Changing Windows NT Font’s Size

Environment: VC6 and NT4

How to change Windows NT Font’s size

Sometimes you need to do something and you know it’s possible because Windows does it all the time. However, you want to do it within the code of your program. Searching the net and MSDN often gives Nada.

That’s the time to document the undocumented.

Changing from small fonts to large fonts and vice versa on Windows NT is done by SetupChangeFontSize in SysSetup.dll:

DWORD WINAPI SetupChangeFontSize( HANDLE HWindow,
                                  LPCWSTR lpszFontSize)

the return value in a win32 Error code for example:

ERROR_SUCCESS   ( Value == 0    )  The operation completed successfully.
ERROR_CANCELLED ( Value == 1223 )  The operation was canceled by the user.


#include “windows.h”
///////////////////////////////////////////////////////////////
/// Arnon Mathias 13-Mar-2002
///////////////////////////////////////////////////////////////

DWORD _MyExitWindows(UINT ExitFlags)
{
/// From the ExitWindowsEx Documentation in the MSDN

HANDLE hToken;
TOKEN_PRIVILEGES tkp;
DWORD dwRetVal;

/// Get a token for this process.
if (!OpenProcessToken(GetCurrentProcess(),
TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &hToken))
{
::MessageBox (NULL,”Open Process Token”,”Exit Windows”,MB_OK);
return (GetLastError());
}

/// Get the LUID for the shutdown privilege.
LookupPrivilegeValue(NULL, SE_SHUTDOWN_NAME,
&tkp.Privileges[0].Luid);

tkp.PrivilegeCount = 1; // one privilege to set
tkp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;

/// Get the shutdown privilege for this process.
AdjustTokenPrivileges(hToken, FALSE, &tkp, 0,
(PTOKEN_PRIVILEGES)NULL, 0);

/// Cannot test the return value of AdjustTokenPrivileges.
if ( (dwRetVal = GetLastError()) != ERROR_SUCCESS)
{
::MessageBox (NULL,”AdjustTokenPrivileges”,”Exit Windows”,MB_OK);
return dwRetVal;
}
/// Shut down or Restart according to ExitFlags
::MessageBox ( NULL,
“Restarting Windows”,
“System settings has changed”,
MB_OK);
if (!ExitWindowsEx(ExitFlags, 0))
{
::MessageBox (NULL,
“Error While trying to exit”,
“Exit Windows”,
MB_OK);
return (GetLastError());
}

return ERROR_SUCCESS;
}

DWORD MyRestartWindows()
{
return _MyExitWindows(EWX_LOGOFF|EWX_REBOOT);
}

DWORD _MyChangeFontSize(unsigned short* lpszFontSize)
{
// the font size string must be in unicode format
HMODULE hModule;
hModule = LoadLibrary(“syssetup.dll”);
if (hModule == NULL)
{
return (GetLastError());
}

typedef DWORD (WINAPI* MYPROC) (HANDLE,LPWSTR);
MYPROC ProcAdd;

ProcAdd = (MYPROC) GetProcAddress(hModule,
“SetupChangeFontSize”);
if (ProcAdd == NULL)
{
return (GetLastError());
}

//////////////////////////////////////////////////////////////////
/// Changing the font size:
/// SetupChangeFontSize Gets two parameters:
/// Handle of the calling window (i used NULL)
/// font size string in unicode format:
/// L”120″ for Large fonts
/// L”96″ for Small fonts
/// SetupChangeFontSize returns 0 if everything went fine

DWORD dwRetVal;
dwRetVal = (ProcAdd) (NULL,lpszFontSize);
if (dwRetVal != ERROR_SUCCESS)
{
return dwRetVal;
}
////////////////////////////////////////////////////////////////

if ( !(FreeLibrary(hModule)) )
{
return (GetLastError());
}
return ERROR_SUCCESS;
}

void Change2LargeFonts()
{
DWORD dwRetVal = _MyChangeFontSize(L”120″);
if (dwRetVal == ERROR_SUCCESS)
{
MyRestartWindows();
}
}

void Change2SmallFonts()
{
DWORD dwRetVal = _MyChangeFontSize(L”96″);
if (dwRetVal == ERROR_SUCCESS)
{
MyRestartWindows();
}
}

int main(int argc, char* argv[])
{
// Change2LargeFonts();
Change2SmallFonts();
return 0;
}

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