SvgUtils.elm

module SvgUtils exposing (..)

import Html exposing (Html)
import Svg
import Svg.Attributes as SvgAttr
import P2D
import P2D exposing (P2D,Angled,shift,rad)
import String

type alias BoundingRect =
  { min : P2D -- minimal x, minimal y
  , max : P2D -- maximal x, maximal y
  }

type alias BoundedSvg m = (BoundingRect, Svg.Svg m)

boundingBox : List P2D -> BoundingRect
boundingBox points =
  let
    (xs,ys) =
      points
      |> List.map P2D.toTuple
      |> List.unzip

    min_x : Float
    min_x = Maybe.withDefault 0.0 <| List.minimum xs
    min_y = Maybe.withDefault 0.0 <| List.minimum ys
    max_x = Maybe.withDefault 0.0 <| List.maximum xs
    max_y = Maybe.withDefault 0.0 <| List.maximum ys
  in
  { min = { x = min_x, y = min_y }
  , max = { x = max_x, y = max_y }
  }

{-| Compute the viewBox attribute of the svg canvas for a given box
 -}
viewBoxBoundings : BoundingRect -> Svg.Attribute msg
viewBoxBoundings bbox =
  [ bbox.min.x -- minimum x coordinate
  , bbox.min.y -- minimum y coordinate
  , bbox.max.x - bbox.min.x -- width
  , bbox.max.y - bbox.min.y -- height
  ]
  |> List.map toString
  |> List.intersperse " "
  |> String.concat
  |> SvgAttr.viewBox

translate : P2D -> Svg.Svg m -> Svg.Svg m
translate delta object =
  let
    transform =
       "translate("
    ++ (toString delta.x)
    ++ ","
    ++ (toString delta.y)
    ++ ")"
  in
  Svg.g
    [ SvgAttr.transform transform ]
    [ object ]

type Alignment = Left | Right | Center

{-| moves the first object on top of the second, aligned to the left
-}
aboveOf' : Float -> (BoundedSvg m) -> (BoundedSvg m) -> (BoundedSvg m)
aboveOf' = aboveOf Center