Tired of presentations being interrupted? Learn how to override and reset power system settings with C (or C++) to ensure that doesn’t happen

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by Lynn Merrill, senior application engineer, Mobility Enabling team, Software Solutions Group, Intel Corp.

Tired of presentations being interrupted? Learn how to override and reset power system settings with C (or C++) to ensure that doesn’t happen.

We have all had this experience. You are in the middle of a fabulous laptop-based presentation where ideas are flowing and the topic is being discussed with great passion. Suddenly, a question arises that requires some rather lengthy discussion. While that question is being considered, the laptop either blanks the screen or the screen saver begins to run. Both scenarios require that we work frantically to restore the screen, and very often require that we re-enter our password. Sometimes this delay derails the flow of dialogue, and a great presentation goes down in flames. The cause for this embarrassment is that we have forgotten to change our power settings to keep the screen from turning off, and we have forgotten to disable the screen saver. Wouldn’t it be great if the presentation application could automatically do that for us and then restore the power-saving settings when we are finished?

The scope of this paper is to provide ideas and examples of what can be done programmatically in software to avoid having the blank or animated screen interrupt your work. We will discuss a variety of approaches to solving this issue, ranging from simple to elaborate. We will describe the specifics of options available to the Windows XP operating system. This paper will also offer coding examples that illustrate ways to override and reset system power settings. Though these examples are given in C they may be defined and used within a C++ class and functional elements could be implemented within the constructor and destructor of the class.

System power and screen saver considerations
Power Settings are available to the Windows XP user via the Control Panel. They are comprised of a collection of settings that govern several areas of the computer, including time delays for turning off the display, powering down the hard drives, and putting the system into a suspended or hibernation state. Different settings can be set for running on AC power and running on battery. Other parts of the collection describe what happens when the power button is pressed, when the lid of a laptop is closed, and when the sleep button is pressed. Still other settings provide that alerts be raised for various features such as low battery or volume control. Various predefined Power Settings are provided to give the user a variety of options that control the performance and power consumption of the system. Once a Power Setting collection is selected, it will govern the actions of the computer based on the settings that are contained within the collection. The user can change these at any time without fear of causing a catastrophic event to the system.