diff options
author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
---|---|---|
committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
tree | 10027f336435511475e392454359edea8e25895d /devtools/shared/qrcode/index.js | |
parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
download | UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.gz UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.lz UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.xz UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.zip |
Add m-esr52 at 52.6.0
Diffstat (limited to 'devtools/shared/qrcode/index.js')
-rw-r--r-- | devtools/shared/qrcode/index.js | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/devtools/shared/qrcode/index.js b/devtools/shared/qrcode/index.js new file mode 100644 index 000000000..ec3442426 --- /dev/null +++ b/devtools/shared/qrcode/index.js @@ -0,0 +1,116 @@ +/* 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 = require("promise"); +const defer = require("devtools/shared/defer"); + +// 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 = 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); +}; |