wumpus-core: Pure Haskell PostScript and SVG generation.

Wumpus - (W)riter (M)onad (P)ost (S)cript.

Wumpus is a kernel library for generating 2D vector pictures, its salient feature is portability due to no FFI dependencies. It can generate PostScript (EPS) files and SVG files. The generated PostScript code is plain [1] and reasonably efficient as the use of stack operations, i.e gsave and grestore, is minimized.

Pictures in Wumpus are made from paths and text labels. Paths themselves are made from points. The usual affine transformations (rotations, scaling, translations) can be applied to geometric objects. Unlike PostScript there is no notion of a current point, Wumpus builds pictures in a coordinate-free style.

GENERAL DRAWBACKS...

For actually drawing pictures, diagrams, etc. Wumpus is very low level. There is a supplemantary package wumpus-basic available that helps create certain types of diagram, but even this lacks the higher-level stuff (polygons, arrows etc.) that would make creating general drawings easy.

Some of the design decisions made for wumpus-core are not sophisticated (e.g. how attributes like colour are handled, and how the bounding boxes of text labels are calculated), so Wumpus might be limited compared to other systems. However, the design permits a fairly simple implementation - which is a priority. Text encoding an exception - I'm not sure how reasonable the design is. The current implementation appears okay for Latin 1 but may be inadequate for other character sets, so I may have to revise it significantly.

WARNING...

The module Core.BoundingBox is likely to be reworked significantly in the future. It has too many functions that do not offer distinct functionality. Some functions were removed in revision 0.17.0 and some more are likely to follow.

The module Extra.PictureLanguage is deprecated. At some point it will be superceded by wumpus-basic but this will not be soon.

\[1\] Because the output is simple, straight-line PostScript code, it is possible to use GraphicsMagick or a similar tool to convert Wumpus's EPS files to many other formats (bitmaps).

Changelog:

1. 20.0 to 0.21.0:

• Removed the instances of the Affine transformation. They have been replaced with special transformation functions: rotatePrimitive, scalePrimitive, translatePrimitive. As Primitives are not in an affine frame until they are lifted to Pictures the affine instances had ill-conceived semantics.

• Due to changes to accommodate the new non-affine transformations, many of the class obligations have changed on the unit of Pictures, Primitives, Bounding Boxes etc. Generally many class contexts that previously required Fractional and Ord on the unit have changed to Real and Floating.

• Removed demo/AffineTest04.hs - there is no longer a rotateAbout operation on Primitives as they do not exist in an affine frame until they they are lifted to Pictures. Added - Scaled.hs, Rotated.hs, Translated,hs.

• Removed the UndecidableInstances pragma from Core.PictureInternal. It looks like Core.Geometry will always need UndecidableInstances though.

• Removed the Ord superclass constriant from the Stroke and Fill classes and derived operations (e.g. zostroke).

Modules

[Index]

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• Package description (revised from the package)

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Package maintainers

• StephenTetley

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