We’re developing an app for a small publisher that wants to sell digital versions of their books for iPad / Android tablets. Any recommendations for a good SDK to use? We’ve tried a few with varying results in performance (some of the PDF SDKs like VFR don’t render image heavy pages as fast), and some of them like Sky ePUB are asking for a huge license fee. Are any good open source or low cost SDKs for PDFs and ePub available that can be used in a commercial app? If available for both Android and iOS that would be a plus!
In addition, we are also planning to DRM protect the books, and the Adobe DRM solution seems to also be very expensive. Any good alternatives?