Preventing Windows Screen-Saver Activation

Originally published on: Tue, 20 Oct 2009 00:54:54 +0000

Some time ago, I wanted to see if the simulated mouse moves generated via calls to the WIN32 API mouse_event function would prevent the screen-saver from triggering.

In the current version of XP ( and some older versions of Windows ) these events do indeed keep the screen-saver from activating.

Please refer to the source below.

busy_mouse.c

// Generate mouse events to prevent the screen-saver from
// activating.
//
// License: MIT / X11
// Copyright (c) 2009 by James K. Lawless
// jimbo@radiks.net http://www.radiks.net/~jimbo
// http://www.mailsend-online.com
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the &amp;quot;Software&amp;quot;), to deal in the Software without
// restriction, including without limitation the rights to use,
// copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED &amp;quot;AS IS&amp;quot;, WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.

// check the state of the Scroll Lock or Caps Lock keys. Return a
// 1 if the requested key is active/on.

#include &amp;lt;windows.h&amp;gt;
#include &amp;lt;stdio.h&amp;gt;
#include &amp;lt;string.h&amp;gt;

#pragma comment(lib,&amp;quot;user32.lib&amp;quot;)

void process_messages(void);

int main(int argc,char **argv) {
   int i;
   printf(&amp;quot;Busy Mouse v1.0 by Jim Lawlessn&amp;quot;);
   printf(&amp;quot;If CAPS LOCK is on, the mouse cursor will move around to prevent any screen-savers from activating.n&amp;quot;);
   for(;;) {
      while(GetKeyState(VK_CAPITAL)&amp;amp;1) {
         for(i=0;i&amp;lt;50;i+=2) {
            mouse_event( MOUSEEVENTF_MOVE,2,0,0,0 );
            process_messages();
         }
         Sleep(200);

         for(i=0;i&amp;lt;50;i+=2) {
            mouse_event( MOUSEEVENTF_MOVE,0,2,0,0 );
            process_messages();
         }
         Sleep(200);

         for(i=0;i&amp;lt;50;i+=2) {
            mouse_event( MOUSEEVENTF_MOVE,-2,0,0,0 );
            process_messages();
         }
         Sleep(200);

         for(i=0;i&amp;lt;50;i+=2) {
            mouse_event( MOUSEEVENTF_MOVE,0,-2,0,0 );
            process_messages();
         }
         Sleep(200);
      }
   }
   processMessages();
}

void process_messages(void) {
MSG m;
while( PeekMessage(&amp;amp;m,0,0,0,PM_REMOVE)) {
    TranslateMessage(&amp;amp;m);
DispatchMessage(&amp;amp;m);
}
}

When you run busy_mouse.exe the program will loop indefinitely. The program checks the CAPS LOCK state. If CAPS LOCK is enabled, it will then move the mouse in a rectangular pattern via mouse_event().

When CAPS LOCK is off, the simulated mouse events halt.

I've used this to keep the screen visible so that I can watch for emails or processes that run long while I'm away from the mouse and keyboard.

The source and executable file for busy_mouse can be downloaded in a single archive at: http://www.mailsend-online.com/wp/busy_mouse.zip

Unless otherwise noted, all code and text entries are Copyright Š2009 by James K. Lawless

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