Change System Settings? SystemParametersInfo()!
I needed to change ClearType settings programmatically. So, I tried to modify registry key values. It worked! But, it did after rebooting. :(
What if you would like to make it effective right away as you click ok button on the control panel?
Write some code with this function:
https://msdn2.microsoft.com/en-us/library/ms724947.aspx
In case of ClearType, settings as follows work:
SPI_SETFONTSMOOTHING (TRUE)
SPI_SETFONTSMOOTHINGCONTRAST (machine specific, 1600 works for me)
SPI_SETFONTSMOOTHINGORIENTATION (depending on your monitor pixel orientation, usually FE_FONTSMOOTHINGORIENTATIONRGB)
SPI_SETFONTSMOOTHINGTYPE (FE_FONTSMOOTHINGCLEARTYPE)