Creating An Object To Pass To An Imported ActiveX Control（C++Builder 中 Mapx 的对象引用）

本文介绍如何在Borland C++ Builder中为导入的ActiveX控件创建对象并分配属性。文章详细解释了标准VCL语法不适用的情况及正确的对象创建方法，并提供了具体的宏命令示例。

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Creating An Object To Pass To An Imported ActiveX Control

NOTE: The following applies only to BCB4 Patch 1 and above.

Once a control is imported, it is fairly easy to access its properties and the properties of its properties. Notation like

Control->Property->Subproperty

is allowed because of the "class"Ptr class (as described in the guide to the header file of imported controls) and its definition of the -> operator.

However, assume you need to create an object to assign to "Property". You cannot use standard VCL notation like:

CControlPropertyClassPtr NewPropertyInstance = new CControlPropertyClassPtr;

That is, you can use that notation, the compiler won't stop you, but you will abort with utlcls assert violations or access violations.

You must instead use (in macro notation)

Prefix##Classname##Disp Name##Disp = Space::Co##Classname::Create(); Prefix##Classname##Ptr Name; Name = Name##Disp;

for instance, if the class is Mapxlib_tlb::CMapXFields, then the Prefix is CMapX, Classname is Fields, Space (the namespace) is Mapxlib_tlb

I'm sure you can determine the equivalents for your imported control classes. Here's an example:

CMapXFieldsDisp FieldsDisp = Mapxlib_tlb::CoFields::Create(); CMapXFieldsPtr Fields; Fields = FieldsDisp;

Once again, for better understanding of these classes, consult the header files and the guide to the header file of imported controls.