hdr.cpp

/*
    This file is part of the KDE project
    SPDX-FileCopyrightText: 2005 Christoph Hormann <chris_hormann@gmx.de>
    SPDX-FileCopyrightText: 2005 Ignacio Castaño <castanyo@yahoo.es>
 
    SPDX-License-Identifier: LGPL-2.0-or-later
*/
 
#include "hdr_p.h"
#include "util_p.h"
 
#include <QColorSpace>
#include <QDataStream>
#include <QFloat16>
#include <QImage>
#include <QLoggingCategory>
#include <QRegularExpressionMatch>
 
#include <QDebug>
 
/* *** HDR_HALF_QUALITY ***
 * If defined, a 16-bits float image is created, otherwise a 32-bits float ones (default).
 */
//#define HDR_HALF_QUALITY // default commented -> you should define it in your cmake file
 
typedef unsigned char uchar;
 
Q_LOGGING_CATEGORY(HDRPLUGIN, "kf.imageformats.plugins.hdr", QtWarningMsg)
 
namespace // Private.
{
#define MAXLINE 1024
#define MINELEN 8 // minimum scanline length for encoding
#define MAXELEN 0x7fff // maximum scanline length for encoding
 
// read an old style line from the hdr image file
// if 'first' is true the first byte is already read
static bool Read_Old_Line(uchar *image, int width, QDataStream &s)
{
    int rshift = 0;
    int i;
 
    uchar *start = image;
    while (width > 0) {
        s >> image[0];
        s >> image[1];
        s >> image[2];
        s >> image[3];
 
        if (s.atEnd()) {
            return false;
        }
 
        if ((image[0] == 1) && (image[1] == 1) && (image[2] == 1)) {
            // NOTE: we don't have an image sample that cover this code
            if (rshift > 31) {
                return false;
            }
            for (i = image[3] << rshift; i > 0 && width > 0; i--) {
                if (image == start) {
                    return false; // you cannot be here at the first run
                }
                // memcpy(image, image-4, 4);
                (uint &)image[0] = (uint &)image[0 - 4];
                image += 4;
                width--;
            }
            rshift += 8;
        } else {
            image += 4;
            width--;
            rshift = 0;
        }
    }
    return true;
}
 
template<class float_T>
void RGBE_To_QRgbLine(uchar *image, float_T *scanline, int width)
{
    for (int j = 0; j < width; j++) {
        // v = ldexp(1.0, int(image[3]) - 128);
        float v;
        int e = qBound(-31, int(image[3]) - 128, 31);
        if (e > 0) {
            v = float(1 << e);
        } else {
            v = 1.0f / float(1 << -e);
        }
 
        auto j4 = j * 4;
        auto vn = v / 255.0f;
        scanline[j4] = float_T(std::min(float(image[0]) * vn, 1.0f));
        scanline[j4 + 1] = float_T(std::min(float(image[1]) * vn, 1.0f));
        scanline[j4 + 2] = float_T(std::min(float(image[2]) * vn, 1.0f));
        scanline[j4 + 3] = float_T(1.0f);
        image += 4;
    }
}
 
QImage::Format imageFormat()
{
#ifdef HDR_HALF_QUALITY
    return QImage::Format_RGBX16FPx4;
#else
    return QImage::Format_RGBX32FPx4;
#endif
}
 
// Load the HDR image.
static bool LoadHDR(QDataStream &s, const int width, const int height, QImage &img)
{
    uchar val;
    uchar code;
 
    // Create dst image.
    img = imageAlloc(width, height, imageFormat());
    if (img.isNull()) {
        qCDebug(HDRPLUGIN) << "Couldn't create image with size" << width << height << "and format RGB32";
        return false;
    }
 
    QByteArray lineArray;
    lineArray.resize(4 * width);
    uchar *image = reinterpret_cast<uchar *>(lineArray.data());
 
    for (int cline = 0; cline < height; cline++) {
#ifdef HDR_HALF_QUALITY
        auto scanline = reinterpret_cast<qfloat16 *>(img.scanLine(cline));
#else
        auto scanline = reinterpret_cast<float *>(img.scanLine(cline));
#endif
 
        // determine scanline type
        if ((width < MINELEN) || (MAXELEN < width)) {
            Read_Old_Line(image, width, s);
            RGBE_To_QRgbLine(image, scanline, width);
            continue;
        }
 
        s >> val;
 
        if (s.atEnd()) {
            return true;
        }
 
        if (val != 2) {
            s.device()->ungetChar(val);
            Read_Old_Line(image, width, s);
            RGBE_To_QRgbLine(image, scanline, width);
            continue;
        }
 
        s >> image[1];
        s >> image[2];
        s >> image[3];
 
        if (s.atEnd()) {
            return true;
        }
 
        if ((image[1] != 2) || (image[2] & 128)) {
            image[0] = 2;
            Read_Old_Line(image + 4, width - 1, s);
            RGBE_To_QRgbLine(image, scanline, width);
            continue;
        }
 
        if ((image[2] << 8 | image[3]) != width) {
            qCDebug(HDRPLUGIN) << "Line of pixels had width" << (image[2] << 8 | image[3]) << "instead of" << width;
            return false;
        }
 
        // read each component
        for (int i = 0, len = int(lineArray.size()); i < 4; i++) {
            for (int j = 0; j < width;) {
                s >> code;
                if (s.atEnd()) {
                    qCDebug(HDRPLUGIN) << "Truncated HDR file";
                    return false;
                }
                if (code > 128) {
                    // run
                    code &= 127;
                    s >> val;
                    while (code != 0) {
                        auto idx = i + j * 4;
                        if (idx < len) {
                            image[idx] = val;
                        }
                        j++;
                        code--;
                    }
                } else {
                    // non-run
                    while (code != 0) {
                        auto idx = i + j * 4;
                        if (idx < len) {
                            s >> image[idx];
                        }
                        j++;
                        code--;
                    }
                }
            }
        }
 
        RGBE_To_QRgbLine(image, scanline, width);
    }
 
    return true;
}
 
static QSize readHeaderSize(QIODevice *device)
{
    int len;
    QByteArray line(MAXLINE + 1, Qt::Uninitialized);
    QByteArray format;
 
    // Parse header
    do {
        len = device->readLine(line.data(), MAXLINE);
 
        if (line.startsWith("FORMAT=")) {
            format = line.mid(7, len - 7 - 1 /*\n*/);
        }
 
    } while ((len > 0) && (line[0] != '\n'));
 
    if (format != "32-bit_rle_rgbe") {
        qCDebug(HDRPLUGIN) << "Unknown HDR format:" << format;
        return QSize();
    }
 
    len = device->readLine(line.data(), MAXLINE);
    line.resize(len);
 
    /*
       TODO: handle flipping and rotation, as per the spec below
       The single resolution line consists of 4 values, a X and Y label each followed by a numerical
       integer value. The X and Y are immediately preceded by a sign which can be used to indicate
       flipping, the order of the X and Y indicate rotation. The standard coordinate system for
       Radiance images would have the following resolution string -Y N +X N. This indicates that the
       vertical axis runs down the file and the X axis is to the right (imagining the image as a
       rectangular block of data). A -X would indicate a horizontal flip of the image. A +Y would
       indicate a vertical flip. If the X value appears before the Y value then that indicates that
       the image is stored in column order rather than row order, that is, it is rotated by 90 degrees.
       The reader can convince themselves that the 8 combinations cover all the possible image orientations
       and rotations.
    */
    QRegularExpression resolutionRegExp(QStringLiteral("([+\\-][XY]) ([0-9]+) ([+\\-][XY]) ([0-9]+)\n"));
    QRegularExpressionMatch match = resolutionRegExp.match(QString::fromLatin1(line));
    if (!match.hasMatch()) {
        qCDebug(HDRPLUGIN) << "Invalid HDR file, the first line after the header didn't have the expected format:" << line;
        return QSize();
    }
 
    if ((match.captured(1).at(1) != u'Y') || (match.captured(3).at(1) != u'X')) {
        qCDebug(HDRPLUGIN) << "Unsupported image orientation in HDR file.";
        return QSize();
    }
 
    return QSize(match.captured(4).toInt(), match.captured(2).toInt());
}
 
} // namespace
 
bool HDRHandler::read(QImage *outImage)
{
    QDataStream s(device());
 
    QSize size = readHeaderSize(s.device());
    if (!size.isValid()) {
        return false;
    }
 
    QImage img;
    if (!LoadHDR(s, size.width(), size.height(), img)) {
        // qDebug() << "Error loading HDR file.";
        return false;
    }
    // The images read by Gimp and Photoshop (including those of the tests) are interpreted with linear color space.
    // By setting the linear color space, programs that support profiles display HDR files as in GIMP and Photoshop.
    img.setColorSpace(QColorSpace(QColorSpace::SRgbLinear));
 
    *outImage = img;
    return true;
}
 
bool HDRHandler::supportsOption(ImageOption option) const
{
    if (option == QImageIOHandler::Size) {
        return true;
    }
    if (option == QImageIOHandler::ImageFormat) {
        return true;
    }
    return false;
}
 
QVariant HDRHandler::option(ImageOption option) const
{
    QVariant v;
 
    if (option == QImageIOHandler::Size) {
        if (auto d = device()) {
            // transactions works on both random and sequential devices
            d->startTransaction();
            auto size = readHeaderSize(d);
            d->rollbackTransaction();
            if (size.isValid()) {
                v = QVariant::fromValue(size);
            }
        }
    }
 
    if (option == QImageIOHandler::ImageFormat) {
        v = QVariant::fromValue(imageFormat());
    }
 
    return v;
}
 
HDRHandler::HDRHandler()
{
}
 
bool HDRHandler::canRead() const
{
    if (canRead(device())) {
        setFormat("hdr");
        return true;
    }
    return false;
}
 
bool HDRHandler::canRead(QIODevice *device)
{
    if (!device) {
        qWarning("HDRHandler::canRead() called with no device");
        return false;
    }
 
    // the .pic taken from official test cases does not start with this string but can be loaded.
    if(device->peek(11) == "#?RADIANCE\n" || device->peek(7) == "#?RGBE\n") {
        return true;
    }
 
    // allow to load offical test cases: https://radsite.lbl.gov/radiance/framed.html
    device->startTransaction();
    QSize size = readHeaderSize(device);
    device->rollbackTransaction();
    if (size.isValid()) {
        return true;
    }
 
    return false;
}
 
QImageIOPlugin::Capabilities HDRPlugin::capabilities(QIODevice *device, const QByteArray &format) const
{
    if (format == "hdr") {
        return Capabilities(CanRead);
    }
    if (!format.isEmpty()) {
        return {};
    }
    if (!device->isOpen()) {
        return {};
    }
 
    Capabilities cap;
    if (device->isReadable() && HDRHandler::canRead(device)) {
        cap |= CanRead;
    }
    return cap;
}
 
QImageIOHandler *HDRPlugin::create(QIODevice *device, const QByteArray &format) const
{
    QImageIOHandler *handler = new HDRHandler;
    handler->setDevice(device);
    handler->setFormat(format);
    return handler;
}
 
#include "moc_hdr_p.cpp"