libdxfrw项目中dxf2text命令可以抽取dwg文件中的文字部分，编译完工程后对手头上的dwg文件提取时发现抽取不完整，对源码进行分析时发现该命令只处理了text部分，不处理mtext部分

bool dx_iface::printText(const std::string& fileI, dx_data *fData){
    unsigned int found = fileI.find_last_of(".");
    std::string fileExt = fileI.substr(found+1);
    std::transform(fileExt.begin(), fileExt.end(),fileExt.begin(), ::toupper);
    cData = fData;
    currentBlock = cData->mBlock;

    bool success = false;
    if (fileExt == "DXF"){
        //loads dxf
        dxfRW* dxf = new dxfRW(fileI.c_str());
        success = dxf->read(this, false);
        delete dxf;
    } else if (fileExt == "DWG"){
        //loads dwg
        dwgR* dwg = new dwgR(fileI.c_str());
        success = dwg->read(this, false);
        delete dwg;
    }

    if (success) {
        for (std::list<DRW_Entity*>::const_iterator it =
                cData->mBlock->ent.begin(); it != cData->mBlock->ent.end();
                ++it) {
            DRW_Entity* e = *it;
            switch (e->eType) {
            case DRW::TEXT:
                std::cout << static_cast<DRW_Text*>(e)->text << std::endl;
                break;
            default:
                break;
            }
        }
    }
    return success;
}