Some small improvements in error handling based on exceptions observed at zxing.org

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

diff --git a/core/src/com/google/zxing/qrcode/detector/Detector.java b/core/src/com/google/zxing/qrcode/detector/Detector.java
index 87a08fb..8f06e8d 100644 (file)
--- a/core/src/com/google/zxing/qrcode/detector/Detector.java
+++ b/core/src/com/google/zxing/qrcode/detector/Detector.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.
@@ -21,8 +21,13 @@ import com.google.zxing.MonochromeBitmapSource;
 import com.google.zxing.ReaderException;
 import com.google.zxing.ResultPoint;
 import com.google.zxing.common.BitMatrix;
+import com.google.zxing.common.DetectorResult;
+import com.google.zxing.common.GenericResultPoint;
+import com.google.zxing.common.GridSampler;
 import com.google.zxing.qrcode.decoder.Version;
 
+import java.util.Hashtable;
+
 /**
  * <p>Encapsulates logic that can detect a QR Code in an image, even if the QR Code
  * is rotated or skewed, or partially obscured.</p>
@@ -44,6 +49,17 @@ public final class Detector {
    * @throws ReaderException if no QR Code can be found
    */
   public DetectorResult detect() throws ReaderException {
+    return detect(null);
+  }
+
+  /**
+   * <p>Detects a QR Code in an image, simply.</p>
+   *
+   * @param hints optional hints to detector
+   * @return {@link DetectorResult} encapsulating results of detecting a QR Code
+   * @throws ReaderException if no QR Code can be found
+   */
+  public DetectorResult detect(Hashtable hints) throws ReaderException {
 
     MonochromeBitmapSource image = this.image;
     if (!BlackPointEstimationMethod.TWO_D_SAMPLING.equals(image.getLastEstimationMethod())) {
@@ -51,25 +67,28 @@ public final class Detector {
     }
 
     FinderPatternFinder finder = new FinderPatternFinder(image);
-    FinderPatternInfo info = finder.find();
+    FinderPatternInfo info = finder.find(hints);
 
     FinderPattern topLeft = info.getTopLeft();
     FinderPattern topRight = info.getTopRight();
     FinderPattern bottomLeft = info.getBottomLeft();
 
     float moduleSize = calculateModuleSize(topLeft, topRight, bottomLeft);
+    if (moduleSize < 1.0f) {
+      throw new ReaderException("Module size too small");
+    }
     int dimension = computeDimension(topLeft, topRight, bottomLeft, moduleSize);
     Version provisionalVersion = Version.getProvisionalVersionForDimension(dimension);
     int modulesBetweenFPCenters = provisionalVersion.getDimensionForVersion() - 7;
 
-    // Guess where a "bottom right" finder pattern would have been
-    float bottomRightX = topRight.getX() - topLeft.getX() + bottomLeft.getX();
-    float bottomRightY = topRight.getY() - topLeft.getY() + bottomLeft.getY();
-
     AlignmentPattern alignmentPattern = null;
     // Anything above version 1 has an alignment pattern
     if (provisionalVersion.getAlignmentPatternCenters().length > 0) {
 
+      // Guess where a "bottom right" finder pattern would have been
+      float bottomRightX = topRight.getX() - topLeft.getX() + bottomLeft.getX();
+      float bottomRightY = topRight.getY() - topLeft.getY() + bottomLeft.getY();
+
       // Estimate that alignment pattern is closer by 3 modules
       // from "bottom right" to known top left location
       float correctionToTopLeft = 1.0f - 3.0f / (float) modulesBetweenFPCenters;
@@ -94,8 +113,7 @@ public final class Detector {
 
     }
 
-    GridSampler sampler = GridSampler.getInstance();
-    BitMatrix bits = sampler.sampleGrid(image, topLeft, topRight, bottomLeft, alignmentPattern, dimension);
+    BitMatrix bits = sampleGrid(image, topLeft, topRight, bottomLeft, alignmentPattern, dimension);
 
     ResultPoint[] points;
     if (alignmentPattern == null) {
@@ -106,6 +124,50 @@ public final class Detector {
     return new DetectorResult(bits, points);
   }
 
+  private static BitMatrix sampleGrid(MonochromeBitmapSource image,
+                                      ResultPoint topLeft,
+                                      ResultPoint topRight,
+                                      ResultPoint bottomLeft,
+                                      ResultPoint alignmentPattern,
+                                      int dimension) throws ReaderException {
+    float dimMinusThree = (float) dimension - 3.5f;
+    float bottomRightX;
+    float bottomRightY;
+    float sourceBottomRightX;
+    float sourceBottomRightY;
+    if (alignmentPattern != null) {
+      bottomRightX = alignmentPattern.getX();
+      bottomRightY = alignmentPattern.getY();
+      sourceBottomRightX = sourceBottomRightY = dimMinusThree - 3.0f;
+    } else {
+      // Don't have an alignment pattern, just make up the bottom-right point
+      bottomRightX = (topRight.getX() - topLeft.getX()) + bottomLeft.getX();
+      bottomRightY = (topRight.getY() - topLeft.getY()) + bottomLeft.getY();
+      sourceBottomRightX = sourceBottomRightY = dimMinusThree;
+    }
+
+    GridSampler sampler = GridSampler.getInstance();
+    return sampler.sampleGrid(
+        image,
+        dimension,
+        3.5f,
+        3.5f,
+        dimMinusThree,
+        3.5f,
+        sourceBottomRightX,
+        sourceBottomRightY,
+        3.5f,
+        dimMinusThree,
+        topLeft.getX(),
+        topLeft.getY(),
+        topRight.getX(),
+        topRight.getY(),
+        bottomRightX,
+        bottomRightY,
+        bottomLeft.getX(),
+        bottomLeft.getY());
+  }
+
   /**
    * <p>Computes the dimension (number of modules on a size) of the QR Code based on the position
    * of the finder patterns and estimated module size.</p>
@@ -114,8 +176,8 @@ public final class Detector {
                                       ResultPoint topRight,
                                       ResultPoint bottomLeft,
                                       float moduleSize) throws ReaderException {
-    int tltrCentersDimension = round(FinderPatternFinder.distance(topLeft, topRight) / moduleSize);
-    int tlblCentersDimension = round(FinderPatternFinder.distance(topLeft, bottomLeft) / moduleSize);
+    int tltrCentersDimension = round(GenericResultPoint.distance(topLeft, topRight) / moduleSize);
+    int tlblCentersDimension = round(GenericResultPoint.distance(topLeft, bottomLeft) / moduleSize);
     int dimension = ((tltrCentersDimension + tlblCentersDimension) >> 1) + 7;
     switch (dimension & 0x03) { // mod 4
       case 0: