组和组字典

组是维护数据库实体的有序集合的容器对象。可以将组视为命名的持久选择集。它们没有指向它们所包含的实体的所有权链接。

擦除实体后，会自动将其从包含该实体的组中删除。如果实体未擦除，则会自动将其重新插入到组中。

使用该函数获取迭代器并单步执行组中的实体。Theclass 还提供了以下功能：将实体追加和预置到组、在组中的特定索引处插入实体、删除实体以及将实体从组中的一个位置转移到另一个位置。查看ObjectARX 引用。AcDbGroup::newIterator()AcDbGroupAcDbGroup

您还可以使用 theclass 的 ,,,, 和函数将属性分配给组的所有成员。这些操作与打开组中的每个实体并直接设置其属性具有相同的效果。setColor()setLayer()setLinetype()setVisibility()setHighlight()AcDbGroup

组应始终存储在 GROUP 字典中，可以按如下方式获取：

AcDbDictionary* pGrpDict = 
    acdbHostApplicationServices()->working Database()->
        getGroupDictionary(pGroupDict, AcDb::kForWrite);

获取 GROUP 字典的另一种方法是在命名对象字典中查找“ACAD_GROUP”。

以下函数是应用程序的一部分，该应用程序首先提示用户选择放置在名为“ASDK_GROUPTEST”的组中的某些实体。然后，它调用函数来循环访问组并删除所有不是行的实体。最后，它将组中的其余实体更改为红色。removeAllButLines()

void groups()
{
    AcDbGroup *pGroup = new AcDbGroup("grouptest");
    AcDbDictionary *pGroupDict;
    acdbHostApplicationServices()->workingDatabase()
        ->getGroupDictionary(pGroupDict, AcDb::kForWrite);
    AcDbObjectId groupId;
    pGroupDict->setAt("ASDK_GROUPTEST", pGroup, groupId);
    pGroupDict->close();
    pGroup->close();
    makeGroup(groupId);
    removeAllButLines(groupId);
}

// Prompts the user to select objects to add to the group,
// opens the group identified by "groupId" passed in as
// an argument, then adds the selected objects to the group.
//
void makeGroup(AcDbObjectId groupId)
{
    ads_name sset;
    int err = acedSSGet(NULL, NULL, NULL, NULL, sset);
    if (err != RTNORM) {
        return;
    }
    AcDbGroup *pGroup;
    acdbOpenObject(pGroup, groupId, AcDb::kForWrite);
    // Traverse the selection set, exchanging each ads_name
    // for an object ID, then adding the object to the group.
    //
    long i, length;
    ads_name ename;
    AcDbObjectId entId;
    acedSSLength(sset, &length);
    for (i = 0; i < length; i++) {
        acedSSName(sset, i, ename);
        acdbGetObjectId(entId, ename);
        pGroup->append(entId);
    }
    pGroup->close();
    acedSSFree(sset);
}

// Accepts an object ID of an AcDbGroup object, opens it,
// then iterates over the group, removing all entities that
// are not AcDbLines and changing all remaining entities in
// the group to color red.
//
void removeAllButLines(AcDbObjectId groupId)
{
    AcDbGroup *pGroup;
    acdbOpenObject(pGroup, groupId, AcDb::kForWrite);
    AcDbGroupIterator *pIter = pGroup->newIterator();
    AcDbObject *pObj;
    for (; !pIter->done(); pIter->next()) {
        pIter->getObject(pObj, AcDb::kForRead);
        // If it is not a line or descended from a line,
        // close it and remove it from the group.  Otherwise,
        // just close it.
        //
        if (!pObj->isKindOf(AcDbLine::desc())) {
            // AcDbGroup::remove() requires that the object
            // to be removed be closed, so close it now.
            //
            pObj->close();
            pGroup->remove(pIter->objectId());
        } else {
            pObj->close();
        }
    }
    delete pIter;
    // Now change the color of all the entities in the group
    // to red (AutoCAD color index number 1).
    //
    pGroup->setColorIndex(1);
    pGroup->close();
}