content: -------------------------------------------------------------------------------
  --- $Id: CairoDrawing.hs#3 2009/07/18 22:48:30 REDMOND\\satnams $
  --- $Source: //depot/satnams/haskell/ThreadScope/CairoDrawing.hs $
  -------------------------------------------------------------------------------
  
  module GUI.Timeline.CairoDrawing
  where
  
  import Graphics.Rendering.Cairo
  import qualified Graphics.Rendering.Cairo as C
  import Control.Monad
  
  -------------------------------------------------------------------------------
  
  {-# INLINE draw_line #-}
  draw_line :: (Integral a, Integral b, Integral c, Integral d) =>
               (a, b) -> (c, d) -> Render ()
  draw_line (x0, y0) (x1, y1)
    = do move_to (x0, y0)
         lineTo (fromIntegral x1) (fromIntegral y1)
         stroke
  
  {-# INLINE move_to #-}
  move_to :: (Integral a, Integral b) => (a, b) -> Render ()
  move_to (x, y)
    = moveTo (fromIntegral x) (fromIntegral y)
  
  {-# INLINE rel_line_to #-}
  rel_line_to :: (Integral a, Integral b) => (a, b) -> Render ()
  rel_line_to (x, y)
    = relLineTo (fromIntegral x) (fromIntegral y)
  
  -------------------------------------------------------------------------------
  
  {-# INLINE draw_rectangle #-}
  draw_rectangle :: (Integral x, Integral y, Integral w, Integral h)
                 => x -> y -> w -> h
                 -> Render ()
  draw_rectangle x y w h = do
    rectangle (fromIntegral x) (fromIntegral y) (fromIntegral w) (fromIntegral h)
    C.fill
  
  -------------------------------------------------------------------------------
  
  {-# INLINE draw_outlined_rectangle #-}
  draw_outlined_rectangle :: (Integral x, Integral y, Integral w, Integral h)
                          => x -> y -> w -> h
                          -> Render ()
  draw_outlined_rectangle x y w h = do
    rectangle (fromIntegral x) (fromIntegral y) (fromIntegral w) (fromIntegral h)
    fillPreserve
    setLineWidth 1
    setSourceRGBA 0 0 0 0.7
    stroke
  
  -------------------------------------------------------------------------------
  
  {-# INLINE draw_rectangle_opt #-}
  draw_rectangle_opt :: (Integral x, Integral y, Integral w, Integral h)
                     => Bool -> x -> y -> w -> h
                     -> Render ()
  draw_rectangle_opt opt x y w h
    = draw_rectangle_opt' opt (fromIntegral x) (fromIntegral y)
                              (fromIntegral w) (fromIntegral h)
  
  draw_rectangle_opt' :: Bool -> Double -> Double -> Double -> Double
                      -> Render ()
  draw_rectangle_opt' opt x y w h
    = do rectangle x y (1.0 `max` w) h
         C.fill
         when opt $ do
           setLineWidth 1
           setSourceRGBA 0 0 0 0.7
           rectangle x y w h
           stroke
  
  -------------------------------------------------------------------------------
  
  {-# INLINE draw_rectangle_outline #-}
  draw_rectangle_outline :: (Integral x, Integral y, Integral w, Integral h)
                         => x -> y -> w -> h
                         -> Render ()
  draw_rectangle_outline x y w h = do
    setLineWidth 2
    rectangle (fromIntegral x) (fromIntegral y) (fromIntegral w) (fromIntegral h)
    stroke
  
  -------------------------------------------------------------------------------
  
  clearWhite :: Render ()
  clearWhite = do
    save
    setOperator OperatorSource
    setSourceRGBA 0xffff 0xffff 0xffff 0xffff
    paint
    restore
  