Image transfer using QTcpsocket

anmol2701

Can anybody guide how to transfer image over QTcpsocket.

anmol2701

Hello Experts!
I am able to send image using below method:

 QByteArray read ;
 inputFile.open(QIODevice::ReadOnly);
 while(1)
 {
     read.clear();
     read = inputFile.read(inputFile.size());
     qDebug() << "Read : " << read.size();
     if(read.size()==0)
          break;
     qDebug() << "Written : " << socket->write(read);
     socket->waitForBytesWritten();
     read.clear();
 }

But how to read data of image on client side and save the image??

p3c0

@anmol2701 Well once you receive data chunks on client side, store it in a QByteArray. Once you receive all the data you can use QImage::fromData to get the image.

anmol2701

@p3c0 Thanks for reply

I am able receive data on client side and i am trying save image as as image format(png or jpg) using following code but after writing ,file is empty.

QString fileName = QFileDialog::getSaveFileName(0,"Save file",QDir::currentPath(),
"Image files (.PNG);;Text files (.txt);;All files (.)",
new QString("Image files (*.PNG)"));
if (!fileName.isEmpty())
{
QFile file(fileName);
if (!file.open(QIODevice::WriteOnly))
{
QImage img(2048,1024,QImage::Format_Indexed8);
img = QImage::fromData(data,"PNG");
}

p3c0

@anmol2701 You don't need QFile to write QImage to the file. Use QImage::save to save the image. To check if it is valid use isNull.
Have you made sure all the data is received on the client side ?

anmol2701

Now I am sending image using following code:

  imageObject = new QImage();
    imageObject->load(imagePath);
    image = QPixmap::fromImage(*imageObject);

    QByteArray ba;              // Construct a QByteArray object
    QBuffer buffer(&ba);        // Construct a QBuffer object using the QbyteArray
    image.save(&buffer, "PNG"); // Save the QImage data into the QBuffer
    socket->write(ba);

Receive all the data on client side, but the saved image is blurred.

p3c0

@anmol2701 If the data received on client side is exactly same on sender side then there should be no problem. Are you sure image that is being send is not blurred ? Or the image that you are loading is of other format and you are saving it as png ?

anmol2701

image sending and saving is png format.
Plz share
Any documentation or link for more details??

p3c0

@anmol2701 I still doubt that some bytes are still missing on client side. How did you check that ?

anmol2701

I was checking qDebug() << "Written : " << socket->write(ba);
or qdeqint64 W_Length = file.readLine(buffer, sizeof(buffer));
On client side qint64 R_bytes = buffer->write(socket->readAll());

p3c0

@anmol2701 So are they equal ?
On sender side you have the image i.e you can check its size in bytes manually and on the client side check the size of the whole bytearray from which you construct the image. They should match exactly.

anmol2701

This post is deleted!

anmol2701

@p3c0 Hi!

Now I am saving image using
image_rcv.loadFromData(test);

It gives error: libpng error: PNG unsigned integer out of range.
Any Suggestion??

p3c0

@anmol2701 Are you now receiving all the data ? I see in your earlier post that you are sending 560 bytes and receiving 533 bytes on client side.

anmol2701

Yes,

Now I am receiving all the data in case of png file.

p3c0

@anmol2701 That error is from libpng. It is not able to reconstruct the image from the data. I guess the data is mismatched.

anmol2701

Hi!

I am able construct image.
Now the problem is with large size of images.

I am following this approach:

while (buffer->canReadLine())
{
QByteArray data_r = buffer->readLine();
image_r.append(data_r);
}
Then create image from Qbytearray image_r.
Any suggestion?

p3c0

@anmol2701 If your earlier logic works perfectly then it should work for all files.
Anyway you can also look at serialization. Qt has provision to serialize some of the Qt data types. QDataStream can be used here to transferQImage directly. Have a look at fortuneserver and fortuneclient example. Try doing similar for QImage.