    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.Rendering.OpenGL.GL.PixelRectangles.Minmax
    -- Copyright   :  (c) Sven Panne 2002-2009
    -- License     :  BSD-style (see the file libraries/OpenGL/LICENSE)
    --
    -- Maintainer  :  sven.panne@aedion.de
    -- Stability   :  stable
    -- Portability :  portable
    --
    -- This module corresponds to a part of section 3.6.1 (Pixel Storage Modes) of
    -- the OpenGL 2.1 specs.
    --
    --------------------------------------------------------------------------------

    module Graphics.Rendering.OpenGL.GL.PixelRectangles.Minmax (
       minmax, getMinmax, resetMinmax
    ) where

    import Foreign.Marshal.Alloc
    import Graphics.Rendering.OpenGL.GL.StateVar
    import Graphics.Rendering.OpenGL.GL.Capability
    import Graphics.Rendering.OpenGL.GL.PeekPoke
    import Graphics.Rendering.OpenGL.GL.PixelData
    import Graphics.Rendering.OpenGL.GL.PixelRectangles.Reset
    import Graphics.Rendering.OpenGL.GL.PixelRectangles.Sink
    import Graphics.Rendering.OpenGL.GL.Texturing.PixelInternalFormat
    import Graphics.Rendering.OpenGL.Raw.ARB.Compatibility (
       glGetMinmax, glGetMinmaxParameteriv, glMinmax, glResetMinmax, gl_MINMAX,
       gl_MINMAX_FORMAT, gl_MINMAX_SINK )
    import Graphics.Rendering.OpenGL.Raw.Core31

    --------------------------------------------------------------------------------

    data MinmaxTarget =
         Minmax

    marshalMinmaxTarget :: MinmaxTarget -> GLenum
    marshalMinmaxTarget x = case x of
       Minmax -> gl_MINMAX

    --------------------------------------------------------------------------------

    minmax :: StateVar (Maybe (PixelInternalFormat, Sink))
    minmax = makeStateVarMaybe (return CapMinmax) getMinmax' setMinmax

    getMinmax' :: IO (PixelInternalFormat, Sink)
    getMinmax' = do
       f <- getMinmaxParameteri unmarshalPixelInternalFormat MinmaxFormat
       s <- getMinmaxParameteri unmarshalSink MinmaxSink
       return (f, s)

    setMinmax :: (PixelInternalFormat, Sink) -> IO ()
    setMinmax (int, sink) =
       glMinmax
          (marshalMinmaxTarget Minmax)
          (marshalPixelInternalFormat' int)
          (marshalSink sink)

    --------------------------------------------------------------------------------

    getMinmax :: Reset -> PixelData a -> IO ()
    getMinmax reset pd =
       withPixelData pd $
          glGetMinmax (marshalMinmaxTarget Minmax) (marshalReset reset)

    --------------------------------------------------------------------------------

    resetMinmax :: IO ()
    resetMinmax = glResetMinmax (marshalMinmaxTarget Minmax)

    --------------------------------------------------------------------------------

    data GetMinmaxParameterPName =
         MinmaxFormat
       | MinmaxSink

    marshalGetMinmaxParameterPName :: GetMinmaxParameterPName -> GLenum
    marshalGetMinmaxParameterPName x = case x of
       MinmaxFormat -> gl_MINMAX_FORMAT
       MinmaxSink -> gl_MINMAX_SINK

    --------------------------------------------------------------------------------

    getMinmaxParameteri :: (GLint -> a) -> GetMinmaxParameterPName -> IO a
    getMinmaxParameteri f p =
       alloca $ \buf -> do
          glGetMinmaxParameteriv
             (marshalMinmaxTarget Minmax)
             (marshalGetMinmaxParameterPName p)
             buf
          peek1 f buf