SDL_DisplayFormatAlpha - Convert a surface to the display format

       This  function takes a surface and copies it to a new surface of the pixel format and colors of the video
       framebuffer plus an alpha channel, suitable  for  fast  blitting  onto  the  display  surface.  It  calls
       SDL_ConvertSurface

       If  you  want  to  take  advantage  of  hardware  colorkey or alpha blit acceleration, you should set the
       colorkey and alpha value before calling this function.

       This function can be used to convert a colourkey to an alpha channel, if the SDL_SRCCOLORKEY flag is  set
       on  the  surface.  The  generated  surface  will then be transparent (alpha=0) where the pixels match the
       colourkey, and opaque (alpha=255) elsewhere.

       SDL_DisplayFormatAlpha - Convert a surface to the display format

       If the conversion fails or runs out of memory, it returns NULL

SDL_ConvertSurface, SDL_SetAlpha, SDL_SetColorKey, SDL_DisplayFormat, SDL_Surface

SDL                                          Tue 11 Sep 2001, 23:01                    SDL_DisplayFormatAlpha(3)

#include"SDL.h"SDL_Surface*SDL_DisplayFormatAlpha(SDL_Surface*surface);