Gantt chart with milestones only

The code below is the source for this graph.

<?php
// Gantt chart with milestones only
require_once 'SVGGraph/autoloader.php';

$options = [
  'auto_fit' => true,
  'structure' => [
    'key' => 0, 'axis_text' => 1, 'value' => 2, 'end' => 3,
    'milestone' => 'm',
  ],
  'show_data_labels' => true,
  'gantt_today' => false,
];

$values = [
  ['M1', 'Start here', '2022-05-02', 'm' => true],
  ['M2', 'Milestone 2', '2022-05-09', 'm' => true],
  ['M3', 'Milestone 3', '2022-05-16', 'm' => true],
  ['M4', 'Another', '2022-05-17', 'm' => true],
  ['M5', 'Another', '2022-05-18', 'm' => true],
  ['M6', 'Last one', '2022-06-02', 'm' => true],
];

$graph = new Goat1000\SVGGraph\SVGGraph(670, 'auto', $options);
$graph->values($values);
$graph->colourRangeHexHSL(0, '#c50', '#c59');
$graph->colourRangeHexHSL(1, '#6a0', '#6a9');
$graph->render('GanttChart');

Please note: the source code above comes from a script used to generate one of the example graphs on the site. This is simply a wrapper page to apply highlighting and make the source code easier to read, so there is no content here to describe what the source code is doing.