Dive pictures: automatically recalculate thumbnails

If a thumbnail and the original picture can be accessed and the
modification date of the thumbnail is before the modification date
of the picture, recalculate the thumbnail.

This causes more disk access and might give strange effects for
picture files with messed up file timestamps (i.e. lying in the
future) or messed up computer clocks (i.e. running in the past).
Therefore, add a preference option to disable the new behavior.
Default is set to enabled.

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

5 files changed, 55 insertions, 15 deletions

diff --git a/core/imagedownloader.cpp b/core/imagedownloader.cpp
index 0c72f3381..da5c86b99 100644
--- a/core/imagedownloader.cpp
+++ b/core/imagedownloader.cpp
@@ -151,8 +151,24 @@ static QImage getThumbnailFromCache(const QString &picture_filename)
 	QString filename = thumbnailFileName(picture_filename);
 	if (filename.isEmpty())
 		return QImage();
-
 	QFile file(filename);
+
+	if (prefs.auto_recalculate_thumbnails) {
+		// Check if thumbnails is older than the (local) image file
+		QString filenameLocal = localFilePath(qPrintable(picture_filename));
+		QFileInfo pictureInfo(filenameLocal);
+		QFileInfo thumbnailInfo(file);
+		if (pictureInfo.exists() && thumbnailInfo.exists()) {
+			QDateTime pictureTime = pictureInfo.lastModified();
+			QDateTime thumbnailTime = thumbnailInfo.lastModified();
+			if (pictureTime.isValid() && thumbnailTime.isValid() && thumbnailTime < pictureTime) {
+				// Both files exist, have valid timestamps and thumbnail was calculated before picture.
+				// Return an empty thumbnail to signal recalculation of the thumbnail
+				return QImage();
+			}
+		}
+	}
+
 	if (!file.open(QIODevice::ReadOnly))
 		return QImage();
 	QDataStream stream(&file);
diff --git a/core/pref.h b/core/pref.h
index 2628c3677..8ca763ce8 100644
--- a/core/pref.h
+++ b/core/pref.h
@@ -154,6 +154,7 @@ struct preferences {
 	int distance_threshold;
 	bool git_local_only;
 	short cloud_timeout;
+	bool auto_recalculate_thumbnails;
 	locale_prefs_t locale; //: TODO: move the rest of locale based info here.
 	update_manager_prefs_t update_manager;
 	dive_computer_prefs_t dive_computer;
diff --git a/core/subsurface-qt/SettingsObjectWrapper.cpp b/core/subsurface-qt/SettingsObjectWrapper.cpp
index d88df5cba..60473ec1a 100644
--- a/core/subsurface-qt/SettingsObjectWrapper.cpp
+++ b/core/subsurface-qt/SettingsObjectWrapper.cpp
@@ -1802,6 +1802,11 @@ int GeneralSettingsObjectWrapper::pscrRatio() const
 	return prefs.pscr_ratio;
 }
 
+bool GeneralSettingsObjectWrapper::autoRecalculateThumbnails() const
+{
+	return prefs.auto_recalculate_thumbnails;
+}
+
 void GeneralSettingsObjectWrapper::setDefaultFilename(const QString& value)
 {
 	if (value == prefs.default_filename)
@@ -1895,6 +1900,18 @@ void GeneralSettingsObjectWrapper::setPscrRatio(int value)
 	emit pscrRatioChanged(value);
 }
 
+void GeneralSettingsObjectWrapper::setAutoRecalculateThumbnails(bool value)
+{
+	if (value == prefs.auto_recalculate_thumbnails)
+		return;
+
+	QSettings s;
+	s.beginGroup(group);
+	s.setValue("auto_recalculate_thumbnails", value);
+	prefs.auto_recalculate_thumbnails = value;
+	emit autoRecalculateThumbnailsChanged(value);
+}
+
 DisplaySettingsObjectWrapper::DisplaySettingsObjectWrapper(QObject *parent) :
 	QObject(parent)
 {
@@ -2266,6 +2283,7 @@ void SettingsObjectWrapper::load()
 	GET_INT("defaultsetpoint", defaultsetpoint);
 	GET_INT("o2consumption", o2consumption);
 	GET_INT("pscr_ratio", pscr_ratio);
+	GET_BOOL("auto_recalculate_thumbnails", auto_recalculate_thumbnails);
 	s.endGroup();
 
 	s.beginGroup("Display");
diff --git a/core/subsurface-qt/SettingsObjectWrapper.h b/core/subsurface-qt/SettingsObjectWrapper.h
index f2c6745d8..a56175ea7 100644
--- a/core/subsurface-qt/SettingsObjectWrapper.h
+++ b/core/subsurface-qt/SettingsObjectWrapper.h
@@ -552,13 +552,14 @@ private:
 
 class GeneralSettingsObjectWrapper : public QObject {
 	Q_OBJECT
-	Q_PROPERTY(QString default_filename      READ defaultFilename       WRITE setDefaultFilename       NOTIFY defaultFilenameChanged)
-	Q_PROPERTY(QString default_cylinder      READ defaultCylinder       WRITE setDefaultCylinder       NOTIFY defaultCylinderChanged)
-	Q_PROPERTY(short default_file_behavior   READ defaultFileBehavior   WRITE setDefaultFileBehavior   NOTIFY defaultFileBehaviorChanged)
-	Q_PROPERTY(bool use_default_file         READ useDefaultFile        WRITE setUseDefaultFile        NOTIFY useDefaultFileChanged)
-	Q_PROPERTY(int defaultsetpoint           READ defaultSetPoint       WRITE setDefaultSetPoint       NOTIFY defaultSetPointChanged)
-	Q_PROPERTY(int o2consumption             READ o2Consumption         WRITE setO2Consumption         NOTIFY o2ConsumptionChanged)
-	Q_PROPERTY(int pscr_ratio                READ pscrRatio             WRITE setPscrRatio             NOTIFY pscrRatioChanged)
+	Q_PROPERTY(QString default_filename         READ defaultFilename           WRITE setDefaultFilename           NOTIFY defaultFilenameChanged)
+	Q_PROPERTY(QString default_cylinder         READ defaultCylinder           WRITE setDefaultCylinder           NOTIFY defaultCylinderChanged)
+	Q_PROPERTY(short default_file_behavior      READ defaultFileBehavior       WRITE setDefaultFileBehavior       NOTIFY defaultFileBehaviorChanged)
+	Q_PROPERTY(bool use_default_file            READ useDefaultFile            WRITE setUseDefaultFile            NOTIFY useDefaultFileChanged)
+	Q_PROPERTY(int defaultsetpoint              READ defaultSetPoint           WRITE setDefaultSetPoint           NOTIFY defaultSetPointChanged)
+	Q_PROPERTY(int o2consumption                READ o2Consumption             WRITE setO2Consumption             NOTIFY o2ConsumptionChanged)
+	Q_PROPERTY(int pscr_ratio                   READ pscrRatio                 WRITE setPscrRatio                 NOTIFY pscrRatioChanged)
+	Q_PROPERTY(bool auto_recalculate_thumbnails READ autoRecalculateThumbnails WRITE setAutoRecalculateThumbnails NOTIFY autoRecalculateThumbnailsChanged)
 
 public:
 	GeneralSettingsObjectWrapper(QObject *parent);
@@ -569,15 +570,17 @@ public:
 	int defaultSetPoint() const;
 	int o2Consumption() const;
 	int pscrRatio() const;
+	bool autoRecalculateThumbnails() const;
 
 public slots:
-	void setDefaultFilename       (const QString& value);
-	void setDefaultCylinder       (const QString& value);
-	void setDefaultFileBehavior   (short value);
-	void setUseDefaultFile        (bool value);
-	void setDefaultSetPoint       (int value);
-	void setO2Consumption         (int value);
-	void setPscrRatio             (int value);
+	void setDefaultFilename           (const QString& value);
+	void setDefaultCylinder           (const QString& value);
+	void setDefaultFileBehavior       (short value);
+	void setUseDefaultFile            (bool value);
+	void setDefaultSetPoint           (int value);
+	void setO2Consumption             (int value);
+	void setPscrRatio                 (int value);
+	void setAutoRecalculateThumbnails (bool value);
 
 signals:
 	void defaultFilenameChanged(const QString& value);
@@ -587,6 +590,7 @@ signals:
 	void defaultSetPointChanged(int value);
 	void o2ConsumptionChanged(int value);
 	void pscrRatioChanged(int value);
+	void autoRecalculateThumbnailsChanged(int value);
 private:
 	const QString group = QStringLiteral("GeneralSettings");
 };
diff --git a/core/subsurfacestartup.c b/core/subsurfacestartup.c
index 18332742b..65b30e7d6 100644
--- a/core/subsurfacestartup.c
+++ b/core/subsurfacestartup.c
@@ -99,6 +99,7 @@ struct preferences default_prefs = {
 #else
 	.cloud_timeout = 5,
 #endif
+	.auto_recalculate_thumbnails = true,
 };
 
 int run_survey;