how to use the "SPI_SETMOUSETRAILS" Parameters - windows

Question

I am learning Win32 API programming. I read this paragraph, it says:
https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-systemparametersinfoa
SPI_SETMOUSETRAILS
Enables or disables the Mouse Trails feature, which improves the visibility of mouse cursor movements by briefly showing a trail of cursors and quickly erasing them.
To disable the feature, set the uiParam parameter to zero or 1. To enable the feature, set uiParam to a value greater than 1 to indicate the number of cursors drawn in the trail.
Windows 2000: This parameter is not supported.
I tried to write the following code:
#include <windows.h>
int main(int argc, char *argv[], char *envp[])
{
//SystemParametersInfo(SPI_SETMOUSETRAILS, NULL,(PVOID)10, 0);
SystemParametersInfo(SPI_SETMOUSETRAILS, NULL,(PVOID)0, 0);
}
But it doesn't seem to make a difference.
Can anyone tell me how this macro works? I couldn't find an example on the Internet, so I am asking here.

Answer 1

Read the documentation again more carefully:
To disable the feature, set the uiParam parameter to zero or 1. To enable the feature, set uiParam to a value greater than 1 to indicate the number of cursors drawn in the trail.
Look at the declaration of the function:
BOOL SystemParametersInfoA(
UINT uiAction,
UINT uiParam,
PVOID pvParam,
UINT fWinIni
);
Your code is setting the uiParam parameter to 0 (disabling the feature), and setting the pvParam parameter to the cursor count (which is ignored).
Try this instead:
#include <windows.h>
int main(int argc, char *argv[], char *envp[])
{
UINT cursorCount = ...;
SystemParametersInfo(SPI_SETMOUSETRAILS, cursorCount, NULL, 0);
return 0;
}
I couldn't find an example on the Internet
Really? When I enter just SPI_SETMOUSETRAILS by itself into Google, literally the 1st link returned contains an example:
http://ntcoder.com/bab/tag/spi_setmousetrails/
SystemParametersInfo is a powerful function which does and retrieves whole lot of things related to windows general behavior for eg: turning on and off certain features like mouse trails which we normally do via control panel->main.cpl
Look up MSDN for more information on SystemParametersInfo. I’ll just show a demo on how to turn on and off mouse trails…
// Turn on mouse trails, showing 10 cursors drawn in the trail
SystemParametersInfo( SPI_SETMOUSETRAILS, 10, 0, 0 );
// Turn off mouse trails, set trail count to 1 or zero to disable trails
SystemParametersInfo( SPI_SETMOUSETRAILS, 1, 0, 0 );