WImage from bytearray

Added by Marcelo Antunes about 5 years ago

In my wt app, images are stored on postgresdb as bytea, and i'm using a "midleware" written on qt to access DB.

Here is how i convert the image from wfileupload to QBytearray to store on DB:

   QImage *image = new QImage(QString(fotoFu->spoolFileName().c_str()));
         QByteArray arr = QByteArray::fromRawData((const char*)image->bits(), image->sizeInBytes());

Here is how i try to "convert" the qbytearray to an image that i can show on a wimage:

         const unsigned char* begin = reinterpret_cast<unsigned char*>(arr.data());
         const unsigned char* end = begin + arr.length();
         std::vector<unsigned char> bufferToCompress( begin, end );

        Wt::WMemoryResource *imgDisp= new Wt::WMemoryResource("image/pjpeg", bufferToCompress);

        Wt::WPainter::Image imag(imgDisp->url(), 120, 120);

log("notice")<<"imgDisp: "<<imag->url();

The internal path of the page where is WFileUpload is:

http://192.168.0.160:8080/?_=/prod/new&wtd=5Oq7tyyB08gO7IcQ

But if i access this link (the link get from imag->url()):

http://192.168.0.160:8080/?_=/produtosservicos/novo&wtd=5Oq7tyyB08gO7IcQ&request=resource&resource=oizwb54&rand=2

The browser gives me the attatched error

regards

Marcelo

Screenshot from 2019-04-01 10-28-01.png (43.2 KB) Screenshot from 2019-04-01 10-28-01.png

Replies (3)

RE: WImage from bytearray - Added by Aziz Gokhan Narin almost 3 years ago

Hello Marcelo,

Did you achieve getting image data as byte array from WImage?

RE: WImage from bytearray - Added by Marcelo Antunes almost 3 years ago

I'm also using QT with wt and did like this:

QByteArray Image::toQByteArray(std::string path){
    std::ifstream file;
    file.open(path,std::ios_base::binary);
    if(!file.is_open())
    {
        return QByteArray();
    }
    file.seekg(0,std::ios::end);
    long fileSize = file.tellg();
    file.seekg(0,std::ios::beg);
    std::vector< char> data((ulong)fileSize,0);
    file.read((&data[0]), fileSize);
    file.close();
    std::vector< char> temp = std::vector<char>(data.begin(), data.end());
    QByteArray imag=QByteArray();
    for(uint i=0;i<temp.size();i++){
        imag.append(temp.at(i));
    }
    return imag;
}

RE: WImage from bytearray - Added by Aziz Gokhan Narin almost 3 years ago

Hello again,

Thank you Marcelo for your quick respond. However I do not use Qt in my project. I need native Wt solution.

Thank you again

Gokhan

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