基于多线程的机制实现图片缩略图的显示。QThread*thread=newThumbnailThread(filename,10-waitseconds);waitseconds++;connect(thread,SIGNAL(thumbnailFinished(QImage)),this,SLOT(addThumbnail(QImage)));connect(thread,SIGNAL(thumbnailFailed(constQString)),this,SLOT(showError(constQString)));connect(thread,SIGNAL(finished()),this,SLO