No output

[Sophivorus]

I installed the latest Graph and Graphviz using Composer in a server with CentOS 6.5 and PHP 5.4.13. I also installed dot using yum install graphviz, it's now available at /usr/bin/dot
I then created a test.php file with the quickstart code, or to be perfectly precise:

<?php

ini_set( 'display_errors', 1 );
error_reporting( E_ALL );

include 'vendor/autoload.php';

$graph = new Fhaculty\Graph\Graph();

$blue = $graph->createVertex('blue');
$blue->setAttribute('graphviz.color', 'blue');

$red = $graph->createVertex('red');
$red->setAttribute('graphviz.color', 'red');

$edge = $blue->createEdgeTo($red);
$edge->setAttribute('graphviz.color', 'grey');

$graphviz = new Graphp\GraphViz\GraphViz();
$graphviz->display($graph);

Then I opened the test.php file in my browser and nothing. No graph, no errors on the screen or log, just nothing. The path /usr/bin/dot is allowed by open_basedir and I tried the latest Chrome and Firefox. The lack of symptoms prevents me from diagnosing, but maybe someone here is more experienced. What can I be missing? Thanks!

[clue]

@lfschenone Documentation is one of the areas that could use some improvements :)

The display() method can be used to launch an image viewer with the resulting graph image and as such only makes sense in CLI or desktop applications. If you're accessing this page through a browser, you would most likely want to output the image data, which can be accessed via createImageData().

[Sophivorus]

Thanks clue, I'm on my way. For the curious, and in case you want to add it to the documentation, the minimal code to output a PNG image in the browser is:

<?php

include 'vendor/autoload.php';

$graph = new Fhaculty\Graph\Graph();

$blue = $graph->createVertex( 'blue' );
$blue->setAttribute( 'graphviz.color', 'blue' );

$red = $graph->createVertex( 'red' );
$red->setAttribute( 'graphviz.color', 'red' );

$edge = $blue->createEdgeTo( $red );
$edge->setAttribute( 'graphviz.color', 'grey' );

$graphviz = new Graphp\GraphViz\GraphViz();
$data = $graphviz->createImageData( $graph );
$image = imagecreatefromstring( $data );
header( 'Content-Type: image/png' );
imagepng( $image );
imagedestroy( $image );

[clue]

Thanks for sharing your findings!

Afaict the following code should have the same effect (untested):

$graphviz->setFormat('png');

header('Content-Type: image/png');
echo $graphviz->createImageData($graph);

Either way, if you want to contribute to the documentation, PRs are very much appreciated! :)

[Sophivorus]

Ok clue! I'm still getting started and having some difficulty to do basic things, but when I have some code going, I'll be happy to contribute with documentation. Cheers!

[clue]

Awesome, keep me posted! :)

having some difficulty to do basic things

These are exactly the kind of things that should be covered in our documentation (eventually…) :)