how to create export pdf and PNG to gantt chart
The Gantt chart in this tutorial is based on the Scheduler control (it's the Scheduler controls switch to Gantt using ViewType="Gantt").
See also: http://doc.daypilot.org/scheduler/gantt-chart/
That means you can export the Scheduler to PNG using Export() method: http://doc.daypilot.org/scheduler/server-side-image-export-png-jpg/
You can also export it to PDF: http://code.daypilot.org/52371/gantt-chart-pdf-export-asp-net-c-vb-net
How do you export the Gantt control?