Plot.hs

{-# LANGUAGE RankNTypes      #-}
{-# LANGUAGE RecordWildCards #-}

-- | Module containing renderable objects and plots for our maps
module GIS.Graphics.Plot where

import           Control.Arrow
import           Data.Colour.Names
import           GIS.Graphics.Types            hiding (title)
import           GIS.Math.Utils
import           GIS.Types
import           GIS.Utils
import           Graphics.Rendering.Chart
import           Graphics.Rendering.Chart.Easy hiding (lens, points)

-- | Given a map, return a `Renderable ()` for use with the
-- """Graphics.Rendering.Char""" module.
mkMapR :: Map -> Renderable ()
mkMapR Map{..} = if _labelEntities
    then mkRenderableLabelled _title _labelledDistricts
    else mkRenderableLabelled _title $ second (pure "") <$> _labelledDistricts

mkRenderablePlots :: String -> [Plot Double Double] -> Renderable ()
mkRenderablePlots title plots = toRenderable $
    layout_title .~ title $ layout_plots .~ plots $ def

mkRenderableLens :: (Show a) => Lens' District a -> [District] -> String -> Renderable ()
mkRenderableLens lens districts title = mkRenderableLabelled title (labelByLens lens districts)

mkRenderableLabelled :: String -> [([Polygon], String)] -> Renderable ()
mkRenderableLabelled title points = mkRenderablePlots title [ plotDataPoints (fst =<< points), plotLabels points ]

-- | Helper function to plot data points as appropriate for a map, i.e. using
-- contiguous lines.
plotDataPoints :: [Polygon] -> Plot Double Double
plotDataPoints points = toPlot $
    plot_lines_values .~ points $ plot_lines_style . line_color .~ opaque blue $ plot_lines_title .~ "Border" $ def

-- | Set labels via a lens field.
labelByLens :: (Show a) => Lens' District a -> [District] -> [([Polygon], String)]
labelByLens lens districts = zip (fmap _shape districts) (fmap (show . view lens) districts)

-- | Helper function to plot labels on a map. The ordinate will be plotted at
-- the centroid of the abscissa, which may be outside the polygon if it is
-- concave.
plotLabels :: [([Polygon], String)] -> Plot Double Double
plotLabels points = toPlot texts
    where pairs = fmap (flatten . first (shittyCentroid . concat)) points
          fontStyle = font_size .~ 15 $ font_weight .~ FontWeightBold $ def
          texts = plot_annotation_values .~ pairs $ plot_annotation_style .~ fontStyle $ def