What is a screensaver?

A screensaver is a pop up simple program within operating systems that appears whenever you leave the keyboard or mouse unattended for a couple of minutes. To find out whether it can start the screensaver or not, Windows sends a message to the foreground application. This command is asking the application, "Can I start the screensaver?" A non- Windows program will not understand the command, and therefore will not answer it. A CBT application will understand it, but will respond with a command that means "No, I'm providing training right now." All other applications should respond positively to the command.

The screensavers were originally designed to protect the computer monitor from phosphor burn-in. The phosphors, used to make the pixels in the display, would glow at a constant rate for such a long period of time that they would actually discolor the glass surface of the CRT. This discoloration would then be visible as a faint image overlaying whatever else was displayed on the monitor.

Now you can use screensavers for: ? Entertainmentmost people use screensavers for the fun of watching them. There are several screensaver categories like: natural environments (e.g. animated waterfalls, aquariums, fireplaces etc.), favorite actor/actress screensavers, cars screensavers etc. ? Advertisementmany companies have developed their own themed screensavers (e.g. a black background with the name of the company scrolling up and down) ? Securitythis might be one of the most important uses .You can simply set a password so when your computer exits the screensaver will actually require a password to go back to its desktop. Many people use this option to prevent others from invading their privacy.

Screensaver Development

A screensaver is really just an executable file, with the extension changed from .exe to .scr. By putting a screensaver file into the Windows or System directory and giving it a .scr extension, Windows knows that it should treat this file as a screensaver and makes it available as an option in the Display properties window.

The bulk of the screen saver is written in C++ and uses OpenGL for rendering. It is shared between both Windows and Macintosh versions. The Windows version also is in C++ and talks directly to the Win32 API (no MSVC classes). The development environment is Microsoft Visual C++ 2005 Express, but a VC++ 6.0 project is also included. The Macintosh version is in a mix of C++ and ObjectiveC, and is built with Xcode. The screensaver interfaces indirectly with the operating system to cause the physical display screen to be overlayed with one or more graphic 'scenes'. The screensaver typically terminates after receiving a message from the operating system that the mouse has been moved or a key has been pressed.

The screensaver file can be programmed in several different ways. It can: ? Simply present a black screen ? Load and display a particular image or group of images ? Display a particular line of text ? Display an animation or series of animations ? Display information from another program or a Web site

To suit the user needs companies designed several types of screensavers based on: ? Shockwave Flash ? Image slide shows ? Play movies and music different formats (avi,mpg,asf/mp3,aac,midi,wav) ? 3D rendering objects ? Open GL support screensavers

Most screensavers offer some combination of these features. Except for the slideshow screensavers that display a sequence of images, screensavers generally move an image, piece of text or animation around the screen. The screensavers that have a custom interface, and do not use the Display properties window at all, are less common. Usually, these screensavers do not have the .scr extension. They require that you install them using a setup program in order to configure them properly.

There are several available software over the internet that lets you make your own screensavers based on Shockwave Flash, Image Slide Show (display your favorite photos) and Movie .The software offers you the possibility to let your imagination get loose and use all kind of multimedia support like Background music support, transition effect support, masking effect support, customizable screensaver Dialog box etc.

Installing and removing screensavers under Microsoft Windows

There are two types of screensavers: ? compressed self installing Screensaver setup files(.EXE) ? stand-alone screensaver file(.SCR)

The easiest way to install a screensaver under MS Windows platform is to download it from the internet and simply follow the install w izard's further instructions. All you have to do during the wizard is to: read and agree the terms and conditions choose the install destination path and choose either if you want or not to create a shortcut icon on the menu folder. Another method is to copy the screensaver w ith his original '.scr' extension on W indow s's root directory c:windows.

To remove a screensaver from your computer simply erase it from c:windows folder where you have initially copied it or access 'add/rem ove program s' within Control Panel ,locate the screensaver from the installed program s list and hit the 'add/rem ove button'.

Configuring your screensaver

1. Click Start, then click Settings and go to Control Panel. 2. When the Control Panel window opens, double-click on the Display icon. This brings up the Display Properties window. 3. Select the Screensaver tab, and select the screensaver you want to use from the drop-down menu. 4. Determine how many minutes you want the system to be idle before Windows launches the screensaver, and enter that amount of time in the box provided. 5. You can click on Preview to see what it will look like in full-screen use. If you want to change the settings, click Settings. Depending on the screensaver, this window can have one or more options that you can modify. 6. Once you have finished changing the settings, click OK. You can also use the screensaver for security by checking the "Password protected" box. Click OK again and your screensaver is set to go!

? 2006 Mastermen Pty Ltd
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