Last year I started some extra work to help bring DigiCel FlipBook to the Mac. FlipBook is software for traditional, hand-drawn animators, and it is actually somewhat unique in the industry. Whereas Flash and Toon Boom are vector-based, FlipBook started life as pencil test software for paper-based workflows. It supports scanning with peg hole auto-registration, camera capture, or drawing with a Wacom tablet.

Customers had been asking for a Mac version for a while, but the initial port from Windows to the Mac was not quite ready. It was missing QuickTime support for import, export, and video capture, and the Win32 compatibility layer was somewhat of a roadblock to a polished Mac product.

I entered the project and ended up re-architecting the application to have a more Mac-like appearance. Instead of using the Win32 library, I wrote a lightweight MFC implementation entirely in Cocoa. MFC is Microsoft’s C++ framework, still widely used even with .NET and C# pushed for new applications. This approach allowed the application to be driven almost purely from Win32 and MFC, but it uses NIBs for all windows and controls because the compatibility framework sits at a much higher level. In several places the Windows code peeks through, but it provides enough flexibility that more and more of the application could be upgraded to a modern Mac look and feel while still sharing a common Windows codebase.

The idea is that by working at the MFC level instead of Win32, you can get by with implementing only a very small subset of the full Microsoft frameworks. If the app only uses a few basic control types, for example, you only need to wrap those onto their Cocoa counterparts and can ignore everything else. (Otherwise you end up rewriting all of Win32 just to load and run the unmodified MFC sources.) Even with that simplification, though, the truth is that I seriously underestimated how much work this would be.

The stack for this ends up looking something like this:

FlipBook diagram

It has been an interesting project, both for the technical challenges and because animation is near to my heart. I plan to use the software in my own personal film projects. Here’s a screenshot of the latest version.

Manton Reece @manton