Allow setting of graph name via graphviz.name attribute

#3

README.md

@@ -33,6 +33,8 @@ Once [installed](#install), let's build and display a sample graph:
 
 ````php
 $graph = new Fhaculty\Graph\Graph();
+// Set graph name to blank to hide default G tooltip for SVG output
+$graph->setAttribute('graphviz.name', '');
 
 $blue = $graph->createVertex('blue');
 $blue->setAttribute('graphviz.color', 'blue');

src/GraphViz.php

@@ -228,7 +228,20 @@ public function createScript(Graph $graph)
         $alg = new Directed($graph);
         $directed = $alg->hasDirected();
 
-        $script = ($directed ? 'di':'') . 'graph G {' . self::EOL;
+        /*
+         * The website [http://www.graphviz.org/content/dot-language] uses the term `ID` when displaying
+         * the abstract grammar for the DOT language.
+         * But the man pages for dot use the term `name` when describing the graph file language.
+         */
+        $name = $graph->getAttribute('graphviz.name');
+        if ($name === null || $name === 'G') {
+            // don't escape a name of G to maintain default behavior
+            $name = 'G';
+        } else {
+            $name = $this->escapeId($name);
+        }
+
+        $script = ($directed ? 'di':'') . 'graph ' . $name . ' {' . self::EOL;
 
         // add global attributes
         $globals = array(

tests/GraphVizTest.php

@@ -21,6 +21,62 @@ public function testGraphEmpty()
 graph G {
 }
 
+VIZ;
+
+        $this->assertEquals($expected, $this->graphViz->createScript($graph));
+    }
+
+    public  function testGraphExplicitDefaultName()
+    {
+        $graph = new Graph();
+        $graph->setAttribute('graphviz.name', 'G');
+
+                $expected = <<<VIZ
+graph G {
+}
+
+VIZ;
+
+        $this->assertEquals($expected, $this->graphViz->createScript($graph));
+    }
+
+    public  function testGraphName()
+    {
+        $graph = new Graph();
+        $graph->setAttribute('graphviz.name', 'My Graph Name');
+
+                $expected = <<<VIZ
+graph "My Graph Name" {
+}
+
+VIZ;
+
+        $this->assertEquals($expected, $this->graphViz->createScript($graph));
+    }
+
+    public  function testGraphBlankName()
+    {
+        $graph = new Graph();
+        $graph->setAttribute('graphviz.name', '');
+
+                $expected = <<<VIZ
+graph "" {
+}
+
+VIZ;
+
+        $this->assertEquals($expected, $this->graphViz->createScript($graph));
+    }
+
+    public  function testGraphNonBlankName()
+    {
+        $graph = new Graph();
+        $graph->setAttribute('graphviz.name', ' ');
+
+                $expected = <<<VIZ
+graph " " {
+}
+
 VIZ;
 
         $this->assertEquals($expected, $this->graphViz->createScript($graph));