3 files changed, 66 insertions, 9 deletions

diff --git a/core/qthelper.cpp b/core/qthelper.cpp
index fb32fabe5..55015d226 100644
--- a/core/qthelper.cpp
+++ b/core/qthelper.cpp
@@ -1054,7 +1054,6 @@ extern "C" void reverseGeoLookup(degrees_t latitude, degrees_t longitude, uint32
 QHash<QString, QByteArray> hashOf;
 QMutex hashOfMutex;
 QHash<QByteArray, QString> localFilenameOf;
-QHash <QString, QImage > thumbnailCache;
 
 static QByteArray getHash(const QString &filename)
 {
@@ -1077,6 +1076,19 @@ const QString hashfile_name()
 	return QString(system_default_directory()).append("/hashes");
 }
 
+static QString thumbnailDir()
+{
+	return QString(system_default_directory()) + "/thumbnails/";
+}
+
+// Return filename of thumbnail if it is known to us.
+// If this is an unknown thumbnail, return an empty string.
+QString thumbnailFileName(const QString &filename)
+{
+	QString hash = getHash(filename).toHex();
+	return hash.isEmpty() ? QString() : thumbnailDir() + hash;
+}
+
 extern "C" char *hashfile_name_string()
 {
 	return copy_qstring(hashfile_name());
@@ -1090,7 +1102,8 @@ void read_hashes()
 		QDataStream stream(&hashfile);
 		stream >> localFilenameOf;
 		stream >> hashOf;
-		stream >> thumbnailCache;
+		QHash <QString, QImage> thumbnailCache;
+		stream >> thumbnailCache;		// For backwards compatibility
 		hashfile.close();
 	}
 	localFilenameOf.remove("");
@@ -1100,6 +1113,9 @@ void read_hashes()
 		if (iter.value().isEmpty())
 			iter.remove();
 	}
+
+	// Make sure that the thumbnail directory exists
+	QDir().mkpath(thumbnailDir());
 }
 
 void write_hashes()
@@ -1111,7 +1127,7 @@ void write_hashes()
 		QDataStream stream(&hashfile);
 		stream << localFilenameOf;
 		stream << hashOf;
-		stream << thumbnailCache;
+		stream << QHash<QString,QImage>();	// Empty thumbnailCache - for backwards compatibility
 		hashfile.commit();
 	} else {
 		qWarning() << "Cannot open hashfile for writing: " << hashfile.fileName();
diff --git a/core/qthelper.h b/core/qthelper.h
index 4c0dcda66..ac1de4df8 100644
--- a/core/qthelper.h
+++ b/core/qthelper.h
@@ -30,6 +30,7 @@ void write_hashes();
 void updateHash(struct picture *picture);
 QByteArray hashFile(const QString &filename);
 QString hashString(const char *filename);
+QString thumbnailFileName(const QString &filename);
 void learnImages(const QDir dir, int max_recursions);
 void add_hash(const QString &filename, const QByteArray &hash);
 void hashPicture(struct picture *picture);
diff --git a/qt-models/divepicturemodel.cpp b/qt-models/divepicturemodel.cpp
index b27799c67..e92a16bd0 100644
--- a/qt-models/divepicturemodel.cpp
+++ b/qt-models/divepicturemodel.cpp
@@ -4,17 +4,58 @@
 #include "core/metrics.h"
 #include "core/divelist.h"
 #include "core/imagedownloader.h"
+#include "core/qthelper.h"
+#include "core/metadata.h"
 
 #include <QtConcurrent>
 
-extern QHash <QString, QImage> thumbnailCache;
-static QMutex thumbnailMutex;
 static const int maxZoom = 3;	// Maximum zoom: thrice of standard size
 
 static QImage getThumbnailFromCache(const PictureEntry &entry)
 {
-	QMutexLocker l(&thumbnailMutex);
-	return thumbnailCache.value(entry.filename);
+	// First, check if we know a hash for this filename
+	QString filename = thumbnailFileName(entry.filename);
+	if (filename.isEmpty())
+		return QImage();
+
+	QFile file(filename);
+	if (!file.open(QIODevice::ReadOnly))
+		return QImage();
+	QDataStream stream(&file);
+
+	// Each thumbnail file is composed of a media-type and an image file.
+	// Currently, the type is ignored. This will be used to mark videos.
+	quint32 type;
+	QImage res;
+	stream >> type;
+	stream >> res;
+	return res;
+}
+
+static void addThumbnailToCache(const QImage &thumbnail, const PictureEntry &entry)
+{
+	if (thumbnail.isNull())
+		return;
+
+	QString filename = thumbnailFileName(entry.filename);
+
+	// If we got a thumbnail, we are guaranteed to have its hash and therefore
+	// thumbnailFileName() should return a filename.
+	if (filename.isEmpty()) {
+		qWarning() << "Internal error: can't get filename of recently created thumbnail";
+		return;
+	}
+
+	QSaveFile file(filename);
+	if (!file.open(QIODevice::WriteOnly))
+		return;
+	QDataStream stream(&file);
+
+	// For format of the file, see comments in getThumnailForCache
+	quint32 type = MEDIATYPE_PICTURE;
+	stream << type;
+	stream << thumbnail;
+	file.commit();
 }
 
 static void scaleImages(PictureEntry &entry, int maxSize)
@@ -25,8 +66,7 @@ static void scaleImages(PictureEntry &entry, int maxSize)
 	if (thumbnail.isNull() || (thumbnail.size().width() < maxSize && thumbnail.size().height() < maxSize)) {
 		qDebug() << "No thumbnail in cache for" << entry.filename;
 		thumbnail = SHashedImage(entry.picture).scaled(maxSize, maxSize, Qt::KeepAspectRatio);
-		QMutexLocker l(&thumbnailMutex);
-		thumbnailCache.insert(entry.filename, thumbnail);
+		addThumbnailToCache(thumbnail, entry);
 	}
 
 	entry.image = thumbnail;