How to change the value of a label linked to a fixed named optional parameter in the API

arad — Fri, 17 Oct 2025 08:57:26 GMT

I’m trying to modify parameters when creating a label.
How can I change the value of a symbol label that is linked to a fixed named optional parameter?
Changing it from the API_LabelType or by modifying the object parameters does not produce the expected result.

GSErrCode SetLabel(API_Element* elem, const GS::UniString& libpartName) { GSErrCode err = NoError; API_LibPart libpart = {}; BNZeroMemory(&libpart, sizeof(API_LibPart)); GS::ucscpy(libpart.docu_UName, libpartName.ToUStr()); err = ACAPI_LibraryPart_Search(&libpart, false); API_ParamOwnerType paramOwner = {}; API_ChangeParamType chgParam = {}; API_GetParamsType getParams = {}; paramOwner.libInd = libpart.index; err = ACAPI_LibraryPart_OpenParameters(&paramOwner); if (err == NoError) { err = ACAPI_LibraryPart_GetActParameters(&getParams); if (err == NoError) { CHCopyC("iReferencePoint", chgParam.name); chgParam.realValue = 5; err = ACAPI_LibraryPart_ChangeAParameter(&chgParam); //can change parameter CHCopyC("AC_TextAlignment_1", chgParam.name); chgParam.realValue = 2; err = ACAPI_LibraryPart_ChangeAParameter(&chgParam); //cannot change parameter if (err == NoError) err = ACAPI_LibraryPart_GetActParameters(&getParams); } ACAPI_LibraryPart_CloseParameters(); } API_Element label = {}; API_ElementMemo labelMemo = {}; BNZeroMemory(&labelMemo, sizeof(API_ElementMemo)); label.header.type.typeID = API_LabelID; label.label.parentType = elem->header.type.typeID; err = ACAPI_Element_GetDefaults(&label, &labelMemo); TurnAutoTextFlagOff(); //This function is defined externally. labelMemo.params = getParams.params; label.label.labelClass = APILblClass_Symbol; label.label.parent = elem->header.guid; label.label.u.symbol.libInd = libpart.index; label.label.u.symbol.ownerType.typeID = elem->header.type.typeID; label.label.u.text.pen = 36; label.label.framed = false; label.label.textWay = APIDir_Parallel; label.label.textSize = 2.6; label.label.hasLeaderLine = false; label.label.pen = 36; label.label.arrowData.arrowPen = 36; label.label.framed = false; label.label.createAtDefaultPosition = true; label.label.u.text.just = APIJust_Center; //not work err = ACAPI_Element_Create(&label, &labelMemo); ACAPI_DisposeElemMemoHdls(&labelMemo); return err; }

Re: How to change the value of a label linked to a fixed named optional parameter in the API

Akos Somorjai — Fri, 17 Oct 2025 12:05:11 GMT

Hi Arad,

AC_ parameters cannot be changed from the API, as they are controlled directly from Archicad (see the GDL reference guide, section "Parameters for Text Handling").

It seems that the API currently ignores the text settings when you create a symbol label. So, my idea is to set the default parameters for a text label (including justification), then create the symbol label. (and set the defaults back if needed)

Best, Akos

Re: How to change the value of a label linked to a fixed named optional parameter in the API

arad — Tue, 21 Oct 2025 00:12:00 GMT

Changing the default label settings first worked well.
Thank you very much, Akos.

topic Re: How to change the value of a label linked to a fixed named optional parameter in the API in Archicad C++ API

How to change the value of a label linked to a fixed named optional parameter in the API

Re: How to change the value of a label linked to a fixed named optional parameter in the API

Re: How to change the value of a label linked to a fixed named optional parameter in the API