109 lines
2.8 KiB
JavaScript
109 lines
2.8 KiB
JavaScript
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @flow
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* @format
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*/
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'use strict';
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const Animation = require('./Animation');
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const {shouldUseNativeDriver} = require('../NativeAnimatedHelper');
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import type {AnimationConfig, EndCallback} from './Animation';
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import type AnimatedValue from '../nodes/AnimatedValue';
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export type DecayAnimationConfig = AnimationConfig & {
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velocity: number | {x: number, y: number},
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deceleration?: number,
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};
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export type DecayAnimationConfigSingle = AnimationConfig & {
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velocity: number,
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deceleration?: number,
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};
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class DecayAnimation extends Animation {
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_startTime: number;
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_lastValue: number;
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_fromValue: number;
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_deceleration: number;
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_velocity: number;
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_onUpdate: (value: number) => void;
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_animationFrame: any;
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_useNativeDriver: boolean;
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constructor(config: DecayAnimationConfigSingle) {
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super();
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this._deceleration =
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config.deceleration !== undefined ? config.deceleration : 0.998;
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this._velocity = config.velocity;
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this._useNativeDriver = shouldUseNativeDriver(config);
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this.__isInteraction =
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config.isInteraction !== undefined ? config.isInteraction : true;
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this.__iterations = config.iterations !== undefined ? config.iterations : 1;
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}
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__getNativeAnimationConfig() {
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return {
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type: 'decay',
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deceleration: this._deceleration,
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velocity: this._velocity,
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iterations: this.__iterations,
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};
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}
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start(
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fromValue: number,
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onUpdate: (value: number) => void,
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onEnd: ?EndCallback,
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previousAnimation: ?Animation,
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animatedValue: AnimatedValue,
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): void {
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this.__active = true;
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this._lastValue = fromValue;
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this._fromValue = fromValue;
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this._onUpdate = onUpdate;
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this.__onEnd = onEnd;
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this._startTime = Date.now();
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if (this._useNativeDriver) {
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this.__startNativeAnimation(animatedValue);
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} else {
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this._animationFrame = requestAnimationFrame(this.onUpdate.bind(this));
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}
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}
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onUpdate(): void {
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const now = Date.now();
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const value =
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this._fromValue +
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(this._velocity / (1 - this._deceleration)) *
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(1 - Math.exp(-(1 - this._deceleration) * (now - this._startTime)));
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this._onUpdate(value);
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if (Math.abs(this._lastValue - value) < 0.1) {
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this.__debouncedOnEnd({finished: true});
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return;
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}
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this._lastValue = value;
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if (this.__active) {
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this._animationFrame = requestAnimationFrame(this.onUpdate.bind(this));
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}
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}
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stop(): void {
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super.stop();
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this.__active = false;
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global.cancelAnimationFrame(this._animationFrame);
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this.__debouncedOnEnd({finished: false});
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}
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}
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module.exports = DecayAnimation;
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