зеркало из https://github.com/mozilla/gecko-dev.git
117 строки
3.5 KiB
JavaScript
117 строки
3.5 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
|
|
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
|
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
|
|
|
|
"use strict";
|
|
|
|
const { Cu } = require("chrome");
|
|
const { Promise: promise } =
|
|
Cu.import("resource://gre/modules/Promise.jsm", {});
|
|
|
|
// Lazily require encoder and decoder in case only one is needed
|
|
Object.defineProperty(this, "Encoder", {
|
|
get: () => require("./encoder/index").Encoder
|
|
});
|
|
Object.defineProperty(this, "QRRSBlock", {
|
|
get: () => require("./encoder/index").QRRSBlock
|
|
});
|
|
Object.defineProperty(this, "QRErrorCorrectLevel", {
|
|
get: () => require("./encoder/index").QRErrorCorrectLevel
|
|
});
|
|
Object.defineProperty(this, "decoder", {
|
|
get: () => {
|
|
// Some applications don't ship the decoder, see moz.build
|
|
try {
|
|
return require("./decoder/index");
|
|
} catch(e) {
|
|
return null;
|
|
}
|
|
}
|
|
});
|
|
|
|
/**
|
|
* There are many "versions" of QR codes, which describes how many dots appear
|
|
* in the resulting image, thus limiting the amount of data that can be
|
|
* represented.
|
|
*
|
|
* The encoder used here allows for versions 1 - 10 (more dots for larger
|
|
* versions).
|
|
*
|
|
* It expects you to pick a version large enough to contain your message. Here
|
|
* we search for the mimimum version based on the message length.
|
|
* @param string message
|
|
* Text to encode
|
|
* @param string quality
|
|
* Quality level: L, M, Q, H
|
|
* @return integer
|
|
*/
|
|
exports.findMinimumVersion = function(message, quality) {
|
|
let msgLength = message.length;
|
|
let qualityLevel = QRErrorCorrectLevel[quality];
|
|
for (let version = 1; version <= 10; version++) {
|
|
let rsBlocks = QRRSBlock.getRSBlocks(version, qualityLevel);
|
|
let maxLength = rsBlocks.reduce((prev, block) => {
|
|
return prev + block.dataCount;
|
|
}, 0);
|
|
// Remove two bytes to fit header info
|
|
maxLength -= 2;
|
|
if (msgLength <= maxLength) {
|
|
return version;
|
|
}
|
|
}
|
|
throw new Error("Message too large");
|
|
};
|
|
|
|
/**
|
|
* Simple wrapper around the underlying encoder's API.
|
|
* @param string message
|
|
* Text to encode
|
|
* @param string quality (optional)
|
|
Quality level: L, M, Q, H
|
|
* @param integer version (optional)
|
|
* QR code "version" large enough to contain the message
|
|
* @return object with the following fields:
|
|
* * src: an image encoded a data URI
|
|
* * height: image height
|
|
* * width: image width
|
|
*/
|
|
exports.encodeToDataURI = function(message, quality, version) {
|
|
quality = quality || "H";
|
|
version = version || exports.findMinimumVersion(message, quality);
|
|
let encoder = new Encoder(version, quality);
|
|
encoder.addData(message);
|
|
encoder.make();
|
|
return encoder.createImgData();
|
|
};
|
|
|
|
/**
|
|
* Simple wrapper around the underlying decoder's API.
|
|
* @param string URI
|
|
* URI of an image of a QR code
|
|
* @return Promise
|
|
* The promise will be resolved with a string, which is the data inside
|
|
* the QR code.
|
|
*/
|
|
exports.decodeFromURI = function(URI) {
|
|
if (!decoder) {
|
|
return promise.reject();
|
|
}
|
|
let deferred = promise.defer();
|
|
decoder.decodeFromURI(URI, deferred.resolve, deferred.reject);
|
|
return deferred.promise;
|
|
};
|
|
|
|
/**
|
|
* Decode a QR code that has been drawn to a canvas element.
|
|
* @param Canvas canvas
|
|
* <canvas> element to read from
|
|
* @return string
|
|
* The data inside the QR code
|
|
*/
|
|
exports.decodeFromCanvas = function(canvas) {
|
|
if (!decoder) {
|
|
throw new Error("Decoder not available");
|
|
}
|
|
return decoder.decodeFromCanvas(canvas);
|
|
};
|