Appendix A Writing Screen Savers

Windows with Multimedia provides special applications called screen savers that start when the mouse and keyboard have been idle for a period of time. Screen savers exist for two main reasons:

To avoid phosphor burn on a display caused by static images.

To conceal sensitive information left on a display.

Clearing a display addresses both goals, but screen savers are not restricted to
this simple use. They can also display animated sequences such as a fish tank
or fireworks. For animated sequences, there's just one rule of thumb: to avoid phosphor burn, keep changing the image.

Windows with Multimedia provides a program that monitors the mouse and keyboard and starts the screen saver after a period of inactivity. Also, the Control Panel includes a Screen Saver applet that allows you to select from a series of screen savers, as well as allowing you to enable or disable the screen-saver feature and specify the time period before which the screen saver is started. The applet also allows you to configure and preview screen savers.

The screen-saver feature is extensible. This chapter describes how to create a custom screen saver and add it to the library of screen savers you can select through the Screen Saver applet.