gestrec

A JavaScript implementation of the Protractor gesture recognizer.

This package provides a JavaScript version of Yang Li's Protractor gesture recognizer. The code is a close port of the Java version that ships as part of the Google Android distribution.

Usage

The gesture recognizer can be used both server-side and client-side. For use in node.js, simply npm install gestrec or include gestrec as a dependency in your package.json file. For use on the client, simply import gestrec.min.js in the browser.

Example

var gestrec = require('gestrec');
var store = new gestrec.GestureStore();
 
// a stroke is a collection of timestamped points
var stroke = new gestrec.Stroke([
  //  gestrec.Point( x, y, t)
  new gestrec.Point( 2, 5, 1),
  new gestrec.Point( 2, 9, 2)
]);
// a gesture is a collection of one or more strokes
var gesture = new gestrec.Gesture([stroke]);
 
// build a recognizer by providing gesture training examples
// repeat to provide multiple examples for each named gesture class
store.addGesture("line_down", gesture);
 
// gestures can be read from JSON-style objects
var down = gestrec.Gesture.fromJSON([[{x:4, y:1, t:1}, {x:4, y:3, t:2}]]),
    left = gestrec.Gesture.fromJSON([[{x:4, y:1, t:1}, {x:8, y:1, t:2}]]);
 
// recognize a matching (high-scoring) gesture
var prediction = store.recognize(down);
console.log(JSON.stringify(prediction));
// [{"name":"line_down","score":67108864}]
 
// recognize a non-matching (low-scoring) gesture
prediction = store.recognize(left);
console.log(JSON.stringify(prediction));
// [{"name":"line_down","score":0.6366197723675814}]

Gesture Training Application

A gesture training application is available online at http://uwdata.github.io/gestrec/.

The application is intended to work with both mouse and touch input. The code for the training application is included in this repository under the trainer folder. Simply open the index.html file in a browser to run locally.

Build Process

We use the gulp build system along with browserify to build gestrec.min.js.

1. Install gulp, as needed. Follow step 1 on the Gulp Getting Started guide.
2. Run npm install in the gestures folder to install dependencies.
3. Run gulp.