GLG 擴展應用程序編程接口（API）是 GLG 工具包的一個可選組件，它在運行時提供高級的動態(tài)配置和編輯功能。
GLG 擴展 API 使應用程序能夠根據(jù)當前配置數(shù)據(jù)即時創(chuàng)建圖形。它還可用于在運行時動態(tài)地向圖形中添加圖形對象，這對于顯示數(shù)量可變的動態(tài)圖標（例如地圖上移動的飛機圖標）的應用程序來說非常重要。使用擴展 API 的另一個例子是自定義圖表繪制應用程序，它可以根據(jù)用戶輸入以交互方式創(chuàng)建對象。
除了用于創(chuàng)建和刪除對象的方法外，擴展 API 還提供高級的內(nèi)省功能，可用于遍歷圖形中的對象，并在運行時動態(tài)確定圖形的內(nèi)容。無論選擇哪種部署選項（C/C++、Java 或 ActiveX），擴展 API 都提供對圖形構建器中所有可用操作的編程訪問權限。

以下列出了需要擴展應用程序編程接口（API）的應用程序類型。

這是一個圖表編輯器，用戶在運行時通過從選項板中選擇一個節(jié)點并將其放置在繪圖中，來創(chuàng)建圖表節(jié)點。

這是一個基于地理信息系統(tǒng)的應用程序，它需要在運行時創(chuàng)建動態(tài)圖標來表示需要可視化的移動物體的位置。由于在設計時圖標數(shù)量是未知的，因此這些圖標是在運行時通過復制一個或多個圖標模板來創(chuàng)建的。可以使用幾個模板來表示不同類型的被監(jiān)測對象。

這是一個網(wǎng)絡監(jiān)測或可視化應用程序，它需要根據(jù)其數(shù)據(jù)庫中的信息在運行時創(chuàng)建一些節(jié)點和連接。擴展 API 用于根據(jù)數(shù)據(jù)庫查詢創(chuàng)建節(jié)點，并根據(jù)接收到的連接信息用連接將它們連接起來。

Programming API

　　While the Graphics Builder is used for interactive design of drawings, the Programming API provides a way for the program to interact with the drawing from a program. The API is the second crucial element of the Toolkit, and provides programming access to objects created in the Builder when the drawing is embedded into an application.

　　The Toolkit provides a number of native programming containers for deploying the Toolkit's graphics in an application, both C/C++ and Java, Unix, Linux and Windows: a Motif/Gtk/Qt widget, an MFC class, Windows custom control, a Java bean and class library, an ActiveX Control and more. Click here for more information on available programming containers and deployment options.

　　A developer will only need to use a single SetResource function call or method to set any of the drawing's resources, which is a result of the resource based Programming API. The programmer needs to know only the name of a given resource, either an intuitive default such as FillColor, or any custom name given to the resource.

　　The Programming API may be used to modify resources of the drawing at run-time and supply dynamic data for real-time updates. The application needs to concern itself only with supplying new resource values, and the Toolkit's engine handles all details of the low-level graphics and damage repair. The updates are data-driven, so no CPU time is consumed if the data does not change. Click here for more information.

　　The API may also be used to handle user interaction, such as object selection or interaction with buttons, sliders and other controls. The object selection is handled transparently by the Toolkit, regardless of the screen size or zooming state, and the program's callback is invoked with all selection information every time an object of interest is selected. Click here for more information.