media: load metadata and thumbnails of raw pictures using libraw

The distinguished photographer shoots raw images. There is a
comprehensive library that can extract metadata and thumbnails
from these images. Let's use it if available.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

core/imagedownloader.cpp

@@ -14,6 +14,9 @@
 #include <QSvgRenderer>
 #include <QDataStream>
 #include <QPainter>
+#ifdef LIBRAW_SUPPORT
+#include <libraw/libraw.h>
+#endif
 
 #include <QtConcurrent>
 
@@ -79,12 +82,40 @@ static bool hasVideoFileExtension(const QString &filename)
 	return false;
 }
 
-// Fetch a picture from the given filename and determine its type (picture of video).
+#ifdef LIBRAW_SUPPORT
+QImage fetchRawThumbnail(const QString &filename)
+{
+	LibRaw raw; // Might think about reusing that, one instance per thread
+
+	// TODO: Convert filename to UTF-16 for windows
+	if (raw.open_file(qPrintable(filename)) != LIBRAW_SUCCESS ||
+	    raw.unpack_thumb() != LIBRAW_SUCCESS) {
+		return QImage();
+	}
+
+	switch (raw.imgdata.thumbnail.tformat) {
+	case LIBRAW_THUMBNAIL_JPEG: {
+		QImage res;
+		res.loadFromData(reinterpret_cast<unsigned char *>(raw.imgdata.thumbnail.thumb),
+				 raw.imgdata.thumbnail.tlength);
+		return res;
+	}
+	case LIBRAW_THUMBNAIL_BITMAP:
+		return QImage(reinterpret_cast<unsigned char *>(raw.imgdata.thumbnail.thumb),
+			      raw.imgdata.thumbnail.twidth, raw.imgdata.thumbnail.theight,
+			      QImage::Format_RGB888);
+	default: // Unsupported
+		return QImage();
+	}
+}
+
+#endif
+
+// Fetch a picture from the given filename and determine its type (picture or video).
 // If this is a non-remote file, fetch it from disk. Remote files are fetched from the
 // net in a background thread. In such a case, the output-type is set to MEDIATYPE_STILL_LOADING.
 // If the input-flag "tryDownload" is set to false, no download attempt is made. This is to
 // prevent infinite loops, where failed image downloads would be repeated ad infinitum.
-// Returns: fetched image, type
 Thumbnailer::Thumbnail Thumbnailer::fetchImage(const QString &urlfilename, const QString &originalFilename, bool tryDownload)
 {
 	QUrl url = QUrl::fromUserInput(urlfilename);
@@ -102,6 +133,12 @@ Thumbnailer::Thumbnail Thumbnailer::fetchImage(const QString &urlfilename, const
 
 		// Try if Qt can parse this image. If it does, use this as a thumbnail.
 		QImage thumb(filename);
+
+#ifdef LIBRAW_SUPPORT
+		// If note, perhaps a raw image?
+		if (thumb.isNull())
+			thumb = fetchRawThumbnail(filename);
+#endif
 		if (!thumb.isNull()) {
 			int size = maxThumbnailSize();
 			thumb = thumb.scaled(size, size, Qt::KeepAspectRatio);

core/metadata.cpp

@@ -7,6 +7,9 @@
 #include <QFile>
 #include <QFileInfo>
 #include <QDateTime>
+#ifdef LIBRAW_SUPPORT
+#include <libraw/libraw.h>
+#endif
 
 // Weirdly, android builds fail owing to undefined UINT64_MAX
 #ifndef UINT64_MAX
@@ -528,6 +531,33 @@ static bool parseASF(QFile &f, metadata *metadata)
 	return false;
 }
 
+// Transform a (deg, min, sec) float triple into microdegrees
+degrees_t degminsec_to_udeg(float a[3])
+{
+	if (a[0] == 0.0 && a[1] == 0.0 && a[2] == 0.0)
+		return { 0 };
+	return { static_cast<int>(round(a[0] * 1'000'000.0 +
+					a[1] * (1'000'000.0/60.0) +
+					a[2] * (1'000'000.0/3600.0))) };
+}
+
+#ifdef LIBRAW_SUPPORT
+static bool parseRaw(const char *fn, metadata *metadata)
+{
+	LibRaw raw; // Might think about reusing that
+
+	// TODO: Convert filename to UTF-16 for windows
+	if (raw.open_file(fn) != LIBRAW_SUCCESS)
+		return false;
+
+	metadata->timestamp = raw.imgdata.other.timestamp;
+	metadata->location.lat = degminsec_to_udeg(raw.imgdata.other.parsed_gps.latitude);
+	metadata->location.lon = degminsec_to_udeg(raw.imgdata.other.parsed_gps.longitude);
+
+	return true;
+}
+#endif
+
 mediatype_t get_metadata(const char *filename_in, metadata *data)
 {
 	data->timestamp = 0;
@@ -535,6 +565,11 @@ mediatype_t get_metadata(const char *filename_in, metadata *data)
 	data->location.lat.udeg = 0;
 	data->location.lon.udeg = 0;
 
+#ifdef LIBRAW_SUPPORT
+	if (parseRaw(filename_in, data))
+		return MEDIATYPE_PICTURE;
+#endif
+
 	QString filename = localFilePath(QString(filename_in));
 	QFile f(filename);
 	if (!f.open(QIODevice::ReadOnly))

core/qthelper.cpp

@@ -1091,6 +1091,17 @@ const QStringList videoExtensionsList = {
 	".avi", ".mp4", ".mov", ".mpeg", ".mpg", ".wmv"
 };
 
+// Raw extensions according to https://en.wikipedia.org/wiki/Raw_image_format
+static const QStringList rawExtensionsList = {
+#ifdef LIBRAW_SUPPORT
+	"*.3fr", "*.ari", "*.arw", "*.bay", "*.braw", "*.crw", "*.cr2", "*.cr3", "*.cap",
+	"*.data", "*.dcs", "*.dcr", "*.dng", "*.drf", "*.eip", "*.erf", "*.fff", "*.gpr",
+	"*.iiq", "*.k25", "*.kdc", "*.mdc", "*.mef", "*.mos", "*.mrw", "*.nef", "*.nrw",
+	"*.obm", "*.orf", "*.pef", "*.ptx", "*.pxn", "*.r3d", "*.raf", "*.raw", "*.rwl",
+	"*.rw2", "*.rwz", "*.sr2", "*.srf", "*.srw", "*.x3f"
+#endif
+};
+
 QStringList mediaExtensionFilters()
 {
 	return imageExtensionFilters() + videoExtensionFilters();
@@ -1101,7 +1112,7 @@ QStringList imageExtensionFilters()
 	QStringList filters;
 	for (QString format: QImageReader::supportedImageFormats())
 		filters.append("*." + format);
-	return filters;
+	return filters + rawExtensionsList;
 }
 
 QStringList videoExtensionFilters()