C# Signature:
[DllImport("user32.dll", SetLastError = true)]
static extern bool SystemParametersInfo(uint uiAction, uint uiParam,
IntPtr pvParam, uint fWinIni);
User-Defined Types:
Notes:
None.
Tips & Tricks:
Please add some!
Sample Code:
// This code works for SPI_GETFOREGROUNDLOCKTIMEOUT, the above signature doesn't. (Ken)
[DllImport("user32.dll", EntryPoint="SystemParametersInfo", SetLastError = true)]
public static extern bool SystemParametersInfoGet(uint action, uint param, ref uint vparam, uint init);
[DllImport("user32.dll", EntryPoint="SystemParametersInfo", SetLastError = true)]
public static extern bool SystemParametersInfoSet(uint action, uint param, uint vparam, uint init);
// get current lock timeout value
uint timeout = 99;
bool retVal = SystemParametersInfoGet(SPI_GETFOREGROUNDLOCKTIMEOUT, 0, ref timeout, 0);
// set current lock timeout value to 0, so focus can be grabbed
SystemParametersInfoSet(SPI_SETFOREGROUNDLOCKTIMEOUT, 0, 0, 0);
SPI_GETNONCLIENTMETRICS is a good way to get user-defined preferences for fonts, colors, icons, etc. There is no other way to do this in .NET as far as I know!
// We can overload this definition, since that's in effect what the unmanaged
// API does anyway.
[DllImport("user32", CharSet=CharSet.Auto)]
private static extern int SystemParametersInfo(int uAction,
int uParam, ref NONCLIENTMETRICS lpvParam, int fuWinIni);
private const int LF_FACESIZE = 32;
// A "logical font" used by old-school windows
[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
private struct LOGFONT
{
public int lfHeight;
public int lfWidth;
public int lfEscapement;
public int lfOrientation;
public int lfWeight;
public byte lfItalic;
public byte lfUnderline;
public byte lfStrikeOut;
public byte lfCharSet;
public byte lfOutPrecision;
public byte lfClipPrecision;
public byte lfQuality;
public byte lfPitchAndFamily;
/// <summary>
/// <see cref="UnmanagedType.ByValTStr"/> means that the string
/// should be marshalled as an array of TCHAR embedded in the
/// structure. This implies that the font names can be no larger
/// than <see cref="LF_FACESIZE"/> including the terminating '\0'.
/// That works out to 31 characters.
/// </summary>
[MarshalAs(UnmanagedType.ByValTStr, SizeConst=LF_FACESIZE)]
public string lfFaceName;
// to shut it up about the warnings
public LOGFONT(string lfFaceName)
{
this.lfFaceName = lfFaceName;
lfHeight = lfWidth = lfEscapement = lfOrientation = lfWeight = 0;
lfItalic = lfUnderline = lfStrikeOut = lfCharSet = lfOutPrecision
= lfClipPrecision = lfQuality = lfPitchAndFamily = 0;
}
}
private struct NONCLIENTMETRICS
{
public int cbSize;
public int iBorderWidth;
public int iScrollWidth;
public int iScrollHeight;
public int iCaptionWidth;
public int iCaptionHeight;
/// <summary>
/// Since <see cref="LOGFONT"/> is a struct instead of a class,
/// we don't have to do any special marshalling here. Much
/// simpler this way.
/// </summary>
public LOGFONT lfCaptionFont;
public int iSMCaptionWidth;
public int iSMCaptionHeight;
public LOGFONT lfSMCaptionFont;
public int iMenuWidth;
public int iMenuHeight;
public LOGFONT lfMenuFont;
public LOGFONT lfStatusFont;
public LOGFONT lfMessageFont;
}
private const int SPI_GETNONCLIENTMETRICS = 41;
OK, so here is how you query for the NONCLIENTMETRICS
NONCLIENTMETRICS metrics = new NONCLIENTMETRICS();
metrics.cbSize = Marshal.SizeOf(metrics);
SystemParametersInfo(SPI_GETNONCLIENTMETRICS, 0, ref metrics, 0);
Now you can use the font info however you want. Here's how to return a GDI+ Font corresponding to the MessageBox font selected by the user. Note that the height is always negative and always returns "world" units.
return new Font(Metrics.lfMessageFont.lfFaceName,
-Metrics.lfMessageFont.lfHeight,
GraphicsUnit.World);
Alternative Managed API:
The System.Windows.Forms.SystemInformation managed class, which uses SystemParametersInfo internally, has many static properties containing user information, system setup, and preferences.
