wumpus-core-0.52.0: Pure Haskell PostScript and SVG generation.





Bounding box with no notion of 'empty'.

Empty pictures cannot be created with Wumpus. This significantly simplifies the implementation of pictures and bounding boxes.

Note - some of the functions exposed by this module are expected to be pertinent only to Wumpus-Core itself.



data BoundingBox u Source

Bounding box of a picture, path, etc. represented by the lower-left and upper-right corners.

Wumpus cannot construct empty pictures - so bounding boxes are spared the obligation to be empty. This greatly helps keep the implementation relatively simple.

BoundingBox operates as a semigroup where boundaryUnion is the addition.




ll_corner :: Point2 u
ur_corner :: Point2 u

Type class

class Boundary t whereSource

Type class extracting the bounding box of an object - Picture, Path etc.


boundary :: u ~ DUnit t => t -> BoundingBox uSource


boundingBox :: Ord u => Point2 u -> Point2 u -> BoundingBox uSource

boundingBox : lower_left_corner * upper_right_corner -> BoundingBox

Contruct a bounding box, vis the BBox constructor with range checking on the corner points.

boundingBox throws an error if the width or height of the constructed bounding box is negative.


destBoundingBox :: BoundingBox u -> (u, u, u, u)Source

destBoundingBox : bbox -> (lower_left_x, lower_left_y, upper_right_x, upper_right_y)

Destructor for BoundingBox, assembles a four-tuple of the x and y values of the corner points.

Arguably this is easier to pattern match upon, as it removes a layer of nesting.

boundaryUnion :: Ord u => BoundingBox u -> BoundingBox u -> BoundingBox uSource

The union of two bounding boxes.

traceBoundary :: (Num u, Ord u) => [Point2 u] -> BoundingBox uSource

traceBoundary : points -> BoundingBox

Trace a list of points, retuning the BoundingBox of their boundary.

** WARNING ** - trace throws a run-time error when supplied with the empty list.

retraceBoundary :: (Num u, Ord u) => (Point2 u -> Point2 u) -> BoundingBox u -> BoundingBox uSource

Perform the supplied transformation on the four corners of the bounding box. Trace the new corners to calculate the resulting bounding box.

NOTE - this helper function is used within Wumpus-Core to re-calculate a bounding box after a rotation for example. It is probably useful only to Wumpus-Core.

boundaryCorners :: BoundingBox u -> (Point2 u, Point2 u, Point2 u, Point2 u)Source

boundaryCorners : bbox -> (bottom_left, bottom_right, top_right, top_left)

Generate all the corners of a bounding box, counter-clock wise from the bottom left, i.e. (bl, br, tr, tl).

boundaryCornerList :: BoundingBox u -> [Point2 u]Source

boundaryCornerList : bbox -> [bottom_left, bottom_right, top_right, top_left]

Generate all the corners of a bounding box, counter-clock wise from the bottom left, i.e. [bl, br, tr, tl].

This is a list version of boundaryCorners which is sometimes more convenient. For instance, to create a vertex path it is more direct to use this list rather than build one from the 4-tuple returned by boundaryCorners.

boundaryCenter :: Fractional u => BoundingBox u -> Point2 uSource

boundaryCenter : bbox -> Point

Return the center of a bounding box.

withinBoundary :: (Tolerance u, Ord u) => Point2 u -> BoundingBox u -> BoolSource

withinBoundary : point * bbox -> Bool

Within test - is the supplied point within the bounding box?

boundaryWidth :: Num u => BoundingBox u -> uSource

boundaryWidth : bbox -> Width

Extract the width of a bounding box.

boundaryHeight :: Num u => BoundingBox u -> uSource

boundaryHeight : bbox -> Height

Extract the height of a bounding box.