29 thoughts on “Reading QRCode with Windows 8 RC”

1. edison 21/06/2012 at 19:27

   hey I am glad that you giving out the interesting codes. I have tried the codes but it isn’t work. Why? Please help me out. Thanks
2. Benjamin Post author22/06/2012 at 14:41

   Hey there,

   Just saying it’s not working will not help me to help you
   Do you any error message? What is actually not working?

   Cheers, Ben
3. edison 22/06/2012 at 17:46

   An exception of type ‘com.google.zxing.ReaderException’ occurred in Silverlight.DLL but was not handled in user code
4. Benjamin Post author25/06/2012 at 11:04

   The ZXing library is raising an exception when the given image is not containing a readable QR code, which is pointing out that your Visual Studio setup is configured to break on any exception, handled or not.
   Please into the Debug menu -> Exceptions…, and uncheck all checkboxes in the Thrown column.
   That should do the trick
5. Kishore 29/06/2012 at 12:23

   Hi Benjamin,

   I am getting exception like “An unhandled exception of type ‘System.Exception’ occurred in mscorlib.dll.Additional information: Exception from HRESULT: 0xC00DABE0″

   Thanks,
   Kishore
6. Marwan 02/07/2012 at 12:28

   Hello Benjamin,

   I was trying to get the QRCodeReader, to decode an image that i added to the project, So hear’s what i’ve done so far:

   
StorageFile st = await Package.Current.InstalledLocation.GetFileAsync(@"Alec-Bradley-QR-Code.bmp");
_imageStream = new InMemoryRandomAccessStream();
Stream s = await st.OpenStreamForReadAsync();
s.CopyTo(_imageStream.AsStreamForWrite());
_datareader = new DataReader(_imageStream.GetInputStreamAt((ulong)54));


   The problem is when getting “luminanceBits[]” I have 2 more/less bits, and that is driving the code to throw an exception “attempted to access data outside the valid range”.
   I am running out of ideas here….. don’t no if skipping 54 bits is the wrong thing or the way i am getting the stream. What’s wrong ?

   (Thank you !)
7. Marwan 09/07/2012 at 08:43

   Hello,

   I managed to get the InMemoryAccessStream from the image and this is what i’ve done:

   
StorageFile file = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFileAsync("Alec-Bradley-QR-Code.bmp");
_imageStream = new InMemoryRandomAccessStream();
using (var inputStream = await file.OpenReadAsync())
{
await RandomAccessStream.CopyAsync(inputStream, _imageStream);
}
_imageStream.Seek(0);

   After getting the stream and the bitmapImage (i get the width and height of the image), I reset the following variables => ‘_dimensions’ ‘_encodingProps’ .

   Now I’m getting this error after decoding the bar-code : ” Index was outside the bounds of the array.” Will keep this topic updated …
8. Suman 18/07/2012 at 07:56

   Hi Guys,

   I am trying the same. Do you guys have any success in scanning the QR code image?
   I am trying with a sample image which has QR code in it.

   Thanks & Regards,
   Suman
9. theCake 23/07/2012 at 20:14

   Hello,
   Great work porting this library to WinRT! However, I was unable to run the sample app. It crashes with an unhandled exception in the _capture.InitializeAsync() line…
   Nevertheless, I wrapped the encoding features of your zxing port into a new library, which I plan to publish on my blog soon.. It features a Task to generate QR codes in one line of code.. If you might want to see the code, or prefer a way to credit you as the one who did the complicated part, just drop me an email =)
   I’d really like to wrap the decoding mechanism as well, but..

   greetings,
   ~theCake
10. Benjamin Post author24/07/2012 at 22:52

    If you mention me for the ZXing port, that’s more than enough

    Happy coding!
11. Chris 25/07/2012 at 09:59

    Hello,

    I have tried your sample but the problem is that I always get the “Exception of type ‘com.google.zxing.ReaderException’ was thrown.” at the QRCodeReader decode and the result is always an empty string. I have not managed to read a QR Barcode yet! Do you have any clue why I can’t get a result?

    @”theCake” : You should not run the project to a simulator. Check it!
12. Benjamin Post author25/07/2012 at 19:17

    Did you try details found on one my previous answers about checking Debug settings?
13. Chris 27/07/2012 at 10:11

    Thanx for the response!

    Yes I have already made these changes.

    The problem is that in the ReedSolomonDecoder.cs the findErrorLocations functions always throws an “throw new ReedSolomonException(“Error locator degree does not match number of roots”)” because the int e is never equal to the numErrors and then everything breaks!

    Can you figure out what is going on?
14. theCake 27/07/2012 at 18:18

    @Chris: Nope, (still?) not working..

    @Benjamin Great!
    Here you go: http://kuchenzeit.wordpress.com/2012/07/23/tcd-device/ (my blogpost)
    And the NuGet package: https://nuget.org/packages/TCD.Device.Camera

    have a nice weekend^
15. kishore 16/08/2012 at 10:49

    How to decode qrcode image ?
16. Adi 16/08/2012 at 11:55

    Hi Benjamin I am using this code

    using (IRandomAccessStream fileStream = await file.OpenAsync(Windows.Storage.FileAccessMode.Read))
    {
    // Set the image source to the selected bitmap
    BitmapImage bitmapImage = new BitmapImage();
    bitmapImage.DecodePixelHeight = decodePixelHeight;
    bitmapImage.DecodePixelWidth = decodePixelWidth;
    bitmapImage.SetSource(fileStream);
    var reader = new Windows.Storage.Streams.DataReader(fileStream.GetInputStreamAt(0));
    await reader.LoadAsync((uint)fileStream.Size);
    byte[] pixels = new byte[fileStream.Size];
    reader.ReadBytes(pixels);
    com.google.zxing.LuminanceSource source = new RGBLuminanceSource(pixels, bitmapImage.DecodePixelWidth,
    bitmapImage.DecodePixelHeight);
    var binarizer = new HybridBinarizer(source);
    var binBitmap = new BinaryBitmap(binarizer);
    var qrRead = new com.google.zxing.oned.MultiFormatUPCEANReader(zxingHints); ;
    var results = qrRead.decode(binBitmap);
    }

    I am trying your project for decoding barcode, but I am getting exception in decode function of OneDReader class. Any help?
17. MrT 22/08/2012 at 15:44

    Hi,

    I’ve tried to use the code to scan barcodes instead of QR codes but I keep getting reader errors. Do you know if there are any issues with the MultiFormatReader?
18. Benjamin Post author22/08/2012 at 16:03

    Hi folks,
    This code is provided as an example, and therefore you should have to check against your image binary content to see where is the issue is coming from.
    As far as I looked at it, the ZXing lib is working pretty fine even with an image opened from the file-system

    Cheers, Ben
19. Vivek Deshmukh 28/08/2012 at 08:37

    hi Benjamin,

    I go through your sample code which is absolutely fine for camera reading.

    but I want to encode QRCode depends on user inputs.
    I know how to call encode function but how to form image after getting BitMatrix in WIRT ?

    Could you please guide me for this ?
20. Scruff.R 23/09/2012 at 14:33

    Hi Benjamin,

    thanks for your great work and the help you provide to users astonishingly quick!

    There is only one silly question, which might seem a bit off topic:
    Wouldn’t it be possible to change the project output “Silverlight.DLL” to something more expressive like e.g. bsQRLib or bsQRLibrary_ZXingPort?
    “Silverlight” is a very general term and a registered trade mark, so using it could lead to confusion (what exactly does this DLL do?) or other problems.

    This said, I really don’t want to appear petty, but rather help to earn your project the respect it deserves, by suggesting to use your OWN NAME (hence the bs prefix) and set it seperate from other projects that might also use “Silverlight” in any other form.

    Cheers,

    Scruff.R
21. Benjamin Post author24/09/2012 at 09:36

    Hello Vivek,

    This is acutally something put aside from C# here, for good performance reasons; this points to doing this in C++ instead.
    Don’t forget that my lazyness led me to do it this way, but the best way would still be to do all the image handling in C++ and then only do the image QRCode mapping in C#.

    Still, if wou want ot have a look at doing bitmap matrix manipulation in C# you definitely need t have a look here, this project actually is an implementation of the missing pieces of Bitmap manipulation in C#.

    Cheers,
    Ben
22. Benjamin Post author24/09/2012 at 09:43

    Hello Scruff,

    That’s a good point, I’ll be doing something around this soon (next 2 weeks time I hope); check back then for new package

    Cheers,
    Ben
23. Scruff.R 25/09/2012 at 00:19

    Hi Ben,

    now some C# stuff.
    While playing a bit with your code, I stumbled over the really slow RGBLuminanceSource(WritableBitmap, int, int) and RGBLuminanceSource(byte[], int, int) didn’t work for me either (same as e.g. post of Adi 16.8. 11:55).
    After reading some comments dealing with these problem in the original ZXing.Net forum, too, I slightly tweaked your code of RGBLuminanceSource into an ARGBLuminanceSource and avoided the time consuming GetPixeli(x,y) by reusing the (byte[], int, int) constructor.

    public ARGBLuminanceSource(byte[] d, int W, int H) : base(W, H)
    {
    __width = W;
    __height = H;
    int pixelCount = W * H; // can forget about 2D (might save time building product W*H over and over again)
    int posSource = 0; // incremenal cursor instead of permanently calculating position might save time
    // additionally rids us of the need to know number of bytes per pixel (add or remove an ++)
    int r, g, b; // declare only once (might save time?)

    // In order to measure pure decoding speed, we convert the entire image to a greyscale array
    // up front, which is the same as the Y channel of the YUVLuminanceSource in the real app.
    luminances = new sbyte[pixelCount];

    // drop extra loop (might save time?)
    for (int posTarget = 0; posTarget > 2);
    }
    }
    }

    public ARGBLuminanceSource(WriteableBitmap d, int W, int H) : this(d.ToByteArray(), W, H) { }

    Cheers,
    Scruff.R
24. Linda Rawson 01/12/2012 at 02:10

    I am also receiving the following error:

    An exception of type ‘com.google.zxing.ReaderException’ occurred in Silverlight.DLL but was not handled in user code

    All of the debug exceptions in the thrown column are not checked.

    I put a try catch around this statement in mainpage.xaml.cs

    Result r = c.decode(bbm);

    if (!String.IsNullOrEmpty(r.Text))
    {
    result = r.Text;
    }

    In the hopes it would ignore the error.

    Any other ideas? I am running VS2012.

    Thanks! You really did a great job here!
25. Linda Rawson 03/12/2012 at 02:42

    I can never get it to read a QR Code. The same as @Chris.

    Here is the image file: http://sensorytech.net/photo%20(63).jpg

    But I got around the getPixel slowness by converting the WriteableBmp into a byte[]

    Stream stream = wb.PixelBuffer.AsStream();
    byte[] pixels = new byte[stream.Length];
    stream.Seek(0, 0);
    stream.Read(pixels, 0, pixels.Length);

    com.google.zxing.LuminanceSource source = new RGBLuminanceSource(pixels, wb.PixelWidth, wb.PixelHeight);
26. Linda Rawson 03/12/2012 at 07:06

    The problem has to do with the colors. From a bitmap using zxing library my first color of my image at (x,y) = (0,0) = R:78, G:10, B:6 but from the writeablebitmap at (0,0) = R:109,G:47,B:24. I am thinking it is the wrong colorspace. Like one is BGR and the other is RGB.

    The FinderPatternInfo never finds any possible centers so never locates the bar code.

    It fails at this line:

    // A winner?
    if (foundPatternCross(stateCount))

    Because the colors are wrong. I am trying to work through the issue but if you guys are better image processors than I am that would be great.
27. Linda Rawson 03/12/2012 at 20:38

    Okay I can finally read a bar code. Feel free to enhance this code but here is how I did it. I added a routine to take the Writeablebitmap into the Sbyte array of luminances.

    private sbyte[] GetLuminance(WriteableBitmap modifiedImage)
    {
    int r = 0, a = 0, i = 0;
    int h = modifiedImage.PixelHeight;
    int w = modifiedImage.PixelWidth;
    Stream stream = modifiedImage.PixelBuffer.AsStream();
    byte[] StreamBuffer = new byte[stream.Length];
    //byte[] tempbuffer = new byte[64000];
    stream.Seek(0, 0);
    stream.Read(StreamBuffer, 0, StreamBuffer.Length);

    sbyte[] luminances = new sbyte[w * h];
    int currentX = 0;
    int currentY = 0;

    for (i = 0; i < StreamBuffer.Length – 4; i = i + 4)
    {
    var a1 = StreamBuffer[i + 3];
    var r1 = StreamBuffer[i + 2];
    var g1 = StreamBuffer[i + 1];
    var b1 = StreamBuffer[i + 0];

    a = 0xff;

    currentX = (i / 4) % w;
    currentY = (i / 4) / w;
    int offset = currentY * w;

    luminances[offset + currentX] = (sbyte)(((int)r1) << 16 | ((int)g1) << 8 | ((int)b1));
    }
    //stream.Seek(0, 0);
    //stream.Write(StreamBuffer, 0, StreamBuffer.Length);
    stream.Dispose();
    modifiedImage.Invalidate();
    return luminances;
    }

    Then I created an overridden method in RGBLuminanceSource.cs

    public RGBLuminanceSource(sbyte[] d, int W, int H, bool Is8Bit)
    : base(W, H)
    {
    __width = W;
    __height = H;
    luminances = d;
    }

    Then I call it like this:

    StorageFile file = await StorageFile.GetFileFromPathAsync(pImageFilePath);

    WriteableBitmap wb = new WriteableBitmap(1, 1);
    wb = await wbm.FromStream(await file.OpenReadAsync());

    com.google.zxing.LuminanceSource source = new RGBLuminanceSource(GetLuminance(wb), wb.PixelWidth, wb.PixelHeight,true);
    var binarizer = new HybridBinarizer(source);
    var binBitmap = new BinaryBitmap(binarizer);

    returnValue = reader.decode(binBitmap).Text;

    Yeah! So excited!
28. Benjamin Post author06/12/2012 at 15:11

    Hello Linda,

    I came up the the same conclusion; I actually found a really faster method to get Bitmap bytes using the BitmapDecoder object.
    But for some reasons the bits given by the BitmapDecoder class against my old slow parsing with DataReader is not giving me the same Bitmap bytes at all!

    This means additional time would be needed to find an acccurate way to either get those bits right or to find the good values for building up the luminance table used by ZXing.

    Cheers,
    Ben
29. Linda Rawson 10/12/2012 at 18:44

    I need some more time to mess with it but I had this code commented out. It is probably something along these lines where you have to switch the colors.

    // Decode image format
    /*var decoder = await BitmapDecoder.CreateAsync(await file.OpenReadAsync());
    var transform = new BitmapTransform();
    var pixelData = await decoder.GetPixelDataAsync(decoder.BitmapPixelFormat, decoder.BitmapAlphaMode, transform, ExifOrientationMode.RespectExifOrientation, ColorManagementMode.ColorManageToSRgb);

    // Swap R and B channels since it’s reversed
    var pixels = pixelData.DetachPixelData();
    for (var i = 0; i < pixels.Length; i += 4)
    {
    var r = pixels[i];
    var b = pixels[i + 2];
    pixels[i] = b;
    pixels[i + 2] = r;
    }*/