    --------------------------------------------------------------------------------
    -- |
    -- Module      :  Graphics.Rendering.OpenGL.GL.PixelRectangles.Minmax
    -- Copyright   :  (c) Sven Panne 2002-2006
    -- 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 ( alloca )
    import Foreign.Ptr ( Ptr )
    import Graphics.Rendering.OpenGL.GL.Capability (
       EnableCap(CapMinmax), makeStateVarMaybe )
    import Graphics.Rendering.OpenGL.GL.BasicTypes ( GLboolean, GLenum, GLint )
    import Graphics.Rendering.OpenGL.GL.Extensions (
       FunPtr, unsafePerformIO, Invoker, getProcAddress )
    import Graphics.Rendering.OpenGL.GL.PeekPoke ( peek1 )
    import Graphics.Rendering.OpenGL.GL.PixelRectangles.ColorTable (
       PixelInternalFormat )
    import Graphics.Rendering.OpenGL.GL.PixelRectangles.Rasterization (
        PixelData(..) )
    import Graphics.Rendering.OpenGL.GL.PixelData ( withPixelData )
    import Graphics.Rendering.OpenGL.GL.Texturing.PixelInternalFormat (
       marshalPixelInternalFormat', unmarshalPixelInternalFormat )
    import Graphics.Rendering.OpenGL.GL.PixelRectangles.Histogram (
       Reset(..), Sink )
    import Graphics.Rendering.OpenGL.GL.PixelRectangles.Reset (
       marshalReset )
    import Graphics.Rendering.OpenGL.GL.PixelRectangles.Sink (
       marshalSink, unmarshalSink )
    import Graphics.Rendering.OpenGL.GL.StateVar ( StateVar )

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

    #include "HsOpenGLExt.h"

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

    data MinmaxTarget =
         Minmax

    marshalMinmaxTarget :: MinmaxTarget -> GLenum
    marshalMinmaxTarget x = case x of
       Minmax -> 0x802e

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

    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)

    EXTENSION_ENTRY("GL_ARB_imaging",glMinmax,GLenum -> GLenum -> GLboolean -> IO ())

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

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

    EXTENSION_ENTRY("GL_ARB_imaging",glGetMinmax,GLenum -> GLboolean -> GLenum -> GLenum -> Ptr a -> IO ())

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

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

    EXTENSION_ENTRY("GL_ARB_imaging",glResetMinmax,GLenum -> IO ())

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

    data GetMinmaxParameterPName =
         MinmaxFormat
       | MinmaxSink

    marshalGetMinmaxParameterPName :: GetMinmaxParameterPName -> GLenum
    marshalGetMinmaxParameterPName x = case x of
       MinmaxFormat -> 0x802f
       MinmaxSink -> 0x8030

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

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

    EXTENSION_ENTRY("GL_ARB_imaging",glGetMinmaxParameteriv,GLenum -> GLenum -> Ptr GLint -> IO ())