-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | A functional interface to 2D drawing in OpenGL
--   
--   This module is a functional wrapper around OpenGL, so you don't have
--   to go into the deep, dark world of imperative stateful programming
--   just to draw stuff. It supports 2D only (for now), with support
--   drawing geometry, images, and text.
@package graphics-drawingcombinators
@version 0.4


-- | Drawing combinators as a functional interface to OpenGL (for 2D
--   drawings only... for now).
--   
--   This module is intended to be imported <tt>qualified</tt>, as in:
--   
--   <pre>
--   import Graphics.DrawingCombinators as Draw
--   </pre>
--   
--   It is recommended that you use this module in combination with SDL; it
--   has not been tested in any other environments. For some reason the
--   selection stuff (<a>selectRegion</a>, <a>click</a>) crashes GHCi, but
--   it works okay compiled.
module Graphics.DrawingCombinators

-- | <tt>Draw a</tt> represents a drawing which returns a value of type a
--   when selected.
data Draw a

-- | Draw a Drawing on the screen in the current OpenGL coordinate system
--   (which, in absense of information, is (-1,-1) in the lower left and
--   (1,1) in the upper right).
runDrawing :: Draw a -> IO ()

-- | Like runDrawing, but clears the screen first, and sets up a little
--   necessary OpenGL state. This is so you can use this module and pretend
--   that OpenGL doesn't exist at all.
draw :: Draw a -> IO ()
type Vec2 = (Double, Double)

-- | Given a bounding box, lower left and upper right in the default
--   coordinate system (-1,-1) to (1,1), return the topmost drawing's value
--   (with respect to <tt><a>over</a></tt>) intersecting that bounding box.
selectRegion :: Vec2 -> Vec2 -> Draw a -> IO (Maybe a)
click :: Vec2 -> Draw a -> IO (Maybe a)
over :: Draw a -> Draw a -> Draw a
overlay :: (a -> a -> a) -> Draw a -> Draw a -> Draw a
empty :: Draw a

-- | Perform initialization of the library. This can fail.
init :: IO ()

-- | Draw a single pixel at the specified point.
point :: Vec2 -> Draw ()

-- | Draw a line connecting the two given points.
line :: Vec2 -> Vec2 -> Draw ()

-- | Draw a regular polygon centered at the origin with n sides.
regularPoly :: Int -> Draw ()

-- | Draw a unit circle centered at the origin. This is equivalent to
--   <tt>regularPoly 24</tt>.
circle :: Draw ()

-- | Draw a convex polygon given by the list of points.
convexPoly :: [Vec2] -> Draw ()

-- | Translate the given drawing by the given amount.
translate :: Vec2 -> Draw a -> Draw a

-- | Rotate the given drawing counterclockwise by the given number of
--   radians.
rotate :: Double -> Draw a -> Draw a

-- | <tt>scale x y d</tt> scales <tt>d</tt> by a factor of <tt>x</tt> in
--   the horizontal direction and <tt>y</tt> in the vertical direction.
scale :: Double -> Double -> Draw a -> Draw a
type Color = (Double, Double, Double, Double)

-- | <tt>color c d</tt> sets the color of the drawing to exactly
--   <tt>c</tt>.
color :: Color -> Draw a -> Draw a

-- | <tt>colorFunc f d</tt> modifies all colors appearing in <tt>d</tt>
--   with the function <tt>f</tt>. For example:
--   
--   <pre>
--   colorFunc (\(r,g,b,a) -&gt; (r,g,b,a/2)) d
--   </pre>
--   
--   Will draw d at greater transparency, regardless of the calls to color
--   within.
colorFunc :: (Color -> Color) -> Draw a -> Draw a

-- | A sprite represents a bitmap image.
data Sprite

-- | Indicate how a nonrectangular image is to be mapped to a sprite.
data SpriteScaling

-- | ScaleMax will set the maximum of the height and width of the image to
--   1.
ScaleMax :: SpriteScaling

-- | ScaleWidth will set the width of the image to 1, and scale the height
--   appropriately.
ScaleWidth :: SpriteScaling

-- | ScaleHeight will set the height of the image to 1, and scale the width
--   appropriately.
ScaleHeight :: SpriteScaling

-- | Convert an SDL.Surface to a Sprite.
surfaceToSprite :: SpriteScaling -> Surface -> IO Sprite

-- | Load an image from a file and create a sprite out of it.
imageToSprite :: SpriteScaling -> FilePath -> IO Sprite

-- | Draw a sprite at the origin.
sprite :: Sprite -> Draw ()
data Font

-- | Load a TTF font from a file.
openFont :: String -> Int -> IO Font

-- | Draw a string using a font. The resulting string will have height 1.
text :: Font -> String -> Draw ()
instance (Monoid a) => Monoid (Draw a)
instance Functor Draw