Hi Leonardo,
Thank you for contacting Syncfusion support.
We have created a simple sample to achieve your requirement for drawing a color bar with percentage and its value in the PDF document by using PDF library. We have attached the sample and output documents for your reference. Kindly please try the below sample on your end and let us know if it is suites your requirement or not.
Please refer the below link for more information.
Please let us know if you need any further assistance on this.
Regards,
Gowthamraj K