DPX Viewer using QLabel

#include <QtGui>
#include "dpx.h"
#include <iostream>

#define UINT_10_TO_8(val) \
(int)(((float)(val & 0x3FF) * (float)(0xFF)) / (float)(0x3FF))

#define DPX_PIXEL_RGB   50

QLabel* LoadDPX()
{
    QString strPath = QFileDialog::getOpenFileName(NULL, "Open DPX File",
                        QDir::homePath(),
                        "*.dpx",
                        NULL, 0);
    if (strPath.isEmpty())
        return NULL;

    DPXHeader hdr;
    DPXImageHeader imgHdr;
    FILE* pf = fopen(strPath.toStdString().c_str(), "r");
    if (!pf)
        return NULL;
    if (!fread(&hdr, sizeof(hdr), 1, pf))
    {
        std::cerr << "Unable to read DPXHeader\n";
        fclose(pf);
        return NULL;
    }
    if (!fread(&imgHdr, sizeof(imgHdr), 1, pf))
    {
        std::cerr << "Unable to read DPXImageHeader\n";
        fclose(pf);
        return NULL;
    }

    // assume 10-bit image
    if (imgHdr.img_element[0].bit_size != 10)
    {
        std::cerr << "Only supports 10-bit DPX\n";
        fclose(pf);
        return NULL;
    }
    // and has RGB interleaved format
    if (imgHdr.img_element[0].descriptor != DPX_PIXEL_RGB)
    {
        std::cerr << "Has to be RGB Interleaved (desciptor == "
            << (int)imgHdr.img_element[0].descriptor << ")\n";
        fclose(pf);
        return NULL;
    }

    int nCount = imgHdr.img_width * imgHdr.img_height;
    size_t read_size = nCount * sizeof(uint32_t);

    QImage* pImg = new QImage(imgHdr.img_width,
                imgHdr.img_height,
                QImage::Format_RGB32);

    // Jump to the right place
    fseek(pf, hdr.image_offset, SEEK_SET);

    if (!fread(pImg->bits(), sizeof(uint32_t), read_size, pf))
    {
        std::cerr << "Unable to read image data\n";
        delete pImg;
        fclose(pf);
        return NULL;
    }

    // now, align the bits properly...
    uint32_t* pData32 = (uint32_t*)pImg->bits();
    uint32_t val32;
    for (int i = 0; i < nCount; i++)
    {
        val32 = *pData32;
        if (imgHdr.img_element[0].packing == 1)
        {
            // 10-bit DPX packed using METHOD A
            // 2 bits padding in least significant bits
            // get rid of this bits
            val32 >>= 2;
        }
        *pData32++ = UINT_10_TO_8(val32) | (UINT_10_TO_8(val32>>10)<<8) |
            (UINT_10_TO_8(val32>>20)<<16) | (0xFF<<24);
    }

    QLabel* pResult = new QLabel;
    pResult->setPixmap(QPixmap::fromImage(*pImg));
    return pResult;
}

int main(int argc, char** argv)
{
    QApplication app(argc, argv);
    QLabel* label = LoadDPX();
    if (!label)
        return 0;
    label->show();
    return app.exec();
}