Wumpus.Core.SVG

SVG is represented using XML.Light. XML.Light is a simple, generic XML representation (almost) everything is an element with attributes.

SVG output is monadic to handle clipping paths and configurable text encoding via a Reader monad.

SVG does not achieve clipping by changing the graphics state (being declarative SVG doesn't have a graphics state as such). Instead a clipping path has an id, subsequent elements that are bound by the clipping path are tagged with a clip-path attribute that references the clipping path id:

 clip-path=\"url(#clip1)\"

The operations to build XML elements (e.g. element_path) don't take more parameters than necessary, and are expected to be augmented with attributes using add_attr and add_attrs from the XML.Light library.

SVG Monad

type SvgM a = SvgT Id a

The SVG monad - which wraps a state monad to generate fresh names.

runSVG :: TextEncoder -> SvgM a -> a

Run the SVG monad.

newClipLabel :: SvgM String

Generate a new clip label.

currentClipLabel :: SvgM String

Get the current clip label.

Build SVG

type SvgPath = [String]

unqualAttr :: String -> String -> Attr

Helper for XML.Light

xmlVersion :: String -> CData

 <?xml version="1.0" encoding="..."?>

svgDocType :: CData

 <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"           
     "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd" > 

gElement :: [Attr] -> [Element] -> Element

 <g> ... </g>

Wumpus uses the g element (group) to achieve nesting.

svgElement :: [Element] -> Element

 <svg xmlns="http://www.w3.org/2000/svg" version="1.1">
 ...
 </svg>

element_circle :: Element

 <circle/>

element_ellipse :: Element

 <ellipse/>

attr_x :: PSUnit u => u -> Attr

 x="..."

attr_y :: PSUnit u => u -> Attr

 y="..."

attr_r :: PSUnit u => u -> Attr

 r="..."

attr_rx :: PSUnit u => u -> Attr

 rx="..."

attr_ry :: PSUnit u => u -> Attr

 ry="..."

attr_cx :: PSUnit u => u -> Attr

 cx="..."

attr_cy :: PSUnit u => u -> Attr

 cy="..."

element_path :: SvgPath -> Element

 <path d="..." />

Note the argument to this function is an attribute rather than content. We have no use for empty paths.

element_clippath :: SvgPath -> Element

 <clipPath>
 ...
 </clipPath>

element_text :: Node t => t -> Element

 <text>...</text>

element_tspan :: String -> Element

 <text>...</text>

content_text :: String -> Content

Render the string as CDataText - see XML.Light.

attr_font_family :: String -> Attr

 font-family="..."

attr_font_size :: Int -> Attr

 font-size="..."

attr_font_weight :: String -> Attr

 font-weight="..."

attr_font_style :: String -> Attr

 font-style="..."

attr_id :: String -> Attr

 id="..."

attr_fill :: PSColour c => c -> Attr

 fill="rgb(..., ..., ...)"

attr_fill_none :: Attr

 fill="none"

attr_stroke :: PSColour c => c -> Attr

 stroke="rgb(..., ..., ...)"

attr_stroke_none :: Attr

 stroke="none"

attr_stroke_width :: PSUnit u => u -> Attr

 stroke-width="..."

attr_stroke_miterlimit :: PSUnit u => u -> Attr

 stroke-miterlimit="..."

attr_stroke_linecap :: LineCap -> Attr

attr_stroke_linejoin :: LineJoin -> Attr

 stroke-linejoin="..."

attr_stroke_dasharray :: [Int] -> Attr

 stroke-dasharray="..."

attr_stroke_dasharray_none :: Attr

 stroke-dasharray="none"

attr_stroke_dashoffset :: Int -> Attr

 stroke-dashoffset="..."

attr_color :: PSColour c => c -> Attr

 color="rgb(..., ..., ...)"

Gray or HSB values will be converted to and rendered as RGB.

attr_clippath :: String -> Attr

 clip-path="url(#...)"

attr_transform :: String -> Attr

 transform=...

val_matrix :: PSUnit u => u -> u -> u -> u -> u -> u -> String

 matrix(..., ..., ..., ..., ..., ...)

val_colour :: PSColour c => c -> String

 rgb(..., ..., ...)

HSB and gray scale are translated to RGB values.

val_rgb :: RGB3 Double -> String

 rgb(..., ..., ...)

val_url :: String -> String

 url(#...)

val_translate :: PSUnit u => u -> u -> String

 translate(..., ...)

path_m :: PSUnit u => u -> u -> String

 M ... ...

c.f. PostScript's moveto.

path_l :: PSUnit u => u -> u -> String

 L ... ...

c.f. PostScript's lineto.

path_s :: PSUnit u => u -> u -> u -> u -> u -> u -> String

 S ... ... ... ... ... ...

c.f. PostScript's curveto.