Structured Append

src/decoder/decodeData/index.ts

@@ -1,12 +1,23 @@
 // tslint:disable:no-bitwise
+import * as assert from "assert";
 import { BitStream } from "./BitStream";
 import { shiftJISTable } from "./shiftJISTable";
 
+export interface StructuredAppendTag {
+  M: number;
+  N: number;
+  parity: number;
+}
+
 export interface Chunk {
   type: Mode;
   text: string;
 }
 
+export interface StructuredAppendChunk extends StructuredAppendTag {
+  type: Mode.StructuredAppend;
+}
+
 export interface ByteChunk {
   type: Mode.Byte | Mode.Kanji;
   bytes: number[];
@@ -17,17 +28,19 @@ export interface ECIChunk {
   assignmentNumber: number;
 }
 
-export type Chunks = Array<Chunk | ByteChunk | ECIChunk>;
+export type Chunks = Array<Chunk | StructuredAppendChunk | ByteChunk | ECIChunk>;
 
 export interface DecodedQR {
   text: string;
   bytes: number[];
   chunks: Chunks;
+  structuredAppend?: StructuredAppendTag;
 }
 
 export enum Mode {
   Numeric = "numeric",
   Alphanumeric = "alphanumeric",
+  StructuredAppend = "structuredappend",
   Byte = "byte",
   Kanji = "kanji",
   ECI = "eci",
@@ -37,10 +50,10 @@ enum ModeByte {
   Terminator = 0x0,
   Numeric = 0x1,
   Alphanumeric = 0x2,
+  StructuredAppend = 0x3,
   Byte = 0x4,
   Kanji = 0x8,
   ECI = 0x7,
-  // StructuredAppend = 0x3,
   // FNC1FirstPosition = 0x5,
   // FNC1SecondPosition = 0x9,
 }
@@ -223,6 +236,26 @@ export function decode(data: Uint8ClampedArray, version: number): DecodedQR {
         type: Mode.Alphanumeric,
         text: alphanumericResult.text,
       });
+    } else if (mode === ModeByte.StructuredAppend) {
+      // QR Standard section 9.2:
+      // > The 4-bit patterns shall be the binary equivalents of (m - 1) and (n - 1) respectively.
+      const structuredAppend: StructuredAppendTag = {
+        M: stream.readBits(4) + 1,
+        N: stream.readBits(4) + 1,
+        parity: stream.readBits(8),
+      };
+      // QR codes sometimes contain duplicate Structured Append tags for redundancy.
+      // If they exist, they are all supposed to be equal. This checks for that:
+      if (typeof result.structuredAppend === "undefined") {
+        result.structuredAppend = structuredAppend;
+      } else {
+        // TODO: should this really be an assert? If the user has a corrupt QR code they probably still want to try to read it.
+        assert.deepStrictEqual(structuredAppend, result.structuredAppend, "QR Code contains inconsistent Structured Append tags.");
+      }
+      result.chunks.push({
+        type: Mode.StructuredAppend,
+        ...result.structuredAppend,
+      });
     } else if (mode === ModeByte.Byte) {
       const byteResult = decodeByte(stream, size);
       result.text += byteResult.text;

src/index.ts

@@ -1,6 +1,6 @@
 import {binarize} from "./binarizer";
 import {BitMatrix} from "./BitMatrix";
-import {Chunks} from "./decoder/decodeData";
+import {Chunks, StructuredAppendTag} from "./decoder/decodeData";
 import {decode} from "./decoder/decoder";
 import {extract} from "./extractor";
 import {locate, Point} from "./locator";
@@ -9,6 +9,7 @@ export interface QRCode {
   binaryData: number[];
   data: string;
   chunks: Chunks;
+  structuredAppend?: StructuredAppendTag;
   location: {
     topRightCorner: Point;
     topLeftCorner: Point;
@@ -39,6 +40,7 @@ function scan(matrix: BitMatrix): QRCode | null {
     binaryData: decoded.bytes,
     data: decoded.text,
     chunks: decoded.chunks,
+    structuredAppend: decoded.structuredAppend,
     location: {
       topRightCorner: extracted.mappingFunction(location.dimension, 0),
       topLeftCorner: extracted.mappingFunction(0, 0),

tests/end-to-end/report.json

@@ -1,7 +1,7 @@
 {
   "counts": {
     "failed": 47,
-    "successful": 207
+    "successful": 222
   },
   "tests": {
     "0": true,
@@ -245,6 +245,21 @@
     "stickerbook-4": true,
     "stickerbook-5": true,
     "stickerbook-6": false,
+    "structured-append-01": true,
+    "structured-append-02": true,
+    "structured-append-03": true,
+    "structured-append-04": true,
+    "structured-append-05": true,
+    "structured-append-06": true,
+    "structured-append-07": true,
+    "structured-append-08": true,
+    "structured-append-09": true,
+    "structured-append-10": true,
+    "structured-append-11": true,
+    "structured-append-12": true,
+    "structured-append-13": true,
+    "structured-append-14": true,
+    "structured-append-15": true,
     "subway-station": false,
     "tattoo-scan": true,
     "trackable-book-1": false,