zxing-html5-qrcode-decoder.ts
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/**
* @fileoverview
* {@interface QrcodeDecoder} wrapper around ZXing library.
*
* @author mebjas <minhazav@gmail.com>
*
* ZXing library forked from https://github.com/zxing-js/library.
*
* The word "QR Code" is registered trademark of DENSO WAVE INCORPORATED
* http://www.denso-wave.com/qrcode/faqpatent-e.html
*/
import * as ZXing from "../third_party/zxing-js.umd";
import {
QrcodeResult,
QrcodeResultDebugData,
QrcodeResultFormat,
Html5QrcodeSupportedFormats,
Logger,
QrcodeDecoderAsync
} from "./core";
/**
* ZXing based Code decoder.
*/
export class ZXingHtml5QrcodeDecoder implements QrcodeDecoderAsync {
private readonly formatMap: Map<Html5QrcodeSupportedFormats, any>
= new Map([
[Html5QrcodeSupportedFormats.QR_CODE, ZXing.BarcodeFormat.QR_CODE ],
[Html5QrcodeSupportedFormats.AZTEC, ZXing.BarcodeFormat.AZTEC ],
[Html5QrcodeSupportedFormats.CODABAR, ZXing.BarcodeFormat.CODABAR ],
[Html5QrcodeSupportedFormats.CODE_39, ZXing.BarcodeFormat.CODE_39 ],
[Html5QrcodeSupportedFormats.CODE_93, ZXing.BarcodeFormat.CODE_93 ],
[
Html5QrcodeSupportedFormats.CODE_128,
ZXing.BarcodeFormat.CODE_128 ],
[
Html5QrcodeSupportedFormats.DATA_MATRIX,
ZXing.BarcodeFormat.DATA_MATRIX ],
[
Html5QrcodeSupportedFormats.MAXICODE,
ZXing.BarcodeFormat.MAXICODE ],
[Html5QrcodeSupportedFormats.ITF, ZXing.BarcodeFormat.ITF ],
[Html5QrcodeSupportedFormats.EAN_13, ZXing.BarcodeFormat.EAN_13 ],
[Html5QrcodeSupportedFormats.EAN_8, ZXing.BarcodeFormat.EAN_8 ],
[Html5QrcodeSupportedFormats.PDF_417, ZXing.BarcodeFormat.PDF_417 ],
[Html5QrcodeSupportedFormats.RSS_14, ZXing.BarcodeFormat.RSS_14 ],
[
Html5QrcodeSupportedFormats.RSS_EXPANDED,
ZXing.BarcodeFormat.RSS_EXPANDED ],
[Html5QrcodeSupportedFormats.UPC_A, ZXing.BarcodeFormat.UPC_A ],
[Html5QrcodeSupportedFormats.UPC_E, ZXing.BarcodeFormat.UPC_E ],
[
Html5QrcodeSupportedFormats.UPC_EAN_EXTENSION,
ZXing.BarcodeFormat.UPC_EAN_EXTENSION ]
]);
private readonly reverseFormatMap: Map<any, Html5QrcodeSupportedFormats>
= this.createReverseFormatMap();
private hints: Map<any, any>;
private verbose: boolean;
private logger: Logger;
public constructor(
requestedFormats: Array<Html5QrcodeSupportedFormats>,
verbose: boolean,
logger: Logger) {
if (!ZXing) {
throw "Use html5qrcode.min.js without edit, ZXing not found.";
}
this.verbose = verbose;
this.logger = logger;
const formats = this.createZXingFormats(requestedFormats);
const hints = new Map();
hints.set(ZXing.DecodeHintType.POSSIBLE_FORMATS, formats);
// TODO(minhazav): Make this configurable by developers.
hints.set(ZXing.DecodeHintType.TRY_HARDER, false);
this.hints = hints;
}
decodeAsync(canvas: HTMLCanvasElement): Promise<QrcodeResult> {
return new Promise((resolve, reject) => {
try {
resolve(this.decode(canvas));
} catch (error) {
reject(error);
}
});
}
private decode(canvas: HTMLCanvasElement): QrcodeResult {
// Note: Earlier we used to instantiate the zxingDecoder once as state
// of this class and use it for each scans. There seems to be some
// stateful bug in ZXing library around RSS_14 likely due to
// https://github.com/zxing-js/library/issues/211.
// Recreating a new instance per scan doesn't lead to performance issues
// and temporarily mitigates this issue.
// TODO(mebjas): Properly fix this issue in ZXing library.
const zxingDecoder = new ZXing.MultiFormatReader(
this.verbose, this.hints);
const luminanceSource
= new ZXing.HTMLCanvasElementLuminanceSource(canvas);
const binaryBitmap
= new ZXing.BinaryBitmap(
new ZXing.HybridBinarizer(luminanceSource));
let result = zxingDecoder.decode(binaryBitmap);
return {
text: result.text,
format: QrcodeResultFormat.create(
this.toHtml5QrcodeSupportedFormats(result.format)),
debugData: this.createDebugData()
};
}
private createReverseFormatMap(): Map<any, Html5QrcodeSupportedFormats> {
let result = new Map();
this.formatMap.forEach(
(value: any, key: Html5QrcodeSupportedFormats, _) => {
result.set(value, key);
});
return result;
}
private toHtml5QrcodeSupportedFormats(zxingFormat: any)
: Html5QrcodeSupportedFormats {
if (!this.reverseFormatMap.has(zxingFormat)) {
throw `reverseFormatMap doesn't have ${zxingFormat}`;
}
return this.reverseFormatMap.get(zxingFormat)!;
}
private createZXingFormats(
requestedFormats: Array<Html5QrcodeSupportedFormats>):
Array<any> {
let zxingFormats = [];
for (const requestedFormat of requestedFormats) {
if (this.formatMap.has(requestedFormat)) {
zxingFormats.push(
this.formatMap.get(requestedFormat));
} else {
this.logger.logError(`${requestedFormat} is not supported by`
+ "ZXingHtml5QrcodeShim");
}
}
return zxingFormats;
}
private createDebugData(): QrcodeResultDebugData {
return { decoderName: "zxing-js" };
}
}