[求助]：handoverto函数的作用

zhoufs_1205

AcDbCurve *pCurve;
     pCurve->handOverTo(pCurveText)
请问handoverto函数的作用:

XDSoft

handOverTo函数的作用是：

对两个对象进行操作，1、一个是数据库中的对象，2、一个是非数据库中的对象。

操作后，非数据库对象2“添加”到数据库中并且继承原数据库对象1的ObjectId值（也可以继承扩展词典等，有选项），1对象变成非数据库对象，不需要时候，可以对1进行delete

详细见ObjectARX帮助：

1. 
   
2. Acad::ErrorStatus
   
3. handOverTo(
   
4.     AcDbObject* pNewObject,
   
5.     Adesk::Boolean keepXData = Adesk::kTrue,
   
6. 
   
7.     Adesk::Boolean keepExtDict = Adesk::kTrue);
   

复制代码

pNewObject        Input pointer to object to be used to replace the current object
keepXData        Input Boolean indicating if xdata is to be transferred during the process
keepExtDict        Input Boolean indicating whether the extension dictionary is passed on from the old object to the new one. If set to kTrue, the extension dictionary will be passed on, otherwise it will be left behind.

This function provides the ability to exchange a non-database-resident object (NDBRO) in place of an existing database-resident object (DBRO) while retaining the objectId, handle, and reactor list of the DBRO. An example of this situation is when the BREAK command is used to break a circle into one or two arc segments. AcDbArc is a completely different class from AcDbCircle, so a new AcDbArc object must be substituted in place of the AcDbCircle
object that is there now, yet the arc must get the handle and objectId that the circle has.

To use the handOverTo() function, the object to be replaced (the AcDbCircle in the example) must be open AcDb::kForWrite. The object's handOverTo() function is called with pNewObject pointing to a non-database-resident object that replaces it (the AcDbArc in the example). keepXData is set to Adesk::kTrue if the xdata is to be retained or Adesk::kFalse if the xdata is to be thrown out. keepExtDict is set to Adesk::kTrue if the extension dictionary and its contents are to be retained, or set to Adesk::kFalse if the extension dictionary and its contents are to be thrown out.

Once returned from this function, the replacement object (the AcDbArc in the example) is open for AcDb::kForWrite and must have its close() member called to commit the change and close out Undo recording. Then it's up to the ObjectARX application to delete the old object (the AcDbCircle in the example) from memory since it's no longer database-resident.
Returns Acad::eObjectToBeDeleted if the operation is successful. If pNewObject is pointing to an object that is already in the database, or the object invoking handOverTo() is not database-resident, then Acad::eIllegalReplacement is returned.

Note This method is not allowed on objects that are transaction resident. If the object on which the method is called is transaction resident, then no handOverTo operation is performed and Acad::eInvalidContext is returned

zhoufs_1205

谢谢你 晓东
                es = pCurve->handOverTo(pCurveText);
                if(es != Acad::eObjectToBeDeleted)
                {
                        delete pCurveText;
                        pCurve->close();
                                     -----------------------------------
                                  }
pCurve是数据库中的对象,pCurveText是非数据库中的对象,对吗?
es != Acad::eObjectToBeDeleted 是指什么情况下?

XDSoft

最初由 zhoufs_1205 发布
[B]谢谢你 晓东
                es = pCurve->handOverTo(pCurveText);
                if(es != Acad::eObjectToBeDeleted)
                {
                        delete pCurveText;
                        pCurve->close();
                                     -----------------------... [/B]

对。

Returns Acad::eObjectToBeDeleted if the operation is successful

如果替换成功，返回Acad::eObjectToBeDeleted，你就可以放心的把替换下的“原来”的数据库内的对象（现在变成非数据库对象）处理了。

zhoufs_1205

请帮我看一下这个程序的错误
void createLine()
{
        AcGePoint3d p1,p2,p3;
        p1.set(0.0,0.0,0.0);
        p2.set(10.0,20.0,0.0);
        p3.set(50.0,20.0,0.0);
        AcDbLine *pLine=new AcDbLine(p1,p2);
        AcDbLine *pLine1=new AcDbLine(p2,p3);
        AcDbBlockTable *pBlockTable;
        AcDbBlockTableRecord *pBlockTableRecord;
        AcDbObjectId pObjectId;
        acdbHostApplicationServices()->workingDatabase()->
                getSymbolTable(pBlockTable,AcDb::kForRead);
        pBlockTable->getAt(ACDB_MODEL_SPACE,pBlockTableRecord,AcDb::kForWrite);
        pBlockTableRecord->appendAcDbEntity(pObjectId,pLine);
        pLine->close();
        pBlockTable->close();
        pBlockTableRecord->close();
        //**********
        acdbOpenAcDbEntity((AcDbEntity* &)pLine,pObjectId,AcDb::kForRead);
        Acad::ErrorStatus es;
        es = pLine->upgradeOpen();       
        es = pLine->handOverTo(pLine1);
        if(es != Acad::eObjectToBeDeleted)
        {
                delete pLine1;
                pLine->close();
        }
}

XDSoft

最初由 zhoufs_1205 发布
[B]请帮我看一下这个程序的错误
void createLine()
{
        AcGePoint3d p1,p2,p3;
        p1.set(0.0,0.0,0.0);
        p2.set(10.0,20.0,0.0);
        p3.set(50.0,20.0,0.0);
        AcDbLine *pLine=new AcDbLine(p1,p2);
        AcDbLine *pLi... [/B]

看看帮助：
To use the handOverTo() function, the object to be replaced (the AcDbCircle in the example) must be open AcDb::kForWrite.

数据库对象必须要以“写”方式打开。

zhoufs_1205

我该成“写”方式打开，CAD还是出错。upgradeOpen()不是就将对象该成“写”方式吗？

XDSoft

最初由 zhoufs_1205 发布
[B]我该成“写”方式打开，CAD还是出错。upgradeOpen()不是就将对象该成“写”方式吗？ [/B]

你测试下：
es = pLine->handOverTo(pLine1);  这个的返回码是什么？

还有把运行提示的错误信息也贴下吧。

yousuika

返回值是对的es = Acad::eObjectToBeDeleted，是不是少了对返回正确的处理，因为最后错误信息是eWasOpenForWrite(请教晓东：如何贴图）

yousuika

这样做就对了
if(es != Acad::eObjectToBeDeleted)
{
delete pLine1;
pLine->close();
}
else
{
es = pLine1->close();
}

XDSoft

最初由 yousuika 发布
[B]返回值是对的es = Acad::eObjectToBeDeleted，是不是少了对返回正确的处理，因为最后错误信息是eWasOpenForWrite(请教晓东：如何贴图） [/B]

if(es != Acad::eObjectToBeDeleted)

这个应该为 if(es == Acad::eObjectToBeDeleted)

成功，才应该做里面的。

不成功应该delete pLine1而是关闭它。


贴图，把图片用“附件”就可以了。发贴的时候下面有这个选项。

XDSoft

最初由 yousuika 发布
[B]这样做就对了
if(es != Acad::eObjectToBeDeleted)
{
delete pLine1;
pLine->close();
}
else
{
es = pLine1->close();
} [/B]

成功后，你还应该delete pLine.

zhoufs_1205

成功后delete pLine，还是 delete pLine1?

XDSoft

最初由 zhoufs_1205 发布
[B]成功后delete pLine，还是 delete pLine1? [/B]

成功后，应该delete 原来在数据库的那个对象。因为那个对象已经成为非数据库的对象了。

yousuika

请教：如果不delete pLine，会有什么致命的错误吗？