clapperboard

Easily set frames to create an animation rendered from an object (like the state of a react component).

Rationale

I found React to be a simple way of rendering an animation—whether svg or simple HTML.

With clapperboard, it is simple of scheduling updates to the React component state or props to animate it.

Installation

Using npm:

npm i --save clapperboard

Usage with react

Simple example of animating a browser:

  import animator from 'clapperboard';
  import React from 'react';
  import ReactDOM from 'react-dom';

  class BrowserAnimation extends React.Component {
    render() {
      return (<div className="browser-animation">
        <div
          className="browser-animation__cursor"
          style={{
            top: this.state.cursor.y.toString() + '%',
            left: this.state.cursor.x.toString() + '%'
          }}
          />
        <div className="browser-animation__top-bar">
          <span className="url">{this.state.url}</span>
        </div>
        <div
          className="browser-animation__document"
          style={{
            backgroundImage: `url(${this.state.currentPage})`,
            backgroundPosition: `0 -${this.state.scrollPosition}px`
          }}
          >
        </div>
      </div>);
    }
  }

  var component; // Render BrowserAnimation and store it here.

  var initialState = {
    cursor: {
      x: 40,
      y: 20
    },
    url: 'https://acme.com/',
    currentPage: 'homepage'
  };

  component.setState(initialState);

  const timeline = [
    ['+1', 'cursor.y', 50],
    ['+0.5', 'cursor', {x: 10, y: 15}],
    ['+0.2', 'url', 'https://acme.com/sign_up', 'type'],
    ['+0.1:signUpPage', 'currentPage', 'sign_up'],
    ['=', 'scrollPosition', 0],
    // ... all the frames here
  ];

  const [stop, onEnd] = animator(initialState, timeline, function (obj) {
      component.setState(obj);
  });

API

Frames

The timeline consists of a list of frames. Each frame is a list of the following: time, property, change, method.

time

The time is in one of these formats:

• +N (where N is a float number of seconds): Frame will be executed N seconds after the previous change is complete
• =: Frame will be executed at the same time as the previous one

Frames can further be 'tagged':

• timingInfo:frameName (ex +1:pageChanged): The frame will be named and will be referenceable as frameName.
• =frameName: The frame will be executed at the same time as frameName.
• frameName+N (where N is a float number of seconds): The frame will be executed N seconds after frameName's change is completed.

These can be combined, so that sessionStart+5:sessionEnd is a valid time.

property

This will be the property of the master object to be changed, in dot format.

change

This is what the property will be changed to.

method

Method can be left empty or be type, in which case the change will be "typed" and not immediate. This is useful to simulate user input.

animator function

The animator function will need to be called with:

• initialState: the object frames will apply changes to
• frames: the list of frames
• callback: a function to call after each change. It will be called with the changed object as only argument
• infinite (optional): set to false to only run the animation once

It will return a function stop which you can use to stop the animation.

Big disclaimer

I'm pretty sure this stuff works, but not 100% sure. I have extracted it from an old project as I needed it again. You're welcome to submit improvements as you see fit.