1. Introduction
The Gyroscope API 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. Use Cases and Requirements
The use cases and requirements are addressed in the Motion Sensors Explainer document.
3. Examples
let sensor = new Gyroscope(); sensor.start(); sensor.onreading = () => { console.log("Angular velocity around the X-axis " + sensor.x); console.log("Angular velocity around the Y-axis " + sensor.y); console.log("Angular velocity around the Z-axis " + sensor.z); }; sensor.onerror = event => console.log(event.error.name, event.error.message);
4. Security and Privacy Considerations
There are no specific security and privacy considerations beyond those described in the Generic Sensor API [GENERIC-SENSOR].
5. Model
The Gyroscope sensor type’s associated Sensor
subclass is the Gyroscope
class.
The Gyroscope has a default sensor, which is the device’s main gyroscope sensor.
The Gyroscope has an associated PermissionName
which is "gyroscope".
A latest reading of a Sensor
of Gyroscope sensor type includes three entries whose keys are "x", "y", "z" and whose values contain current angular
velocity about the corresponding axes.
The angular velocity is the rate at which the device rotates about a specified axis in a local coordinate system defined by the device. 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 in a local coordinate system defined by the device, such that positive rotation around an axis is clockwise when viewed along the positive direction of the axis (see figure below).
Note: The local coordinate system of a mobile device is usually defined relative to the device’s screen when the device in its default orientation (see figure below).
6. API
6.1. The Gyroscope Interface
[Constructor
(optional SensorOptionssensorOptions
), SecureContext, Exposed=Window] interfaceGyroscope
: Sensor { readonly attribute double?x
; readonly attribute double?y
; readonly attribute double?z
; };
To Construct a Gyroscope Object the user agent must invoke the construct a Sensor object abstract operation.
6.1.1. Gyroscope.x
The x
attribute of the Gyroscope
interface represents the current angular velocity around X-axis.
In other words, this attribute returns the result of invoking get value from latest reading with
6.1.2. Gyroscope.y
The y
attribute of the Gyroscope
interface represents the current angular velocity around Y-axis.
In other words, this attribute returns the result of invoking get value from latest reading with
6.1.3. Gyroscope.z
The z
attribute of the Gyroscope
interface represents the current angular velocity around Z-axis.
In other words, this attribute returns the result of invoking get value from latest reading with
7. Acknowledgements
Tobie Langel for the work on Generic Sensor API.
8. 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]