Barcode decoder implementation using the new ZXing ReadBarcode API

This avoids the need for our own binarizer implementation and thus
potentially an image copy, as ZXing can now consume at least some
image formats directly from the raw QImage data, which means less
code and slightly more performance for us. This however needs latest
ZXing master, so we'll only really benefit from this with ZXing's next
release.

src/barcodedecoder.cpp

@@ -18,6 +18,9 @@
 #include <ZXing/DecodeHints.h>
 #include <ZXing/MultiFormatReader.h>
 #include <ZXing/Result.h>
+#ifdef ZXING_USE_READBARCODE
+#include <ZXing/ReadBarcode.h>
+#endif
 #endif
 
 using namespace KItinerary;
@@ -161,17 +164,58 @@ BarcodeDecoder::BarcodeType formatToType(ZXing::BarcodeFormat format)
     return BarcodeDecoder::None;
 }
 
+#ifdef ZXING_USE_READBARCODE
+static ZXing::ImageFormat zxingImageFormat(QImage::Format format)
+{
+    switch (format) {
+        case QImage::Format_ARGB32:
+        case QImage::Format_RGB32:
+#if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
+            return ZXing::ImageFormat::BGRX;
+#else
+            return ZXing::ImageFormat::XRGB;
+#endif
+        case QImage::Format_RGB888:
+            return ZXing::ImageFormat::RGB;
+        case QImage::Format_RGBX8888:
+        case QImage::Format_RGBA8888:
+            return ZXing::ImageFormat::RGBX;
+        case QImage::Format_Grayscale8:
+            return ZXing::ImageFormat::Lum;
+        default:
+            return ZXing::ImageFormat::None;
+    }
+    Q_UNREACHABLE();
+}
+
+static ZXing::Result zxingReadBarcode(const QImage &img, const ZXing::DecodeHints &hints)
+{
+    return ZXing::ReadBarcode({img.bits(), img.width(), img.height(), zxingImageFormat(img.format()), img.bytesPerLine()}, hints);
+}
+#endif
+
 void BarcodeDecoder::decodeZxing(const QImage &img, BarcodeDecoder::BarcodeTypes format, BarcodeDecoder::Result &result) const
 {
-    QImagePureBinarizer binarizer(img);
     ZXing::DecodeHints hints;
 #if ZXING_VERSION >= QT_VERSION_CHECK(1, 1, 0)
     hints.setFormats(typeToFormats(format));
 #else
     hints.setPossibleFormats(typeToFormats(format));
 #endif
+
+#ifdef ZXING_USE_READBARCODE
+    hints.setBinarizer(ZXing::Binarizer::FixedThreshold);
+    hints.setIsPure(true);
+
+    // convert if img is in a format ZXing can't handle directly
+    const auto res = zxingImageFormat(img.format()) == ZXing::ImageFormat::None ?
+        zxingReadBarcode(img.convertToFormat(QImage::Format_Grayscale8), hints) : zxingReadBarcode(img, hints);
+#else
+    QImagePureBinarizer binarizer(img);
     ZXing::MultiFormatReader reader(hints);
     const auto res = reader.read(binarizer);
+#endif
+
     if (res.isValid()) {
         // detect content type
         result.contentType = Result::Any;

src/config-kitinerary.h.cmake

@@ -22,6 +22,14 @@
 #define ZXING_VERSION_PATCH @ZXing_VERSION_PATCH@
 #define ZXING_VERSION ((@ZXing_VERSION_MAJOR@<<16)|(@ZXing_VERSION_MINOR@<<8)|(@ZXing_VERSION_PATCH@))
 
+// QT_VERSION_CHECK isn't available in here for the below check
+#define K_VERSION_CHECK(major, minor, patch) ((major<<16)|(minor<<8)|(patch))
+
+// this might compile with older versions too, but it only actually works post 1.1.1
+#if ZXING_VERSION > K_VERSION_CHECK(1, 1, 1)
+#define ZXING_USE_READBARCODE
+#endif
+
 #cmakedefine HAVE_KCAL
 #cmakedefine HAVE_LIBXML2
 #cmakedefine HAVE_PHONENUMBER

src/qimagepurebinarizer.cpp

@@ -5,7 +5,7 @@
 */
 
 #include "qimagepurebinarizer.h"
-#ifdef HAVE_ZXING
+#if defined(HAVE_ZXING) && !defined(ZXING_USE_READBARCODE)
 
 #include <ZXing/BitArray.h>
 

src/qimagepurebinarizer.h

@@ -8,7 +8,7 @@
 #define KITINERARY_QIMAGEPUREBINARIZER_H
 
 #include "config-kitinerary.h"
-#ifdef HAVE_ZXING
+#if defined(HAVE_ZXING) && !defined(ZXING_USE_READBARCODE)
 
 #include <QImage>