Read barcode from PDF document



  • Hi, I have a question. Is there a way to convert pdf to jpg?
    I need to read the images from a pdf document. I am using QZXing to read barcodes. Barcodes must be in image format (jpg, png ...)

    Thanks for the help.


  • Qt Champions 2017

    Hi
    You can use command lines tools to do it.
    https://gist.github.com/yura/670974



  • Ok. But I want do this in my application. Your solution working on other application.



  • Hi! ImageMagick can convert PDF to JPEG. If you don't want to use it as a command-line tool, you can also use it as a library.


  • Qt Champions 2017

    @jacekkozik
    There is no good way to do this directly in Qt.
    You might be able to display a pdf and screen grab it but calling external cmdline program with
    QProcess will work far better.
    Or as wieland suggest using ImageMagick library.

    There is also this
    http://blog.qt.io/blog/2017/01/30/new-qtpdf-qtlabs-module/
    Says "QPdfDocument can render a PDF page to a QImage"
    But i have not tried it.



  • @mrjj said in Read barcode from PDF document:

    There is also this
    http://blog.qt.io/blog/2017/01/30/new-qtpdf-qtlabs-module/
    Says "QPdfDocument can render a PDF page to a QImage"

    Awesome! \o/



  • Ok, i downloaded ImageMagick-i686-pc-mingw32.tar.gz.
    And now as I type

    convert f.pdf d.jpg
    

    f.pdf is in the same directory as convert.exe

    I get the message:

    convert.exe: UnableToOpenConfigureFile `delegates.xml' @ warning/configure.c/GetConfigureOptions/616.
    convert.exe: `%s' (%d) "gs" -q -dQUIET -dSAFER -dBATCH -dNOPAUSE -dNOPROMPT -dMaxBitmap=500000000 -dAlignToPixels=0 -dGridFitTT=2 "-sDEVICE=pngalpha" -dTextAlphaBits=4 -dGraphicsAlphaBits=4 "-r72x72"  "-sOutputFile=C:/Users/ADMINI~1/AppData/Local/Temp/magick-21380jSugM5nyzl-T-1" "-fC:/Users/ADMINI~1/AppData/Local/Temp/magick-21380wnE6NbHjVB6v" "-fC:/Users/ADMINI~1/AppData/Local/Temp/magick-21380qrAlRMgDXCHT" @ error/utility.c/SystemCommand/2033.
    convert.exe: PostscriptDelegateFailed `f.pdf': No such file or directory @ error/pdf.c/ReadPDFImage/682.
    convert.exe: NoImagesDefined `d.jpg' @ error/convert.c/ConvertImageCommand/3106.
    


  • When working with PostScript files, ImageMagick relies on another program, "Ghostscript" for the reading and conversion of PostScript and PDF files into a image format it can use. That is to read such documents, Ghostscript needs to be installed on your computer. Its latest version can be downloaded at github.


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