@zxing/browser
Version:
ZXing for JS's browser layer.
909 lines • 38 kB
JavaScript
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
import { ArgumentException, BinaryBitmap, ChecksumException, DecodeHintType, FormatException, HybridBinarizer, NotFoundException, } from '@zxing/library';
import { HTMLCanvasElementLuminanceSource } from '../common/HTMLCanvasElementLuminanceSource';
import { canEnumerateDevices, hasNavigator } from '../common/navigator-utils';
const defaultOptions = {
delayBetweenScanAttempts: 500,
delayBetweenScanSuccess: 500,
tryPlayVideoTimeout: 5000,
};
/**
* Base class for browser code reader.
*/
export class BrowserCodeReader {
/**
* Creates an instance of BrowserCodeReader.
* @param {Reader} reader The reader instance to decode the barcode
* @param hints Holds the hints the user sets for the Reader.
*/
constructor(reader, hints = new Map(), options = {}) {
this.reader = reader;
this.hints = hints;
this.options = Object.assign(Object.assign({}, defaultOptions), options);
}
/**
* Allows to change the possible formats the decoder should
* search for while scanning some image. Useful for changing
* the possible formats during BrowserCodeReader::scan.
*/
set possibleFormats(formats) {
this.hints.set(DecodeHintType.POSSIBLE_FORMATS, formats);
}
/**
* Defines what the videoElement src will be.
*
* @param videoElement
* @param stream The stream to be added as a source.
*/
static addVideoSource(videoElement, stream) {
// Older browsers may not have `srcObject`
try {
// @note Throws Exception if interrupted by a new loaded request
videoElement.srcObject = stream;
}
catch (err) {
console.error("got interrupted by new loading request");
}
}
/**
* Enables or disables the torch in a media stream.
*
* @experimental This doesn't work across all browsers and is still a Draft.
*/
static mediaStreamSetTorch(track, onOff) {
return __awaiter(this, void 0, void 0, function* () {
yield track.applyConstraints({
advanced: [{
fillLightMode: onOff ? 'flash' : 'off',
torch: onOff ? true : false,
}],
});
});
}
/**
* Checks if the stream has torch support.
*/
static mediaStreamIsTorchCompatible(params) {
const tracks = params.getVideoTracks();
for (const track of tracks) {
if (BrowserCodeReader.mediaStreamIsTorchCompatibleTrack(track)) {
return true;
}
}
return false;
}
/**
*
* @param track The media stream track that will be checked for compatibility.
*/
static mediaStreamIsTorchCompatibleTrack(track) {
try {
const capabilities = track.getCapabilities();
return 'torch' in capabilities;
}
catch (err) {
// some browsers may not be compatible with ImageCapture
// so we are ignoring this for now.
// tslint:disable-next-line:no-console
console.error(err);
// tslint:disable-next-line:no-console
console.warn('Your browser may be not fully compatible with WebRTC and/or ImageCapture specs. Torch will not be available.');
return false;
}
}
/**
* Checks if the given video element is currently playing.
*/
static isVideoPlaying(video) {
return video.currentTime > 0 && !video.paused && video.readyState > 2;
}
/**
* Searches and validates a media element.
*/
static getMediaElement(mediaElementId, type) {
const mediaElement = document.getElementById(mediaElementId);
if (!mediaElement) {
throw new ArgumentException(`element with id '${mediaElementId}' not found`);
}
if (mediaElement.nodeName.toLowerCase() !== type.toLowerCase()) {
throw new ArgumentException(`element with id '${mediaElementId}' must be an ${type} element`);
}
return mediaElement;
}
/**
* Receives a source and makes sure to return a Video Element from it or fail.
*/
static createVideoElement(videoThingy) {
if (videoThingy instanceof HTMLVideoElement) {
return videoThingy;
}
if (typeof videoThingy === 'string') {
return BrowserCodeReader.getMediaElement(videoThingy, 'video');
}
if (!videoThingy && typeof document !== 'undefined') {
const videoElement = document.createElement('video');
videoElement.width = 200;
videoElement.height = 200;
return videoElement;
}
throw new Error('Couldn\'t get videoElement from videoSource!');
}
/**
* Receives a source and makes sure to return an Image Element from it or fail.
*/
static prepareImageElement(imageSource) {
if (imageSource instanceof HTMLImageElement) {
return imageSource;
}
if (typeof imageSource === 'string') {
return BrowserCodeReader.getMediaElement(imageSource, 'img');
}
if (typeof imageSource === 'undefined') {
const imageElement = document.createElement('img');
imageElement.width = 200;
imageElement.height = 200;
return imageElement;
}
throw new Error('Couldn\'t get imageElement from imageSource!');
}
/**
* Sets a HTMLVideoElement for scanning or creates a new one.
*
* @param videoElem The HTMLVideoElement to be set.
*/
static prepareVideoElement(videoElem) {
const videoElement = BrowserCodeReader.createVideoElement(videoElem);
// @todo the following lines should not always be done this way, should conditionally
// change according were we created the element or not
// Needed for iOS 11
videoElement.setAttribute('autoplay', 'true');
videoElement.setAttribute('muted', 'true');
videoElement.setAttribute('playsinline', 'true');
return videoElement;
}
/**
* Checks if and HTML image is loaded.
*/
static isImageLoaded(img) {
// During the onload event, IE correctly identifies any images that
// weren't downloaded as not complete. Others should too. Gecko-based
// browsers act like NS4 in that they report this incorrectly.
if (!img.complete) {
return false;
}
// However, they do have two very useful properties: naturalWidth and
// naturalHeight. These give the true size of the image. If it failed
// to load, either of these should be zero.
if (img.naturalWidth === 0) {
return false;
}
// No other way of checking: assume it’s ok.
return true;
}
/**
* Creates a binaryBitmap based in a canvas.
*
* @param canvas HTML canvas element containing the image source draw.
*/
static createBinaryBitmapFromCanvas(canvas) {
const luminanceSource = new HTMLCanvasElementLuminanceSource(canvas);
const hybridBinarizer = new HybridBinarizer(luminanceSource);
return new BinaryBitmap(hybridBinarizer);
}
/**
* Overwriting this allows you to manipulate the snapshot image in anyway you want before decode.
*/
static drawImageOnCanvas(canvasElementContext, srcElement) {
canvasElementContext.drawImage(srcElement, 0, 0);
}
static getMediaElementDimensions(mediaElement) {
if (mediaElement instanceof HTMLVideoElement) {
return {
height: mediaElement.videoHeight,
width: mediaElement.videoWidth,
};
}
if (mediaElement instanceof HTMLImageElement) {
return {
height: mediaElement.naturalHeight || mediaElement.height,
width: mediaElement.naturalWidth || mediaElement.width,
};
}
throw new Error('Couldn\'t find the Source\'s dimensions!');
}
/**
* 🖌 Prepares the canvas for capture and scan frames.
*/
static createCaptureCanvas(mediaElement) {
if (!mediaElement) {
throw new ArgumentException('Cannot create a capture canvas without a media element.');
}
if (typeof document === 'undefined') {
throw new Error('The page "Document" is undefined, make sure you\'re running in a browser.');
}
const canvasElement = document.createElement('canvas');
const { width, height } = BrowserCodeReader.getMediaElementDimensions(mediaElement);
canvasElement.style.width = width + 'px';
canvasElement.style.height = height + 'px';
canvasElement.width = width;
canvasElement.height = height;
return canvasElement;
}
/**
* Just tries to play the video and logs any errors.
* The play call is only made is the video is not already playing.
*/
static tryPlayVideo(videoElement) {
return __awaiter(this, void 0, void 0, function* () {
if (videoElement === null || videoElement === void 0 ? void 0 : videoElement.ended) {
// tslint:disable-next-line:no-console
console.error('Trying to play video that has ended.');
return false;
}
if (BrowserCodeReader.isVideoPlaying(videoElement)) {
// tslint:disable-next-line:no-console
console.warn('Trying to play video that is already playing.');
return true;
}
try {
yield videoElement.play();
return true;
}
catch (error) {
// tslint:disable-next-line:no-console
console.warn('It was not possible to play the video.', error);
return false;
}
});
}
/**
* Creates a canvas and draws the current image frame from the media element on it.
*
* @param mediaElement HTML media element to extract an image frame from.
*/
static createCanvasFromMediaElement(mediaElement) {
const canvas = BrowserCodeReader.createCaptureCanvas(mediaElement);
const ctx = canvas.getContext('2d');
if (!ctx) {
throw new Error('Couldn\'t find Canvas 2D Context.');
}
BrowserCodeReader.drawImageOnCanvas(ctx, mediaElement);
return canvas;
}
/**
* Creates a binaryBitmap based in some image source.
*
* @param mediaElement HTML element containing drawable image source.
*/
static createBinaryBitmapFromMediaElem(mediaElement) {
const canvas = BrowserCodeReader.createCanvasFromMediaElement(mediaElement);
return BrowserCodeReader.createBinaryBitmapFromCanvas(canvas);
}
static destroyImageElement(imageElement) {
imageElement.src = '';
imageElement.removeAttribute('src');
imageElement = undefined;
}
/**
* Lists all the available video input devices.
*/
static listVideoInputDevices() {
return __awaiter(this, void 0, void 0, function* () {
if (!hasNavigator()) {
throw new Error('Can\'t enumerate devices, navigator is not present.');
}
if (!canEnumerateDevices()) {
throw new Error('Can\'t enumerate devices, method not supported.');
}
const devices = yield navigator.mediaDevices.enumerateDevices();
const videoDevices = [];
for (const device of devices) {
const kind = device.kind === 'video' ? 'videoinput' : device.kind;
if (kind !== 'videoinput') {
continue;
}
const deviceId = device.deviceId || device.id;
const label = device.label || `Video device ${videoDevices.length + 1}`;
const groupId = device.groupId;
const videoDevice = { deviceId, label, kind, groupId };
videoDevices.push(videoDevice);
}
return videoDevices;
});
}
/**
* Let's you find a device using it's Id.
*/
static findDeviceById(deviceId) {
return __awaiter(this, void 0, void 0, function* () {
const devices = yield BrowserCodeReader.listVideoInputDevices();
if (!devices) {
return;
}
return devices.find((x) => x.deviceId === deviceId);
});
}
/**
* Unbinds a HTML video src property.
*/
static cleanVideoSource(videoElement) {
if (!videoElement) {
return;
}
// forgets about that element 😢
try {
videoElement.srcObject = null;
}
catch (err) {
videoElement.src = '';
}
if (videoElement) {
videoElement.removeAttribute('src');
}
}
/**
* Stops all media streams that are created.
*/
static releaseAllStreams() {
if (BrowserCodeReader.streamTracker.length !== 0) {
// tslint:disable-next-line:no-console
BrowserCodeReader.streamTracker.forEach((mediaStream) => {
mediaStream.getTracks().forEach((track) => track.stop());
});
}
BrowserCodeReader.streamTracker = [];
}
/**
* Waits for a video to load and then hits play on it.
* To accomplish that, it binds listeners and callbacks to the video element.
*
* @param element The video element.
* @param callbackFn Callback invoked when the video is played.
*/
static playVideoOnLoadAsync(element, timeout) {
return __awaiter(this, void 0, void 0, function* () {
// if canplay was already fired, we won't know when to play, so just give it a try
const isPlaying = yield BrowserCodeReader.tryPlayVideo(element);
if (isPlaying) {
return true;
}
return new Promise((resolve, reject) => {
// waits 3 seconds or rejects.
const timeoutId = setTimeout(() => {
if (BrowserCodeReader.isVideoPlaying(element)) {
// if video is playing then we had success, just ignore
return;
}
reject(false);
element.removeEventListener('canplay', videoCanPlayListener);
}, timeout);
/**
* Should contain the current registered listener for video loaded-metadata,
* used to unregister that listener when needed.
*/
const videoCanPlayListener = () => {
BrowserCodeReader.tryPlayVideo(element).then((hasPlayed) => {
clearTimeout(timeoutId);
element.removeEventListener('canplay', videoCanPlayListener);
resolve(hasPlayed);
});
};
// both should be unregistered after called
element.addEventListener('canplay', videoCanPlayListener);
});
});
}
/**
* Sets the new stream and request a new decoding-with-delay.
*
* @param stream The stream to be shown in the video element.
* @param decodeFn A callback for the decode method.
*/
static attachStreamToVideo(stream, preview, previewPlayTimeout = 5000) {
return __awaiter(this, void 0, void 0, function* () {
const videoElement = BrowserCodeReader.prepareVideoElement(preview);
BrowserCodeReader.addVideoSource(videoElement, stream);
yield BrowserCodeReader.playVideoOnLoadAsync(videoElement, previewPlayTimeout);
return videoElement;
});
}
/**
* Returns a Promise that resolves when the given image element loads.
*/
static _waitImageLoad(element) {
return new Promise((resolve, reject) => {
const timeout = 10000;
// waits 10 seconds or rejects.
const timeoutId = setTimeout(() => {
if (BrowserCodeReader.isImageLoaded(element)) {
// if video is playing then we had success, just ignore
return;
}
// removes the listener
element.removeEventListener('load', imageLoadedListener);
// rejects the load
reject();
}, timeout);
const imageLoadedListener = () => {
clearTimeout(timeoutId);
// removes the listener
element.removeEventListener('load', imageLoadedListener);
// resolves the load
resolve();
};
element.addEventListener('load', imageLoadedListener);
});
}
/**
* Checks if the `callbackFn` is defined, otherwise throws.
*/
static checkCallbackFnOrThrow(callbackFn) {
if (!callbackFn) {
throw new ArgumentException('`callbackFn` is a required parameter, you cannot capture results without it.');
}
}
/**
* Standard method to dispose a media stream object.
*/
static disposeMediaStream(stream) {
stream.getVideoTracks().forEach((x) => x.stop());
stream = undefined;
}
/**
* Gets the BinaryBitmap for ya! (and decodes it)
*/
decode(element) {
// get binary bitmap for decode function
const canvas = BrowserCodeReader.createCanvasFromMediaElement(element);
return this.decodeFromCanvas(canvas);
}
/**
* Call the encapsulated readers decode
*/
decodeBitmap(binaryBitmap) {
return this.reader.decode(binaryBitmap, this.hints);
}
/**
* Decodes some barcode from a canvas!
*/
decodeFromCanvas(canvas) {
const binaryBitmap = BrowserCodeReader.createBinaryBitmapFromCanvas(canvas);
return this.decodeBitmap(binaryBitmap);
}
/**
* Decodes something from an image HTML element.
*/
decodeFromImageElement(source) {
return __awaiter(this, void 0, void 0, function* () {
if (!source) {
throw new ArgumentException('An image element must be provided.');
}
const element = BrowserCodeReader.prepareImageElement(source);
// onLoad will remove it's callback once done
// we do not need to dispose or destroy the image
// since it came from the user
return yield this._decodeOnLoadImage(element);
});
}
/**
* Decodes an image from a URL.
*/
decodeFromImageUrl(url) {
return __awaiter(this, void 0, void 0, function* () {
if (!url) {
throw new ArgumentException('An URL must be provided.');
}
const element = BrowserCodeReader.prepareImageElement();
// loads the image.
element.src = url;
try {
// it waits the task so we can destroy the created image after
return yield this.decodeFromImageElement(element);
}
finally {
// we created this element, so we destroy it
BrowserCodeReader.destroyImageElement(element);
}
});
}
/**
* Continuously tries to decode the barcode from a stream obtained from the given constraints
* while showing the video in the specified video element.
*
* @param {MediaStream} [constraints] the media stream constraints to get s valid media stream to decode from
* @param {string|HTMLVideoElement} [previewElem] the video element in page where to show the video while
* decoding. Can be either an element id or directly an HTMLVideoElement. Can be undefined, in
* which case no video will be shown.
*/
decodeFromConstraints(constraints, previewElem, callbackFn) {
return __awaiter(this, void 0, void 0, function* () {
BrowserCodeReader.checkCallbackFnOrThrow(callbackFn);
const stream = yield this.getUserMedia(constraints);
try {
return yield this.decodeFromStream(stream, previewElem, callbackFn);
}
catch (error) {
BrowserCodeReader.disposeMediaStream(stream);
throw error;
}
});
}
/**
* In one attempt, tries to decode the barcode from a stream obtained from the given constraints
* while showing the video in the specified video element.
*
* @param {MediaStream} [constraints] the media stream constraints to get s valid media stream to decode from
* @param {string|HTMLVideoElement} [preview] the video element in page where to show the video
* while decoding. Can be either an element id or directly an HTMLVideoElement. Can be undefined,
* in which case no video will be shown.
*/
decodeFromStream(stream, preview, callbackFn) {
return __awaiter(this, void 0, void 0, function* () {
BrowserCodeReader.checkCallbackFnOrThrow(callbackFn);
const timeout = this.options.tryPlayVideoTimeout;
const video = yield BrowserCodeReader.attachStreamToVideo(stream, preview, timeout);
// IF we receive a stream from the user, it's not our job to dispose it
const finalizeCallback = () => {
// stops video tracks and releases the stream reference
BrowserCodeReader.disposeMediaStream(stream);
// this video was just a preview, so in order
// to release the stream we gotta stop showing
// it (the stream) in the video element
BrowserCodeReader.cleanVideoSource(video);
};
const originalControls = this.scan(video, callbackFn, finalizeCallback);
const videoTracks = stream.getVideoTracks();
const controls = Object.assign(Object.assign({}, originalControls), { stop() {
originalControls.stop();
},
streamVideoConstraintsApply(constraints, trackFilter) {
return __awaiter(this, void 0, void 0, function* () {
const tracks = trackFilter ? videoTracks.filter(trackFilter) : videoTracks;
for (const track of tracks) {
yield track.applyConstraints(constraints);
}
});
},
streamVideoConstraintsGet(trackFilter) {
return videoTracks.find(trackFilter).getConstraints();
},
streamVideoSettingsGet(trackFilter) {
return videoTracks.find(trackFilter).getSettings();
},
streamVideoCapabilitiesGet(trackFilter) {
return videoTracks.find(trackFilter).getCapabilities();
} });
const isTorchAvailable = BrowserCodeReader.mediaStreamIsTorchCompatible(stream);
if (isTorchAvailable) {
const torchTrack = videoTracks === null || videoTracks === void 0 ? void 0 : videoTracks.find((t) => BrowserCodeReader.mediaStreamIsTorchCompatibleTrack(t));
const switchTorch = (onOff) => __awaiter(this, void 0, void 0, function* () {
yield BrowserCodeReader.mediaStreamSetTorch(torchTrack, onOff);
});
controls.switchTorch = switchTorch;
controls.stop = () => __awaiter(this, void 0, void 0, function* () {
originalControls.stop();
yield switchTorch(false);
});
}
return controls;
});
}
/**
* Continuously tries to decode the barcode from the device specified by device while showing
* the video in the specified video element.
*
* @param {string|null} [deviceId] the id of one of the devices obtained after calling
* getVideoInputDevices. Can be undefined, in this case it will decode from one of the
* available devices, preferring the main camera (environment facing) if available.
* @param {string|HTMLVideoElement|null} [video] the video element in page where to show the video
* while decoding. Can be either an element id or directly an HTMLVideoElement. Can be undefined,
* in which case no video will be shown.
*/
decodeFromVideoDevice(deviceId, previewElem, callbackFn) {
return __awaiter(this, void 0, void 0, function* () {
BrowserCodeReader.checkCallbackFnOrThrow(callbackFn);
let videoConstraints;
if (!deviceId) {
videoConstraints = { facingMode: 'environment' };
}
else {
videoConstraints = { deviceId: { exact: deviceId } };
}
const constraints = { video: videoConstraints };
return yield this.decodeFromConstraints(constraints, previewElem, callbackFn);
});
}
/**
* Decodes something from an image HTML element.
*/
decodeFromVideoElement(source, callbackFn) {
return __awaiter(this, void 0, void 0, function* () {
BrowserCodeReader.checkCallbackFnOrThrow(callbackFn);
if (!source) {
throw new ArgumentException('A video element must be provided.');
}
// we do not create a video element
const element = BrowserCodeReader.prepareVideoElement(source);
const timeout = this.options.tryPlayVideoTimeout;
// plays the video
yield BrowserCodeReader.playVideoOnLoadAsync(element, timeout);
// starts decoding after played the video
return this.scan(element, callbackFn);
});
}
/**
* Decodes a video from a URL until it ends.
*/
decodeFromVideoUrl(url, callbackFn) {
return __awaiter(this, void 0, void 0, function* () {
BrowserCodeReader.checkCallbackFnOrThrow(callbackFn);
if (!url) {
throw new ArgumentException('An URL must be provided.');
}
// creates a new element
const element = BrowserCodeReader.prepareVideoElement();
// starts loading the video
element.src = url;
const finalizeCallback = () => {
// dispose created video element
BrowserCodeReader.cleanVideoSource(element);
};
const timeout = this.options.tryPlayVideoTimeout;
// plays the video
yield BrowserCodeReader.playVideoOnLoadAsync(element, timeout);
// starts decoding after played the video
const controls = this.scan(element, callbackFn, finalizeCallback);
return controls;
});
}
/**
* In one attempt, tries to decode the barcode from a stream obtained from the given
* constraints while showing the video in the specified video element.
*
* @param constraints the media stream constraints to get s valid media stream to decode from
* @param videoSource the video element in page where to show the video while decoding.
* Can be either an element id or directly an HTMLVideoElement. Can be undefined,
* in which case no video will be shown.
* The decoding result.
*/
decodeOnceFromConstraints(constraints, videoSource) {
return __awaiter(this, void 0, void 0, function* () {
const stream = yield this.getUserMedia(constraints);
return yield this.decodeOnceFromStream(stream, videoSource);
});
}
/**
* In one attempt, tries to decode the barcode from a stream obtained from the given
* constraints while showing the video in the specified video element.
*
* @param {MediaStream} [constraints] the media stream constraints to get s valid media stream to decode from
* @param {string|HTMLVideoElement} [video] the video element in page where to show the video while decoding.
* Can be either an element id or directly an HTMLVideoElement. Can be undefined,
* in which case no video will be shown.
*/
decodeOnceFromStream(stream, preview) {
return __awaiter(this, void 0, void 0, function* () {
const receivedPreview = Boolean(preview);
const video = yield BrowserCodeReader.attachStreamToVideo(stream, preview);
try {
const result = yield this.scanOneResult(video);
return result;
}
finally {
if (!receivedPreview) {
BrowserCodeReader.cleanVideoSource(video);
}
}
});
}
/**
* In one attempt, tries to decode the barcode from the device specified by deviceId
* while showing the video in the specified video element.
*
* @param deviceId the id of one of the devices obtained after calling getVideoInputDevices.
* Can be undefined, in this case it will decode from one of the available devices,
* preferring the main camera (environment facing) if available.
* @param videoSource the video element in page where to show the video while decoding.
* Can be either an element id or directly an HTMLVideoElement. Can be undefined,
* in which case no video will be shown.
*/
decodeOnceFromVideoDevice(deviceId, videoSource) {
return __awaiter(this, void 0, void 0, function* () {
let videoConstraints;
if (!deviceId) {
videoConstraints = { facingMode: 'environment' };
}
else {
videoConstraints = { deviceId: { exact: deviceId } };
}
const constraints = { video: videoConstraints };
return yield this.decodeOnceFromConstraints(constraints, videoSource);
});
}
/**
* Decodes something from an image HTML element.
*/
decodeOnceFromVideoElement(source) {
return __awaiter(this, void 0, void 0, function* () {
if (!source) {
throw new ArgumentException('A video element must be provided.');
}
// we do not create a video element
const element = BrowserCodeReader.prepareVideoElement(source);
const timeout = this.options.tryPlayVideoTimeout;
// plays the video
yield BrowserCodeReader.playVideoOnLoadAsync(element, timeout);
// starts decoding after played the video
return yield this.scanOneResult(element);
});
}
/**
* Decodes a video from a URL.
*/
decodeOnceFromVideoUrl(url) {
return __awaiter(this, void 0, void 0, function* () {
if (!url) {
throw new ArgumentException('An URL must be provided.');
}
// creates a new element
const element = BrowserCodeReader.prepareVideoElement();
// starts loading the video
element.src = url;
const task = this.decodeOnceFromVideoElement(element);
try {
// it waits the task so we can destroy the created image after
return yield task;
}
finally {
// we created this element, so we destroy it
BrowserCodeReader.cleanVideoSource(element);
}
});
}
/**
* Tries to decode from the video input until it finds some value.
*/
scanOneResult(element, retryIfNotFound = true, retryIfChecksumError = true, retryIfFormatError = true) {
return new Promise((resolve, reject) => {
// reuses the scan API, but returns at the first successful result
this.scan(element, (result, error, controls) => {
if (result) {
// good result, returning
resolve(result);
controls.stop();
return;
}
if (error) {
// checks if it should retry
if (error instanceof NotFoundException && retryIfNotFound) {
return;
}
if (error instanceof ChecksumException && retryIfChecksumError) {
return;
}
if (error instanceof FormatException && retryIfFormatError) {
return;
}
// not re-trying
controls.stop(); // stops scan loop
reject(error); // returns the error
}
});
});
}
/**
* Continuously decodes from video input.
*
* @param element HTML element to scan/decode from. It will not be disposed or destroyed.
* @param callbackFn Called after every scan attempt, being it successful or errored.
* @param finalizeCallback Called after scan process reaches the end or stop is called.
*/
scan(element, callbackFn, finalizeCallback) {
BrowserCodeReader.checkCallbackFnOrThrow(callbackFn);
/**
* The HTML canvas element, used to draw the video or image's frame for decoding.
*/
let captureCanvas = BrowserCodeReader.createCaptureCanvas(element);
/**
* The HTML canvas element context.
*/
let captureCanvasContext;
try {
captureCanvasContext = captureCanvas.getContext('2d', { willReadFrequently: true });
}
catch (e) {
captureCanvasContext = captureCanvas.getContext('2d');
}
// cannot proceed w/o this
if (!captureCanvasContext) {
throw new Error('Couldn\'t create canvas for visual element scan.');
}
const disposeCanvas = () => {
captureCanvasContext = undefined;
captureCanvas = undefined;
};
let stopScan = false;
let lastTimeoutId;
// can be called to break the scan loop
const stop = () => {
stopScan = true;
clearTimeout(lastTimeoutId);
disposeCanvas();
if (finalizeCallback) {
finalizeCallback();
}
};
// created for extensibility
const controls = { stop };
// this async loop allows infinite (or almost? maybe) scans
const loop = () => {
if (stopScan) {
// no need to clear timeouts as none was create yet in this scope.
return;
}
try {
BrowserCodeReader.drawImageOnCanvas(captureCanvasContext, element);
const result = this.decodeFromCanvas(captureCanvas);
callbackFn(result, undefined, controls);
lastTimeoutId = setTimeout(loop, this.options.delayBetweenScanSuccess);
}
catch (error) {
callbackFn(undefined, error, controls);
const isChecksumError = error instanceof ChecksumException;
const isFormatError = error instanceof FormatException;
const isNotFound = error instanceof NotFoundException;
if (isChecksumError || isFormatError || isNotFound) {
// trying again
lastTimeoutId = setTimeout(loop, this.options.delayBetweenScanAttempts);
return;
}
// not trying again
disposeCanvas();
if (finalizeCallback) {
finalizeCallback(error);
}
}
};
// starts the async loop
loop();
return controls;
}
/**
* Waits for the image to load and then tries to decode it.
*/
_decodeOnLoadImage(element) {
return __awaiter(this, void 0, void 0, function* () {
const isImageLoaded = BrowserCodeReader.isImageLoaded(element);
if (!isImageLoaded) {
yield BrowserCodeReader._waitImageLoad(element);
}
return this.decode(element);
});
}
/**
* Get MediaStream from browser to be used.
* @param constraints constraints the media stream constraints to get s valid media stream to decode from.
* @private For private use.
*/
getUserMedia(constraints) {
return __awaiter(this, void 0, void 0, function* () {
const stream = yield navigator.mediaDevices.getUserMedia(constraints);
BrowserCodeReader.streamTracker.push(stream);
return stream;
});
}
}
/**
* Keeps track to created media streams.
* @private there is no need this array to be accessible from outside.
*/
BrowserCodeReader.streamTracker = [];
//# sourceMappingURL=BrowserCodeReader.js.map