146 строки
3.8 KiB
JavaScript
146 строки
3.8 KiB
JavaScript
/**
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* Portions 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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* @emails oncall+react_native
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* @flow
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* @format
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*/
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/**
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* BezierEasing - use bezier curve for transition easing function
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* https://github.com/gre/bezier-easing
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* @copyright 2014-2015 Gaetan Renaudeau. MIT License.
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*/
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'use strict';
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const bezier = require('../bezier');
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const identity = function(x) {
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return x;
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};
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function assertClose(a, b, precision = 3) {
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expect(a).toBeCloseTo(b, precision);
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}
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function makeAssertCloseWithPrecision(precision) {
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return function(a, b) {
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assertClose(a, b, precision);
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};
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}
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function allEquals(be1, be2, samples, assertion) {
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if (!assertion) {
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assertion = assertClose;
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}
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for (let i = 0; i <= samples; ++i) {
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const x = i / samples;
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assertion(be1(x), be2(x));
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}
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}
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function repeat(n) {
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return function(f) {
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for (let i = 0; i < n; ++i) {
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f();
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}
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};
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}
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describe('bezier', function() {
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it('should be a function', function() {
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expect(typeof bezier === 'function').toBe(true);
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});
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it('should creates an object', function() {
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expect(typeof bezier(0, 0, 1, 1) === 'function').toBe(true);
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});
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it('should fail with wrong arguments', function() {
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expect(function() {
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bezier(0.5, 0.5, -5, 0.5);
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}).toThrow();
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expect(function() {
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bezier(0.5, 0.5, 5, 0.5);
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}).toThrow();
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expect(function() {
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bezier(-2, 0.5, 0.5, 0.5);
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}).toThrow();
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expect(function() {
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bezier(2, 0.5, 0.5, 0.5);
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}).toThrow();
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});
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describe('linear curves', function() {
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it('should be linear', function() {
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allEquals(bezier(0, 0, 1, 1), bezier(1, 1, 0, 0), 100);
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allEquals(bezier(0, 0, 1, 1), identity, 100);
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});
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});
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describe('common properties', function() {
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it('should be the right value at extremes', function() {
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repeat(10)(function() {
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const a = Math.random(),
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b = 2 * Math.random() - 0.5,
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c = Math.random(),
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d = 2 * Math.random() - 0.5;
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const easing = bezier(a, b, c, d);
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expect(easing(0)).toBe(0);
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expect(easing(1)).toBe(1);
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});
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});
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it('should approach the projected value of its x=y projected curve', function() {
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repeat(10)(function() {
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const a = Math.random(),
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b = Math.random(),
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c = Math.random(),
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d = Math.random();
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const easing = bezier(a, b, c, d);
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const projected = bezier(b, a, d, c);
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const composed = function(x) {
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return projected(easing(x));
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};
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allEquals(identity, composed, 100, makeAssertCloseWithPrecision(2));
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});
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});
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});
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describe('two same instances', function() {
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it('should be strictly equals', function() {
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repeat(10)(function() {
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const a = Math.random(),
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b = 2 * Math.random() - 0.5,
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c = Math.random(),
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d = 2 * Math.random() - 0.5;
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allEquals(bezier(a, b, c, d), bezier(a, b, c, d), 100, 0);
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});
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});
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});
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describe('symmetric curves', function() {
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it('should have a central value y~=0.5 at x=0.5', function() {
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repeat(10)(function() {
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const a = Math.random(),
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b = 2 * Math.random() - 0.5,
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c = 1 - a,
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d = 1 - b;
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const easing = bezier(a, b, c, d);
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assertClose(easing(0.5), 0.5, 2);
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});
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});
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it('should be symmetrical', function() {
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repeat(10)(function() {
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const a = Math.random(),
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b = 2 * Math.random() - 0.5,
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c = 1 - a,
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d = 1 - b;
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const easing = bezier(a, b, c, d);
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const sym = function(x) {
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return 1 - easing(1 - x);
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};
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allEquals(easing, sym, 100, makeAssertCloseWithPrecision(2));
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});
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});
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});
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});
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