Method changeimage

src/3rdparty/QXlsx/source/xlsxdocument.cpp:1288–1318

add by liufeijin 20181025 {{

//  add by liufeijin 20181025 {{
bool Document::changeimage(int filenoinmidea, QString newfile)
{
	Q_D(const Document);

    QImage newpic(newfile);
	
    auto mediaFileToLoad = d->workbook->mediaFiles();
    const auto mf = mediaFileToLoad[filenoinmidea];
	
	const QString suffix = newfile.mid(newfile.lastIndexOf(QLatin1Char('.'))+1);
	QString mimetypemy;
    if(QString::compare(QLatin1String("jpg"), suffix, Qt::CaseInsensitive)==0)
       mimetypemy=QStringLiteral("image/jpeg");
    if(QString::compare(QLatin1String("bmp"), suffix, Qt::CaseInsensitive)==0)
       mimetypemy=QStringLiteral("image/bmp");
    if(QString::compare(QLatin1String("gif"), suffix, Qt::CaseInsensitive)==0)
       mimetypemy=QStringLiteral("image/gif");
    if(QString::compare(QLatin1String("png"), suffix, Qt::CaseInsensitive)==0)
       mimetypemy=QStringLiteral("image/png");
	
	QByteArray ba;
	QBuffer buffer(&ba);
	buffer.setBuffer(&ba);
	buffer.open(QIODevice::WriteOnly);
	newpic.save(&buffer,suffix.toLocal8Bit().data());
	
	mf->set(ba,suffix,mimetypemy);
	mediaFileToLoad[filenoinmidea]=mf;
	
	return true;
}
// liufeijin }}