Create and detect custom gestures on React Native

React Native Gesture Detector

Create and detect custom gestures on React Native.

Example app and usage

Feel free to test Snack Expo demo or run the included demo app locally:

$ git clone https://github.com/mxmzb/react-native-gesture-detector.git
$ cd react-native-gesture-detector/example
$ yarn
$ yarn start

Check the code for the screens to see how they are done!

Intro

This package originated from a real life need to detect custom gestures. The idea for implementation originated from this stellar answer on StackOverflow. The result is not 100% foolproof, but rock solid, performant and extremely simple to use.

The package comes with another, insanely cool component GestureRecorder, which allows you to create gestures on the fly. Yep, just plug it in, paint the gesture and you will receive the coordinate data for your supercomplex, custom gesture. You can use it to just use the data points as a predefined gesture in your app, or you can even let your app users create their own custom gestures, if that fits your game plan!

Because the library significantly uses React hooks, you must use at least [email protected].

Installation

$ yarn add react-native-gesture-detector
$ yarn add react-native-gesture-handler lodash # install peer dependencies

Quickstart

import GestureDetector, {
  GestureRecorder,
  GesturePath,
  Cursor,
} from "react-native-gesture-detector";

const gestures = {
  // this will result in the gesture shown in the first demo give above
  Coil: [
    { x: 10, y: -30 }, // This is a coordinate object
    { x: 25, y: -15 },
    { x: 40, y: -10 },
    { x: 55, y: -15 },
    { x: 70, y: -30 },
    { x: 85, y: -45 },
    { x: 90, y: -65 },
    { x: 85, y: -85 },
    { x: 70, y: -100 },
    { x: 55, y: -115 },
    { x: 40, y: -130 },
    { x: 20, y: -130 },
    { x: 0, y: -130 },
    { x: -20, y: -130 },
    { x: -35, y: -115 },
    { x: -50, y: -100 },
    { x: -65, y: -85 },
    { x: -80, y: -70 },
    { x: -80, y: -55 },
    { x: -80, y: -30 },
    { x: -80, y: -15 },
    { x: -80, y: 0 },
    { x: -65, y: 15 },
    { x: -50, y: 30 },
    { x: -35, y: 45 },
    { x: -20, y: 60 },
    { x: 0, y: 65 },
    { x: 20, y: 70 },
    { x: 40, y: 70 },
  ],
};

const CoilExample = () => (
  <GestureDetector
    onGestureFinish={(gesture) => console.log(`Gesture "${gesture}" finished!`)}
    onProgress={({ gesture, progress }) => {
      console.log(`Gesture: ${gesture}, progress: ${progress}`);
    }}
    onPanRelease={() => {
      console.log("User released finger!");
    }}
    gestures={gestures}
    slopRadius={35}
  >
    {({ coordinate }) => (
      <View style={{ position: "relative", width: "100%", height: "100%" }}>
        <GesturePath path={gestures["Coil"]} color="green" slopRadius={35} />
        {coordinate && <Cursor {...coordinate} />}
      </View>
    )}
  </GestureDetector>
);

const RecordGestureExample = () => {
  // finishedGesture will look like gestures["Coil"] from the top
  const [finishedGesture, setFinishedGesture] = useState([]);

  return (
    <GestureRecorder onPanRelease={(gesture) => setFinishedGesture(gesture)}>
      {({ gesture }) => (
        <View style={{ position: "relative", width: "100%", height: "100%" }}>
          <GesturePath path={gesture} color="green" slopRadius={35} />
        </View>
      )}
    </GestureRecorder>
  );
};

Documentation and API

GestureDetector

GestureDetector is a render props component. The child function has the form children({ coordinate: { x: number, y: number } })

GestureRecorder

GestureRecorder is a render props component. The child function has the form children({ gesture: [{ x: string, y: string }, { x: string, y: string }, ...], gestureDirectionHistory: [{ x: string, y: string }, { x: string, y: string }, ...], offset: { x: number, y: number } }).

gesture is an array of coordinates. They are generated based on the pointDistance prop of the component.

gestureDirectionHistory will tell you accordingly to gesture which direction the gesture is moving there. This might give somewhat unreliable data currently. A direction object looks like { x: "left", y: "up" }.

offset will artificially add an horizontal and vertical offset to the coordinates. This does not change the detection of the defined gesture at all. It's just a helper to use with the GesturePath component to paint the path where you actually draw. Check the GestureRecorder example screen for more details on this.

GesturePath

GesturePath is a helper component, which paints a gesture visually in a container. The container should have position: absolute; set in its style property. { x, y } is a coordinate object. An array of coordinate objects must be passed to paint the gesture on the screen. This component should be only used in development to define and refine gestures.

Cursor

Paints a black, round indicator at the passed coordinate. The only useful situation is in development and you probably will use it like this, where coordinate is passed from the GestureDetector render props function:

{coordinate && <Cursor {...coordinate} />}

GitHub