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Initialization Control

The following methods and properties help with the initialization of the library.

License Control

API Name	Description
license	Use an alphanumeric string to specify the license.

Create and Destroy Instances

API Name	Description
createInstance()	Creates a `LabelRecognizer` instance.
destroyContext()	Destroies the LabelRecognizer instance.
isContextDestroyed()	Returns whether the instance has been destroyed.

Set Up the Environment

API Name	Description
engineResourcePath	Specifies the path from where the recognition engine and models, etc. can be loaded.
loadWasm()	Loads the recognition engine and models.
isWasmLoaded()	Returns whether the recognition engine and models have been loaded.
getVersion()	Returns the version of the library.
detectEnvironment()	Assess the running environment regarding the features the library requires to run.

license

Use an alphanumeric string to specify the license. Note that the license must be specified before the methods createInstance() and loadWasm() .

static license: string;

createInstance

Creates a LabelRecognizer instance.

static createInstance(config?: any): Promise<LabelRecognizer>

Parameters

config : Configures how to create the instance. At present, it only specifies one of the built-in runtimeSettings templates which include

Name	Description
`number`	For pure number recognition.
`numberLetter`	For number and English letter recognition.
`numberUpperCase`	For number and uppercase English letter recognition.
`letter`	For pure English letter recognition.
`passportMRZ`	For passport MRZ recognition.
`visaMRZ_A`	For Visa (Country not Credit Card) MRZ recognition.
`VIN`	For VIN (vehicle identification number) recognition.
`VIN_NA`	For North American VIN (vehicle identification number) recognition.

When recognizing from video input, add the prefix “video-“ for a slightly different template optimized for continuous frame recognition. For example, use video-passportMRZ to read the MRZ on passports with a camera.

Return value

A promise resolving to the created LabelRecognizer object.

Code Snippet

let recognizer = await Dynamsoft.DLR.LabelRecognizer.createInstance({
    runtimeSettings: "video-passportMRZ"
});
recognizer.startScanning();

destroyContext

Destroys the LabelRecognizer instance. If your page needs to create a new instance from time to time, don’t forget to destroy unused old instances.

destroyContext(): Promise<void>

Parameters

None.

Return value

A promise that resolves when the operation succeeds.

Code Snippet

let recognizer = await Dynamsoft.DLR.LabelRecognizer.createInstance();
// ... decode ...
recognizer.destroyContext();

isContextDestroyed

Returns whether the instance has been destroyed.

isContextDestroyed(): boolean

engineResourcePath

Specifies the path to find the engine(s). The property needs to be set before loadWasm. If not specified, the library will try to find the engine in the same location as the main JavaScript file (dlr.js).

static engineResourcePath: string

Code Snippet

Dynamsoft.DLR.LabelRecognizer.engineResourcePath = "https://cdn.jsdelivr.net/npm/dynamsoft-label-recognizer@2.2.0/dist/";
await Dynamsoft.DLR.LabelRecognizer.loadWasm();

loadWasm

Downloads and compiles the engine to get it loaded/ready for a LabelRecognizer instance to be created. You can call this API to silently set the operating environment of the library as soon as the page is loaded, avoiding unnecessary waiting time when using the library later.

If this API is not called beforehand, it will be called automatically when creating a LabelRecognizer instance.

static loadWasm(): Promise<void>

Code Snippet

window.addEventListener('DOMContentLoaded', (event) => {
    Dynamsoft.DLR.LabelRecognizer.loadWasm();
});

isWasmLoaded

Returns whether the engine is loaded/ready.

static isWasmLoaded(): boolean

getVersion

Returns the version of the library including the detailed version numbers of the engine and the main JavaScript code.

Only valid after loadWasm has been called.

static getVersion(): string

Code Snippet

console.log(Dynamsoft.DLR.LabelRecognizer.getVersion());
await Dynamsoft.DLR.LabelRecognizer.loadWasm();
console.log(Dynamsoft.DLR.LabelRecognizer.getVersion());

detectEnvironment

Returns a report on the current running environments.

static detectEnvironment(): Promise<any>

Code Snippet

console.log(Dynamsoft.DLR.LabelRecognizer.detectEnvironment());
// {"wasm":true, "worker":true, "getUserMedia":true, "camera":true, "browser":"Chrome", "version":90, "OS":"Windows"}