@tamagui/react-native-web-lite/src/vendor/react-native/Animated/animations/DecayAnimation.js

React Native for Web

/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @format
 */

'use strict'

import { Animation } from './Animation'

import { shouldUseNativeDriver } from '../NativeAnimatedHelper'

class DecayAnimation extends Animation {
  _startTime
  _lastValue
  _fromValue
  _deceleration
  _velocity
  _onUpdate
  _animationFrame
  _useNativeDriver

  constructor(config) {
    super()
    this._deceleration = config.deceleration ?? 0.998
    this._velocity = config.velocity
    this._useNativeDriver = shouldUseNativeDriver(config)
    this.__isInteraction = config.isInteraction ?? !this._useNativeDriver
    this.__iterations = config.iterations ?? 1
  }

  __getNativeAnimationConfig() {
    return {
      type: 'decay',
      deceleration: this._deceleration,
      velocity: this._velocity,
      iterations: this.__iterations,
    }
  }

  start(fromValue, onUpdate, onEnd, previousAnimation, animatedValue) {
    this.__active = true
    this._lastValue = fromValue
    this._fromValue = fromValue
    this._onUpdate = onUpdate
    this.__onEnd = onEnd
    this._startTime = Date.now()
    if (this._useNativeDriver) {
      this.__startNativeAnimation(animatedValue)
    } else {
      this._animationFrame = requestAnimationFrame(this.onUpdate.bind(this))
    }
  }

  onUpdate() {
    const now = Date.now()

    const value =
      this._fromValue +
      (this._velocity / (1 - this._deceleration)) *
        (1 - Math.exp(-(1 - this._deceleration) * (now - this._startTime)))

    this._onUpdate(value)

    if (Math.abs(this._lastValue - value) < 0.1) {
      this.__debouncedOnEnd({ finished: true })
      return
    }

    this._lastValue = value
    if (this.__active) {
      this._animationFrame = requestAnimationFrame(this.onUpdate.bind(this))
    }
  }

  stop() {
    super.stop()
    this.__active = false
    global.cancelAnimationFrame(this._animationFrame)
    this.__debouncedOnEnd({ finished: false })
  }
}

export { DecayAnimation }
export default DecayAnimation