With C++ and Qt how do I display a 16-bit raw file as an image?

Question

I am looking to display heightmaps from the video game Battlefield 2 as images in my application.
I am new to C++ and Qt and it might be straight forward but what I am having trouble with is displaying a grayscale 16-bit 1025x1025 2101250 bytes image. There is no header to the file. I need access to the displayed pixels (does not have to be pixel perfect precision) so I can point to a pixel and get its value.

What I have tried

I have loaded the binary data into a QByteArray from a QFile and I have attempted to use the QImage::fromData function to make the image but I am making a lot of mistakes and spending a lot of time not getting very far. It is my hope that posting here will give me the clue(s) that I need to progress. Here is my code:

void LearningBinaryReader::setupReader()
{
    qDebug("Attempting to open file..");
    QFile file("HeightmapPrimary.raw");
    if (!file.open(QFile::ReadOnly))
    {
        qDebug("Could not open file");
        return;
    } else {
        qDebug() << file.fileName() << " opened";
    }
    QByteArray data = file.readAll();
    file.flush();
    file.close();

    qDebug() << data.count() << "bytes loaded.";
}

From here I am at a loss of what to do. I have read some of the Qt documentation, but I being new I need a guide in the right direction to understand this problem and get the solution.

Please note I am pretty much a beginner so don't discount easy solutions that I might not have thought of. I would like to do this just using the Qt framework.

Answer 1

Just a guess. Maybe try something like this?

#include <QColor>
...
QByteArray data=file.readAll();

// create an empty image of the right size.  We'll use 32-bit RGB for simplicity
QImage img(1025,1025, QImage::Format_RGB32);

// Access the image at low level.  From the manual, a 32-bit RGB image is just a
// vector of QRgb (which is really just some integer typedef)
QRgb *pixels=reinterpret_cast<QRgb*>(img.bits());

// Now copy our image data in.  We'll assume 16-bit LE format for the input data.
// Since we only have 8 bits of grayscale color resolution in a 32-bit RGB, we'll
// just chop off the most significant 8 bits (the second byte of each pair) and 
// make a pixel out of that.  If this doesn't work, our assumption might be off --
// perhaps assume 16-bit BE format.  In that case we'd want the first byte of each
// pair.
for (size_t i=0;2*i<data.size();++i)
{
    uchar pixel_msb=data[2*i+1]; // or maybe try =data[2*i+0]
    pixels[i]=qRgb(pixel_msb, pixel_msb, pixel_msb);
}

// (do something with the resulting 'img')

edit: oops, QImage::Format_RGB32 instead of QImage::Format_RGB