This function returns the previous mode and sets the new mode for the current drawing surface in the range 0-5 inclusive with the
SmoothingModeDefault = 0 (no smoothing)
SmoothingModeHighSpeed = 1 (no smoothing)
SmoothingModeHighQuality = 2 (8x4 box filter)
SmoothingModeNone = 3 (no smoothing)
SmoothingModeAntiAlias8x4 = 4 (8x4 box filter)
SmoothingModeAntiAlias8x8 = 5 (8x8 box filter)
Smoothing performed by an 8 X 4 box filter gives better results for nearly vertical lines than it does for nearly horizontal lines. Smoothing performed by an 8 X 8 box filter gives equally good results for nearly vertical and nearly horizontal lines. The 8x8 algorithm produces higher quality smoothing but is slower than the 8 X 4 algorithm.
Note that, if the current opacity is 256 then calling SET_SMOOTHING_MODE@ will set the opacity to 255 to activate the GDI+ library.
%gr[smooth4] sets the opacity to 255 and the smoothing mode to 4.
%gr[smooth8] sets the opacity to 255 and the smoothing mode to 5.