Alternate multi QR Code reader from Hannes

[zxing.git] / core / src / com / google / zxing / qrcode / QRCodeReader.java

diff --git a/core/src/com/google/zxing/qrcode/QRCodeReader.java b/core/src/com/google/zxing/qrcode/QRCodeReader.java
index adc53b3..f3ddb54 100644 (file)
--- a/core/src/com/google/zxing/qrcode/QRCodeReader.java
+++ b/core/src/com/google/zxing/qrcode/QRCodeReader.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2007 Google Inc.
+ * Copyright 2007 ZXing authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,23 +16,36 @@
 
 package com.google.zxing.qrcode;
 
+import com.google.zxing.BarcodeFormat;
 import com.google.zxing.DecodeHintType;
 import com.google.zxing.MonochromeBitmapSource;
 import com.google.zxing.Reader;
 import com.google.zxing.ReaderException;
 import com.google.zxing.Result;
 import com.google.zxing.ResultPoint;
+import com.google.zxing.ResultMetadataType;
 import com.google.zxing.common.BitMatrix;
+import com.google.zxing.common.DecoderResult;
+import com.google.zxing.common.DetectorResult;
 import com.google.zxing.qrcode.decoder.Decoder;
 import com.google.zxing.qrcode.detector.Detector;
-import com.google.zxing.qrcode.detector.DetectorResult;
 
 import java.util.Hashtable;
 
 /**
- * @author srowen@google.com (Sean Owen)
+ * This implementation can detect and decode QR Codes in an image.
+ *
+ * @author Sean Owen
  */
-public final class QRCodeReader implements Reader {
+public class QRCodeReader implements Reader {
+
+  private static final ResultPoint[] NO_POINTS = new ResultPoint[0];
+
+  private final Decoder decoder = new Decoder();
+
+  protected Decoder getDecoder() {
+    return decoder;
+  }
 
   /**
    * Locates and decodes a QR code in an image.
@@ -46,43 +59,71 @@ public final class QRCodeReader implements Reader {
 
   public Result decode(MonochromeBitmapSource image, Hashtable hints)
       throws ReaderException {
-    String text;
+    DecoderResult decoderResult;
     ResultPoint[] points;
     if (hints != null && hints.containsKey(DecodeHintType.PURE_BARCODE)) {
       BitMatrix bits = extractPureBits(image);
-      text = Decoder.decode(bits);
-      points = new ResultPoint[0];
+      decoderResult = decoder.decode(bits);
+      points = NO_POINTS;
     } else {
-      DetectorResult result = new Detector(image).detect();
-      text = Decoder.decode(result.getBits());
-      points = result.getPoints();
+      DetectorResult detectorResult = new Detector(image).detect(hints);
+      decoderResult = decoder.decode(detectorResult.getBits());
+      points = detectorResult.getPoints();
     }
-    return new Result(text, points);
+
+    Result result = new Result(decoderResult.getText(), decoderResult.getRawBytes(), points, BarcodeFormat.QR_CODE);
+    if (decoderResult.getByteSegments() != null) {
+      result.putMetadata(ResultMetadataType.BYTE_SEGMENTS, decoderResult.getByteSegments());
+    }
+    return result;
   }
 
-  private static BitMatrix extractPureBits(MonochromeBitmapSource image)
-      throws ReaderException {
+  /**
+   * This method detects a barcode in a "pure" image -- that is, pure monochrome image
+   * which contains only an unrotated, unskewed, image of a barcode, with some white border
+   * around it. This is a specialized method that works exceptionally fast in this special
+   * case.
+   */
+  private static BitMatrix extractPureBits(MonochromeBitmapSource image) throws ReaderException {
     // Now need to determine module size in pixels
-    // First, skip white border
+
+    int height = image.getHeight();
+    int width = image.getWidth();
+    int minDimension = Math.min(height, width);
+
+    // First, skip white border by tracking diagonally from the top left down and to the right:
     int borderWidth = 0;
-    while (!image.isBlack(borderWidth, borderWidth)) {
+    while (borderWidth < minDimension && !image.isBlack(borderWidth, borderWidth)) {
       borderWidth++;
     }
+    if (borderWidth == minDimension) {
+      throw ReaderException.getInstance();
+    }
+
+    // And then keep tracking across the top-left black module to determine module size
     int moduleEnd = borderWidth;
-    while (image.isBlack(moduleEnd, moduleEnd)) {
+    while (moduleEnd < minDimension && image.isBlack(moduleEnd, moduleEnd)) {
       moduleEnd++;
     }
+    if (moduleEnd == minDimension) {
+      throw ReaderException.getInstance();
+    }
+
     int moduleSize = moduleEnd - borderWidth;
 
-    int rowEndOfSymbol = image.getWidth() - 1;
-    while (!image.isBlack(rowEndOfSymbol, borderWidth)) {
+    // And now find where the rightmost black module on the first row ends
+    int rowEndOfSymbol = width - 1;
+    while (rowEndOfSymbol >= 0 && !image.isBlack(rowEndOfSymbol, borderWidth)) {
       rowEndOfSymbol--;
     }
+    if (rowEndOfSymbol < 0) {
+      throw ReaderException.getInstance();
+    }
     rowEndOfSymbol++;
 
+    // Make sure width of barcode is a multiple of module size
     if ((rowEndOfSymbol - borderWidth) % moduleSize != 0) {
-      throw new ReaderException("Bad module size / width: " + moduleSize +
-          " / " + (rowEndOfSymbol - borderWidth));
+      throw ReaderException.getInstance();
     }
     int dimension = (rowEndOfSymbol - borderWidth) / moduleSize;
 
@@ -91,6 +132,12 @@ public final class QRCodeReader implements Reader {
     // little off, this will help recover.
     borderWidth += moduleSize >> 1;
 
+    int sampleDimension = borderWidth + (dimension - 1) * moduleSize;
+    if (sampleDimension >= width || sampleDimension >= height) {
+      throw ReaderException.getInstance();
+    }
+
+    // Now just read off the bits
     BitMatrix bits = new BitMatrix(dimension);
     for (int i = 0; i < dimension; i++) {
       int iOffset = borderWidth + i * moduleSize;