org.neo4j.visualization.graphviz.GraphvizWriter Maven / Gradle / Ivy

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Utility component to generate Graphviz .dot notation from Neo4j graphs.
There is a newer version: 3.2.0-alpha05
/*
 * Copyright (c) 2002-2016 "Neo Technology,"
 * Network Engine for Objects in Lund AB [http://neotechnology.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.visualization.graphviz;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import java.nio.charset.StandardCharsets;

import org.neo4j.visualization.Visualizer;
import org.neo4j.walk.Walker;

/**
 * An object that writes a graph to a specified destination in graphviz dot
 * format.
 */
public final class GraphvizWriter
{
    private final GraphStyle style;

    /**
     * Create a new Graphviz writer.
     * @param configuration
     *            the style parameters determining how the style of the output
     *            of this writer.
     */
    public GraphvizWriter( StyleParameter... configuration )
    {
        this( new GraphStyle( configuration ) );
    }

    public GraphvizWriter( GraphStyle style )
    {
        this.style = style;
    }

    /**
     * Emit a graph to a file in graphviz format using this writer.
     * @param dest
     *            the file to write the graph to.
     * @param walker
     *            a walker that walks the graph to emit.
     * @throws IOException
     *             if there is an error in outputting to the specified file.
     */
    public void emit( File dest, Walker walker ) throws IOException
    {
        OutputStream stream = new FileOutputStream( dest );
        emit( stream, walker );
        stream.close();
    }

    /**
     * Emit a graph to an output stream in graphviz format using this writer.
     * @param outputStream
     *            the stream to write the graph to.
     * @param walker
     *            a walker that walks the graph to emit.
     * @throws IOException
     *             if there is an error in outputting to the specified stream.
     */
    public void emit( OutputStream outputStream, Walker walker )
        throws IOException
    {
        if ( outputStream instanceof PrintStream )
        {
            emit( walker, new GraphvizRenderer( style, (PrintStream) outputStream ) );
        }
        else
        {
            emit( walker, new GraphvizRenderer( style,
                    new PrintStream( outputStream, true, StandardCharsets.UTF_8.name() ) ) );
        }
    }

    private void emit( Walker walker, GraphvizRenderer renderer )
        throws IOException
    {
        walker.accept( new Visualizer<>( renderer ) );
    }
}