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#lang scribble/doc
@(require "common.rkt" (for-label mrlib/graph))

@title[#:style 'toc]{Graphs}

@defmodule[mrlib/graph]{The @racketmodname[mrlib/graph] library
provides a graph drawing toolkit built out of @racket[pasteboard%]s.}

@local-table-of-contents[]

@include-section["graph-pasteboard-intf.scrbl"]
@include-section["graph-pasteboard-mixin.scrbl"]
@include-section["graph-snip-intf.scrbl"]
@include-section["graph-snip-mixin.scrbl"]

@section{Graph Functions}

@defproc*[([(add-links [parent (is-a?/c graph-snip<%>)]
                       [child (is-a?/c graph-snip<%>)])
            void?]
           [(add-links [parent (is-a?/c graph-snip<%>)]
                       [child (is-a?/c graph-snip<%>)])
            void?]
           [(add-links [parent (is-a?/c graph-snip<%>)]
                       [child (is-a?/c graph-snip<%>)]
                       [dark-pen (or/c (is-a?/c pen) false/c)]
                       [light-pen (or/c (is-a?/c pen) false/c)]
                       [dark-brush (or/c (is-a?/c brush%) false/c)]
                       [light-brush (or/c (is-a?/c brush%) false/c)]
                       [label (or/c string? false/c) #f])
            void?]
           [(add-links [parent (is-a?/c graph-snip<%>)]
                       [child (is-a?/c graph-snip<%>)]
                       [dark-pen (or/c (is-a?/c pen) false/c)]
                       [light-pen (or/c (is-a?/c pen) false/c)]
                       [dark-brush (or/c (is-a?/c brush%) false/c)]
                       [light-brush (or/c (is-a?/c brush%) false/c)]
                       [dx real?]
                       [dy real?]
                       [label (or/c string? false/c) #f])
           void?])]{

Connects a parent snip to a child snip within a pasteboard.

The default @racket[dark-pen]/@racket[dark-brush] and
@racket[light-pen]/@racket[light-brush] are blue and purple,
respectively. The @racket[dark-pen] and @racket[dark-brush] are used
when the mouse cursor is over the snip (or a child or parent), and the
@racket[light-pen] and @racket[light-brush] are used when the mouse
cursor is not over the snip. The brush is used to draw inside the
arrow head and the pen is used to draw the border of the arrowhead and
the line connecting the two snips.

if @racket[label] is provided and not @racket[#f], it is used as a
label on the edge.

When @racket[dx] and @racket[dy] are provided, the are offsets for the
head and the tail of the arrow. Otherwise, @racket[0] offsets are
used.}

@defproc[(add-links/text-colors [parent (is-a?/c graph-snip<%>)]
                                [child (is-a?/c graph-snip<%>)]
                                [dark-pen (or/c (is-a?/c pen) false/c)]
                                [light-pen (or/c (is-a?/c pen) false/c)]
                                [dark-brush (or/c (is-a?/c brush%) false/c)]
                                [light-brush (or/c (is-a?/c brush%) false/c)]
                                [dark-text (or/c (is-a?/c color%) false/c)]
                                [light-text (or/c (is-a?/c color) false/c)]
                                [dx real?]
                                [dy real?]
                                [label (or/c string? false/c)])
          void?]{

Like @racket[add-links], but with extra @racket[dark-text] and
@racket[light-text] arguments to set the colors of the label.}

@defproc[(remove-links [parent (is-a?/c graph-snip<%>)]
                       [child (is-a?/c graph-snip<%>)])
          void?]{

Disconnects a parent snip from a child snip within a pasteboard.}

@defproc[(set-link-label [parent (is-a?/c graph-snip<%>)]
                         [child (is-a?/c graph-snip<%>)]
                         [label (or/c string? false/c)])
          void?]{

Changes the label on the edge going from @racket[child] to
@racket[parent] to be @racket[label].  If there is no existing edge
between the two nodes, then nothing happens.}


@defproc[(dot-positioning [pb (is-a?/c pasteboard%)]
                          [option (or/c dot-label neato-label neato-hier-label neato-ipsep-label) 
                                  dot-label]
                          [overlap-or-horizontal? boolean? #f])
         void?]{
  This finds the sizes of the @racket[graph-snip<%>]s in @racket[pb] and their 
  children and then passes that information to @tt{dot} or @tt{neato} (depending
  on @racket[option]), extracting a layout and then applying it to the 
  snips in @racket[pb].
  
  If @racket[option] is @racket[dot-label], then @racket[overlap-or-horizontal?]
  controls whether @tt{dot} uses a horizontal or vertical alignment.
  If @racket[option] is any of the other options, it controls whether or not
  @tt{neato} is allowed to overlap nodes.
  
  If @racket[find-dot] returns @racket[#f], this function does nothing.
}

@defproc[(find-dot [neato? boolean? #f]) (or/c path? #f)]{
  Tries to find the @tt{dot} or @tt{neato} binary and, if it succeeds,
  returns the path to it. If it cannot find it, returns
  @racket[#f].
}

@defthing[dot-label string?]{
  A string describing the regular dot option for graph layout that @racket[dot-positioning] uses.
}
@defthing[neato-label string?]{
  A string describing the neato option for graph layout that @racket[dot-positioning] uses.
}
@defthing[neato-hier-label string?]{
  A string describing the neato hierarchical option for graph layout that 
  @racket[dot-positioning] uses.
}
@defthing[neato-ipsep-label string?]{
  A string describing the neato ipsep option for graph layout that @racket[dot-positioning] uses.
}
