    void WebPImage::writeMetadata()
    {
        if (io_->open() != 0) {
            throw Error(kerDataSourceOpenFailed, io_->path(), strError());
        }
        IoCloser closer(*io_);
        BasicIo::AutoPtr tempIo(new MemIo);
        assert (tempIo.get() != 0);

        doWriteMetadata(*tempIo); // may throw
        io_->close();
        io_->transfer(*tempIo); // may throw
    } // WebPImage::writeMetadata
    void WebPImage::writeMetadata()
    {
        if (io_->open() != 0) {
            throw Error(kerDataSourceOpenFailed, io_->path(), strError());
        }
        IoCloser closer(*io_);
        BasicIo::AutoPtr tempIo(new MemIo);
        assert (tempIo.get() != 0);

        doWriteMetadata(*tempIo);  
        io_->close();
        io_->transfer(*tempIo);  
    }  