| BOOL SystemParametersInfo(uAction, uParam, lpvParam, fuWinIni) | |||||
| UINT uAction; | /* system parameter to query or set | */ | |||
| UINT uParam; | /* depends on system parameter | */ | |||
| void FAR* lpvParam; | /* depends on system parameter | */ | |||
| UINT fuWinIni; | /* WIN.INI update flag | */ | |||
The SystemParametersInfo function queries or sets system-wide parameters. This function can also update the WIN.INI file while setting a parameter.
uAction
Specifies the system-wide parameter to query or set. This parameter can be one of the following values:
| Value | Meaning |
| SPI_GETBEEP | Retrieves a BOOL value that indicates whether the warning beep is on or off. |
| SPI_GETBORDER | Retrieves the border multiplying factor that determines the width of a window's sizing border. |
| SPI_GETFASTTASKSWITCH | Determines whether fast task switching is on or off. |
| SPI_GETGRIDGRANULARITY | Retrieves the current granularity value of the desktop sizing grid. |
| SPI_GETICONTITLELOGFONT | Retrieves the logical-font information for the current icon-title font. |
| SPI_GETICONTITLEWRAP | Determines whether icon-title wrapping is on or off. |
| SPI_GETKEYBOARDDELAY | Retrieves the keyboard repeat-delay setting. |
| SPI_GETKEYBOARDSPEED | Retrieves the keyboard repeat-speed setting. |
| SPI_GETMENUDROPALIGNMENT | Determines whether pop-up menus are left-aligned or right-aligned relative to the corresponding menu-bar item. |
| SPI_GETMOUSE | Retrieves the mouse speed and the mouse threshold values, which Windows uses to calculate mouse acceleration. |
| SPI_GETSCREENSAVEACTIVE | Retrieves a BOOL value that indicates whether screen saving is on or off. |
| SPI_GETSCREENSAVETIMEOUT | Retrieves the screen-saver time-out value. |
| SPI_ICONHORIZONTALSPACING | Sets the width, in pixels, of an icon cell. |
| SPI_ICONVERTICALSPACING | Sets the height, in pixels, of an icon cell. |
| SPI_LANGDRIVER | Forces the user to load a new language driver. |
| SPI_SETBEEP | Turns the warning beep on or off. |
| SPI_SETBORDER | Sets the border multiplying factor that determines the width of a window's sizing border. |
| SPI_SETDESKPATTERN | Sets the current desktop pattern to the value specified in the Pattern entry in the WIN.INI file or to the pattern specified by the lpvParam parameter. |
| SPI_SETDESKWALLPAPER | Specifies the filename that contains the bitmap to be used as the desktop wallpaper. |
| SPI_SETDOUBLECLKHEIGHT | Sets the height of the rectangle within which the second click of a double-click must fall for it to be registered as a double-click. |
| SPI_SETDOUBLECLICKTIME | Sets the double-click time for the mouse. The double-click time is the maximum number of milliseconds that may occur between the first and second clicks of a double-click. |
| SPI_SETDOUBLECLKWIDTH | Sets the width of the rectangle in which the second click of a double-click must fall to be registered as a double-click. |
| SPI_SETFASTTASKSWITCH | Turns fast task switching on or off. |
| SPI_SETGRIDGRANULARITY | Sets the granularity of the desktop sizing grid. |
| SPI_SETICONTITLELOGFONT | Sets the font that is used for icon titles. |
| SPI_SETICONTITLEWRAP | Turns icon-title wrapping on or off. |
| SPI_SETKEYBOARDDELAY | Sets the keyboard repeat-delay setting. |
| SPI_SETKEYBOARDSPEED | Sets the keyboard repeat-speed setting. |
| SPI_SETMENUDROPALIGNMENT | Sets the alignment value of pop-up menus. |
| SPI_SETMOUSE | Sets the mouse speed and the x and y mouse-threshold values. |
| SPI_SETMOUSEBUTTONSWAP | Swaps or restores the meaning of the left and right mouse buttons. |
| SPI_SETSCREENSAVEACTIVE | Sets the state of the screen saver. |
| SPI_SETSCREENSAVETIMEOUT | Sets the screen-saver time-out value. |
uParam
Depends on the uAction parameter. For more information, see the following Comments section.
lpvParam
Depends on the uAction parameter. For more information, see the following Comments section.
fuWinIni
If a system parameter is being set, specifies whether the WIN.INI file is updated, and if so, whether the WM_WININICHANGE message is broadcast to all top-level windows to notify them of the change. This parameter can be a combination of the following values:
| Value | Meaning |
| SPIF_UPDATEINIFILE | Writes the new system-wide parameter setting to the WIN.INI file. |
| SPIF_SENDWININICHANGE | Broadcasts a WM_WININICHANGE message after WIN.INI is updated. This flag has no effect if SPIF_UPDATEINIFILE is not specified. |
The return value is nonzero if the function is successful. Otherwise, it is zero.
The SystemParameterInfo function is intended for applications, such as Control Panel, that allow the user to customize the Windows environment.
The following table describes the uParam and lpvParam parameters for each SPI_ constant:
| Constant | uParam | lpvParam |
| SPI_GETBEEP | 0 | Points to a BOOL variable that receives TRUE if the beep is on, FALSE if it is off. | |
| SPI_GETBORDER | 0 | Points to an integer variable that receives the border multiplying factor. | |
| SPI_GETFASTTASKSWITCH | 0 | Points to a BOOL variable that receives TRUE if fast task switching is on, FALSE if it is off. | |
| SPI_GETGRIDGRANULARITY | 0 | Points to an integer variable that receives the grid-granularity value. | |
| SPI_GETICONTITLELOGFONT | Size of LOGFONT structure | Points to a LOGFONT structure that receives the logical-font information. | |
| SPI_GETICONTITLEWRAP | 0 | Points to a BOOL variable that receives TRUE if wrapping is on, FALSE if wrapping is off. | |
| SPI_GETKEYBOARDDELAY | 0 | Points to an integer variable that receives the keyboard repeat-delay setting. | |
| SPI_GETKEYBOARDSPEED | 0 | Points to a WORD variable that receives the current keyboard repeat-speed setting. | |
| SPI_GETMENUDROPALIGNMENT | 0 | Points to a BOOL variable that receives TRUE if pop-up menus are right-aligned, FALSE if they are left-aligned. | |
| SPI_GETMOUSE | 0 | Points to an integer array name lpiMouse, where lpiMouse[0] receives the WIN.INI entry MouseThreshold1, lpiMouse[1] receives the entry MouseThreshold2, and lpiMouse[2] receives the entry MouseSpeed. | |
| SPI_GETSCREENSAVEACTIVE | 0 | Points to a BOOL variable that receives TRUE if the screen saver is active, FALSE if it is not. | |
| SPI_GETSCREENSAVETIMEOUT | 0 | Points to an integer variable that receives the screen-saver time-out value, in milliseconds. | |
| SPI_ICONHORIZONTALSPACING | New width, in pixels, for horizontal spacing of icons | Is NULL if the icon cell width, in pixels, is returned in uParam. If this value is a pointer to an integer, the current horizontal spacing is returned in that variable and uParam is ignored. | |
| SPI_ICONVERTICALSPACING | New height, in pixels, for vertical spacing of icons | Is NULL if the icon cell height, in pixels, is returned in uParam. If this value is a pointer to an integer, the current vertical spacing is returned in that variable and uParam is ignored. | |
| SPI_LANGDRIVER | 0 | Points to a string containing the new language driver filename. The application should make sure that all other international settings remain consistent when changing the language driver. | |
| SPI_SETBEEP | TRUE = turn the beep on; FALSE = turn the beep off | Is NULL. | |
| SPI_SETBORDER | Border multiplying factor | Is NULL. | |
| SPI_SETDESKPATTERN | 0 or –1 | Specifies the desktop pattern. If this value is NULL and the uParam parameter is –1, the value is reread from the WIN.INI file. This value can also be a null-terminated string (LPSTR) containing a sequence of 8 numbers that represent the new desktop pattern; for example, “170 85 170 85 170 85 170 85” represents a 50% gray pattern. | |
| SPI_SETDESKWALLPAPER | 0 | Points to a string that specifies the name of the bitmap file. | |
| SPI_SETDOUBLECLKHEIGHT | Double-click height, in pixels | Is NULL. | |
| SPI_SETDOUBLECLICKTIME | Double-click time, in milliseconds | Is NULL. | |
| SPI_SETDOUBLECLKWIDTH | Double-click width, in pixels | Is NULL. | |
| SPI_SETFASTTASKSWITCH | TRUE = turn on fast task switching; FALSE = turn it off | Is NULL. | |
| SPI_SETGRIDGRANULARITY | Grid granularity, , | ||
| SPI_SETICONTITLELOGFONT | Size of the LOGFONT structure | Points to a LOGFONT structure that defines the font to use for icon titles. If uParam is set to zero and lParam is set to NULL, Windows uses the icon-title font and spacings that were in effect when Windows was started. | |
| SPI_SETICONTITLEWRAP | TRUE = turn wrapping on; FALSE = turn wrapping off | Is NULL. | |
| SPI_SETKEYBOARDDELAY | Keyboard-delay setting | Is NULL. | |
| SPI_SETKEYBOARDSPEED | Repeat-speed setting | Is NULL. | |
| SPI_SETMENUDROPALIGNMENT | TRUE = right-alignment; FALSE = left-alignment | Is NULL. | |
| SPI_SETMOUSE | 0 | Points to an integer array named lpiMouse, where lpiMouse[0] receives the WIN.INI entry xMouseThreshold, lpiMouse[1] receives the entry yMouseThreshold, and lpiMouse[2] receives the entry MouseSpeed. | |
| SPI_SETMOUSEBUTTONSWAP | TRUE = reverse the meaning of the left and right mouse buttons; FALSE = restore the buttons to their original meanings | Is NULL. | |
| SPI_SETSCREENSAVEACTIVE | TRUE = activate screen saving; FALSE = deactivate screen saving | Is NULL. | |
| SPI_SETSCREENSAVETIMEOUT | Idle time-out duration, in seconds, before screen is saved | Is NULL. | |
The following example retrieves the value for the DoubleClickSpeed entry from the WIN.INI file and uses the value to initialize an edit control. In this example, while the WM_COMMAND message is being processed, the user-specified value is retrieved from the edit control and used to set the double-click time.
char szBuf[32];
int iResult;
case WM_INITDIALOG:
/* Initialize edit control to the current double-click time. */
iResult = GetProfileInt("windows",
"DoubleClickSpeed", 550);
itoa(iResult, szBuf, 10);
SendDlgItemMessage(hdlg, IDD_DCLKTIME, WM_SETTEXT, 0,
(DWORD) (LPSTR) szBuf);
.
. /* Initialize any other controls. */
.
return FALSE;
case WM_COMMAND:
switch(wParam) {
case IDOK:
/* Set double-click time to a user-specified value. */
SendDlgItemMessage(hdlg, IDD_DCLKTIME, WM_GETTEXT,
sizeof(szBuf), (DWORD) (LPSTR) szBuf);
SystemParametersInfo(SPI_SETDOUBLECLICKTIME, atoi(szBuf),
(LPVOID) NULL, SPIF_UPDATEINIFILE |
SPIF_SENDWININICHANGE);
.
. /* Set any other system-wide parameters. */
.
EndDialog(hdlg, TRUE);
return TRUE;
}