Add the option to ignore barcode aspect ratio heuristics

This allows to run barcode decoding on images that contain a barcode only
as a much smaller element. This is slower of course, but in some cases is
the only way we can get to the barcode.

src/lib/barcodedecoder.cpp

@@ -90,18 +90,23 @@ void BarcodeDecoder::clearCache()
     m_cache.clear();
 }
 
-bool BarcodeDecoder::isPlausibleSize(int width, int height)
+bool BarcodeDecoder::isPlausibleSize(int width, int height, BarcodeDecoder::BarcodeTypes hint)
 {
     // normalize to landscape
     if (height > width) {
         std::swap(width, height);
     }
 
-    return width > MinSourceImageWidth && height > MinSourceImageHeight && width < MaxSourceImageWidth && height < MaxSourceImageHeight;
+    return width > MinSourceImageWidth && height > MinSourceImageHeight
+        && ((width < MaxSourceImageWidth && height < MaxSourceImageHeight) || (hint & IgnoreAspectRatio));
 }
 
 bool BarcodeDecoder::isPlausibleAspectRatio(int width, int height, BarcodeDecoder::BarcodeTypes hint)
 {
+    if (hint & IgnoreAspectRatio) {
+        return true;
+    }
+
     // normalize to landscape
     if (height > width) {
         std::swap(width, height);
@@ -129,7 +134,7 @@ bool BarcodeDecoder::isPlausibleAspectRatio(int width, int height, BarcodeDecode
 
 bool BarcodeDecoder::maybeBarcode(int width, int height, BarcodeDecoder::BarcodeTypes hint)
 {
-    return isPlausibleSize(width, height) && isPlausibleAspectRatio(width, height, hint);
+    return isPlausibleSize(width, height, hint) && isPlausibleAspectRatio(width, height, hint);
 }
 
 #ifdef HAVE_ZXING
@@ -272,6 +277,11 @@ void BarcodeDecoder::decodeIfNeeded(const QImage &img, BarcodeDecoder::BarcodeTy
         return;
     }
 
+    if (hint & IgnoreAspectRatio) {
+        decodeZxing(img, hint, result);
+        return;
+    }
+
     const auto aspectRatio = img.width() < img.height() ?
         (float)img.height() / (float)img.width() :
         (float)img.width() / (float)img.height();

src/lib/barcodedecoder.h

@@ -41,6 +41,7 @@ public:
         Code39 = 16,
         Code93 = 32,
         Code128 = 64,
+        IgnoreAspectRatio = 128, /// search for barcodes anywhere in the image, rather than assuming the image is primarily containing the barcode
         AnySquare = Aztec | QRCode | DataMatrix,
         Any2D = AnySquare | PDF417,
         Any1D = Code39 | Code93 | Code128,
@@ -66,7 +67,7 @@ public:
      *  to perform them manually if a cheaper way to obtain the image dimension exists
      *  that does not require a full QImage creation.
      */
-    static bool isPlausibleSize(int width, int height);
+    static bool isPlausibleSize(int width, int height, BarcodeTypes hint);
 
     /** Checks if the given image dimensions are a barcode of type @p hint.
      *  See above.

src/lib/pdf/pdfbarcodeutil.cpp

@@ -22,7 +22,7 @@ bool PdfBarcodeUtil::maybeBarcode(const PdfImage &img, BarcodeDecoder::BarcodeTy
     const auto w = img.width();
     const auto h = img.height();
 
-    if (!BarcodeDecoder::isPlausibleSize(img.sourceWidth(), img.sourceHeight()) || !BarcodeDecoder::isPlausibleAspectRatio(w, h, hint)) {
+    if (!BarcodeDecoder::isPlausibleSize(img.sourceWidth(), img.sourceHeight(), hint) || !BarcodeDecoder::isPlausibleAspectRatio(w, h, hint)) {
         return false;
     }