Returns accelerometer data captured at a specific point in time.
Acceleration values include the effect of gravity (9.81 m/s^2), so that when a device lies flat and facing up, x, y, and z values returned should be 0, 0, and 9.81.
Properties returned:
x: Number value
y: Number value
z: Number value
timestamp: Unix Timestamp when sample was taken
accelerometer.registerListener()
Listeners supply an onData callback which will be invoked with the data argument set to the same format as a read function call. The onError callback will be called on an error condition, if called, no subsequent onData callbacks are executed. The argument provided to the onError function is a string error message.
Listener options:
Currently the only option supported for all sensors is the sampling period in milliseconds.
watchRemover = journey.sensors.accelerometer.registerListener(
function onData(result) {
// Do something with result here, e.g.
var listenerTimestamp = result.timestamp.toString();
},
function onError(error) {
console.log('Received error', error);
},
{
periodMs: 1000
}
);
compass.read()
Returns compass data captured at a specific point in time.
Properties returned:
magneticHeading: The heading in degrees from 0-359.99 at a single moment in time. (Number)
trueHeading: The heading relative to the geographic North Pole in degrees 0-359.99 at a single moment in time. A negative value indicates that the true heading can't be determined. (Number)
headingAccuracy: The deviation in degrees between the reported heading and the true heading. (Number)
timestamp: Unix Timestamp when sample was taken
compass.registerListener()
orientation.read()
Properties returned:
alpha: Number value
beta: Number value
gamma: Number value
timestamp: Unix Timestamp when sample was taken
orientation.registerListener()
Example Code
The below example code shows a view that allows a user to read and start/stop watching accelerometer data. The returned data saved to LocalDB objects and is presented in tables.
// This function is called when the app navigates to this view (using a link)
function init() {
// initialize any data here that should be available when the view is shown
view.watch_period_ms = 1000;
}
// This function is called when the user returns to this view from another view
function resume(from) { }
function read() {
// For accelerometer data use journey.sensors.accelerometer
// For compass data use journey.sensors.compass
// For orientation data use journey.sensors.orientation
var result = journey.sensors.accelerometer.read();
view.read_results = Object.keys(result).map(function (key) {
return LocalDB.data_row.create({
key: key,
value: result[key]
})
});
view.read_timestamp = result.timestamp.toString();
}
var watchRemover;
function watch() {
// For accelerometer data use journey.sensors.accelerometer
// For compass data use journey.sensors.compass
// For orientation data use journey.sensors.orientation
watchRemover = journey.sensors.accelerometer.registerListener(
function onData(result) {
if (view.watch_results && view.watch_results.length) {
view.watch_results.map(function (item) { item.destroy() });
}
view.watch_results = Object.keys(result).map(function (key) {
return LocalDB.data_row.create({
key: key,
value: result[key]
})
});
view.listener_timestamp = result.timestamp.toString();
journey.forceDigest();
},
function onError(error) {
console.log('Received error', error);
},
{
periodMs: view.watch_period_ms
});
view.is_watching = true;
}
function stopWatch() {
if (watchRemover) {
watchRemover();
watchRemover = null;
};
view.is_watching = false;
}
// This function is called when the app navigates to this view (using a link)
async function init() {
// initialize any data here that should be available when the view is shown
view.watch_period_ms = 1000;
}
// This function is called when the user returns to this view from another view
async function resume(from: ResumeFrom) { }
async function read() {
const result = await journey.sensors.accelerometer.read();
view.read_results = Object.keys(result).map(key => LocalDB.data_row.create({
key: key,
value: result[key]
}));
view.read_timestamp = result.timestamp.toString();
}
let watchRemover: () => void;
async function watch() {
watchRemover = await journey.sensors.accelerometer.registerListener(
result => {
if (view.watch_results?.length) {
view.watch_results.map(item => item.destroy());
}
view.watch_results = Object.keys(result).map(key => LocalDB.data_row.create({
key: key,
value: result[key]
}));
view.listener_timestamp = result.timestamp.toString();
journey.forceDigest();
},
console.log,
{
periodMs: view.watch_period_ms
});
view.is_watching = true;
}
async function stopWatch() {
if (watchRemover) {
await watchRemover();
watchRemover = null;
}
view.is_watching = false;
}
