graphviz-java

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Use graphviz with pure java. Create graphviz models using java code and convert them into nice graphics.

How it works

Prerequisites

API

Parsing

Examples

Images

Configuration

Javadoc

Sketchy

How it works

To execute the graphviz layout engine, one of these options is used:

The method(s) to be used can be configured with the Graphviz.useEngine() method.

Prerequisites

This project heavily uses classes from java.awt. Therefore, it does not work on android.

Maven

This project is available via Maven:

<dependency>
    <groupId>guru.nidi</groupId>
    <artifactId>graphviz-java</artifactId>
    <version>0.16.3</version>
</dependency>

graphviz-java contains all needed dependencies including one to J2V8 for the current platform (Linux, Mac OS X, Windows). This should be ok for most use cases.

gradle does not support this way of defining a dependency. Gradle users have to manually add a dependency to J2V8, e.g. com.eclipsesource.j2v8:j2v8_linux_x86_64:4.6.0

Instead of graphviz-java there are two alternative dependencies that can be used:

Instead of J2V8, one can also use the JDK javascript engine Nashorn. If Nashorn is too slow or on JDK version 15 or newer (where Nashorn has been removed), the graal javascript engine is a third option. It needs this additional dependency:

<dependency>
    <groupId>org.graalvm.js</groupId>
    <artifactId>js</artifactId>
    <version>20.0.0</version>
</dependency>

Logging

Graphviz-java uses the SLF4J facade to log. Users must therefore provide a logging implementation like LOGBack

<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.3</version>
</dependency>

or Log4j

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.13.0</version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-slf4j-impl</artifactId>
    <version>2.13.0</version>
</dependency>

API

The API is separated into a mutable and immutable part. The basic usage is as follows (assuming import static guru.nidi.graphviz.model.Factory.*).

Immutable

Graph g = graph("example1").directed()
        .graphAttr().with(Rank.dir(LEFT_TO_RIGHT))
        .with(
                node("a").with(Color.RED).link(node("b")),
                node("b").link(to(node("c")).with(Style.DASHED))
        );
Graphviz.fromGraph(g).height(100).render(Format.PNG).toFile(new File("example/ex1.png"));

Global attributes are set using the graphAttr, linkAttr and nodeAttr methods. Nodes are styled using the with method. To style edges, use the static method to which returns a Link that also has a with method. The with method accepts predefined attributes like Style, Arrow or Shape as well as everything defined in the Graphviz reference e.g. with("weight", 5)

Attention: Node a = node("a"); a.with(Color.RED); Is not working as it might be expected. All "mutating" methods like with on nodes, links and graphs create new objects and leave the original object unchanged. So in the example above, variable a contains a node that is NOT red. If you want a red node, do a = a.with(Color.RED) or use the mutable API.

Mutable

MutableGraph g = mutGraph("example1").setDirected(true).add(
        mutNode("a").add(Color.RED).addLink(mutNode("b")));
Graphviz.fromGraph(g).width(200).render(Format.PNG).toFile(new File("example/ex1m.png"));

Imperative

There is a third possibility to use the API, based on the mutable version. Its form is closer to the way dot files are written. In the lambda of the MutableGraph.use method, all referenced nodes, links and graphs are automatically added to the parent graph, without explicitly calling the add method.

MutableGraph g = mutGraph("example1").setDirected(true).use((gr, ctx) -> {
    mutNode("b");
    nodeAttrs().add(Color.RED);
    mutNode("a").addLink(mutNode("b"));
});
Graphviz.fromGraph(g).width(200).render(Format.PNG).toFile(new File("example/ex1i.png"));

This corresponds to the following dot file:

digraph example1 {
    b
    node[color=red]
    a -> b
}

Kotlin DSL

Kotlin DSL is still experimental. Things can change and any feedback is very welcome.

<dependency>
    <groupId>guru.nidi</groupId>
    <artifactId>graphviz-kotlin</artifactId>
    <version>0.16.3</version>
</dependency>

The kotlin DSL based on the imperative API. It defines that following elements:

To enable the functions, use import guru.nidi.graphviz.*

graph(directed = true) {
    edge["color" eq "red", Arrow.TEE]
    node[Color.GREEN]
    graph[Rank.dir(LEFT_TO_RIGHT)]

    "a" - "b" - "c"
    ("c"[Color.RED] - "d"[Color.BLUE])[Arrow.VEE]
    "d" / NORTH - "e" / SOUTH
}.toGraphviz().render(PNG).toFile(File("example/ex1.png"))

Parsing

Dot files can be parsed and thus manipulated. Given this file color.dot:

graph {
    { rank=same; white}
    { rank=same; cyan; yellow; pink}
    { rank=same; red; green; blue}
    { rank=same; black}

    white -- cyan -- blue
    white -- yellow -- green
    white -- pink -- red

    cyan -- green -- black
    yellow -- red -- black
    pink -- blue -- black
}

Then running this program:

try (InputStream dot = getClass().getResourceAsStream("/color.dot")) {
    MutableGraph g = new Parser().read(dot);
    Graphviz.fromGraph(g).width(700).render(Format.PNG).toFile(new File("example/ex4-1.png"));

    g.graphAttrs()
            .add(Color.WHITE.gradient(Color.rgb("888888")).background().angle(90))
            .nodeAttrs().add(Color.WHITE.fill())
            .nodes().forEach(node ->
            node.add(
                    Color.named(node.name().toString()),
                    Style.lineWidth(4).and(Style.FILLED)));
    Graphviz.fromGraph(g).width(700).render(Format.PNG).toFile(new File("example/ex4-2.png"));
}

results in this graphics:

Examples

Complex example

Node
        main = node("main").with(Label.html("<b>main</b><br/>start"), Color.rgb("1020d0").font()),
        init = node(Label.markdown("**_init_**")),
        execute = node("execute"),
        compare = node("compare").with(Shape.RECTANGLE, Style.FILLED, Color.hsv(.7, .3, 1.0)),
        mkString = node("mkString").with(Label.lines(LEFT, "make", "a", "multi-line")),
        printf = node("printf");

Graph g = graph("example2").directed().with(
        main.link(
                to(node("parse").link(execute)).with(LinkAttr.weight(8)),
                to(init).with(Style.DOTTED),
                node("cleanup"),
                to(printf).with(Style.BOLD, Label.of("100 times"), Color.RED)),
        execute.link(
                graph().with(mkString, printf),
                to(compare).with(Color.RED)),
        init.link(mkString));

Graphviz.fromGraph(g).width(900).render(Format.PNG).toFile(new File("example/ex2.png"));

Example with records

import static guru.nidi.graphviz.attribute.Records.*;
import static guru.nidi.graphviz.model.Compass.*;
Node
        node0 = node("node0").with(Records.of(rec("f0", ""), rec("f1", ""), rec("f2", ""), rec("f3", ""), rec("f4", ""))),
        node1 = node("node1").with(Records.of(turn(rec("n4"), rec("v", "719"), rec("")))),
        node2 = node("node2").with(Records.of(turn(rec("a1"), rec("805"), rec("p", "")))),
        node3 = node("node3").with(Records.of(turn(rec("i9"), rec("718"), rec("")))),
        node4 = node("node4").with(Records.of(turn(rec("e5"), rec("989"), rec("p", "")))),
        node5 = node("node5").with(Records.of(turn(rec("t2"), rec("v", "959"), rec("")))),
        node6 = node("node6").with(Records.of(turn(rec("o1"), rec("794"), rec("")))),
        node7 = node("node7").with(Records.of(turn(rec("s7"), rec("659"), rec(""))));
Graph g = graph("example3").directed()
        .graphAttr().with(Rank.dir(LEFT_TO_RIGHT))
        .with(
                node0.link(
                        between(port("f0"), node1.port("v", SOUTH)),
                        between(port("f1"), node2.port(WEST)),
                        between(port("f2"), node3.port(WEST)),
                        between(port("f3"), node4.port(WEST)),
                        between(port("f4"), node5.port("v", NORTH))),
                node2.link(between(port("p"), node6.port(NORTH_WEST))),
                node4.link(between(port("p"), node7.port(SOUTH_WEST))));
Graphviz.fromGraph(g).width(900).render(Format.PNG).toFile(new File("example/ex3.png"));

Images

Images can be included in graphviz in two ways.

One possibility is using the \ tag inside a HTML label:

Graphviz.useEngine(new GraphvizCmdLineEngine());
Graphviz g = Graphviz.fromGraph(graph()
        .with(node(Label.html("<table border='0'><tr><td><img src='graphviz.png' /></td></tr></table>"))));
g.basedir(new File("example")).render(Format.PNG).toFile(new File("example/ex7.png"));

Because viz.js does not support \ tags, this works only when using the command line engine.

The other possibility is the image attribute of a node:

Graphviz g = Graphviz.fromGraph(graph()
        .with(node(" ").with(Size.std().margin(.8, .7), Image.of("graphviz.png"))));
g.basedir(new File("example")).render(Format.PNG).toFile(new File("example/ex8.png"));

This works with all engines.

In both cases, the basedir() method can be used to define where relative paths are looked up.

Configuration

The size of the resulting image, the rendering engine and the output format can be configured:

Graphviz.useEngine(new GraphvizCmdLineEngine()); // Rasterizer.builtIn() works only with CmdLineEngine
Graph g = graph("example5").directed().with(node("abc").link(node("xyz")));
Graphviz viz = Graphviz.fromGraph(g);
viz.width(200).render(Format.SVG).toFile(new File("example/ex5.svg"));
viz.width(200).rasterize(Rasterizer.BATIK).toFile(new File("example/ex5b.png"));
viz.width(200).rasterize(Rasterizer.SALAMANDER).toFile(new File("example/ex5s.png"));
viz.width(200).rasterize(Rasterizer.builtIn("pdf")).toFile(new File("example/ex5p"));
String dot = viz.render(Format.DOT).toString();
String json = viz.engine(Engine.NEATO).render(Format.JSON).toString();
BufferedImage image = viz.render(Format.PNG).toImage();

To rasterize with batik, provide this library on the classpath:

<dependency>
    <groupId>org.apache.xmlgraphics</groupId>
    <artifactId>batik-rasterizer</artifactId>
    <version>1.10</version>
</dependency>

Javadoc

To use graphviz inside javadoc comments, add this to pom.xml:

<build>
  <plugins>
    <plugin>
      <artifactId>maven-javadoc-plugin</artifactId>
      <version>3.1.0</version>
      <configuration>
        <taglet>guru.nidi.graphviz.GraphvizTaglet</taglet>
        <tagletArtifact>
          <groupId>guru.nidi</groupId>
          <artifactId>graphviz-taglet</artifactId>
          <version>0.16.3</version>
        </tagletArtifact>
      </configuration>
    </plugin>
  </plugins>
</build>

To use this with JDK 9 or later, replace graphviz-taglet with graphviz-taglet9.

The usage inside javadoc is then as follows:

/**
 * Support graphviz inside javadoc.
 * <p>
 * {@graphviz
 * graph test { a -- b }
 * }
 * </p>
 * So easy.
 */
public class GraphvizTaglet implements Taglet {}

Sketchy

To change the appearance of the graph into something more sketchy / hand drawn, the RoughFilter can be used. First, add the rough module to the dependencies:

<dependency>
    <groupId>guru.nidi</groupId>
    <artifactId>graphviz-rough</artifactId>
    <version>0.16.3</version>
</dependency>

Then, apply the RoughFilter to the graph:

final Graph g = graph("ex1").directed().with(
        graph().cluster()
                .nodeAttr().with(Style.FILLED, Color.WHITE)
                .graphAttr().with(Style.FILLED, Color.LIGHTGREY, Label.of("process #1"))
                .with(node("a0").link(node("a1").link(node("a2")))),
        graph("x").cluster()
                .nodeAttr().with(Style.FILLED)
                .graphAttr().with(Color.BLUE, Label.of("process #2"))
                .with(node("b0").link(node("b1").link(node("b2")))),
        node("start").with(Shape.M_DIAMOND).link("a0", "b0"),
        node("a0").with(Style.FILLED, Color.RED.gradient(Color.BLUE)).link("b1"),
        node("b1").link("a2"),
        node("a2").link("end"),
        node("b2").link("end"),
        node("end").with(Shape.M_SQUARE)
);

Graphviz.fromGraph(g)
        .filter(new RoughFilter()
                .bowing(2)
                .curveStepCount(6)
                .roughness(1)
                .fillStyle(FillStyle.hachure().width(2).gap(5).angle(0))
                .font("*serif", "Comic Sans MS"))
        .render(Format.PNG)
        .toFile(new File("example/ex1-rough.png"));

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