Some change with input object

src/device/DeviceManager.cpp

@@ -101,6 +101,7 @@ void DeviceManager::timerEvent(QTimerEvent *event) {
                 //preview scan
             else{
                 const char * data = GetPreviewData();
+                if (!data) return;
                 QByteArray bytes =QByteArray::fromRawData(data,140*140);
                 TRIGGER_EVENT(GUIEvents::ResponsePreviewData, nullptr, (QObject*)(&bytes));
                 delete [] data;