Importing Type Library Information
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To make information about the COM server available to your client application, you must import the information about the server that is stored in the server's type library. Your application can then use the resulting generated classes to control the server object.
There are two ways to import type library information:
- You can use the Import Component wizard to import all available information about the server types, objects, and interfaces. This is the most general method, because it lets you import information from any type library and can optionally generate component wrappers for all creatable CoClasses in the type library that are not flagged as Hidden, Restricted, or PreDeclID.
- You can also use the Import Component wizard if you are importing from the type library of an ActiveX control. This imports the same type information, but only creates component wrappers for CoClasses that represent ActiveX controls.
- You can use the command line utility TLIBIMP.EXE, which provides additional configuration options not available from within the IDE.
- A type library generated using a wizard is automatically imported using the same mechanism as the import type library menu item.
Regardless of which method you choose to import type library information, the resulting dialog creates a unit with the name TypeLibName_TLB, where TypeLibName is the name of the type library. This file contains declarations for the classes, types, and interfaces defined in the type library. By including it in your project, those definitions are available to your application so that you can create objects and call their interfaces. This file may be recreated by the IDE from time to time; as a result, making manual changes to the file is not recommended.
In addition to adding type definitions to the TypeLibName_TLB unit, the dialog can also create VCL class wrappers for any CoClasses defined in the type library. When you use the Import Type Library dialog, these wrappers are optional. When you use the Import ActiveX dialog, they are always generated for all CoClasses that represent controls.
The generated class wrappers represent the CoClasses to your application, and expose the properties and methods of its interfaces. If a CoClass supports the interfaces for generating events (IConnectionPointContainer and IConnectionPoint), the VCL class wrapper creates an event sink so that you can assign event handlers for the events as simply as you can for any other component. If you tell the dialog to install the generated VCL classes on the Tool Palette, you can use the Object Inspector to assign property values and event handlers.
For more details about the code generated when you import a type library, see Code Generated When You Import Type Library Information.