== 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 title) → unspecified</procedure>
Write a dot preamble.
; width : Width in pixels
; height : Height in pixels
; font-size : Font-size in pt
; title : Title of the graph
<enscript highlight="scheme">(define write-dot-preamble
  (case-lambda
    (()
     (write-dot-preamble
       (default-width)
       (default-height)
       (default-font-size)
       (default-title)))
    ((width height font-size title)
     (display "digraph G {")
     (display "node [style=filled, fontname=monospace, shape=circle];")
     (display "edge [fontname=monospace, dir=none];")
     (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 x y color) → unspecified</procedure>
Write a node
; label : The node's label
; x : The x-coordinate of the node
; y : The y-coordinate of the node
<enscript highlight="scheme">(define (write-node label x y color)
  (format
    #t
    "~a [pos=\"~a,~a\", color=~a];"
    label
    (* x (linear-scale))
    (* y (linear-scale))
    color))
</enscript>
=== {{write-edge}}
<procedure>(write-edge whence whither) → unspecified</procedure>
Write an edge
; whence : The label whence
; whither : The lable whither
<enscript highlight="scheme">(define (write-edge whence whither) (format #t "~a -> ~a;" whence whither))
</enscript>
=== About this egg

==== Author

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

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