Portability | GHC |
---|---|

Stability | highly unstable |

Maintainer | stephen.tetley@gmail.com |

Base types for Drawing Objects, Graphics / Images (a Graphic that also returns an answer), etc.

Base classes for monadic drawing.

Note on suffix names. Function types suffixed `F`

are functions
from same-to-same, e.g.:

type Point2F u = Point2 u -> Point2 u

Functional types subfixed `R`

are functions from some static
context to the answer type (c.f the ReaderMonad), e.g.:

newtype DrawingR a = DrawingR { getDrawingR :: DrawingContext -> a }

The suffix `M`

is used for classes defining monadic actions.

** WARNING ** - some names are expected to change.

- type family MonUnit m :: *
- class Monad m => TraceM m where
- class Monad m => DrawingCtxM m where
- askDC :: m DrawingContext
- localize :: (DrawingContext -> DrawingContext) -> m a -> m a

- asksDC :: DrawingCtxM m => (DrawingContext -> a) -> m a
- class Monad m => PointSupplyM m where
- data HPrim u
- hprimToList :: HPrim u -> [PrimElement u]
- singleH :: PrimElement u -> HPrim u
- type Point2F u = Point2 u -> Point2 u
- type DPoint2F = Point2F Double
- data DrawingR a
- type LocDrawingR u a = Point2 u -> DrawingR a
- type DLocDrawingR a = LocDrawingR Double a
- runDrawingR :: DrawingContext -> DrawingR a -> a
- type Graphic u = DrawingR (HPrim u)
- type DGraphic = Graphic Double
- runGraphic :: DrawingContext -> Graphic u -> HPrim u
- xlinkGraphic :: XLink -> Graphic u -> Graphic u
- type LocGraphic u = Point2 u -> Graphic u
- type DLocGraphic = LocGraphic Double
- type Image u a = DrawingR (a, HPrim u)
- type DImage a = Image Double a
- type LocImage u a = Point2 u -> Image u a
- type DLocImage a = LocImage Double a
- runImage :: DrawingContext -> Image u a -> (a, HPrim u)
- intoImage :: DrawingR a -> Graphic u -> Image u a
- intoLocImage :: LocDrawingR u a -> LocGraphic u -> LocImage u a
- xlinkImage :: XLink -> Image u a -> Image u a
- type ConnDrawingR u a = Point2 u -> Point2 u -> DrawingR a
- type DConnDrawingR a = ConnDrawingR Double a
- type ConnGraphic u = Point2 u -> Point2 u -> Graphic u
- type DConnGraphic = ConnGraphic Double
- type ConnImage u a = Point2 u -> Point2 u -> Image u a
- type DConnImage a = ConnImage Double a
- intoConnImage :: ConnDrawingR u a -> ConnGraphic u -> ConnImage u a

# Drawing monads.

type family MonUnit m :: *Source

DUnit is always for fully saturated type constructors, so (seemingly) an equivalent type family is needed for monads.

class Monad m => TraceM m whereSource

Collect elementary graphics as part of a larger drawing.

TraceM works much like a writer monad.

class Monad m => DrawingCtxM m whereSource

askDC :: m DrawingContextSource

localize :: (DrawingContext -> DrawingContext) -> m a -> m aSource

DrawingCtxM DrawingR | |

DrawingCtxM m => DrawingCtxM (DirectionT m) | |

DrawingCtxM (Drawing u) | |

Monad m => DrawingCtxM (DrawingT u m) | |

DrawingCtxM m => DrawingCtxM (TurtleT u m) | |

DrawingCtxM m => DrawingCtxM (ScalingT ux uy u m) |

asksDC :: DrawingCtxM m => (DrawingContext -> a) -> m aSource

Project a value out of a context.

class Monad m => PointSupplyM m whereSource

A monad that supplies points, e.g. a turtle monad.

(u ~ MonUnit m, Monad m, Num u) => PointSupplyM (TurtleT u m) |

# Base types

Graphics objects, even simple ones (line, arrow, dot) might
need more than one primitive (path or text label) for their
construction. Hence, the primary representation that all the
others are built upon must support *concatenation* of
primitives.

Wumpus-Core has a type Picture - made from one or more Primitives - but Pictures include support for affine frames. For drawing many simple graphics (dots, connector lines...) that do not need individual affine transformations this is a penalty. A list of Primitives is therefore more suitable representation, and a Hughes list which supports efficient concatenation is wise.

hprimToList :: HPrim u -> [PrimElement u]Source

singleH :: PrimElement u -> HPrim uSource

Drawings in Wumpus-Basic have an implicit *graphics state*
the `DrawingContext`

, the most primitive building block is
a function from the DrawingContext to some polymorphic answer.

This functional type is represented concretely as `DrawingR`

.

DrawingR :: DrawingContext -> a

type LocDrawingR u a = Point2 u -> DrawingR aSource

type DLocDrawingR a = LocDrawingR Double aSource

runDrawingR :: DrawingContext -> DrawingR a -> aSource

Run a *Drawing Function* with the supplied *Drawing Context*.

runGraphic :: DrawingContext -> Graphic u -> HPrim uSource

xlinkGraphic :: XLink -> Graphic u -> Graphic uSource

type LocGraphic u = Point2 u -> Graphic uSource

Commonly graphics take a start point as well as a drawing context.

Here they are called a LocGraphic - graphic with a (starting) location.

type DLocGraphic = LocGraphic DoubleSource

type Image u a = DrawingR (a, HPrim u)Source

Images return a value as well as drawing. A *node* is a
typical example - nodes are drawing but the also support
taking anchor points.

runImage :: DrawingContext -> Image u a -> (a, HPrim u)Source

intoLocImage :: LocDrawingR u a -> LocGraphic u -> LocImage u aSource

xlinkImage :: XLink -> Image u a -> Image u aSource

type ConnDrawingR u a = Point2 u -> Point2 u -> DrawingR aSource

type DConnDrawingR a = ConnDrawingR Double aSource

type ConnGraphic u = Point2 u -> Point2 u -> Graphic uSource

ConnGraphic is a connector drawn between two points contructing a Graphic.

type DConnGraphic = ConnGraphic DoubleSource

type ConnImage u a = Point2 u -> Point2 u -> Image u aSource

ConImage is a connector drawn between two points constructing an Image.

type DConnImage a = ConnImage Double aSource

intoConnImage :: ConnDrawingR u a -> ConnGraphic u -> ConnImage u aSource