AcDbHatch修改后为什么不能更新显示[求助]

stoneball

AcDbHatch修改后为什么不能更新：
如下一段代码，获得AcDbHatch，修改他的填充图案和颜色，结果颜色修改正确，但图案修改后无论是用Redraw等命令都无法更新显示，只有再编辑后才更新显示。为什么？？？
void test()
{
        AcDbHatch* pObj;
        ads_name ent;
        ads_point pt1;
        acedEntSel("\nhacth:",ent,pt1);
        AcDbObjectId objId;
        Acad::ErrorStatus es;
        acdbGetObjectId(objId,ent);
        acdbOpenObject(pObj,objId,AcDb::kForWrite);
    es = pObj->evaluateHatch();
    es = pObj->setPattern(AcDbHatch::kPreDefined, "ANGLE");
        es = pObj->setColorIndex(3);
        es = pObj->downgradeOpen();///!!!!!!!!!!!!!!!!!!!!!!!
        es = pObj->draw(); //更新实体
        pObj->recordGraphicsModified(Adesk::kTrue);
        pObj->close();
       
        acedUpdateDisplay();
        actrTransactionManager->flushGraphics();

        return;
}