NAME

       gv_tcl - graph manipulation in tcl

SYNOPSIS

       #!/usr/bin/tclsh
       package require gv

USAGE

       Requires tcl8.3 or later.

INTRODUCTION

       gv_tcl  is  a  dynamically  loaded  extension  for  tcl  that provides access to the graph
       facilities of graphviz.

COMMANDS

       New graphs

       New empty graph
              <graph_handle> gv::graph <name>
              <graph_handle> gv::digraph <name>
              <graph_handle> gv::strictgraph <name>
              <graph_handle> gv::strictdigraph <name>

       New graph from a dot-syntax string or file
              <graph_handle> gv::readstring <string>
              <graph_handle> gv::read <string> filename
              <graph_handle> gv::read <channel>

       Add new subgraph to existing graph
              <graph_handle> gv::graph <graph_handle> <name>

       New nodes

       Add new node to existing graph
              <node_handle> gv::node <graph_handle> <name>

       New edges

       Add new edge between existing nodes
              <edge_handle> gv::edge <tail_node_handle> <head_node_handle>

       Add a new edge between an existing tail node, and a named head node which will be  induced
       in the graph if it doesn't already exist
              <edge_handle> gv::edge <tail_node_handle> <head_name>

       Add  a new edge between an existing head node, and a named tail node which will be induced
       in the graph if it doesn't already exist
              <edge_handle> gv::edge <tail_name> <head_node_handle>

       Add a new edge between named tail  and head nodes which will be induced in  the  graph  if
       they don't already exist
              <edge_handle> gv::edge <graph_handle> <tail_name> <head_name>

       Setting attribute values

       Set value of named attribute of graph/node/edge - creating attribute if necessary
              <string> gv::setv <graph_handle> <attr_name> <attr_value>
              <string> gv::setv <node_handle> <attr_name> <attr_value>
              <string> gv::setv <edge_handle> <attr_name> <attr_value>

       Set value of existing attribute of graph/node/edge (using attribute handle)
              <string> gv::setv <graph_handle> <attr_handle> <attr_value>
              <string> gv::setv <node_handle> <attr_handle> <attr_value>
              <string> gv::setv <edge_handle> <attr_handle> <attr_value>

       Getting attribute values

       Get value of named attribute of graph/node/edge
              <string> gv::getv <graph_handle> <attr_name>
              <string> gv::getv <node_handle> <attr_name>
              <string> gv::getv <edge_handle> <attr_name>

       Get value of attribute of graph/node/edge (using attribute handle)
              <string> gv::getv <graph_handle> <attr_handle>
              <string> gv::getv <node_handle> <attr_handle>
              <string> gv::getv <edge_handle> <attr_handle>

       Obtain names from handles
              <string> gv::nameof <graph_handle>
              <string> gv::nameof <node_handle>
              <string> gv::nameof <attr_handle>

       Find handles from names
              <graph_handle> gv::findsubg <graph_handle> <name>
              <node_handle> gv::findnode <graph_handle> <name>
              <edge_handle> gv::findedge <tail_node_handle> <head_node_handle>
              <attr_handle> gv::findattr <graph_handle> <name>
              <attr_handle> gv::findattr <node_handle> <name>
              <attr_handle> gv::findattr <edge_handle> <name>

       Misc graph navigators returning handles
              <node_handle> gv::headof <edge_handle>
              <node_handle> gv::tailof <edge_handle>
              <graph_handle> gv::graphof <graph_handle>
              <graph_handle> gv::graphof <edge_handle>
              <graph_handle> gv::graphof <node_handle>
              <graph_handle> gv::rootof <graph_handle>

       Obtain handles of proto node/edge for setting default attribute values
              <node_handle> gv::protonode <graph_handle>
              <edge_handle> gv::protoedge <graph_handle>

       Iterators

       Iteration termination tests
              <boolean_string> gv::ok <graph_handle>
              <boolean_string> gv::ok <node_handle>
              <boolean_string> gv::ok <edge_handle>
              <boolean_string> gv::ok <attr_handle>

       Iterate over subgraphs of a graph
              <graph_handle> gv::firstsubg <graph_handle>
              <graph_handle> gv::nextsubg <graph_handle> <subgraph_handle>

       Iterate over supergraphs of a graph (obscure and rarely useful)
              <graph_handle> gv::firstsupg <graph_handle>
              <graph_handle> gv::nextsupg <graph_handle> <subgraph_handle>

       Iterate over edges of a graph
              <edge_handle> gv::firstedge <graph_handle>
              <edge_handle> gv::nextedge <graph_handle> <edge_handle>

       Iterate over outedges of a graph
              <edge_handle> gv::firstout <graph_handle>
              <edge_handle> gv::nextout <graph_handle> <edge_handle>

       Iterate over edges of a node
              <edge_handle> gv::firstedge <node_handle>
              <edge_handle> gv::nextedge <node_handle> <edge_handle>

       Iterate over out-edges of a node
              <edge_handle> gv::firstout <node_handle>
              <edge_handle> gv::nextout <node_handle> <edge_handle>

       Iterate over head nodes reachable from out-edges of a node
              <node_handle> gv::firsthead <node_handle>
              <node_handle> gv::nexthead <node_handle> <head_node_handle>

       Iterate over in-edges of a graph
              <edge_handle> gv::firstin <graph_handle>
              <edge_handle> gv::nextin <node_handle> <edge_handle>

       Iterate over in-edges of a node
              <edge_handle> gv::firstin <node_handle>
              <edge_handle> gv::nextin <graph_handle> <edge_handle>

       Iterate over tail nodes reachable from in-edges of a node
              <node_handle> gv::firsttail <node_handle>
              <node_handle> gv::nexttail <node_handle> <tail_node_handle>

       Iterate over nodes of a graph
              <node_handle> gv::firstnode <graph_handle>
              <node_handle> gv::nextnode <graph_handle> <node_handle>

       Iterate over nodes of an edge
              <node_handle> gv::firstnode <edge_handle>
              <node_handle> gv::nextnode <edge_handle> <node_handle>

       Iterate over attributes of a graph
              <attr_handle> gv::firstattr <graph_handle>
              <attr_handle> gv::nextattr <graph_handle> <attr_handle>

       Iterate over attributes of an edge
              <attr_handle> gv::firstattr <edge_handle>
              <attr_handle> gv::nextattr <edge_handle> <attr_handle>

       Iterate over attributes of a node
              <attr_handle> gv::firstattr <node_handle>
              <attr_handle> gv::nextattr <node_handle> <attr_handle>

       Remove graph objects
              <boolean_string> gv::rm <graph_handle>
              <boolean_string> gv::rm <node_handle>
              <boolean_string> gv::rm <edge_handle>

       Layout

       Annotate a graph with layout attributes and values using a specific layout engine
              <boolean_string> gv::layout <graph_handle> <string> engine

       Render

       Render a layout into attributes of the graph
              <boolean_string> gv::render <graph_handle>

       Render a layout to stdout
              <boolean_string> gv::render <graph_handle> <string> format

       Render to an open file
              <boolean_string> gv::render <graph_handle> <string> format <channel> fout

       Render a layout to an unopened file by name
              <boolean_string> gv::render <graph_handle> <string> format <string> filename

       Render to a string result
              <string> gv::renderresult <graph_handle> ing <string> format
              gv::renderresult <graph_handle> <string> format <string> outdata

       Render to an open channel
              <boolean_string>   gv::renderchannel   <graph_handle>   <string>   format  <string>
              channelname

       Render a layout to a malloc'ed string, to be free'd by the caller

       (deprecated - too easy to leak memory)

       (still needed for "eval [gv::renderdata $G tk]" )
              <string> gv::renderdata <graph_handle> <string> format

       Writing graph back to file
              <boolean_string> gv::write <graph_handle> <string> filename
              <boolean_string> gv::write <graph_handle> <channel>

       Graph transformation tools
              <boolean_string> gv::tred <graph_handle>

KEYWORDS

       graph, dot, neato, fdp, circo, twopi, tcl.

                                         03 February 2023                                gv(3tcl)