PFM: Portable FloatMap read only support

Simple HDR format supported by GIMP (read/write) and Photoshop (read/write).

README.md

@@ -19,6 +19,7 @@ The following image formats have read-only support:
 - Krita (kra)
 - OpenRaster (ora)
 - Pixar raster (pxr)
+- Portable FloatMap (pfm)
 - Photoshop documents (psd, psb, pdd, psdt)
 - Radiance HDR (hdr)
 - Sun Raster (im1, im8, im24, im32, ras, sun)

autotests/CMakeLists.txt

@@ -66,6 +66,7 @@ endmacro()
 kimageformats_read_tests(
     hdr
     pcx
+    pfm
     psd
     pxr
     qoi

src/imageformats/CMakeLists.txt

@@ -83,6 +83,10 @@ kimageformats_add_plugin(kimg_pic SOURCES pic.cpp)
 
 ##################################
 
+kimageformats_add_plugin(kimg_pfm SOURCES pfm.cpp)
+
+##################################
+
 kimageformats_add_plugin(kimg_psd SOURCES psd.cpp scanlineconverter.cpp)
 
 ##################################

src/imageformats/pfm.cpp

@@ -0,0 +1,324 @@
+/*
+    This file is part of the KDE project
+    SPDX-FileCopyrightText: 2024 Mirco Miranda <mircomir@outlook.com>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+/*
+ * See also: https://www.pauldebevec.com/Research/HDR/PFM/
+ */
+
+#include "pfm_p.h"
+#include "util_p.h"
+
+#include <QColorSpace>
+#include <QDataStream>
+#include <QIODevice>
+#include <QImage>
+#include <QLoggingCategory>
+
+Q_DECLARE_LOGGING_CATEGORY(LOG_PFMPLUGIN)
+Q_LOGGING_CATEGORY(LOG_PFMPLUGIN, "kf.imageformats.plugins.pfm", QtWarningMsg)
+
+class PfmHeader
+{
+private:
+    /*!
+     * \brief m_bw True if grayscale.
+     */
+    bool m_bw;
+
+    /*!
+     * \brief m_ps True if saved by Photoshop (Photoshop variant).
+     *
+     * When \a false the format of the header is the following (GIMP):
+     * [type]
+     * [xres] [yres]
+     * [byte_order]
+     *
+     * When \a true the format of the header is the following (Photoshop):
+     * [type]
+     * [xres]
+     * [yres]
+     * [byte_order]
+     */
+    bool m_ps;
+
+    /*!
+     * \brief m_width The image width.
+     */
+    qint32 m_width;
+
+    /*!
+     * \brief m_height The image height.
+     */
+    qint32 m_height;
+
+    /*!
+     * \brief m_byteOrder The image byte orger.
+     */
+    QDataStream::ByteOrder m_byteOrder;
+
+public:
+    PfmHeader() :
+        m_bw(false),
+        m_ps(false),
+        m_width(0),
+        m_height(0),
+        m_byteOrder(QDataStream::BigEndian)
+    {
+
+    }
+
+    bool isValid() const
+    {
+        return (m_width > 0 && m_height > 0);
+    }
+
+    bool isBlackAndWhite() const
+    {
+        return m_bw;
+    }
+
+    bool isPhotoshop() const
+    {
+        return m_ps;
+    }
+
+    qint32 width() const
+    {
+        return m_width;
+    }
+
+    qint32 height() const
+    {
+        return m_height;
+    }
+
+    QSize size() const
+    {
+        return QSize(m_width, m_height);
+    }
+
+    QDataStream::ByteOrder byteOrder() const
+    {
+        return m_byteOrder;
+    }
+
+    QImage::Format format() const
+    {
+        if (isValid()) {
+            return isBlackAndWhite() ? QImage::Format_Grayscale16 : QImage::Format_RGBX32FPx4;
+        }
+        return QImage::Format_Invalid;
+    }
+
+    bool read(QIODevice *d)
+    {
+        auto pf = d->read(3);
+        if (pf == QByteArray("PF\n")) {
+            m_bw = false;
+        } else if (pf == QByteArray("Pf\n")) {
+            m_bw = true;
+        } else {
+            return false;
+        }
+        auto wh = QString::fromLatin1(d->readLine(128));
+        auto list = wh.split(QStringLiteral(" "));
+        if (list.size() == 1) {
+            m_ps = true; // try for Photoshop version
+            list << QString::fromLatin1(d->readLine(128));
+        }
+        if (list.size() != 2) {
+            return false;
+        }
+        auto ok_o = false;
+        auto ok_w = false;
+        auto ok_h = false;
+        auto o = QString::fromLatin1(d->readLine(128)).toDouble(&ok_o);
+        auto w = list.first().toInt(&ok_w);
+        auto h = list.last().toInt(&ok_h);
+        if (!ok_o || !ok_w || !ok_h || o == 0) {
+            return false;
+        }
+        m_width = w;
+        m_height = h;
+        m_byteOrder = o > 0 ? QDataStream::BigEndian : QDataStream::LittleEndian;
+        return isValid();
+    }
+
+    bool peek(QIODevice *d)
+    {
+        d->startTransaction();
+        auto ok = read(d);
+        d->rollbackTransaction();
+        return ok;
+    }
+} ;
+
+PFMHandler::PFMHandler()
+{
+}
+
+bool PFMHandler::canRead() const
+{
+    if (canRead(device())) {
+        setFormat("pfm");
+        return true;
+    }
+    return false;
+}
+
+bool PFMHandler::canRead(QIODevice *device)
+{
+    if (!device) {
+        qCWarning(LOG_PFMPLUGIN) << "PFMHandler::canRead() called with no device";
+        return false;
+    }
+
+    PfmHeader h;
+    if (!h.peek(device)) {
+        return false;
+    }
+
+    return h.isValid();
+}
+
+bool PFMHandler::read(QImage *image)
+{
+    PfmHeader header;
+
+    if (!header.read(device())) {
+        qCWarning(LOG_PFMPLUGIN) << "PFMHandler::read() invalid header";
+        return false;
+    }
+
+    QDataStream s(device());
+    s.setFloatingPointPrecision(QDataStream::SinglePrecision);
+    s.setByteOrder(header.byteOrder());
+
+    auto img = imageAlloc(header.size(), header.format());
+    if (img.isNull()) {
+        qCWarning(LOG_PFMPLUGIN) << "PFMHandler::read() error while allocating the image";
+        return false;
+    }
+
+    for (auto y = 0, h = img.height(); y < h; ++y) {
+        float f;
+        if (header.isBlackAndWhite()) {
+            auto line = reinterpret_cast<quint16*>(img.scanLine(header.isPhotoshop() ? y : h - y - 1));
+            for (auto x = 0, w = img.width(); x < w; ++x) {
+                s >> f;
+                // QColorSpace does not handle gray linear profile, so I have to convert to non-linear
+                f = f < 0.0031308f ? (f * 12.92f) : (1.055 * std::pow(f, 1.0 / 2.4) - 0.055);
+                line[x] = quint16(std::clamp(f, float(0), float(1)) * std::numeric_limits<quint16>::max() + float(0.5));
+
+                if (s.status() != QDataStream::Ok) {
+                    qCWarning(LOG_PFMPLUGIN) << "PFMHandler::read() detected corrupted data";
+                    return false;
+                }
+            }
+        } else {
+            auto line = reinterpret_cast<float*>(img.scanLine(header.isPhotoshop() ? y : h - y - 1));
+            for (auto x = 0, n = img.width() * 4; x < n; x += 4) {
+                s >> f;
+                line[x] = std::clamp(f, float(0), float(1));
+                s >> f;
+                line[x + 1] = std::clamp(f, float(0), float(1));
+                s >> f;
+                line[x + 2] = std::clamp(f, float(0), float(1));
+                line[x + 3] = float(1);
+
+                if (s.status() != QDataStream::Ok) {
+                    qCWarning(LOG_PFMPLUGIN) << "PFMHandler::read() detected corrupted data";
+                    return false;
+                }
+            }
+        }
+    }
+
+    if (!header.isBlackAndWhite()) {
+        img.setColorSpace(QColorSpace(QColorSpace::SRgbLinear));
+    }
+
+    *image = img;
+    return true;
+}
+
+bool PFMHandler::supportsOption(ImageOption option) const
+{
+    if (option == QImageIOHandler::Size) {
+        return true;
+    }
+    if (option == QImageIOHandler::ImageFormat) {
+        return true;
+    }
+    if (option == QImageIOHandler::Endianness) {
+        return true;
+    }
+    return false;
+}
+
+QVariant PFMHandler::option(ImageOption option) const
+{
+    QVariant v;
+
+    if (option == QImageIOHandler::Size) {
+        if (auto d = device()) {
+            PfmHeader h;
+            if (h.peek(d)) {
+                v = QVariant::fromValue(h.size());
+            }
+        }
+    }
+
+    if (option == QImageIOHandler::ImageFormat) {
+        if (auto d = device()) {
+            PfmHeader h;
+            if (h.peek(d)) {
+                v = QVariant::fromValue(h.format());
+            }
+        }
+    }
+
+    if (option == QImageIOHandler::Endianness) {
+        if (auto d = device()) {
+            PfmHeader h;
+            if (h.peek(d)) {
+                v = QVariant::fromValue(h.byteOrder());
+            }
+        }
+    }
+
+    return v;
+}
+
+QImageIOPlugin::Capabilities PFMPlugin::capabilities(QIODevice *device, const QByteArray &format) const
+{
+    if (format == "pfm") {
+        return Capabilities(CanRead);
+    }
+    if (!format.isEmpty()) {
+        return {};
+    }
+    if (!device->isOpen()) {
+        return {};
+    }
+
+    Capabilities cap;
+    if (device->isReadable() && PFMHandler::canRead(device)) {
+        cap |= CanRead;
+    }
+    return cap;
+}
+
+QImageIOHandler *PFMPlugin::create(QIODevice *device, const QByteArray &format) const
+{
+    QImageIOHandler *handler = new PFMHandler;
+    handler->setDevice(device);
+    handler->setFormat(format);
+    return handler;
+}
+
+#include "moc_pfm_p.cpp"

src/imageformats/pfm.json

@@ -0,0 +1,4 @@
+{
+    "Keys": [ "pfm" ],
+    "MimeTypes": [ "image/x-pfm" ]
+}

src/imageformats/pfm_p.h

@@ -0,0 +1,37 @@
+/*
+    This file is part of the KDE project
+    SPDX-FileCopyrightText: 2024 Mirco Miranda <mircomir@outlook.com>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+#ifndef KIMG_PFM_P_H
+#define KIMG_PFM_P_H
+
+#include <QImageIOPlugin>
+
+class PFMHandler : public QImageIOHandler
+{
+public:
+    PFMHandler();
+
+    bool canRead() const override;
+    bool read(QImage *image) override;
+
+    bool supportsOption(QImageIOHandler::ImageOption option) const override;
+    QVariant option(QImageIOHandler::ImageOption option) const override;
+
+    static bool canRead(QIODevice *device);
+};
+
+class PFMPlugin : public QImageIOPlugin
+{
+    Q_OBJECT
+    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QImageIOHandlerFactoryInterface" FILE "pfm.json")
+
+public:
+    Capabilities capabilities(QIODevice *device, const QByteArray &format) const override;
+    QImageIOHandler *create(QIODevice *device, const QByteArray &format = QByteArray()) const override;
+};
+
+#endif // KIMG_PFM_P_H