Add directed lighting source spot to the image with user-defined settings.

Produce an image that looks like as if there is light directed into it.
| Framework | Member |
|---|---|
| .NET | FunctionalLightCommand |
| .NET 6+ | FunctionalLightCommand |
| iOS / OS X | FunctionalLightCommand |
| Java | FunctionalLightCommand |
| C DLL | L_FunctionalLightBitmap |
| C++ Class Library | LBitmap::FunctionalLight |
Imaging, Document, and Medical