QR code reading with cam

[makgab]

Hi!
How can I read a QR code from camera (ex. webcamera)?
The LazBarcode component can generate QR code (not reading).
I would like to read QR code (decode to string) and process it.
 
Is there any component or solution for this?

[avra]

Maybe trying to use some existing Delphi code?
https://github.com/Spelt/ZXing.Delphi

[Jurassic Pork]

hello,
there is also  DelphiZXingQRCodeEx

DelphiZXingQRCodeEx is a Delphi port of the QR Code functionality from ZXing, an open source barcode image processing library.

The code was initially ported to Delphi by Senior Debenu Developer, Kevin Newman (project DelphiZXingQRCode, see links below). Then it was changed by Michael Demidov. The changes are listed in CHANGELOG.md.

The most fundamental differences are:

Error correction level has been fixed.
Support for programmer-defined charsets. As an example, I implemented Win-1251 Russian charset and URL encoding (when non-Latin characters are represented as %-codes).
Exception handling has been added. There is no more Access Violation when input string is too long.
New QRGraphics.pas unit has been added that contains several functions to draw the QR Code on a given canvas (TCanvas) and to generate either a bitmap or a metafile.
Still compatible with older versions of Delphi (at least Delphi 7). Compatible with Lazarus (1.2.6, for Windows), see CHANGELOG.md (section 5).
The port retains the original Apache License (v2.0).

Friendly, J.P

[avra]

there is also  DelphiZXingQRCodeEx

Are you sure that it can decode QR, and not just generate QR?

[makgab]

I would like to use platform independent solution. I try to use opencv and zbar...

[Jurassic Pork]

oops     sorry Avra,
it seems that the project   DelphiZXingQRCodeEx is a QRcode encoder not a decoder.

[Jurassic Pork]

hello,
using tprocess and zbarimg command line program , you can decode qr code image (BarCodeFile is a qrcode image file) :

code example Lazarus 1.6 Windows 7 :

Code: Pascal  [Select][+][-]

1. procedure TForm1.ReadBarCode(BarCodeFile : String);
2.       const READ_BYTES = 2048;
3.       var
4.       aProcess: TProcess; //TProcess is crossplatform is best way
5.       MemStream: TMemoryStream;
6.       NumBytes: LongInt;
7.       BytesRead: LongInt;
8.       Lines: TStringList;
9.     begin
10.      // A temp Memorystream is used to buffer the output
11.      MemStream := TMemoryStream.Create;
12.      Lines :=TStringList.Create;
13.      BytesRead := 0;
14.  
15.        aProcess := TProcess.Create(nil);
16.        aProcess.Executable := 'zbarimg.exe';
17.        aProcess.Parameters.Add('-q');
18.        aProcess.Parameters.Add(BarCodeFile);
19.        aprocess.ShowWindow := swoHIDE;
20.        AProcess.Options := AProcess.Options + [poUsePipes,poStderrToOutPut];
21.        Memo1.Lines.Clear;
22.        Memo1.Lines.Add('Trying to decode BarCode Image  ...');
23.        aProcess.Execute;
24.        while aProcess.Running do
25.        begin
26.          // make sure we have room
27.          MemStream.SetSize(BytesRead + READ_BYTES);
28.          // try reading it
29.          NumBytes := aProcess.Output.Read((MemStream.Memory + BytesRead)^, READ_BYTES);
30.          if NumBytes > 0 // All read() calls will block, except the final one.
31.             then Inc(BytesRead, NumBytes)
32.          else
33.             BREAK // Program has finished execution.
34.        end;
35.        MemStream.SetSize(BytesRead);
36.        Lines.LoadFromStream(MemStream);
37.        Memo1.lines.AddStrings(Lines);
38.        aProcess.Free;
39.        Lines.Free;
40.        MemStream.Free;
41.     end;      

Friendly, JP

[makgab]

Thanks! the opencv camera capture works. I need to solve the qr code recognize.
I use the zbarimg as you showed it.

But I would like to recognize the qr code with nice solution (without any external app). (ZXingDelphi using?)

[makgab]

I found the ZXing for Lazarus: https://github.com/MichaelDemidov/DelphiZXingQRCodeEx

The sample works.But does it has encoding function only?
How can I decode a string from an image (TImage)?

The LazBarcode is very good too! Bit it can generate QR Code.   It cannot read/scan QR Code...

[LacaK]

IIRC there are any C libraries ...
May be do pascal port will be not so complicated (I did port of QRencode library, but it is encode only solution)
But I am not sure if there will not be needed any preprocesing of image.
(remove noise etc.)

[makgab]

I don't know the QR code structure. So it is not easy for me.

[makgab]

I found the port of zbarimg: http://blog.freehand.com.ua/2013/03/zbar-reading-bar-codes-in-delphi.html
Original source: http://www.freehand.com.ua/Projects/ZBar/Project.zip

I tried to compile it under Lazarus (win32) and it was success, but at run time it has access violation at line:
zbarimg_.lpr:

    processor := zbar_processor_create(0);

What is wrong?

(Lazarus source is attached. The dlls are near zbarimg_.exe locally.)

[Jurassic Pork]

hello,
you need to add mode delphi directive in your source code because it come from delphi

in the zbarimg_.lpr file :

Code: Pascal  [Select][+][-]

1. program zbarimg_;
2. {$mode delphi}{$H+}
3. {$APPTYPE CONSOLE}
4. {$R *.res}
5. uses
6.   SysUtils,
7.   ZBar in 'lib/ZBar.pas',
8. //  magick_wand in 'lib/ImageMagick/wand/magick_wand.pas', magick wand and imagemagick units
9. //  ImageMagick in 'lib/ImageMagick/magick/ImageMagick.pas'; are included in lazarus
10.     magick_wand,ImageMagick;    

in the zbar.pas file :

Code: Pascal  [Select][+][-]

1. unit zbar;
2. {$mode delphi}{$H+}
3. interface
4. {$MINENUMSIZE 4}
5. uses
6.   Windows, SysUtils, Classes {, dbc, DLL96V1, DLLSP96};  

you need to have also imagemagick and libzbar installed in your system or put all the dll of those libraries in your project folder (see zbar_files attachment)

with the qr_code_example , i get qr_code_result (see attachments)

OK with Lazarus 1.6 Windows 32 bits  , Libzbar 0.10 , ImageMagick 6.9.3-7-Q8-x86

there is a bug to be corrected :  image is scanned twice.

Friendly, J.P

[makgab]

I have still same error: acces violation... 
I downloaded it: http://www.imagemagick.org/download/binaries/ImageMagick-6.9.3-7-Q8-x86-dll.exe
...and installed it and copy the dlls to project folder.
I modified the zbarimg_.lpr and zbar.pas files.

Do you take a look at my attached files?

[jma_sp]

http://www.thonky.com/qr-code-tutorial/format-version-information