 is complete
  },
})
tl.add(itp)

In this example:

• The timeline will start automatically;
• Interpol 1, will interpolate x value between 0 and 100 during 1 second;
• Interpol 2, will start when Interpol 1 is complete and will interpolate x value between 100 and 50 during 0.5 second.

Props

Props types

For more flexibility, there is three ways to define a single prop:

new Interpol({
  // 1. a simple number, implicite from is `0`
  // to use only when `from` is `0`
  x: 100,

  // 2. an array
  // [from, to]
  x: [0, 100],

  // 3. an object with explicite `from` and `to` properties
  // { from?, to, ease?, reverseEase? }
  x: { from: 0, to: 100 },
})

Computed prop values

from and to can be a number or a function that return a number. Three ways to define a to computed value on the same prop model:

new Interpol({
  // 1. number
  x: () => Math.random(),

  // 2. array
  x: [0, () => Math.random()],

  // 3. object
  x: { from: 0, to: () => Math.random() },
})

In order to refresh computed values, you can use the refreshComputedValues method:

const itp = new Interpol({
  // ...
})
itp.refreshComputedValues()

Styles helper

One of the main usage of Interpol is to animate DOM element style properties. The API provide styles, a core helper function to simplify the DOM manipulation. The function uses a DOM cache to associate multiple transformation functions with the same DOM element at the same time.

Definition:

declare const styles: (
  element: HTMLElement | HTMLElement[] | Record<any, number> | null,
  props: Record<string, string | number>,
  autoUnits: boolean = true,
) => void

Example:

import { Interpol, styles } from "./Interpol"

new Interpol({
  x: [-100, 0],
  y: [0, 50],
  opacity: [0, 1],
  onUpdate: ({ x, y, opacity }) => {
    // set updated interpol values to the DOM element
    styles(element, { x, y, opacity })

    // Is Equivalent to:
    // element.style.transform = `translate3d(${x}px, ${y}px, 0px)`
    // element.style.opacity = opacity
  },
})

Easing

ease & reversedEase functions are used to interpolate the progress value. the default one is (t) => t.

new Interpol({
  ease: (t) => 1 - Math.pow(1 - t, 4),
})

GSAP like ease functions are available in interpol as string or object:

import { Interpol, Power3 } from "@wbe/interpol"

// as typed string
new Interpol({
  ease: "power3.out",
})

// or, import the object
new Interpol({
  ease: Power3.out,
})

API

interpol constructor

import { EaseFn } from "./ease"

// A Value can be a number or a computed number
type Value = number | (() => number)

// The propsValues type can be a single number, an array or an object
export type PropsValues =
  // 1. to
  | Value
  // 2. [from, to]
  | [Value, Value]
  // 3. { from, to, ease }
  | Partial<{ from: Value; to: Value; ease: Ease; reverseEase: Ease }>

/**
 * Interpol constructor
 */
interface IInterpolConstruct<K extends keyof Props> {
  // inline props are an interpol list object, 3 definition types
  // default: /
  [x: string]: PropsValues

  // Interpolation duration between `from` and `to` values (millisecond).
  // ex: 1000 is 1 second
  // default: `1000`
  duration?: number | (() => number)

  // Interpol easing function
  // default: `t => t` (lineal easing)
  ease?: EaseName | EaseFn

  // Overwrite easing function on reverse
  // default: /
  reverseEase?: EaseName | EaseFn

  // Make interpol paused at start (not autoplay)
  // default: `false`
  paused?: boolean

  // Add delay before first start
  // default: `false`
  delay?: number

  // Enable debug to get interpol logs information
  // default: `false`
  debug?: boolean

  // Called when interpol is ready to play
  // default: /
  beforeStart?: (
    props: Record<K, number>,
    time: number,
    progress: number,
    instance: Interpol,
  ) => void

  // Called on frame update
  // default: /
  onUpdate?: (props: Record<K, number>, time: number, progress: number, instance: Interpol) => void

  // Called when interpol is complete
  // default: /
  onComplete?: (
    props: Record<K, number>,
    time: number,
    progress: number,
    instance: Interpol,
  ) => void

  // Execute onUpdate method when the Interpol instance is create
  // default: false
  immediateRender?: boolean
}

Interpol methods

import { Interpol } from "@wbe/Interpol"

const itp = new Interpol()

// Play the interpol
// play(from: number = 0): Promise<any>
itp.play(from)

// Reverse and play the interpol
// reverse(from: number = 1): Promise<any>
itp.reverse(from)

// Pause the interpol
// pause(): void
itp.pause()

// Resumes playing without altering direction (forward or reversed).
// resume(): void
itp.resume()

// Stop the interpol, will reset time, delta and progress.
// stop(): void
itp.stop()

// Compute 'from', 'to' and 'duration' values if there are functions
// refreshComputedValues(): void
itp.refreshComputedValues()

// Seek to a specific time
// seek(progress: number, suppressEvents = true): void
// progress: number between 0 and 1
itp.seek(progress)

Timeline constructor

interface ITimelineConstruct {
  // Execute on frame update
  // default: /
  onUpdate?: (time: number, progress: number) => void

  // Execute on complete
  // default: /
  onComplete?: (time: number, progress: number) => void

  // Enable debug to get timeline instance logs
  // default: `false`
  debug?: boolean

  // Disable timeline autoplay
  // default: `false`
  paused: boolean
}

Timeline methods

import { Timeline } from "@wbe/Interpol"

const tl = new Timeline()

// add(interpol: Interpol | IInterpolConstruct, offset: number | string = "0"): Timeline
// @param interpol: Interpol object or Interpol instance
// @param offset:
//  - relative to the previous interpol (string): "+=100", "-=100", "100", "-100"
//  - absolute (number): 0 (from the tl beginning), 100
tl.add(Interpol, offset)

// start the timeline
// play(from: number = 0): Promise<any>
tl.play(from)

// reverse and play the timeline
// reverse(from: number = 1): Promise<any>
tl.reverse(from)

// paused the timeline, will keep time, delta and progress.
// pause(): void
tl.pause()

// resume the timeline after pause.
// resume(): void
tl.resume()

// stop the timeline, will reset time, delta and progress.
// stop(): void
tl.stop()

// compute 'from', 'to' and 'duration' values on each adds if there are functions
refreshComputedValues(): void

// seek to a specific time
// seek(progress: number, suppressEvents = true, suppressTlEvents = true): void
// progress is a number between 0 and 1
tl.seek(progress)

Options

Global option Object is available to set property for each Interpol & Timeline instance.

Ticker

Disable internal raf

It's possible to disable the internal raf and use your own raf callback if needed.

import { InterpolOptions } from "@wbe/interpol"

// disable internal raf to use your own raf
InterpolOptions.ticker.disable()
const tick = (e) => {
  // execute Ticker.raf() callback on your own raf
  InterpolOptions.ticker.raf(e)
  requestAnimationFrame(tick)
}
requestAnimationFrame(tick)

Use the internal Ticker instance globally

The internal Ticker instance is available for a global application use. You can add your own raf callback to the Ticker instance and choose the rank of the callback handler.

import { InterpolOptions } from "@wbe/interpol"

// Set a new raf callback to the Ticker instance
const tickHandler = (t) => console.log(t)
const rank = 1
InterpolOptions.ticker.add(tickHandler, rank)
// ...
InterpolOptions.ticker.remove(tick)

Defaults properties

import { InterpolOptions } from "@wbe/interpol"
// Set default duration factor for all interpol instances, 1 is millisecond / 1000 is second
InterpolOptions.durationFacror = 1
// Set default duration for all interpol instances
InterpolOptions.duration = 1000
// Set default easing for all interpol instances
InterpolOptions.ease = (t) => t * t

Dev examples

# install dependencies
pnpm i

# build and watch lib changes
pnpm run build:watch

# start tests and watch
pnpm run test:watch

# start dev server for all examples
pnpm run dev

# Or run a specific example
pnpm run dev --filter interpol-basic
pnpm run dev --filter {example-name}

Credits

• gsap
• animate
• animini
• signal

About

Interpol is an open-source project created and maintained by Willy Brauner.

License

See the LICENSE file for license rights and limitations (MIT).