Gyroscope Sensor

1. Introduction

The Gyroscope Sensor extends the Generic Sensor API [GENERIC-SENSOR] to provide information about the angular velocity around the device’s local X, Y and Z axis in terms of radian per seconds units.

2. Examples

let sensor = new GyroscopeSensor();
sensor.start();
    
sensor.onchange = event => {
    console.log("Rotation rate around the X-axis " + event.reading.rotationRateX);
    console.log("Rotation rate around the Y-axis " + event.reading.rotationRateY);
    console.log("Rotation rate around the Z-axis " + event.reading.rotationRateZ);
};

sensor.onerror = event => console.log(event.error.name, event.error.message);

3. Security and Privacy Considerations

There are no specific security and privacy considerations beyond those described in the Generic Sensor API [GENERIC-SENSOR].

4. Model

The Gyroscope Sensor’s associated Sensor subclass is the GyroscopeSensor class.

The Gyroscope Sensor’s associated SensorReading subclass is the GyroscopeSensorReading class.

The Gyroscope Sensor has a default sensor, which is the device’s main gyroscope sensor.

The Gyroscope Sensor has a single supported reporting mode which is "auto".

The Gyroscope Sensor’s permission name is "gyroscope". It has no associated PermissionDescriptor.

The Gyroscope Sensor has an associated abstract operation to retrieve the sensor permission which must simply return a permission whose name is "gyroscope".

The Gyroscope Sensor has an associated abstract operation to construct a SensorReading object which creates a new GyroscopeSensorReading object and sets each of its rotationRateX rotationRateY and rotationRateZ attributes to the current angular velocity about the corresponding axis.

The current angular velocity is the rate at which the device rotates about a specified axis. Its unit is the radian per second (rad/s) [SI].

The sign of the current angular velocity depends on the rotation direction and it must be according to the right-hand convention, such that positive rotation around an axis is clockwise when viewed along the positive direction of the axis (see figure below).

5. API

5.1. The GyroscopeSensor Interface

[Constructor(optional SensorOptions sensorOptions)]
interface GyroscopeSensor : Sensor {
  readonly attribute GyroscopeSensorReading? reading;
};

To Construct an GyroscopeSensor Object the user agent must invoke the construct a Sensor object abstract operation.

5.2. The GyroscopeSensorReading Interface

[Constructor(GyroscopeSensorReadingInit GyroscopeSensorReadingInit)]
interface GyroscopeSensorReading : SensorReading {
    readonly attribute unrestricted double rotationRateX;
    readonly attribute unrestricted double rotationRateY;
    readonly attribute unrestricted double rotationRateZ;
};
  
dictionary GyroscopeSensorReadingInit {
    unrestricted double rotationRateX = 0;
    unrestricted double rotationRateY = 0;
    unrestricted double rotationRateZ = 0;
};

5.2.1. The GyroscopeSensorReading constructor

5.2.2. The attribute

The rotationRateX attribute of the GyroscopeSensorReading interface represents the current angular velocity around X-axis.

The rotationRateY attribute of the GyroscopeSensorReading interface represents the current angular velocity around Y-axis.

The rotationRateX attribute of the GyroscopeSensorReading interface represents the current angular velocity around Z-axis.

6. Acknowledgements

Tobie Langel for the work on Generic Sensor API.

7. Conformance

Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

A conformant user agent must implement all the requirements listed in this specification that are applicable to user agents.

The IDL fragments in this specification must be interpreted as required for conforming IDL fragments, as described in the Web IDL specification. [WEBIDL]