Easing

The Easing module implements common easing functions. This module is used by Animated.timing() to convey physically believable motion in animations.

You can find a visualization of some common easing functions at http://easings.net/

Predefined animations

The Easing module provides several predefined animations through the following methods:

• back provides a basic animation where the object goes slightly back before moving forward
• bounce provides a bouncing animation
• ease provides a basic inertial animation
• elastic provides a basic spring interaction

Standard functions

Three standard easing functions are provided:

• linear
• quad
• cubic

The poly function can be used to implement quartic, quintic, and other higher power functions.

Additional functions

Additional mathematical functions are provided by the following methods:

• bezier provides a cubic bezier curve
• circle provides a circular function
• sin provides a sinusoidal function
• exp provides an exponential function

The following helpers are used to modify other easing functions.

• in runs an easing function forwards
• inOut makes any easing function symmetrical
• out runs an easing function backwards

Example

TypeScript

JavaScript

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Reference

Methods

step0()

static step0(n: number);

A stepping function, returns 1 for any positive value of n.

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step1()

static step1(n: number);

A stepping function, returns 1 if n is greater than or equal to 1.

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linear()

static linear(t: number);

A linear function, f(t) = t. Position correlates to elapsed time one to one.

http://cubic-bezier.com/#0,0,1,1

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ease()

static ease(t: number);

A basic inertial interaction, similar to an object slowly accelerating to speed.

http://cubic-bezier.com/#.42,0,1,1

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quad()

static quad(t: number);

A quadratic function, f(t) = t * t. Position equals the square of elapsed time.

http://easings.net/#easeInQuad

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cubic()

static cubic(t: number);

A cubic function, f(t) = t * t * t. Position equals the cube of elapsed time.

http://easings.net/#easeInCubic

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poly()

static poly(n: number);

A power function. Position is equal to the Nth power of elapsed time.

n = 4: http://easings.net/#easeInQuart n = 5: http://easings.net/#easeInQuint

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sin()

static sin(t: number);

A sinusoidal function.

http://easings.net/#easeInSine

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circle()

static circle(t: number);

A circular function.

http://easings.net/#easeInCirc

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exp()

static exp(t: number);

An exponential function.

http://easings.net/#easeInExpo

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elastic()

static elastic(bounciness: number);

A basic elastic interaction, similar to a spring oscillating back and forth.

Default bounciness is 1, which overshoots a little bit once. 0 bounciness doesn't overshoot at all, and bounciness of N > 1 will overshoot about N times.

http://easings.net/#easeInElastic

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back()

static back(s)

Use with Animated.parallel() to create a basic effect where the object animates back slightly as the animation starts.

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bounce()

static bounce(t: number);

Provides a basic bouncing effect.

http://easings.net/#easeInBounce

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bezier()

static bezier(x1: number, y1: number, x2: number, y2: number);

Provides a cubic bezier curve, equivalent to CSS Transitions' transition-timing-function.

A useful tool to visualize cubic bezier curves can be found at http://cubic-bezier.com/

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in()

static in(easing: number);

Runs an easing function forwards.

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out()

static out(easing: number);

Runs an easing function backwards.

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inOut()

static inOut(easing: number);

Makes any easing function symmetrical. The easing function will run forwards for half of the duration, then backwards for the rest of the duration.