// draw thumbnail of frame
if(event->type() == ApiTraceEvent::Frame) {
ApiTraceFrame *frame = static_cast<ApiTraceFrame*>(event);
- QImage thumbnail = frame->thumbnail();
+ const QImage & thumbnail = frame->thumbnail();
if (!thumbnail.isNull()) {
painter->drawImage(option.rect.topLeft() + offset, thumbnail);
offset += QPoint(option.rect.height() + 16, 0);