Add Farbfeld read only support

src/imageformats/ff.cpp

@@ -0,0 +1,259 @@
+/*
+    This file is part of the KDE project
+    SPDX-FileCopyrightText: 2026 Mirco Miranda <mircomir@outlook.com>
+
+    SPDX-License-Identifier: LGPL-2.0-or-later
+*/
+
+// Specs: https://tools.suckless.org/farbfeld/
+
+#include "ff_p.h"
+#include "util_p.h"
+
+#include <QColorSpace>
+#include <QIODevice>
+#include <QImage>
+#include <QLoggingCategory>
+#include <QtEndian>
+
+Q_DECLARE_LOGGING_CATEGORY(LOG_FFPLUGIN)
+
+#ifdef QT_DEBUG
+Q_LOGGING_CATEGORY(LOG_FFPLUGIN, "kf.imageformats.plugins.ff", QtDebugMsg)
+#else
+Q_LOGGING_CATEGORY(LOG_FFPLUGIN, "kf.imageformats.plugins.ff", QtWarningMsg)
+#endif
+
+/* *** FF_MAX_IMAGE_WIDTH and FF_MAX_IMAGE_HEIGHT ***
+ * The maximum size in pixel allowed by the plugin.
+ */
+#ifndef FF_MAX_IMAGE_WIDTH
+#define FF_MAX_IMAGE_WIDTH KIF_LARGE_IMAGE_PIXEL_LIMIT
+#endif
+#ifndef FF_MAX_IMAGE_HEIGHT
+#define FF_MAX_IMAGE_HEIGHT FF_MAX_IMAGE_WIDTH
+#endif
+
+#define HEADER_SIZE 16
+
+class FFHeader
+{
+private:
+    QByteArray m_rawHeader;
+
+public:
+    FFHeader()
+    {
+
+    }
+
+    bool isValid() const
+    {
+        if (m_rawHeader.size() < HEADER_SIZE) {
+            return false;
+        }
+        return m_rawHeader.startsWith(QByteArray::fromRawData("farbfeld", 8));
+    }
+
+    bool isSupported() const
+    {
+        auto w = width();
+        auto h = height();
+        if (w < 1 || w > FF_MAX_IMAGE_WIDTH || h < 1 || h > FF_MAX_IMAGE_HEIGHT) {
+            return false;
+        }
+        return format() != QImage::Format_Invalid;
+    }
+
+    qint32 width() const
+    {
+        if (!isValid()) {
+            return 0;
+        }
+        return qFromBigEndian<qint32>(m_rawHeader.data() + 8);
+    }
+
+    qint32 height() const
+    {
+        if (!isValid()) {
+            return 0;
+        }
+        return qFromBigEndian<qint32>(m_rawHeader.data() + 12);
+    }
+
+    QSize size() const
+    {
+        return QSize(width(), height());
+    }
+
+    QImage::Format format() const
+    {
+        if (!isValid()) {
+            return QImage::Format_Invalid;
+        }
+        return QImage::Format_RGBA64;
+    }
+
+    bool read(QIODevice *d)
+    {
+        m_rawHeader = d->read(HEADER_SIZE);
+        if (m_rawHeader.size() != HEADER_SIZE) {
+            return false;
+        }
+        return isValid();
+    }
+
+    bool peek(QIODevice *d)
+    {
+        m_rawHeader = d->peek(HEADER_SIZE);
+        if (m_rawHeader.size() != HEADER_SIZE) {
+            return false;
+        }
+        return isValid();
+    }
+};
+
+class FFHandlerPrivate
+{
+public:
+    FFHandlerPrivate() {}
+    ~FFHandlerPrivate() {}
+
+    FFHeader m_header;
+};
+
+FFHandler::FFHandler()
+    : QImageIOHandler()
+    , d(new FFHandlerPrivate)
+{
+}
+
+bool FFHandler::canRead() const
+{
+    if (canRead(device())) {
+        setFormat("ff");
+        return true;
+    }
+    return false;
+}
+
+bool FFHandler::canRead(QIODevice *device)
+{
+    if (!device) {
+        qCWarning(LOG_FFPLUGIN) << "FFHandler::canRead() called with no device";
+        return false;
+    }
+
+    FFHeader h;
+    if (!h.peek(device)) {
+        return false;
+    }
+
+    return h.isSupported();
+}
+
+bool FFHandler::read(QImage *image)
+{
+    auto&& header = d->m_header;
+
+    if (!header.read(device())) {
+        qCWarning(LOG_FFPLUGIN) << "FFHandler::read() invalid header";
+        return false;
+    }
+
+    auto img = imageAlloc(header.size(), header.format());
+    if (img.isNull()) {
+        qCWarning(LOG_FFPLUGIN) << "FFHandler::read() error while allocating the image";
+        return false;
+    }
+
+    auto d = device();
+
+    auto size = img.bytesPerLine();
+    for (auto y = 0, h = img.height(); y < h; ++y) {
+        auto line = reinterpret_cast<char*>(img.scanLine(y));
+        if (d->read(line, size) != size) {
+            qCWarning(LOG_FFPLUGIN) << "FFHandler::read() error while reading image scanline";
+            return false;
+        }
+#if Q_LITTLE_ENDIAN
+        for (auto i = 0; i < size; i += 2) {
+            std::swap(line[i], line[i + 1]);
+        }
+#endif
+    }
+
+    img.setColorSpace(QColorSpace(QColorSpace::SRgb));
+
+    *image = img;
+    return true;
+}
+
+bool FFHandler::supportsOption(ImageOption option) const
+{
+    if (option == QImageIOHandler::Size) {
+        return true;
+    }
+    if (option == QImageIOHandler::ImageFormat) {
+        return true;
+    }
+    return false;
+}
+
+QVariant FFHandler::option(ImageOption option) const
+{
+    QVariant v;
+
+    if (option == QImageIOHandler::Size) {
+        auto&& h = d->m_header;
+        if (h.isValid()) {
+            v = QVariant::fromValue(h.size());
+        } else if (auto d = device()) {
+            if (h.peek(d)) {
+                v = QVariant::fromValue(h.size());
+            }
+        }
+    }
+
+    if (option == QImageIOHandler::ImageFormat) {
+        auto&& h = d->m_header;
+        if (h.isValid()) {
+            v = QVariant::fromValue(h.format());
+        } else if (auto d = device()) {
+            if (h.peek(d)) {
+                v = QVariant::fromValue(h.format());
+            }
+        }
+    }
+
+    return v;
+}
+
+QImageIOPlugin::Capabilities FFPlugin::capabilities(QIODevice *device, const QByteArray &format) const
+{
+    if (format == "ff") {
+        return Capabilities(CanRead);
+    }
+    if (!format.isEmpty()) {
+        return {};
+    }
+    if (!device->isOpen()) {
+        return {};
+    }
+
+    Capabilities cap;
+    if (device->isReadable() && FFHandler::canRead(device)) {
+        cap |= CanRead;
+    }
+    return cap;
+}
+
+QImageIOHandler *FFPlugin::create(QIODevice *device, const QByteArray &format) const
+{
+    QImageIOHandler *handler = new FFHandler;
+    handler->setDevice(device);
+    handler->setFormat(format);
+    return handler;
+}
+
+#include "moc_ff_p.cpp"