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September 24, 2020
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Quickstart Guide to Screensavers

  • By Karl Moore
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Your actual screensaver needs to be able to handle user responses. When the mouse moves, it needs to quit or prompt for a password. The cursor should be invisible and the task keys should be disabled. This section handles these issues.

Hiding the Cursor

  • Add the following API declaration to a module in your screensaver application:
Declare Function ShowCursor Lib "user32" _    (ByVal bShow As Long) As Long
  • Pass the ShowCursor API call a True or False to show or hide the cursor, respectively. For example, this code hides the cursor: Call ShowCursor(False)

Disabling Task Keys

Task key combinations, such as CTRL-ALT-DEL, ALT-TAB and CTRL-F4, should be disabled when your screensaver starts, then re-enabled when it quits.

  • Add the following code to a module in your screensaver application:
Private Const SPI_SCREENSAVERRUNNING = 97&Declare Function SystemParametersInfo Lib "user32" _    Alias "SystemParametersInfoA" (ByVal uAction As _    Long, ByVal uParam As Long, lpvParam As Any, ByVal _    fuWinIni As Long) As LongPublic Sub EnableTaskKeys(Enabled As Boolean)If Enabled = False Then    'Disable CTRL+ALT+DELETE    SystemParametersInfo SPI_SCREENSAVERRUNNING, 1&, 0&, 0Else    ' Enable CTRL+ALT+DELETE    SystemParametersInfo SPI_SCREENSAVERRUNNING, 0&, 0&, 0End IfEnd Sub
  • To use this code, run the EnableTaskKeys method, passing a True or False argument to enable or disable the task keys respectively. For example, to enable the task keys, run: EnableTaskKeys (True)

Checking for Mouse Movement

You need to monitor mouse movement in your screensaver, so you know when to either quit or prompt for a password.

  • Add the following code behind the MouseMove event of your Form:
Static intMoveCount As IntegerIntMoveCount = intMoveCount + 1If intMoveCount > 5 Then Unload MyScreenSaverForm




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This article was originally published on November 20, 2002

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