void ModifyAllEntity()
    {
        // 下面读取图中指定块的属性。
        McDbBlockTableRecordPointer spBlkRec(MCDB_MODEL_SPACE,
            acdbCurDwg(),McDb::kForRead);

        if(spBlkRec.openStatus() != Mcad::eOk)
        {
            return;
        }

        // 生成遍历数据库用的遍历器.
        McDbBlockTableRecordIterator* pIterator = NULL;
        spBlkRec->newIterator(pIterator);

        if(pIterator == NULL)
            return;

        std::auto_ptr<McDbBlockTableRecordIterator> spIter(pIterator);

        // 遍历数据库

        for(;!pIterator->done();pIterator->step() )
        {
            McDbObjectId id;
            pIterator->getEntityId(id);

            McDbObjectPointer<AcDbEntity> spEntity(id,McDb::kForWrite);
            if(spEntity.openStatus() != Mcad::eOk)
                continue;

            spEntity->setColorIndex(MrxDbgUtils::kWhite);

            if(McDbLine::cast(spEntity.object()) != NULL)
            {
                // 是个直线实体
                McDbLine* pLine = McDbLine::cast(spEntity.object());
            }
            else if(McDbArc::cast(spEntity.object()) != NULL)
            {
                // 是个圆弧实体
                McDbArc* pArc = McDbArc::cast(spEntity.object());
            }
            else if(McDbText::cast(spEntity.object()) != NULL)
            {
                // 是个文字实体
                McDbText* pText = McDbText::cast(spEntity.object());
            }
            /*
            else if... ...
            */

        }
    }