From ComponentOne Studio 2016v1 onwards C1Report is replaced by FlexReport. It is Fast and Lightweight. You can easily update your existing C1Report definition files to FlexReport by directly opening them in C1FlexReportDesigner. Please refer to the below links:
Now, you can view PDF files in FlexViewer using C1PdfDocumentSource. Please refer to the below link for more information:
Please let us know if you need any further assistance.