Delphi Developers' Handbook

Chapter 15: Other Delphi Extensions

A Summary of the ToolsAPI

In this and the last few chapters, weÆve discussed a number of the ToolsAPI classes for extending the Delphi environment. However, other classes that relate to the Delphi environment (such as the run-time type information weÆll discuss in the next chapter) appear in the VCL source code. What follows is a summary of the ToolsAPI, listing all of the classes in a single section. This is far from a complete reference: it is only a list of the classes defined by each unit, with short descriptions. YouÆll find additional details (primarily extended comments) in the source code files themselves, and there is no reason to duplicate that information here.

Below, you may notice that weÆve skipped a file of the ToolsAPI directory. In fact, we intentionally didnÆt include the DsgnIntf unit, since it doesnÆt define interfaces to the Delphi environment, but internal editor classes, such as component and property editors. We discussed these classes in detail in Chapters 12 and 13. Some more information on custom form designers will follow after this section.

The VirtIntf Unit

TInterface	A generic interface class, implementing a reference-counting mechanism. Most of the other interface classes derive from this one.
TIStream	The abstract base class of interfaces for the internal Delphi stream classes, described in the next section.

The IStreams Unit

TIVCLStreamAdapter and TIStreamAdapter	The base classes of the other interface streams, used to map a TIStream into a plain TStream object.
TIMemoryStream	Implements a wrapper for the TMemoryStream class and inherits from the TIStreamAdapter class. We used this class in the form wizard example from the previous chapter.
TIFileStream	Implements a wrapper for a TFileStream class and inherits from the TIVCLStreamAdapter class.
TVirtualStream	Implements a wrapper for a generic TIStream object and inherits from the TStream class.

The FileIntf Unit

TIVirtualFileSystem

Implements the virtual file system for the Delphi environment. An add-in tool might implement and use a different file system.

• A virtual file system is a mechanism for mapping file operations onto data structures which are not file based. You should have noticed that in Delphi you can open a string list into the editor. This is accomplished with a virtual file system: the editor thinks that the string list is a file and loads it. The read and write operations on this "fake" file are mapped by a virtual file system into operations on the string list object.

The ToolIntf Unit

TIMenuItemIntf	The interface class for each menu item and pull-down menu of the Delphi environment. We used this class in the add-in wizard in the previous chapter.
TIMainMenuIntf	The interface for Delphi menu system. This is a lightweight class youÆll use to access to the menus.
TIAddInNotifier	Used by wizards and version control systems so that Delphi can notify them about some file or project action. We used this class in our VCS Demo.
TIToolServices	In practice, the interface to Delphi itself, including project information, actions you can perform, and many more features. WeÆve used the global ToolServices object of this class in many examples in this chapter and the previous two. This is frequently the entry point for other interfaces.

The ExpIntf Unit

TIExpert

The class you should derive from to create custom wizards. We saw several examples of this class in the previous chapter.

The VcsIntf Unit

TIVCSClient

The class you should derive from to create a custom version control system. WeÆve already seen examples of this class in this chapter.

The EditIntf Unit

TIModuleInterface	The interface of a module: a form, a unit, a project file, a resource file, and so on. WeÆve used this in the last version of the Project VCS example.
TIModuleNotifier	A notifier for the module, with more notifications than a generic project notifier. WeÆve used this in the last version of the Project VCS example.
TIResourceFile	The interface to a resource file.
TIResourceEntry	The interface to an entry within a resource file.
TIComponentInterface	The interface for a component at design-time.
TIFormInterface	The interface for a form at design-time.
TIEditorInterface	The interface for a module loaded in the editor.
TIEditReader	The interface for reading text in the editor.
TIEditWriter	The interface for writing text in the editor. WeÆve used this in the last version of the Project VCS example.
TIEditView	The interface for setting the reading or writing position within an editor file.
TIProjectCreator	The interface used by the ToolServices.ProjectCreate method to initialize a new project in a flexible way.
TIModuleCreator	The interface used by the ToolServices.ModuleCreate method to add a new unit to a project in a flexible way.