Description

Jager is an library for touch gesture / symbols recognition.

Features

• Simple API
• Fast recognition (around 0.2 ms)
• Recognition on-the-fly
• No outside dependencies, just pure JavaScript

Usage

Library is used in next projects:

• Keep your sheep
• AntiPacMan

Documentation

Contents

• Quick Start
• Examples
• Options
• Methods
• License

Quick Start

• Clone the repo: git clone https://github.com/vmikhav/jager.git

In the browser:

<script src="/path/to/jager.js"></script>
<script>
    var jager = new Jager();
</script>

Examples

const jager = new Jager();
jager.addPoint({x, y});
let symbols = jager.recognise();

Also you can see this demo page.

Options

path

Array of points (x, y) for recognition

symbols

Object with symbols enumeration

if (jager.recognise() === jager.symbols['pigtail']) { }

symbolsRules

Array of symbol patterns. Pattern contain the following fields:

• symbol: {name, index} Symbol info.
• sections: Array Rules for path sections. Each rule contain the following elements:
  • x -1|0|1 Section orientation in X line. Should be 0 if y is not 0.
  • y -1|0|1 Section orientation in Y line. Should be 0 if x is not 0.
  • skip bool Optional If true, this section can be skipped in mismatch case.
• quarters: function (sX, sY, eX, eY) Callback function to check start and end point positions. Each param is in integer range [0, 3] (top-left corner is (0, 0), bottom-right is (3, 3)).

{
  symbol: this.symbols['circle'],
  sections: [{x: -1, y: 0, skip: true}, {x: 0, y: 1}, {x: 1, y: 0}, {x: 0, y: -1}, {x: -1, y: 0}],
  quarters: function (sX, sY, eX, eY) {
    return sY === 0 && eY === 0 && Math.abs(sX - eX) <= 1 && sX <= 2;
  }
}

Methods

reset()

Reset current path.

point(evt)

Extract point object from the event data.

• evt: Event parameter.

pushPoint(point)

Add point to current path without changes.

• point: Point object, contains x and y.

addPoint(point[, distanceFilter[, smoothFactor]])

Add point to current path with smoothing.

• point: Point object, contains x and y.
• distanceFilter: Ignore point if squared distance to previous point is less than distanceFilter.
• smoothFactor: How smooth will be current path. Decimal in [0, 1).

recognise([debug])

Recognizes the painted gesture.

• debug: Bool optional If true jager logging the symbol info.

drawPatch(ctx)

Draw current path in given ctx.

• ctx: Context Canvas context.

License

This software is licensed under the MIT © vmikhav