Debug: Error reporting for SHashedImage loading

Overwrite QImage::load() in SHashedImage so that we can perform better
error reporting.

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

core/imagedownloader.cpp

@@ -6,6 +6,7 @@
 #include "imagedownloader.h"
 #include <unistd.h>
 #include <QString>
+#include <QImageReader>
 
 #include <QtConcurrent>
 
@@ -102,6 +103,16 @@ static void loadPicture(struct picture *picture, bool fromHash)
 	download.load(fromHash);
 }
 
+// Overwrite QImage::load() so that we can perform better error reporting.
+bool SHashedImage::load(const QString &fileName, const char *format)
+{
+	QImageReader reader(fileName, format);
+	static_cast<QImage&>(*this) = reader.read();
+	if (isNull())
+		qInfo() << "Error loading image" << fileName << (int)reader.error() << reader.errorString();
+	return !isNull();
+}
+
 SHashedImage::SHashedImage(struct picture *picture) : QImage()
 {
 	QUrl url = QUrl::fromUserInput(localFilePath(QString(picture->filename)));

core/imagedownloader.h

@@ -20,6 +20,7 @@ private:
 };
 
 class SHashedImage : public QImage {
+	bool load(const QString &fileName, const char *format=nullptr);
 public:
 	SHashedImage(struct picture *picture);
 };