Wumpus.Extra.PictureLanguage

Type classes and derived functions to compose 2D pictures.

The operations are fairly standard - see Regions in Paul Hudak's 'The Haskell School of Expression' and the pretty printing libraries wl-pprint and Text.PrettyPrint.HughesPJ (pretty printing combinators are some ways in 'One and a half D' as they have horizontal operations but only carriage return in the vertical.

WARNING - this module may change in detail if not in spirit quite significantly in future.

These drawing operations are pretty fundamental and a compentent functional drawing program should provide them in some formulation. However the implementation herein needs some more thought.

Data types for alignment

data HAlign

Horizontal alignment - align to the top, center or bottom.

Constructors

HTop

HCenter

HBottom

Instances

Eq HAlign

Show HAlign

data VAlign

Vertical alignment - align to the left, center or bottom.

Constructors

VLeft

VCenter

VRight

Instances

Eq VAlign

Show VAlign

Type family and classes

type family PUnit a

The type of points within a Picture.

class Horizontal a where

Move horizontally.

Methods

moveH :: PUnit a -> a -> a

leftBound :: a -> PUnit a

rightBound :: a -> PUnit a

Instances

(Num u, Ord u) => Horizontal (Picture u)

class Vertical a where

Move vertically.

Methods

moveV :: PUnit a -> a -> a

topBound :: a -> PUnit a

bottomBound :: a -> PUnit a

Instances

(Num u, Ord u) => Vertical (Picture u)

class Composite a where

 a `over` b

Place 'picture' a over b. The idea of over here is the same as z-ordering in 2D design programs. Implementations of this class should 'draw' picture a over b but move neither.

Similarly beneath should 'draw' the first picture behind the second but move neither.

Beneath has a default definition:

 beneath = flip over

Methods

over :: a -> a -> a

beneath :: a -> a -> a

Instances

(Num u, Ord u) => Composite (Picture u)

class Move a where

Move in both the horizontal and vertical.

Methods

move :: PUnit a -> PUnit a -> a -> a

Instances

(Num u, Ord u) => Move (Picture u)

class Blank a where

Create a picture that has no content but occupies space (i.e. it has a bounding box).

Methods

blank :: PUnit a -> PUnit a -> a

Instances

(Num u, Ord u) => Blank (Picture u)

Bounds

Corresponding operations are available on bounding boxes - the definitions here have different type class obligations.

center :: (Horizontal a, Vertical a, Fractional u, u ~ PUnit a) => a -> Point2 u

The center of a picture.

topleft :: (Horizontal a, Vertical a, u ~ PUnit a) => a -> Point2 u

Extract the top-left corner.

topright :: (Horizontal a, Vertical a, u ~ PUnit a) => a -> Point2 u

Extract the top-right corner.

bottomleft :: (Horizontal a, Vertical a, u ~ PUnit a) => a -> Point2 u

Extract the bottom-left corner.

bottomright :: (Horizontal a, Vertical a, u ~ PUnit a) => a -> Point2 u

Extract the bottom-right corner.

Composition

(-@-) :: (Horizontal a, Vertical a, Composite a, Move a, Fractional u, u ~ PUnit a) => a -> a -> a

 a -@- b

Center a on top of b, a is potentially moved and drawn over b.

(->-) :: (Horizontal a, Composite a, Num u, u ~ PUnit a) => a -> a -> a

 a ->- b

Horizontal composition - move b, placing it to the right of a.

(-<-) :: (Horizontal a, Composite a, Num u, u ~ PUnit a) => a -> a -> a

 a -<- b

Horizontal composition - move a, placing it to the left of b.

(-//-) :: (Vertical a, Composite a, Num u, u ~ PUnit a) => a -> a -> a

 a -//- b

Vertical composition - move b, placing it below a.

above :: (Vertical a, Composite a, Num u, u ~ PUnit a) => a -> a -> a

 a `above` b

Vertical composition - move a, placing it above b.

below :: (Vertical a, Composite a, Num u, u ~ PUnit a) => a -> a -> a

 a `below` b

Vertical composition - move a, placing it below b

at :: (Move a, u ~ PUnit a) => a -> Point2 u -> a

Place the picture at the supplied point.

centeredAt :: (Horizontal a, Vertical a, Move a, Composite a, Blank a, Fractional u, u ~ PUnit a) => a -> Point2 u -> a

Center the picture at the supplied point.

stackOnto :: Composite a => [a] -> a -> a

 xs `stackOnto` a

Stack the list of pictures xs over a.

Note, the first picture in the list is drawn at the top, the last picture is draw over a.

hcat :: (Horizontal a, Composite a, Num u, u ~ PUnit a) => a -> [a] -> a

 x ->- xs

Concatenate the list pictures xs horizontally with (->-) starting at x.

vcat :: (Vertical a, Composite a, Num u, u ~ PUnit a) => a -> [a] -> a

 x -//- xs

Concatenate the list of pictures xs vertically with (-//-) starting at x.

stackOntoCenter :: (Horizontal a, Vertical a, Composite a, Move a, Fractional u, u ~ PUnit a) => [a] -> a -> a

Stack pictures centered ontop of each other - the first picture in the list is drawn at the top, last picture is on drawn at the bottom.

hspace :: (Num u, Composite a, Horizontal a, Blank a, u ~ PUnit a) => u -> a -> a -> a

 hspace n a b

Concatenate the pictures a and b with (->-) - injecting a space of n units to separate the pictures.

vspace :: (Num u, Composite a, Vertical a, Blank a, u ~ PUnit a) => u -> a -> a -> a

 vspace n a b

Concatenate the pictures a and b with (-//-) - injecting a space of n units to separate the pictures.

hsep :: (Num u, Composite a, Horizontal a, Blank a, u ~ PUnit a) => u -> a -> [a] -> a

 hsep n x xs

Concatenate the list of pictures xs horizontally with hspace starting at x. The pictures are interspersed with spaces of n units.

vsep :: (Num u, Composite a, Vertical a, Blank a, u ~ PUnit a) => u -> a -> [a] -> a

 vsep n x xs

Concatenate the list of pictures xs vertically with vspace starting at x. The pictures are interspersed with spaces of n units.

Compose with alignment

alignH :: (Fractional u, Composite a, Horizontal a, Vertical a, Move a, u ~ PUnit a) => HAlign -> a -> a -> a

 alignH z a b

Move picture b up or down to be horizontally aligned along a line from the top, center or bottom of picture a

alignV :: (Fractional u, Composite a, Horizontal a, Vertical a, Move a, u ~ PUnit a) => VAlign -> a -> a -> a

 alignV z a b

Move picture b left or right to be vertically aligned along a line from the left side, center or right side of picture a

hcatA :: (Fractional u, Horizontal a, Vertical a, Composite a, Move a, u ~ PUnit a) => HAlign -> a -> [a] -> a

Variant of hcat that aligns the pictures as well as concatenating them.

vcatA :: (Fractional u, Horizontal a, Vertical a, Composite a, Move a, u ~ PUnit a) => VAlign -> a -> [a] -> a

Variant of vcat that aligns the pictures as well as concatenating them.

hsepA :: (Fractional u, Horizontal a, Vertical a, Composite a, Move a, Blank a, u ~ PUnit a) => HAlign -> u -> a -> [a] -> a

Variant of hsep that aligns the pictures as well as concatenating and spacing them.

vsepA :: (Fractional u, Horizontal a, Vertical a, Composite a, Move a, Blank a, u ~ PUnit a) => VAlign -> u -> a -> [a] -> a

Variant of vsep that aligns the pictures as well as concatenating and spacing them.

Special function for text

multilabel :: (Fractional u, Ord u, TextLabel t) => t -> u -> VAlign -> [String] -> Point2 u -> Picture u

Create multiple lines of text.

The dimension argument is the linespacing, measured as the distance between the upper lines descender and the lower lines ascender.

An error is throw if the list of strings is empty