Line.hs

{-# OPTIONS_GHC -Wall #-}
{-# LANGUAGE CPP #-}
#if ( __GLASGOW_HASKELL__ < 820 )
{-# OPTIONS_GHC -fno-warn-incomplete-patterns #-}
#endif

-- | Points on a chart connected by lines.
module Chart.Line
  ( LineOptions(..)
  , oneline
  , lines
  , glines
  , lineChart
  , lineChart_
  , glineChart
  , glineChart_
  ) where

import Chart.Core
import Chart.Glyph
import Data.Default (Default(..))
import Diagrams.Prelude hiding ((<>))
import NumHask.Pair
import NumHask.Prelude
import NumHask.Rect

-- | The main features of a line (that distinguish it from a glyph say) is that:
--
-- - it exists over multiple points (a line can't exist at a single point)
--
-- - line rendering is normalized to the eventual physical chart
--
data LineOptions = LineOptions
  { lineSize :: Double -- ^ normalized
  , lineColor :: AlphaColour Double
  }

instance Default LineOptions where
  def = LineOptions 0.02 ublue

-- | A line connecting a series of points
--
-- > lines def (dataXY cos (Range 0 (4*pi)) n)
--
-- ![lines example](other/linesExample.svg)
--
lines :: (Traversable f, R2 r) => LineOptions -> f (r Double) -> Chart b
lines (LineOptions s c) xs =
  case NumHask.Prelude.head xs of
    Nothing -> mempty
    Just p ->
      trailLike (trailFromVertices (toList $ p_ <$> xs) `at` p_ p) # lcA c #
      lwN s

-- | A single line connecting 2 points
oneline :: (R2 r) => LineOptions -> Pair (r Double) -> Chart b
oneline (LineOptions s c) (Pair x0 x1) =
  stroke (trailFromVertices [p_ x0, p_ x1] `at` p_ x0) # lcA c # lwN s

-- | A chart of lines
lineChart ::
     (Traversable f)
  => [LineOptions]
  -> Aspect
  -> Rect Double
  -> [f (Pair Double)]
  -> Chart b
lineChart optss (Aspect asp) r xyss =
  mconcat $ zipWith lines optss (projectss r asp xyss)

-- | A chart of lines scaled to its own range
--
-- > import Data.Colour.Palette.Harmony (tetrad)
-- > ls = map (uncurry Pair) <$> [[(0.0,1.0),(1.0,1.0),(2.0,5.0)],
-- >                              [(0.0,0.0),(3.0,3.0)], [(0.5,4.0),(0.5,0)]]
-- > lopts = zipWith (\x y -> LineOptions x (withOpacity y 0.6)) [0.01,0.02,0.005]
-- >         (tetrad blue)
-- > lineChart_ lopts sixbyfour ls
--
-- ![lineChart_ example](other/lineChart_Example.svg)
--
lineChart_ ::
     (Traversable f) => [LineOptions] -> Aspect -> [f (Pair Double)] -> Chart b
lineChart_ optss asp xyss = lineChart optss asp (range xyss) xyss

-- | Lines with glyphs atop eack point
glines ::
     (Traversable f, R2 r)
  => LineOptions
  -> GlyphOptions b
  -> f (r Double)
  -> Chart b
glines opts gopts xs = glyphs gopts xs <> lines opts xs

-- | A chart of glines
glineChart ::
     (Traversable f)
  => [LineOptions]
  -> [GlyphOptions b]
  -> Aspect
  -> Rect Double
  -> [f (Pair Double)]
  -> Chart b
glineChart ls gs (Aspect asp) r xyss =
  mconcat $
  getZipList $
  glines <$> ZipList ls <*> ZipList gs <*> ZipList (projectss r asp xyss)

-- | A chart of glyphs_lines scaled to its own range
--
-- > let gopts = zipWith (\x y -> def {glyphColor=transparent,
-- >         glyphBorderColor=withOpacity x 0.6, glyphShape=y}) (tetrad green)
-- >         [triangle, square, circle]
-- >
-- > glineChart_ lopts gopts sixbyfour ls
--
-- ![lineChart_ example](other/glineChart_Example.svg)
--
glineChart_ ::
     (Traversable f)
  => [LineOptions]
  -> [GlyphOptions b]
  -> Aspect
  -> [f (Pair Double)]
  -> Chart b
glineChart_ ls gs asp xyss = glineChart ls gs asp (range xyss) xyss