README.md

go-graphviz

Go bindings for Graphviz ( port of version 2.40.1 )

Features

• No need to install Graphviz library ( brew install graphviz or apt-get install graphviz )
• Supports parsing for DOT language
• Supports rendering graph in pure Go
• Supports switch renderer to your own
• Supports type safed property setting
• gvc cgraph cdt are available as sub package

Currently supported Layout

circo dot fdp neato nop nop1 nop2 osage patchwork sfdp twopi

Currently supported format

dot svg png jpg

Installation

$ go get github.com/goccy/go-graphviz

Synopsis

1. Write DOT Graph in Go

package main

import (
  "bytes"
  "fmt"
  "log"

  "github.com/goccy/go-graphviz"
)

func main() {
  g := graphviz.New()
  graph, err := g.Graph()
  if err != nil {
    log.Fatal(err)
  }
  defer func() {
    if err := graph.Close(); err != nil {
      log.Fatal(err)
    }
    g.Close()
  }()
  n, err := graph.CreateNode("n")
  if err != nil {
    log.Fatal(err)
  }
  m, err := graph.CreateNode("m")
  if err != nil {
    log.Fatal(err)
  }
  e, err := graph.CreateEdge("e", n, m)
  if err != nil {
    log.Fatal(err)
  }
  e.SetLabel("e")
  var buf bytes.Buffer
  if err := g.Render(graph, "dot", &buf); err != nil {
    log.Fatal(err)
  }
  fmt.Println(buf.String())
}

2. Parse DOT Graph

path := "/path/to/dot.gv"
b, err := ioutil.ReadFile(path)
if err != nil {
  log.Fatal(err)
}
graph, err := graphviz.ParseBytes(b)

3. Render Graph

g := graphviz.New()
graph, err := g.Graph()
if err != nil {
  log.Fatal(err)
}

// create your graph

// 1. write encoded PNG data to buffer
var buf bytes.Buffer
if err := g.Render(graph, graphviz.PNG, &buf); err != nil {
  log.Fatal(err)
}

// 2. get as image.Image instance
image, err := g.RenderImage(graph)
if err != nil {
  log.Fatal(err)
}

// 3. write to file directly
if err := g.RenderFilename(graph, graphviz.PNG, "/path/to/graph.png"); err != nil {
  log.Fatal(err)
}

Tool

dot

Installation

$ go get github.com/goccy/go-graphviz/cmd/dot

Usage

Usage:
  dot [OPTIONS]

Application Options:
  -T=         specify output format ( currently supported: dot svg png jpg ) (default: dot)
  -K=         specify layout engine ( currently supported: circo dot fdp neato nop nop1 nop2 osage patchwork sfdp twopi )
  -o=         specify output file name

Help Options:
  -h, --help  Show this help message

How it works

go-graphviz has four layers.

1. graphviz package provides facade interface for manipulating all features of graphviz library
2. gvc cgraph cdt are sub packages ( FYI: C library section in https://www.graphviz.org/documentation )
3. internal/ccall package provides bridge interface between Go and C
4. go-graphviz includes full graphviz sources

License

MIT