How to Use SystemParametersInfo API for Control Panel Settings

- Standard and Professional Editions of Microsoft Visual Basic for

  Windows, versions 2.0 and 3.0

SUMMARY

The SystemParametersInfo API call can be used to get and set Windows settings that are normally set from the Desktop by using the Control Panel.

MORE INFORMATION

You can call the SystemParametersInfo API to set and get all the settings controlled by the Windows Control Panel. Normally a user would have to choose the Windows Control Panel to view or change system settings such as granularity, wallpaper, or icon title wrap. Instead of forcing the user to set things manually using the Control Panel you can have your program call the SystemParametersInfo API to set them automatically.

Use the following Visual Basic for Windows Declare for the API. Enter it all as one, single line:

   Declare Function SystemParametersInfo Lib "User" (ByVal uAction
      As Integer, ByVal uparam As Integer, lpvParam As Any, ByVal fuWinIni
      As Integer) As Integer

   uAction    system parameter to query or set
   uParam     depends on system parameter
   lpvParam   depends on system parameter
   fuWinIni   WIN.INI update flag

   CONST SPI_GETBEEP=1
   CONST SPI_SETBEEP=2
   CONST SPI_GETMOUSE=3
   CONST SPI_SETMOUSE=4
   CONST SPI_GETBORDER=5
   CONST SPI_SETBORDER=6
   CONST SPI_GETKEYBOARDSPEED=10
   CONST SPI_SETKEYBOARDSPEED=11
   CONST SPI_LANGDRIVER=12
   CONST SPI_ICONHORIZONTALSPACING=13
   CONST SPI_GETSCREENSAVETIMEOUT=14
   CONST SPI_SETSCREENSAVETIMEOUT=15
   CONST SPI_GETSCREENSAVEACTIVE=16
   CONST SPI_SETSCREENSAVEACTIVE=17
   CONST SPI_GETGRIDGRANULARITY=18
   CONST SPI_SETGRIDGRANULARITY=19
   CONST SPI_SETDESKWALLPAPER=20
   CONST SPI_SETDESKPATTERN=21
   CONST SPI_GETKEYBOARDDELAY=22
   CONST SPI_SETKEYBOARDDELAY=23
   CONST SPI_ICONVERTICALSPACING=24
   CONST SPI_GETICONTITLEWRAP=25
   CONST SPI_SETICONTITLEWRAP=26
   CONST SPI_GETMENUDROPALIGNMENT=27
   CONST SPI_SETMENUDROPALIGNMENT=28
   CONST SPI_SETDOUBLECLKWIDTH=29
   CONST SPI_SETDOUBLECLKHEIGHT=30
   CONST SPI_GETICONTITLELOGFONT=31
   CONST SPI_SETDOUBLECLICKTIME=32
   CONST SPI_SETMOUSEBUTTONSWAP=33
   CONST SPI_SETICONTITLELOGFONT=34
   CONST SPI_GETFASTTASKSWITCH=35
   CONST SPI_SETFASTTASKSWITCH=36

When used with a GET constant, the lpvParam argument returns the current value of the setting. When used with a SET constant, it is a NULL. The exceptions to these rules are documented in the Windows version 3.1 SDK help file.

The fuWinIni argument updates the WIN.INI file:

   Const SPIF_SENDWININICHANGE = &H2
   Const SPIF_UPDATEINIFILE = &H1

Example One

 icon spacing setting. The following example gives the correct arguments

1. Create a Visual Basic project, and add the following controls to a form:

      Control Name   Caption
      ----------------------
      Command1       Read
      Command2       Set
      Text1
      Label1         Icon Horizontal Spacing
   
   

2. Add the following code to the general declarations section of the form:

   Const SPIF_SENDWININICHANGE = &H2 Const SPIF_UPDATEINIFILE = &H1 Const SPI_ICONHORIZONTALSPACING = 13 Dim uAction As Integer Dim uparam As Integer

      ' Enter the following Declare as one, single line:
      Declare Function SystemParametersInfo Lib "User" (ByVal uAction As
         Integer, ByVal uparam As Integer, lpvParam As Any, ByVal fuWinIni As
         Integer) As Integer
   
   

3. Add the following code to the Command1_Click event:

   uAction = 0 uparam = 0 ret% = SystemParametersInfo(SPI_ICONHORIZONTALSPACING, uAction, uparam, SPIF_UPDATEINIFILE Or SPIF_SENDWININICHANGE) text1.Text = uparam

4. Add the following code to the Command2_Click event:

   uAction = Val(text1.Text) uparam = 0

      ' Enter the following as one, single line:
      x% = SystemParametersInfo(SPI_ICONHORIZONTALSPACING, uAction,
         ByVal 0&, SPIF_UPDATEINIFILE Or SPIF_SENDWININICHANGE)
   
   

5. Run the program, and click the Read button. The current setting of the icon horizontal spacing will be displayed in the Text1 box. Enter a new number(32 is the lowest setting accepted) in the Text1 box, and click the Read button. The spacing will be reset. To see the new setting, bring up the Windows Task list, and choose Arrange Icons.

Example Two

1. Create a Visual Basic project and add the following controls to a form:

      Control Name   Caption
      -----------------------------
      Command1       Wrapping True
      Command2       Wrapping False
   
   

2. Add the following code to the general declarations section of the form:

      ' Enter the following Declare as one, single line:
      Declare Function SystemParametersInfo Lib "User" (ByVal uAction As
         Integer, ByVal uparam As Integer, lpvParam As Any, ByVal fuWinIni As
         Integer) As Integer
      Const SPI_SETICONTITLEWRAP = 26
      Const SPIF_SENDWININICHANGE = &H2
      Const SPIF_UPDATEINIFILE = &H1
   
   

3. Add the following code to the Command1 Click event:

      ' Enter the following as one, single line:
      x% = SystemParametersInfo(SPI_SETICONTITLEWRAP, True, 0&,
         SPIF_UPDATEINIFILE Or SPIF_SENDWININICHANGE)
   
   

4. Add the following code to the Command2 Click event:

      ' Enter the following as one, single line:
      x% = SystemParametersInfo(SPI_SETICONTITLEWRAP, False, 0&,
         SPIF_UPDATEINIFILE Or SPIF_SENDWININICHANGE)
   
   

5. Run the program and watch the icon titles as you click the two buttons.

Example Three

1. Create a Visual Basic project and add the following controls to a form:

      Control Name   Caption
      -----------------------------
      Command1       Change Wallpaper to Rivets
   
   

2. Add the following code to the general declarations section of the form:

   Const SPIF_UPDATEINIFILE = &H1 Const SPI_SETDESKWALLPAPER = 20 Const SPIF_SENDWININICHANGE = &H2

      ' Enter the following Declare as one, single line:
      Declare Function SystemParametersInfo Lib "User" (ByVal uAction As
         Integer, ByVal uparam As Integer, ByVal lpvParam As String, ByVal
         fuWinIni As Integer) As Integer
   
   

3. Add the following code to the Command1 Click event:

      Sub Command1_Click ()
         filenm$ = "C:\Windows\rivets.bmp"
   
         ' Enter the following two lines as one, single line:
         x% = SystemParametersInfo(SPI_SETDESKWALLPAPER, 0&,
            filenm$, SPIF_UPDATEINIFILE Or SPIF_SENDWININICHANGE)
      End Sub
   
   

4. Run the program and watch the wallpaper change to RIVETS.BMP.