wumpus-core

Pure Haskell PostScript and SVG generation.

Wumpus-Core is a low-level library for generating static 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 and someways efficient as the use of stack operations, i.e gsave and grestore, is minimized (unfortunately there is no sharing so the generated PostScript can be huge...).

Although Wumpus-Core only generates vector output, the generated PostScript can be interpreted by GraphicsMagick or a similar tool to convert EPS files into bitmap image files (e.g JPEGs).

Wumpus-Core makes pictures from paths and text labels. Paths themselves are made from points. The usual affine transformations (rotations, scaling, translations) can be applied to Pictures. Unlike PostScript there is no notion of a current point, Wumpus-Core builds pictures by direct positioning of each element.

GENERAL DRAWBACKS...

For actually building pictures, diagrams, etc. Wumpus-Core is very low-level. There are two supplementary packages Wumpus-Basic and Wumpus-Drawing also on Hackage that aim to be a higher-level basis for creating certain types of diagram, but they are experimental - functionality is added and dropped between releases and curently the API is too unstable to write code upon (they should be considered a technology preview rather than re-usable libraries).

Also, some of the design decisions made for Wumpus-Core are not sophisticated - e.g. how path and text attributes like colour are handled, and how the bounding boxes of text labels are calculated. Compared to other systems, Wumpus might be rather limited, however, the design permits a fairly simple implementation.

Changelog:

v0.52.0 to v0.52.1:

• Removed internal (<>) format combinator that caused problems for GHC 7.4.

v0.51.0 to v0.52.0:

• Added limited support for adding SVG ids to text and Primitives.

• Fixed types of d2r and r2d to Double for degrees, rather than a parametric (Real a, Floating a) type. Although this is less general, it removes the burden of type annotating the common case.

• Added the vector functions orthoVec, vsum and vdiff to Core.Geometry.

• Re-named clip to clipPrimitive

v0.50.0 to v0.51.0:

• Added special cases to handle continuity to the function lineDirection in Core.Geometry.

• Added zeroVec to Core.Geometry.

• Extended some Haddock documentation.

v0.43.0 to v0.50.0:

• Major change hence the version number jump - the notion of parametric unit has been removed from the Picture objects (it for remains the Geometric objects Point2, Vec2 etc.). Certain useful units, e.g. em and en, are contextual on the "current point size", and having a parametric unit here was actually a hinderance to supporting units properly in higher-level layers. Now all Picture objects (those defined or exported from Core.Picture) are fixed to use Double

• representing PostScript points. Higher level layers that intend to support alternative units must translate drawing objects to PostScript point measurements before calling the Picture API. Geometric objects - objects defined in Core.Geometry, e.g. Point2, Vec2 - are still polymorphic on unit.

• Picture API change - Various function names changed. lineTo becomes absLineTo and curveTo becomes absCurveTo. The path builders are qualified with Prim, vertexPath becomes vertexPrimPath, vectorPath becomes vectorPrimPath, emptyPath becomes emptyPrimPath and curvedPath becomes curvedPrimPath. xlink becomes xlinkPrim.

• API change - PtSize data type replaced by AfmUnit for font measurements.

• API and representation change - clipping paths are represented as Primitive constructor rather than a Picture constructor. This should make them more useful. The type of the function clip in Core.Picture has likewise changed.

• Picture API change - changed primPath to absPrimPath, added the functions relPrimPath, relLineTo, relCurveTo.

• Added the class Tolerance to Core.Geometry and made the Eq instances of Point2, Vec2 and BoundingBox tolerant. Tolerance accounts for a fairly lax equality on floating point numbers - it is suitable for Wumpus (printing) where high accuracy is needed.

v0.42.1 to v0.43.0:

• API change - the function bezierCircle in Core.Geometry has changed. It now implements a better method of drawing circles with Bezier curves and no longer needs the subvision factor. The old circle drawing function has been retained as subdivisionCircle as it is useful for corroborating bezierCircle, but the general use of subdivisionCircle should be avoided.

• Added a function bezierEllipse to Core.Geometry.