ElenixOS System API

The eos namespace is the core system API provided by ElenixOS for JavaScript script runtime. Through this API, applications and watchfaces can access system services, page navigation, time information, configuration storage, console logging, and other functions.

Namespace Structure

eos
├── eos.console      — Console Logging
│   ├── .log()
│   ├── .info()
│   ├── .warn()
│   ├── .error()
│   └── .debug()
├── eos.view         — View Management
│   └── .active()
├── eos.activity     — Activity Management
│   ├── .current()
│   ├── .visible()
│   ├── .bottom()
│   ├── .watchface()
│   ├── .rootScreen()
│   ├── .getView()
│   ├── .setView()
│   ├── .getTitle()
│   ├── .setTitle()
│   ├── .getType()
│   ├── .setType()
│   ├── .setAppHeaderVisible()
│   ├── .isAppHeaderVisible()
│   ├── .enter()
│   ├── .back()
│   └── .isTransitionInProgress()
├── eos.config       — Configuration Storage
│   ├── .setStr()
│   ├── .setBool()
│   ├── .setNumber()
│   ├── .getStr()
│   ├── .getBool()
│   └── .getNumber()
├── eos.time         — Time Service
│   └── .getNow()
├── eos.appHeader    — App Header
│   ├── .setTitle()
│   ├── .hide()
│   └── .show()
├── eos.clockHand    — Clock Hands
│   ├── .create()
│   ├── .center()
│   └── .placePivot()
├── Constants
│   ├── eos.FONT_SIZE_*
│   ├── eos.DISPLAY_*
│   ├── eos.CLOCK_HAND_*
│   └── eos.ACTIVITY_TYPE_*

Console Logging (eos.console)

Provides different levels of log output for debugging and information recording.

Methods

eos.console.log(message)
eos.console.info(message)
eos.console.warn(message)
eos.console.error(message)
eos.console.debug(message)

Parameters:

message: String, the log message to output

Returns: None

Description: All logging methods accept a string parameter and output it to the system log. The current script ID is automatically added as a prefix for easy differentiation between logs from different applications.

Example

eos.console.log("Application started");
eos.console.info("User logged in");
eos.console.warn("Low battery");
eos.console.error("Failed to load resource");
eos.console.debug("Position: x=" + x + ", y=" + y);

View Management (eos.view)

Used to get the active View object of the current Activity, which is the foundation for creating UI components.

eos.view.active()

const view = eos.view.active();

Parameters: None

Returns: LVGL object of type lv_obj_t, the View of the current Activity

Description: This method returns the LVGL object associated with the current Activity. All UI components should be created with this as the parent object. Equivalent to eos_view_active() in the C layer.

Example

// Get current View and create UI components
const view = eos.view.active();
const label = new lv.label(view);
label.setText("Hello, ElenixOS!");
label.center();

const button = new lv.button(view);
button.setSize(100, 50);
button.align(lv.ALIGN_CENTER, 0, 40);

Activity Management (eos.activity)

Provides page navigation and Activity query functions. Activity is the page management unit of ElenixOS.

Query Methods

eos.activity.current()

const activity = eos.activity.current();

Get the current Activity (top of the stack).

Parameters: None

Returns: Activity object of type eos_activity_t, returns undefined on failure

eos.activity.visible()

const activity = eos.activity.visible();

Get the currently fully displayed Activity (transition animation complete).

Parameters: None

Returns: Activity object of type eos_activity_t, returns undefined on failure

eos.activity.bottom()

const activity = eos.activity.bottom();

Get the bottom Activity (usually the watchface Activity).

Parameters: None

Returns: Activity object of type eos_activity_t, returns undefined on failure

eos.activity.watchface()

const activity = eos.activity.watchface();

Get the watchface Activity.

Parameters: None

Returns: Activity object of type eos_activity_t, returns undefined on failure

eos.activity.rootScreen()

const screen = eos.activity.rootScreen();

Get the root screen object.

Parameters: None

Returns: Root screen object of type lv_obj_t

eos.activity.isTransitionInProgress()

const isTransitioning = eos.activity.isTransitionInProgress();

Check if Activity transition animation is in progress.

Parameters: None

Returns: boolean — true if transition is in progress, false if idle

View Management

eos.activity.getView(activity)

const view = eos.activity.getView(activity);

Get the View object of the specified Activity.

Parameters:

activity: Activity object (returned by methods like eos.activity.current())

Returns: View object of type lv_obj_t, returns undefined on failure

eos.activity.setView(activity, view)

eos.activity.setView(activity, view);

Set the View object of the specified Activity.

Parameters:

activity: Activity object
view: LVGL object to be used as the Activity's View

Returns: None

Title Management

eos.activity.getTitle(activity)

const title = eos.activity.getTitle(activity);

Get the title of an Activity.

Parameters:

activity: Activity object

Returns: string, returns undefined on failure

eos.activity.setTitle(activity, title)

eos.activity.setTitle(activity, title);

Set the title of an Activity.

Parameters:

activity: Activity object
title: String title

Returns: None

Type Management

eos.activity.getType(activity)

const type = eos.activity.getType(activity);

Get the type of an Activity.

Parameters:

activity: Activity object

Returns: Number, corresponding to eos.ACTIVITY_TYPE_* constants

eos.activity.setType(activity, type)

eos.activity.setType(activity, type);

Set the type of an Activity.

Parameters:

activity: Activity object
type: Number, use eos.ACTIVITY_TYPE_* constants

Returns: None

AppHeader Visibility

eos.activity.setAppHeaderVisible(activity, visible)

eos.activity.setAppHeaderVisible(activity, visible);

Set AppHeader visibility for an Activity.

Parameters:

activity: Activity object
visible: Boolean value

Returns: None

eos.activity.isAppHeaderVisible(activity)

const visible = eos.activity.isAppHeaderVisible(activity);

Check if Activity's AppHeader is visible.

Parameters:

activity: Activity object

Returns: boolean

eos.activity.enter(activity)

eos.activity.enter(activity);

Enter the specified Activity (push Activity to top of stack and display).

Parameters:

activity: Activity object to enter

Returns: None

eos.activity.back()

eos.activity.back();

Return to the previous Activity (destroy current top Activity, restore previous Activity).

Parameters: None

Returns: boolean — true if operation succeeded, false if failed

Configuration Storage (eos.config)

Provides JSON file-based persistent key-value storage. Each application/watchface has its own independent storage space.

Storage Path:

Application: <EOS_SYS_DIR>/app/app_data/<app_id>/config.json
Watchface: <EOS_SYS_DIR>/app/watchface_data/<wf_id>/config.json

Write Methods

eos.config.setStr(key, value)

eos.config.setStr("username", "Alice");

Store a string value.

Parameters:

key: String, key name
value: String, value to store

Returns: None

eos.config.setBool(key, value)

eos.config.setBool("dark_mode", true);

Store a boolean value.

Parameters:

key: String, key name
value: Boolean

Returns: None

eos.config.setNumber(key, value)

eos.config.setNumber("volume", 75);

Store a number value.

Parameters:

key: String, key name
value: Number

Returns: None

Read Methods

eos.config.getStr(key)

const username = eos.config.getStr("username");

Read a string value. Returns undefined if key doesn't exist.

Parameters:

key: String, key name

Returns: string or undefined

eos.config.getBool(key)

const darkMode = eos.config.getBool("dark_mode");

Read a boolean value. Returns false if key doesn't exist.

Parameters:

key: String, key name

Returns: boolean

eos.config.getNumber(key)

const volume = eos.config.getNumber("volume");

Read a number value. Returns 0 if key doesn't exist.

Parameters:

key: String, key name

Returns: number

Complete Example

// Save user settings
eos.config.setStr("username", "Alice");
eos.config.setBool("dark_mode", true);
eos.config.setNumber("volume", 75);

// Read user settings
const username = eos.config.getStr("username");
const darkMode = eos.config.getBool("dark_mode");
const volume = eos.config.getNumber("volume");

eos.console.log("User: " + username + ", Dark Mode: " + darkMode + ", Volume: " + volume);

Time Service (eos.time)

Provides functionality to get the current system time.

eos.time.getNow()

const now = eos.time.getNow();

Parameters: None

Returns: Time object containing the following fields:

Field	Type	Description	Range
`year`	number	Year	e.g. 2026
`month`	number	Month	1-12
`day`	number	Day	1-31
`hour`	number	Hour	0-23
`min`	number	Minute	0-59
`sec`	number	Second	0-59
`ms`	number	Millisecond	0-999
`day_of_week`	number	Day of week	0-6 (0=Sunday)

Example

const now = eos.time.getNow();
eos.console.log("Current time: " + now.year + "-" + now.month + "-" + now.day + " " + now.hour + ":" + now.min + ":" + now.sec);

// Display time on watchface
const view = eos.view.active();
const timeLabel = new lv.label(view);

function updateTime() {
    const t = eos.time.getNow();
    const timeStr = String(t.hour).padStart(2, '0') + ":" + String(t.min).padStart(2, '0');
    timeLabel.setText(timeStr);
    timeLabel.center();
}

Controls the application's top navigation bar (AppHeader).

eos.appHeader.setTitle(view, title)

eos.appHeader.setTitle(view, "Settings");

Set the app header title for the current Activity.

Parameters:

view: View object or null
title: Title string or null/undefined

Returns: None

eos.appHeader.hide()

eos.appHeader.hide();

Hide the app header.

Parameters: None

Returns: None

eos.appHeader.show()

eos.appHeader.show();

Show the app header and refresh the current Activity's title.

Parameters: None

Returns: None

Example

// Set title
eos.appHeader.setTitle(null, "My App");

// Hide header
eos.appHeader.hide();

// Show header
eos.appHeader.show();

Clock Hands (eos.clockHand)

Create and manage clock hands (hour, minute, second) for watchfaces.

eos.clockHand.create(obj, src, type, cx, cy)

const hand = eos.clockHand.create(parent, "path/to/hand.png", eos.CLOCK_HAND_HOUR, cx, cy);

Create a clock hand image.

Parameters:

obj: Parent LVGL object
src: String, path to the hand image resource (relative to app/watchface assets directory)
type: Hand type, use eos.CLOCK_HAND_* constants
cx: Rotation center X coordinate (relative to top-left of image)
cy: Rotation center Y coordinate (relative to top-left of image)

Returns: Hand object of type lv_obj_t

eos.clockHand.center(obj)

eos.clockHand.center(hand);

Align the hand object's center to its parent's center.

Parameters:

obj: Hand LVGL object

Returns: None

eos.clockHand.placePivot(obj, x, y)

eos.clockHand.placePivot(hand, cx, cy);

Set the rotation center position of the hand object.

Parameters:

obj: Hand LVGL object
x: Rotation center X coordinate
y: Rotation center Y coordinate

Returns: None

Complete Example

// Get current View
const view = eos.view.active();

// Create watchface background
const bg = new lv.image(view);
bg.setSrc("A:background.png");
bg.center();

// Create hour hand
const hourHand = eos.clockHand.create(view, "hour_hand.png", eos.CLOCK_HAND_HOUR, 5, 50);
eos.clockHand.center(hourHand);

// Create minute hand
const minHand = eos.clockHand.create(view, "min_hand.png", eos.CLOCK_HAND_MINUTE, 5, 65);
eos.clockHand.center(minHand);

// Create second hand
const secHand = eos.clockHand.create(view, "sec_hand.png", eos.CLOCK_HAND_SECOND, 3, 70);
eos.clockHand.center(secHand);

System Constants

ElenixOS defines the following constants under the eos namespace for use in JavaScript scripts.

Font Sizes

Constant	Value	Description
`eos.FONT_SIZE_LARGE`	30	Large font size
`eos.FONT_SIZE_MEDIUM`	26	Medium font size
`eos.FONT_SIZE_SMALL`	22	Small font size

Display Dimensions

Constant	Value	Description
`eos.DISPLAY_WIDTH`	240	Screen width (pixels)
`eos.DISPLAY_HEIGHT`	240	Screen height (pixels)

Hand Types

Constant	Value	Description
`eos.CLOCK_HAND_HOUR`	0	Hour hand
`eos.CLOCK_HAND_MINUTE`	1	Minute hand
`eos.CLOCK_HAND_SECOND`	2	Second hand

Activity Types

Constant	Value	Description
`eos.ACTIVITY_TYPE_NULL`	0	Null type
`eos.ACTIVITY_TYPE_APP`	1	Application page
`eos.ACTIVITY_TYPE_APP_LIST`	2	Application list
`eos.ACTIVITY_TYPE_WATCHFACE`	3	Watchface page
`eos.ACTIVITY_TYPE_WATCHFACE_LIST`	4	Watchface list

Error Handling

Error Types

Errors are thrown when API call parameters are incorrect. Common error causes:

Error Message	Cause
`Invalid argument count`	Incorrect number of arguments
`Invalid argument type`	Incorrect argument type
`Usage: xxx(key, value)`	Usage hint showing correct calling method
`Can't load config`	Configuration storage loading failed
`No current activity`	No active Activity

Error Handling Example

try {
    const view = eos.view.active();
    if (view) {
        const label = new lv.label(view);
        label.setText("Hello!");
    }
} catch (err) {
    eos.console.error("Error: " + err);
}

Complete Example: Counter App

// Get current View
const view = eos.view.active();

// Set title
eos.appHeader.setTitle(null, "Counter");

// Read saved count
let count = eos.config.getNumber("count");

// Create display label
const countLabel = new lv.label(view);
countLabel.setStyleTextFont(eos.FONT_SIZE_LARGE, 0);
countLabel.setText(String(count));
countLabel.align(lv.ALIGN_CENTER, 0, -30);

// Create increment button
const incBtn = new lv.button(view);
incBtn.setSize(80, 50);
incBtn.align(lv.ALIGN_CENTER, -50, 30);
incBtn.addEventCb(function() {
    count++;
    countLabel.setText(String(count));
    eos.config.setNumber("count", count);
}, lv.EVENT_CLICKED, null);

const incLabel = new lv.label(incBtn);
incLabel.setText("+1");

// Create decrement button
const decBtn = new lv.button(view);
decBtn.setSize(80, 50);
decBtn.align(lv.ALIGN_CENTER, 50, 30);
decBtn.addEventCb(function() {
    count--;
    countLabel.setText(String(count));
    eos.config.setNumber("count", count);
}, lv.EVENT_CLICKED, null);

const decLabel = new lv.label(decBtn);
decLabel.setText("-1");

Complete Example: Digital Watchface

function updateWatchface() {
    const now = eos.time.getNow();

    // Format time
    const timeStr = String(now.hour).padStart(2, '0') + ":" +
                    String(now.min).padStart(2, '0');

    // Format date
    const dateStr = now.year + "-" +
                    String(now.month).padStart(2, '0') + "-" +
                    String(now.day).padStart(2, '0');

    // Update UI
    timeLabel.setText(timeStr);
    dateLabel.setText(dateStr);

    // Update hand angles
    const hourAngle = (now.hour % 12) * 30 + now.min * 0.5;
    const minAngle = now.min * 6 + now.sec * 0.1;
    const secAngle = now.sec * 6;
}

// Get View and create UI
const view = eos.view.active();
eos.appHeader.hide();

// Create time label
const timeLabel = new lv.label(view);
timeLabel.setStyleTextFont(eos.FONT_SIZE_LARGE, 0);
timeLabel.align(lv.ALIGN_CENTER, 0, -20);

// Create date label
const dateLabel = new lv.label(view);
dateLabel.setStyleTextFont(eos.FONT_SIZE_SMALL, 0);
dateLabel.align(lv.ALIGN_CENTER, 0, 10);

// Update every second
const timer = new lv.timer(function() {
    updateWatchface();
}, 1000, null);
updateWatchface();

JS API General Usage — Understand JS API conventions
LVGL UI API — Detailed LVGL UI component documentation
Activity and View — Activity system details

Namespace Structure​

Console Logging (eos.console)​

Methods​

Example​

View Management (eos.view)​

eos.view.active()​

Example​

Activity Management (eos.activity)​

Query Methods​

eos.activity.current()​

eos.activity.visible()​

eos.activity.bottom()​

eos.activity.watchface()​

eos.activity.rootScreen()​

eos.activity.isTransitionInProgress()​

View Management​

eos.activity.getView(activity)​

eos.activity.setView(activity, view)​

Title Management​

eos.activity.getTitle(activity)​

eos.activity.setTitle(activity, title)​

Type Management​

eos.activity.getType(activity)​

eos.activity.setType(activity, type)​

AppHeader Visibility​

eos.activity.setAppHeaderVisible(activity, visible)​

eos.activity.isAppHeaderVisible(activity)​

Navigation Methods​

eos.activity.enter(activity)​

eos.activity.back()​

Configuration Storage (eos.config)​

Write Methods​

eos.config.setStr(key, value)​

eos.config.setBool(key, value)​

eos.config.setNumber(key, value)​

Read Methods​

eos.config.getStr(key)​

eos.config.getBool(key)​

eos.config.getNumber(key)​

Complete Example​

Time Service (eos.time)​

eos.time.getNow()​

Example​

App Header (eos.appHeader)​

eos.appHeader.setTitle(view, title)​

eos.appHeader.hide()​

eos.appHeader.show()​

Example​

Clock Hands (eos.clockHand)​

eos.clockHand.create(obj, src, type, cx, cy)​

eos.clockHand.center(obj)​

eos.clockHand.placePivot(obj, x, y)​

Complete Example​

System Constants​

Font Sizes​

Display Dimensions​

Hand Types​

Activity Types​

Error Handling​

Error Types​

Error Handling Example​

Complete Example: Counter App​

Complete Example: Digital Watchface​

Related Documentation​

Namespace Structure

Console Logging (eos.console)

Methods

Example

View Management (eos.view)

eos.view.active()

Example

Activity Management (eos.activity)

Query Methods

eos.activity.current()

eos.activity.visible()

eos.activity.bottom()

eos.activity.watchface()

eos.activity.rootScreen()

eos.activity.isTransitionInProgress()

View Management

eos.activity.getView(activity)

eos.activity.setView(activity, view)

Title Management

eos.activity.getTitle(activity)

eos.activity.setTitle(activity, title)

Type Management

eos.activity.getType(activity)

eos.activity.setType(activity, type)

AppHeader Visibility

eos.activity.setAppHeaderVisible(activity, visible)

eos.activity.isAppHeaderVisible(activity)

Navigation Methods

eos.activity.enter(activity)

eos.activity.back()

Configuration Storage (eos.config)

Write Methods

eos.config.setStr(key, value)

eos.config.setBool(key, value)

eos.config.setNumber(key, value)

Read Methods

eos.config.getStr(key)

eos.config.getBool(key)

eos.config.getNumber(key)

Complete Example

Time Service (eos.time)

eos.time.getNow()

Example

App Header (eos.appHeader)

eos.appHeader.setTitle(view, title)

eos.appHeader.hide()

eos.appHeader.show()

Example

Clock Hands (eos.clockHand)

eos.clockHand.create(obj, src, type, cx, cy)

eos.clockHand.center(obj)

eos.clockHand.placePivot(obj, x, y)

Complete Example

System Constants

Font Sizes

Display Dimensions

Hand Types

Activity Types

Error Handling

Error Types

Error Handling Example

Complete Example: Counter App

Complete Example: Digital Watchface

Related Documentation