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 0000000000..4dcc4f6598
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+++ b/devtools/shared/qrcode/index.js
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+/* 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";
+
+// Lazily require encoder and decoder in case only one is needed
+Object.defineProperty(this, "Encoder", {
+  get: () =>
+    require("resource://devtools/shared/qrcode/encoder/index.js").Encoder,
+});
+Object.defineProperty(this, "QRRSBlock", {
+  get: () =>
+    require("resource://devtools/shared/qrcode/encoder/index.js").QRRSBlock,
+});
+Object.defineProperty(this, "QRErrorCorrectLevel", {
+  get: () =>
+    require("resource://devtools/shared/qrcode/encoder/index.js")
+      .QRErrorCorrectLevel,
+});
+Object.defineProperty(this, "decoder", {
+  get: () => {
+    // Some applications don't ship the decoder, see moz.build
+    try {
+      return require("resource://devtools/shared/qrcode/decoder/index.js");
+    } 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) {
+  const msgLength = message.length;
+  const qualityLevel = QRErrorCorrectLevel[quality];
+  for (let version = 1; version <= 10; version++) {
+    const 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);
+  const 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();
+  }
+  return new Promise((resolve, reject) => {
+    decoder.decodeFromURI(URI, resolve, reject);
+  });
+};
+
+/**
+ * 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);
+};