Hi Daniel,
Thank you for using Syncfusion products.
We normally draw texts and images of the PDF document in the HTML5 canvas element for printing the same as an image in the PDF viewer control. This is the behavior when the printing is done using the canvas element in the web based controls. The low quality of the printed document is because of the low dpi of the canvas element. However, we will consider to improve the quality of the printed copy of the PDF document. We considered this as a feature request and it will be available in any of our upcoming releases.
Please let us know if need any further assistance.
Regards,
Sabari Anand