extended the decodeImage function to support image scaling in case of unwanted too big image.

source/CameraImageWrapper.cpp

@@ -54,30 +54,27 @@ unsigned char* CameraImageWrapper::copyMatrix() const
     return newMatrix;
 }
 
-bool CameraImageWrapper::setImage(QString fileName)
+bool CameraImageWrapper::setImage(QString fileName, int maxWidth, int maxHeight)
 {
     bool isLoaded = image.load(fileName);
 
     if(!isLoaded)
         return false;
 
-    if(image.width() > QApplication::desktop()->width())
-        image = image.scaled(QApplication::desktop()->width(), image.height(), Qt::IgnoreAspectRatio);
+    scale(maxWidth, maxHeight);
 
-    if(image.height() > QApplication::desktop()->height())
-        image = image.scaled(image.width(), QApplication::desktop()->height(), Qt::IgnoreAspectRatio);
     return true;
 }
 
-bool CameraImageWrapper::setImage(QImage newImage)
+bool CameraImageWrapper::setImage(QImage newImage, int maxWidth, int maxHeight)
 {
     if(newImage.isNull())
         return false;
 
     image = newImage.copy();
 
-    if(image.width() > 640)
-        image = image.scaled(640, image.height(), Qt::KeepAspectRatio, isSmoothTransformationEnabled ? Qt::SmoothTransformation : Qt::FastTransformation);
+    scale(maxWidth, maxHeight);
+
     return true;
 }
 
@@ -94,8 +91,6 @@ QImage CameraImageWrapper::grayScaleImage(QImage::Format f)
     }
 
     return tmp;
-
-    //return image.convertToFormat(f);
 }
 
 QImage CameraImageWrapper::getOriginalImage()
@@ -103,43 +98,6 @@ QImage CameraImageWrapper::getOriginalImage()
     return image;
 }
 
-
-//unsigned char* CameraImageWrapper::getRow(int y, unsigned char* row)
-//{
-//    int width = getWidth();
-
-//    if (row == NULL)
-//    {
-//        row = new unsigned char[width];
-//        pRow = row;
-//    }
-
-//    for (int x = 0; x < width; x++)
-//        row[x] = getPixel(x,y);
-
-//    return row;
-//}
-
-//unsigned char* CameraImageWrapper::getMatrix()
-//{
-//    int width = getWidth();
-//    int height =  getHeight();
-//    unsigned char* matrix = new unsigned char[width*height];
-//    unsigned char* m = matrix;
-
-//    for(int y=0; y<height; y++)
-//    {
-//        unsigned char* tmpRow;
-//        memcpy(m, tmpRow = getRow(y, NULL), width);
-//        m += width * sizeof(unsigned char);
-
-//        delete tmpRow;
-//    }
-
-//    pMatrix = matrix;
-//    return matrix;
-//}
-
 ArrayRef<char> CameraImageWrapper::getRow(int y, ArrayRef<char> row) const
 {
     int width = getWidth();
@@ -182,3 +140,13 @@ void CameraImageWrapper::setSmoothTransformation(bool enable)
 {
     isSmoothTransformationEnabled = enable;
 }
+
+void CameraImageWrapper::scale(int maxWidth, int maxHeight)
+{
+    if((maxWidth != 1 || maxHeight != 1) && (image.width() > maxWidth || image.height() > maxHeight))
+        image = image.scaled(
+                    maxWidth != -1 ? maxWidth : image.width(),
+                    maxHeight != -1 ? maxHeight : image.height(),
+                    Qt::KeepAspectRatio,
+                    isSmoothTransformationEnabled ? Qt::SmoothTransformation : Qt::FastTransformation);
+}

source/CameraImageWrapper.h

@@ -24,8 +24,8 @@ public:
     /**
       * Set the source of the image. If it fails,  returns false.
       */
-    bool setImage(QString fileName);
-    bool setImage(QImage newImage);
+    bool setImage(QString fileName, int maxWidth=-1, int maxHeight=-1);
+    bool setImage(QImage newImage, int maxWidth=-1, int maxHeight=-1);
 
     QImage grayScaleImage(QImage::Format f);
     QImage getOriginalImage();
@@ -39,6 +39,9 @@ public:
     ArrayRef<char> getMatrix() const;
 
     void setSmoothTransformation(bool enable);
+
+private:
+    void scale(int maxWidth, int maxHeight);
   
 private:
     QImage image;

source/QZXing.h

@@ -69,15 +69,20 @@ public:
 public slots:
     /**
       * The decoding function. Will try to decode the given image based on the enabled decoders.
+      * If the image width is larger than maxWidth or image height is larger
+      * than maxHeight then the image will be scaled down. Either way, in case of scaling, the aspect
+      * ratio of the image will be kept.
       *
+      * The smoothTransformation flag determines whether the transformation will be smooth or fast.
+      * Smooth transformation provides better results but fast transformation is...faster.
       */
-    QString decodeImage(QImage image);
+    QString decodeImage(QImage image, int maxWidth=-1, int maxHeight=-1, bool smoothTransformation = false);
 
     /**
       * The decoding function. Will try to decode the given image based on the enabled decoders.
       * The input image is read from a local image file.
       */
-    QString decodeImageFromFile(QString imageFilePath);
+    QString decodeImageFromFile(QString imageFilePath, int maxWidth=-1, int maxHeight=-1, bool smoothTransformation = false);
 
     /**
       * The decoding function accessible from QML
@@ -99,6 +104,10 @@ public slots:
       */
     int getProcessTimeOfLastDecoding();
 
+    /**
+      * Get the decoders that are enabled at the moment.
+      * Returns a uint which is a bitwise OR of DecoderFormat enumeration values.
+      */
     uint getEnabledFormats() const;
     /**
       * Set the enabled decoders.
@@ -118,6 +127,11 @@ private:
     DecoderFormatType enabledDecoders;
     QObject* imageHandler;
     int processingTime;
+
+    /**
+      * If true, the decoding operation will take place at a different thread.
+      */
+    bool isThreaded;
 };
 
 #endif // QZXING_H

source/qzxing.cpp

@@ -95,22 +95,33 @@ void QZXing::setDecoder(const uint &hint)
     emit enabledFormatsChanged();
 }
 
-QString QZXing::decodeImage(QImage image)
+QString QZXing::decodeImage(QImage image, int maxWidth, int maxHeight, bool smoothTransformation)
 {
     QTime t;
     t.start();
     Ref<Result> res;
     emit decodingStarted();
 
-	if(image.isNull())
-	{
-		emit decodingFinished(false);
-		processingTime = -1;
-		return "";
-	}
+    if(image.isNull())
+    {
+        emit decodingFinished(false);
+        processingTime = -1;
+        return "";
+    }
 
     try{
-        Ref<LuminanceSource> imageRef(new CameraImageWrapper(image));
+        CameraImageWrapper* ciw;
+
+        if(maxWidth > 0 || maxHeight > 0)
+        {
+            ciw = new CameraImageWrapper();
+            ciw->setSmoothTransformation(smoothTransformation);
+            ciw->setImage(image, maxWidth, maxHeight);
+        }
+        else
+            ciw = new CameraImageWrapper(image);
+
+        Ref<LuminanceSource> imageRef(ciw);
         GlobalHistogramBinarizer* binz = new GlobalHistogramBinarizer(imageRef);
 
         Ref<Binarizer> bz (binz);
@@ -134,12 +145,12 @@ QString QZXing::decodeImage(QImage image)
     }
 }
 
-QString QZXing::decodeImageFromFile(QString imageFilePath)
+QString QZXing::decodeImageFromFile(QString imageFilePath, int maxWidth, int maxHeight, bool smoothTransformation)
 {
 	//used to have a check if this image exists
 	//but was removed because if the image file path doesn't point to a valid image
 	// then the QImage::isNull will return true and the decoding will fail eitherway.
-	return decodeImage(QImage(imageFilePath));
+    return decodeImage(QImage(imageFilePath), maxWidth, maxHeight, smoothTransformation);
 }
 
 QString QZXing::decodeImageQML(QObject *item)