diagrams-contrib-1.1.2: Collection of user contributions to diagrams EDSL

Copyright(c) 2012 Joachim Breitner
LicenseBSD-style (see LICENSE)
Safe HaskellNone



A method for laying out diagrams using a circle packing algorithm. For details on the algorithm, see Optimisation.CirclePacking in the module circle-packing.

Here is an example:

import Optimisation.CirclePacking
import Diagrams.TwoD.Vector       (e)

colorize = zipWith fc $
    cycle [red,blue,yellow,magenta,cyan,bisque,firebrick,indigo]

objects = colorize $
    [ circle r  | r <- [0.1,0.2..1.6] ] ++
    [ hexagon r | r <- [0.1,0.2..0.7] ] ++
    [ decagon r | r <- [0.1,0.2..0.7] ]

-- Just a approximation, diagram objects do not have an exact radius
radiusApproximation o = maximum [ radius (e (alpha @@ turn)) o | alpha <- [0,0.1..1.0]]

circlePackingExample =
    position $ map (\(o,(x,y)) -> (p2 (x,y),o)) $
    packCircles radiusApproximation objects



renderCirclePacking :: Monoid' m => RadiusFunction b m -> [QDiagram b R2 m] -> QDiagram b R2 m Source

Combines the passed objects, whose radius is estimated using the given RadiusFunction, so that they do not overlap (according to the radius function) and otherwise form, as far as possible, a tight circle.

createCirclePacking :: Monoid' m => (a -> Double) -> (a -> QDiagram b R2 m) -> [a] -> QDiagram b R2 m Source

More general version of renderCirclePacking. You can use this if you have more information available in the values of type a that allows you to calculate the radius better (or even exactly).

type RadiusFunction b m = QDiagram b R2 m -> Double Source

The type of radius-estimating functions for Diagrams such as approxRadius and circleRadius. When you can calculate the radius better, but not any more once you converted your data to a diagram, use createCirclePacking.

approxRadius :: Monoid' m => Int -> RadiusFunction b m Source

A safe approximation. Calculates the outer radius of the smallest axis-aligned polygon with the given number of edges that contains the object. A parameter of 4 up to 8 should be sufficient for most applications.

circleRadius :: Monoid' m => RadiusFunction b m Source

An unsafe approximation. This is the radius of the largest circle that fits in the rectangular bounding box of the object, so it may be too small. It is, however, exact for circles, and there is no function that is safe for all diagrams and exact for circles.