== graphviz

Some Graphviz abstractions
[[toc:]]
=== {{default-width}}
<parameter>default-width → 1600</parameter>

<enscript highlight="scheme">(define default-width (make-parameter 1600))
</enscript>
=== {{write-dot-preamble}}
<procedure>(write-dot-preamble) → unspecified</procedure>
<procedure>(write-dot-preamble width height font-size) → unspecified</procedure>
Write a dot preamble.
; width : Width in pixels
; height : Height in pixels
; font-size : Font-size in pt
<enscript highlight="scheme">(define write-dot-preamble
  (case-lambda
    (()
     (write-dot-preamble (default-width) (default-height) (default-font-size)))
    ((width height font-size)
     (display "digraph G {")
     (unless
       (null? (default-graph-attributes))
       (format
         #t
         "graph [~a];"
         (attributes->string (default-graph-attributes))))
     (unless
       (null? (default-node-attributes))
       (format #t "node [~a];" (attributes->string (default-node-attributes))))
     (unless
       (null? (default-edge-attributes))
       (format #t "edge [~a];" (attributes->string (default-edge-attributes))))
     (if (and width height)
       (begin
         (format #t "graph [fontsize=~a, ratio=fill];" font-size)
         (let ((width-in-inches (px->in width))
               (height-in-inches (px->in height)))
           (format
             #t
             "graph [viewport=\"~a,~a\", size=\"~a,~a!\"];"
             (in->dot width-in-inches)
             (in->dot height-in-inches)
             width-in-inches
             height-in-inches)))))))
</enscript>
=== {{write-dot-postscript}}
<procedure>(write-dot-postscript) → unspecified</procedure>
Write the dot postscript

<enscript highlight="scheme">(define (write-dot-postscript) (display "}"))
</enscript>
=== {{write-node}}
<procedure>(write-node label) → unspecified</procedure>
<procedure>(write-node label attributes) → unspecified</procedure>
Write a node
; label : The node's label
; attributes : Other attributes of the node
<enscript highlight="scheme">(define write-node
  (case-lambda
    ((label) (write-node label '()))
    ((label attributes)
     (format #t "~a [~a];" label (attributes->string attributes)))))
</enscript>
=== {{write-edge}}
<procedure>(write-edge whence whither) → unspecified</procedure>
<procedure>(write-edge whence whither attributes) → unspecified</procedure>
Write an edge
; whence : The label whence
; whither : The lable whither
; attributes : Other attributes of the edge
<enscript highlight="scheme">(define write-edge
  (case-lambda
    ((whence whither) (write-edge whence whither '()))
    ((whence whither attributes) (format #t "~a -> ~a;" whence whither))))
</enscript>
=== About this egg

==== Author

[[/users/klutometis|Peter Danenberg]]
==== Colophon

Documented by [[/egg/cock|cock]].