Class: Engine<ResultT, ParamsT, ProcessorT>

@geenee/armature.Engine

Core generic engine

Engine is a core of any app and organizer of a pipeline. It's responsible to interact with lower-level instances and at the same time provide simple and user-friendly interface. Engine combines together data (video) capturing, processing and rendering. It's created for particular Processor. Processor's constructor is provided to the engine and former initializes, sets up and controls state of processor during life-circle of the application. Results of processing and captured image are passed to a Renderer attached to the Engine. Notable feature is fast rescaling of images for processing down to the requested resolution in cases when available camera output is bigger. Engine parameters have an option to limit processed image size. Original video stream can be preserved on request, this is useful when processing cannot handle high resolution images but you still want to render high quality video in your app. All core components: Engine, Processor, and Renderer are generics parametrized by type of processing results and optionally tuning parameters.

Type parameters

Name	Type	Description
ResultT	extends Object	Type of processing results
ParamsT	extends ProcParams	Type of processor parameters
ProcessorT	extends Processor<ResultT, ParamsT>	Type of processor

Hierarchy

• EventEmitterT<EngineEvents>

  ↳ Engine

  ↳↳ AsyncEngine

Constructors

constructor

• new Engine<ResultT, ParamsT, ProcessorT>(Processor, engineParams?, Source?)

Constructor

Type parameters

Name	Type	Description
ResultT	extends Object	Type of processing results
ParamsT	extends ProcParams	Type of processor parameters
ProcessorT	extends Processor<ResultT, ParamsT, ProcessorT>	Type of processor

Parameters

Name	Type	Default value	Description
Processor	() => ProcessorT	undefined	Processor class or its constructor
engineParams?	EngineParams	undefined	Parameters of the engine
Source	() => VideoSource	VideoCapture	Video source class or its constructor

Overrides

EventEmitterT.constructor

Properties

engineParams

• Protected Optional engineParams: EngineParams

---

processCanvas

• Protected Optional processCanvas: HTMLCanvasElement

Shallow copy of canvas with video for processors

---

processSize

• Protected processSize: Size

Size of video for processors

---

processor

• Protected processor: ProcessorT

Processor utilized by the engine

---

renderers

• Protected renderers: Renderer<ResultT>[] = []

Renderer attached to the engine

---

resizeBuffer

• Protected Optional resizeBuffer: ImageBuffer

Buffer to resize frames

---

resizeEnabled

• Protected resizeEnabled: boolean = false

Original stream is resized

---

streamCanvas

• Protected Optional streamCanvas: HTMLCanvasElement

Shallow copy of canvas with video for renderers

---

streamSize

• Protected streamSize: Size

Size of video for renderers

---

video

• Protected video: VideoSource

Video source instance

---

videoRatio

• Protected videoRatio: number

Ratio of video stream

Methods

addListener

▸ addListener<E>(event, listener): Engine<ResultT, ParamsT, ProcessorT>

Adds the listener function to the end of the listeners array

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
listener	EngineEvents[E]	The callback function

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.addListener

---

addRenderer

▸ addRenderer(renderer): Promise<void>

Attach Renderer to the engine

Parameters

Name	Type	Description
renderer	Renderer<ResultT>	Object to be attached

Returns

Promise<void>

---

emit

▸ emit<E>(event, ...args): boolean

Synchronously calls each of the listeners registered for the event

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
...args	Args<EngineEvents[E]>	Arguments passed to the listeners

Returns

boolean

True if the event had listeners, False otherwise

Inherited from

EventEmitterT.emit

---

enqueue

▸ Protected enqueue(): void

Enqueue the next iteration

Returns

void

---

eventNames

▸ eventNames(): (string | symbol)[]

List of emitter's events

Returns

(string | symbol)[]

List of emitter's events

Inherited from

EventEmitterT.eventNames

---

getMaxListeners

▸ getMaxListeners(): number

Maximum number of listeners per event

Returns

number

Maximum number of listeners per event

Inherited from

EventEmitterT.getMaxListeners

---

init

▸ init(procParams): Promise<boolean>

Initialize engine. Sets up processor.

The SDK access token is required parameter that authenticates the user and enables the SDK on the current url. By default, path to required wasm modules provided with SDK packages is the current url. You can change the root path to wasms passing root parameter.

Parameters

Name	Type
procParams	ParamsT

Returns

Promise<boolean>

Status of initialization

---

iterate

▸ Protected iterate(): Promise<void>

Iterate

Returns

Promise<void>

---

listenerCount

▸ listenerCount<E>(event): number

The number of listeners listening to the event

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event

Returns

number

Number of listeners

Inherited from

EventEmitterT.listenerCount

---

listeners

▸ listeners<E>(event): Function[]

Copy of the array of listeners for the event

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event

Returns

Function[]

Copy of the listeners array

Inherited from

EventEmitterT.listeners

---

off

▸ off<E>(event, listener): Engine<ResultT, ParamsT, ProcessorT>

Removes the listener from the listener array for the event

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
listener	EngineEvents[E]	The callback function

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.off

---

on

▸ on<E>(event, listener): Engine<ResultT, ParamsT, ProcessorT>

Adds the listener function to the event

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
listener	EngineEvents[E]	The callback function

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.on

---

once

▸ once<E>(event, listener): Engine<ResultT, ParamsT, ProcessorT>

Adds a one-time listener function for the event

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
listener	EngineEvents[E]	The callback function

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.once

---

pause

▸ pause(): void

Pause pipeline.

Nothing happens if pipeline is not started yet.

Returns

void

---

prependListener

▸ prependListener<E>(event, listener): Engine<ResultT, ParamsT, ProcessorT>

Adds the listener function to the beginning of the listeners array

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
listener	EngineEvents[E]	The callback function

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.prependListener

---

prependOnceListener

▸ prependOnceListener<E>(event, listener): Engine<ResultT, ParamsT, ProcessorT>

Adds a one-time listener function to the beginning of the listeners array

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
listener	EngineEvents[E]	The callback function

Returns

Engine<ResultT, ParamsT, ProcessorT>

Inherited from

EventEmitterT.prependOnceListener

---

rawListeners

▸ rawListeners<E>(event): Function[]

Copy of the array of listeners for the event including wrappers

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event

Returns

Function[]

Copy of the listeners array

Inherited from

EventEmitterT.rawListeners

---

removeAllListeners

▸ removeAllListeners<E>(event?): Engine<ResultT, ParamsT, ProcessorT>

Removes all listeners, or those of the specified event

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event?	E	The name of the event

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.removeAllListeners

---

removeListener

▸ removeListener<E>(event, listener): Engine<ResultT, ParamsT, ProcessorT>

Removes the specified listener from the listener array

Type parameters

Name	Type
E	extends keyof EngineEvents

Parameters

Name	Type	Description
event	E	The name of the event
listener	EngineEvents[E]	The callback function

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.removeListener

---

removeRenderer

▸ removeRenderer(renderer): void

Remove attached Renderer

Parameters

Name	Type	Description
renderer	Renderer<ResultT>	Renderer to be removed

Returns

void

---

reset

▸ reset(): void

Reset pipeline

Stops pipeline, resets video capture and processor. After reset one needs to reinitialize video capture calling setup() before pipeline can be started again.

Returns

void

---

resizeVideo

▸ Protected resizeVideo(size): void

Callback called when video resolution is changed

Parameters

Name	Type	Description
size	Size	Size of the video

Returns

void

---

setMaxListeners

▸ setMaxListeners(n): Engine<ResultT, ParamsT, ProcessorT>

Sets maximum number of listeners per event

Parameters

Name	Type	Description
n	number	Maximum number of listeners

Returns

Engine<ResultT, ParamsT, ProcessorT>

This EventEmitter

Inherited from

EventEmitterT.setMaxListeners

---

setup

▸ setup(videoParams?): Promise<boolean>

Setup engine. Initializes video capture.

Video capture can be setup by simplified VideoParams opening default front/rear camera with provided resolution, custom MediaStreamConstraints providing the most flexible way to setup video stream (e.g. set deviceId), or external MediaStream allowing custom video sources (e.g. from file).

Parameters

Name	Type	Description
videoParams?	VideoSourceParams	Parameters of video capture

Returns

Promise<boolean>

Status of initialization

---

setupProcessor

▸ Protected setupProcessor(procParams): Promise<boolean>

Setup processor

Parameters

Name	Type
procParams	ParamsT

Returns

Promise<boolean>

---

setupSize

▸ Protected setupSize(size): Promise<void>

Setup video size

Parameters

Name	Type
size	Size

Returns

Promise<void>

---

setupVideo

▸ Protected setupVideo(videoParams?): Promise<boolean>

Setup video capture

Parameters

Name	Type
videoParams?	VideoSourceParams

Returns

Promise<boolean>

---

start

▸ start(): Promise<void>

Start pipeline.

Pipeline can be started only after successful init and setup.

Returns

Promise<void>