用QT自建了一个登陆帐号(root)的目录：C:\Documents and Settings\root\soft\temp,但在这个目录下QImage save 图片时失败，如何解决？XP下没有问题，在此目录下生成日志文件也没有问题。
QImage fixedImage(videoW, videoH, QImage::Format_ARGB32_Premultiplied);
QPainter painter(&fixedImage);
painter.setCompositionMode(QPainter::CompositionMode_Source);
painter.fillRect(fixedImage.rect(), Qt::transparent);
painter.setCompositionMode(QPainter::CompositionMode_SourceOver);
for(i=0; i<count; i++)
{
int idx = listIdx.at(i);
double ratio = m_treeItem->mdata("effect_video_ratio").toDouble();
QRect r = m_treeItem->getDataItem("effect_item_rect", idx).toRect();
r.moveLeft(r.left() * ratio);
r.moveTop(r.top() * ratio);
painter.drawImage(r.topLeft(), *img);
}
painter.end();
bool bOk = fixedImage.save(watermarkFile);
