Notice: This documentation is archived. For the latest product features and documentation, please visit Dynamsoft Capture Vision Documentation.

JavaScript API Reference

The primary class of the library is LabelRecognizer . The following code snippets shows the basic usage.

Recognize a still image

let labelRecognizer = await Dynamsoft.DLR.LabelRecognizer.createInstance();
let results = await labelRecognizer.recognize(imageSource);
for (let result of results) {
    for (let lineResult of result.lineResults) {
        console.log(lineResult.text);
    }
}

Recognize continuous video frames

let labelRecognizer = await Dynamsoft.DLR.LabelRecognizer.createInstance({
    runtimeSettings: "video-passportMRZ"
});
labelRecognizer.onFrameRead = results => {
    for (let result of results) {
        for (let lineResult of result.lineResults) {
            console.log(lineResult.text);
        }
    }
};
labelRecognizer.startScanning(true);

The APIs for this class include

Initialization Control

The following static methods and properties help to set up the runtime environment for the library.

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.

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.

License Control

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

UI Control

API Name	Description
getUIElement()	Returns the HTML element that is used by the `LabelRecognizer` instance.
setUIElement()	Specifies an HTML element for the `LabelRecognizer` instance to use as its UI.
defaultUIElementURL	Returns or sets the URL of the .html file that defines the default UI Element.
highlightFillStyle	Specifies the color used inside the shape which highlights a found line of text.
highlightStrokeStyle	Specifies the color used to paint the outline of the shape which highlights a found line of text.
highlightLineWidth	Specifies the line width of the outline of the shape which highlights a found line of text.
regionMaskFillStyle	Specifies the color used in the square-loop shape between the actual scanning area and the boundary of the video input.
regionMaskStrokeStyle	Specifies the color used to paint the outline of the scanning region.
regionMaskLineWidth	Specifies the width of the outline of the scanning region.

Recognition

Recognize Labels from Still Images

API Name	Description
recognize()	Decodes labels from an image.
recognizeBase64String()	Decodes labels from a base64-encoded image (with or without MIME).
recognizeUrl()	Decodes labels from an image specified by its URL.
recognizeBuffer()	Decodes labels from raw image data.

Recognize Labels from Video Frames

API Name	Description
onUniqueRead	This event is triggered when a new, unduplicated label is found.
onFrameRead	This event is triggered after the library finishes scanning a frame.
recognizeCurrentFrame()	Scans the current frame of the video for labels.
startScanning()	Starts continuous scanning of incoming frames.
stopScanning()	Stops continuous scanning.

Settings

Scan Settings

API Name	Description
whenToPlaySoundforSuccessfulRead	Sets when to play sound on text recognition.
soundOnSuccessfullRead	Specifies the sound to play on text recognition.
whenToVibrateforSuccessfulRead	Sets when to vibrate on text recognition.
vibrateDuration	Returns or sets how long the vibration lastsin milliseconds.
getScanSettings	Returns the current scan settings.
updateScanSettings	Changes scan settings with the object passed in.

Runtime Settings

API Name	Description
updateRuntimeSettingsFromString()	Updates runtime settings with a template represented by a JSON string.
outputRuntimeSettingsToString()	Output the current runtime settings to a JSON string.

Auxiliary

API Name	Description
ifSaveOriginalImageInACanvas	Whether to save the original image into a < canvas> element.
getOriginalImageInACanvas()	Returns an `HTMLCanvasElement` that holds the original image.

Interfaces and Enumerations

In order to make the code more predictable and readable, the library defines a series of supporting interfaces and enumerations.