Palm OS Programming With Satellite Forms (cont.)

Third Party Extensions

Maybe the most powerful feature of the Satellite Forms Application Programming Interface (API) is the ability to expand the capabilities of Satellite Forms with extensions called SFX plug-ins and SFX controls. You can write your own extensions or use extensions written by others. For example, Satellite Forms provides several extensions, including an SFX plug-in called "Square Root" and an SFX control called "Slider." You can add these extensions to your applications and create new extensions of your own.

To load an extension into a Satellite Forms application, select Extensions from the App Designer's View menu, or click on the Manage Extensions button on the Misc Toolbar. This will open a list of the available extensions. Here, you can select the extensions you want to load in your application.

Extensions that are loaded into your application appear in the Contents window. You can expand the listing of an extension and show its methods by clicking on the plus sign to the left of the extension's name. You can double-click on each of the extension's methods to find out more about them. For example, if you load the Square Root plug-in and double-click on it, you will find that it has two methods: About and SqrRoot. The About method brings up the extensions About dialog box, providing general information. The SqrRoot method performs the square root function.

When you first load an extension into your application, Satellite Forms will automatically enable the Include Extensions in Download option under App Designer's handheld menu. The extension will be downloaded to the handheld during your next HotSync. It is unnecessary to download the extension again unless it has changed. For that reason, App Designer turns off the option after the download. It will turn the option on again if you add another extension. Every time you open a project that includes extensions, App Designer enables this option (for one download).

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