i have this code:

[pascal]
function LoadGLTexture(filename: string; var TextureID : GLuInt ): Boolean;
var
// Create storage space for the texture
TextureImage: PSDL_Surface;
begin
// Load The Bitmap, Check For Errors, If Bitmap's Not Found Quit
TextureImage := IMG_Load(pchar(filename));
[/pascal]

that uses sdl_image..
How ho i check if the loaded image has alpha channel or not ? i've looked at the TSDL_Surface and PixelFormat but i've found nothing..

Thanks