Issue #3516271: Improve positioning of GraphViz sections

Haven't worked out how to label the groups yet, but this at least improves the chaotic positioning of the groups, and that helps.

migrate_visualize.theme.inc

@@ -48,17 +48,22 @@ function template_preprocess_migration_visualize_graphviz(array &$variables) {
 
   $typeAttributes = _migrate_visualize_graph_type_attributes();
 
+  $groups = [
+    'source' => 0,
+    'process' => 1,
+    'destination' => 2
+  ];
+
   /** @var \Fhaculty\Graph\Vertex $vertex */
-  foreach ($graph->getVertices() as $k => $vertex) {
+  foreach ($graph->getVertices() as $vertex) {
     if ($type = $vertex->getAttribute('migrate_visualize.type')) {
-      $groups = ['source' => 0, 'process' => 1, 'destination' => 2];
       $groupId = explode(':', $type)[0];
       if (isset($groups[$groupId])) {
         $vertex->setGroup($groups[$groupId]);
       }
     }
 
-    $vertex->setAttribute('graphviz.class', HTML::cleanCssIdentifier(str_replace(':', '-', $vertex->getId())));
+    $vertex->setAttribute('graphviz.class', Html::cleanCssIdentifier(str_replace(':', '-', $vertex->getId())));
 
     $vertexType = $vertex->getAttribute('migrate_visualize.type');
     if ($label = $vertex->getAttribute('migrate_visualize.label')) {
@@ -71,23 +76,23 @@ function template_preprocess_migration_visualize_graphviz(array &$variables) {
     }
   }
 
-  // Attributes for edges.
   $graphvizAttributes = [
     'colorscheme' => 'set19',
-    'penwidth' => 2,
+    'penwidth' => 1,
   ];
 
-  // Base edge colors on origin vertex type.
   $edgeTypes = [
-    'source' => ['colorscheme' => 'bupu9'],
-    'source:field' => ['colorscheme' => 'bupu9'],
-    'process' => ['colorscheme' => 'bupu9'],
-    'process:field' => ['colorscheme' => 'bupu9'],
-    'process:pipeline:step' => ['colorscheme' => 'bupu9'],
-    'plugin' => ['colorscheme' => 'bupu9'],
-    'process:plugin' => ['colorscheme' => 'bupu9'],
-    'destination' => ['color' => 'goldenrod3'],
-    'destination:field' => ['color' => 'goldenrod3'],
+    'source' => ['minlen' => 3],
+    'source:field' => ['minlen' => 3],
+    'process' => ['minlen' => 3],
+    'process:field' => ['minlen' => 3],
+    'process:pipeline' => ['minlen' => 5],
+    'process:pipeline:step' => ['minlen' => 1],
+    'plugin' => ['minlen' => 1],
+    'process:plugin' => ['maxlen' => 1],
+    'destination' => ['maxlen' => 1],
+    'destination:field' => ['maxlen' => 5],
+    'pseudofield' => ['maxlen' => 10],
   ];
 
   /** @var \Fhaculty\Graph\Edge\Directed $edge */
@@ -123,11 +128,12 @@ function template_preprocess_migration_visualize_graphviz(array &$variables) {
     $variables['graphviz'] = $graphViz->createImageHTML($graph);
   }
   catch (UnexpectedValueException $exception) {
-    \Drupal::messenger()->addError(t('Unable to invoke graphviz commands. <a href="@docs">Please check GraphViz is installed</a>.', [
+    \Drupal::messenger()->addError(t('Unable to invoke graphviz commands (error %error). <a href="@docs">Please check GraphViz is installed</a>.', [
       '@docs' => 'https://git.drupalcode.org/project/migrate_visualize/-/tree/1.0.x#graphviz-server-install',
+      '%error' => $exception->getMessage(),
     ]));
   }
-  catch (Exception $exception) {
+  catch (\Exception $exception) {
     \Drupal::messenger()->addError($exception->getMessage());
   }
 }