Receiving raw image data through TCP for display using Qt

[yeye_olive]

What value does QImage::byteCount() return? Scanlines must be 32-bit aligned, which generally introduces some padding; though there shouldn't be any if your image is 8 pixels wide and 8 bits deep.

By the way, you do not need to go through a temporary buffer. Just read into QImage::bits() directly.

[benz6699]

What value does QImage::byteCount() return? Scanlines must be 32-bit aligned, which generally introduces some padding; though there shouldn't be any if your image is 8 pixels wide and 8 bits deep.

By the way, you do not need to go through a temporary buffer. Just read into QImage::bits() directly.

QImage::byteCount() return the value I expect which is 80 (I "ask" the sensor to send me 8 x 10 x1 byte image). So what else can I check more?

Can you show me the code of how to read data directly into QImage::bits()? Thanks.

[yeye_olive]

QImage::byteCount() return the value I expect which is 80 (I "ask" the sensor to send me 8 x 10 x1 byte image). So what else can I check more?

Could you post a minimal complete example reproducing the problem?

Can you show me the code of how to read data directly into QImage::bits()? Thanks.

Sure, something like: result = my_qiodevice_ptr->read(my_qimage.bits() + number_of_bytes_already_read, my_qimage.byteCount() - number_of_bytes_already_read);

[benz6699]

Could you post a minimal complete example reproducing the problem?

#include "client.h"
#include <QHostAddress>
#include "mainwindow.h"
#include <QtGui>
#include <QAbstractSocket>
#include <QImage>
 
Client::Client(QWidget *parent) :
    QWidget(parent)
{
    socket = new QTcpSocket(this);  
    connect(socket, SIGNAL(readyRead()),this, SLOT(tcpReady()) );
}
 
int Client::capture(int mode, int NBRLine)
{
    if (socket->state() != QTcpSocket::ConnectedState)
    {
        socket->connectToHost("192.168.0.65", 1096);
    }
    /* send command to retrieve raw image data from sensor */
    if(socket->waitForConnected(5000))
    {
        QByteArray block;
        QDataStream out(&block, QIODevice::WriteOnly);
        out.setVersion(QDataStream::Qt_4_0);
        out.setByteOrder(QDataStream::LittleEndian);
        //out << qint32(0) << qint32(0) << qint32(0) << qint32(1);
        out << qint32(9) << qint32(1) << qint32(0) << mode << qint32(10) << qint32(2) << qint32(0) << NBRLine ;
        socket->write(block);
        socket->flush();
    }
    else
    {
        return false;
    }
}
 
 
int Client::tcpReady()
{
    QDataStream input(socket);
    input.setVersion(QDataStream::Qt_4_0);
    input.setByteOrder(QDataStream::LittleEndian);
    qint32 cmdID, counter, metaSize, CmdNbr, min, max, value, error, width, height;
    QByteArray buffer;
 
    int sizereceived = 0;
    int sizeAvailable = 0;
 
    forever{
        if (socket->bytesAvailable() < sizeof(qint32))
        {
            return 0;
        }
        input >> cmdID;
        // We get the data response with cmdID = 100 when we send a command to get parameter value
        if (cmdID == 100)
        {
            input >> counter >> metaSize >> CmdNbr >> min >>  max >> value;
        }
        // We get the data response with cmdID = 101 when we send a command to set parameter value
        else if (cmdID == 101)
        {
            input >> counter >> metaSize >> CmdNbr >> error;
        }
        // Here we get a streaming raw image data
        else if (cmdID == 1)
        {
            break;
        }
        else
        {
            return 0;
        }
    }
 
    // Here we read the data and construct image
    input >> counter >> metaSize >> width >> height; 
    int pixel = width * height;
    char *temp = new char[pixel];
    //char *temp = 0;
    int read = input.readRawData(temp, pixel);
    buffer.append(temp, pixel);
    QImage image = QImage(width, height, QImage::Format_Indexed8);
    delete [] temp;
 
    int m_index = 0;
    for (int i = 0; i < (pixel-1); ++i, ++m_index)
    {
        image.bits()[m_index] = buffer[i];
    }
    int cnt = image.byteCount();
    bool gray =  image.isGrayscale();
 
   if( !image.isNull() )
   {
      int result = image.save("E:/temp1.png", "PNG",1);
   }
    return 1;
}

#include "client.h"
#include <QHostAddress>
#include "mainwindow.h"
#include <QtGui>
#include <QAbstractSocket>
#include <QImage>

Client::Client(QWidget *parent) :
    QWidget(parent)
{
    socket = new QTcpSocket(this);  
    connect(socket, SIGNAL(readyRead()),this, SLOT(tcpReady()) );
}

int Client::capture(int mode, int NBRLine)
{
    if (socket->state() != QTcpSocket::ConnectedState)
    {
        socket->connectToHost("192.168.0.65", 1096);
    }
    /* send command to retrieve raw image data from sensor */
    if(socket->waitForConnected(5000))
    {
        QByteArray block;
        QDataStream out(&block, QIODevice::WriteOnly);
        out.setVersion(QDataStream::Qt_4_0);
        out.setByteOrder(QDataStream::LittleEndian);
        //out << qint32(0) << qint32(0) << qint32(0) << qint32(1);
        out << qint32(9) << qint32(1) << qint32(0) << mode << qint32(10) << qint32(2) << qint32(0) << NBRLine ;
        socket->write(block);
        socket->flush();
    }
    else
    {
        return false;
    }
}


int Client::tcpReady()
{
    QDataStream input(socket);
    input.setVersion(QDataStream::Qt_4_0);
    input.setByteOrder(QDataStream::LittleEndian);
    qint32 cmdID, counter, metaSize, CmdNbr, min, max, value, error, width, height;
    QByteArray buffer;

    int sizereceived = 0;
    int sizeAvailable = 0;

    forever{
        if (socket->bytesAvailable() < sizeof(qint32))
        {
            return 0;
        }
        input >> cmdID;
        // We get the data response with cmdID = 100 when we send a command to get parameter value
        if (cmdID == 100)
        {
            input >> counter >> metaSize >> CmdNbr >> min >>  max >> value;
        }
        // We get the data response with cmdID = 101 when we send a command to set parameter value
        else if (cmdID == 101)
        {
            input >> counter >> metaSize >> CmdNbr >> error;
        }
        // Here we get a streaming raw image data
        else if (cmdID == 1)
        {
            break;
        }
        else
        {
            return 0;
        }
    }

    // Here we read the data and construct image
    input >> counter >> metaSize >> width >> height; 
    int pixel = width * height;
    char *temp = new char[pixel];
    //char *temp = 0;
    int read = input.readRawData(temp, pixel);
    buffer.append(temp, pixel);
    QImage image = QImage(width, height, QImage::Format_Indexed8);
    delete [] temp;

    int m_index = 0;
    for (int i = 0; i < (pixel-1); ++i, ++m_index)
    {
        image.bits()[m_index] = buffer[i];
    }
    int cnt = image.byteCount();
    bool gray =  image.isGrayscale();

   if( !image.isNull() )
   {
      int result = image.save("E:/temp1.png", "PNG",1);
   }
    return 1;
}

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Sure, something like: result = my_qiodevice_ptr->read(my_qimage.bits() + number_of_bytes_already_read, my_qimage.byteCount() - number_of_bytes_already_read);

I tried the following code, but it give me the error message" :-1: error: C2664: 'qint64 QIODevice::read(char *,qint64)' : cannot convert parameter 1 from 'uchar *' to 'char *' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast."

input >> counter >> metaSize >> width >> height; 
int pixel = width * height;
 
QImage image = QImage(width, height, QImage::Format_Indexed8);
socket->read(image.bits(), pixel);

input >> counter >> metaSize >> width >> height; 
int pixel = width * height;

QImage image = QImage(width, height, QImage::Format_Indexed8);
socket->read(image.bits(), pixel);

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