Having lovely hookup diagrams, interactive code editors and Doxygen output for the API is nice, but... What's needed is a mid-level introduction to the library once you've gotten past the basic tutorials and solid examples for the commonly used API calls (most of which are simple, but still).
Having lovely hookup diagrams, interactive code editors and Doxygen output for the API is nice, but... What's needed is a mid-level introduction to the library once you've gotten past the basic tutorials and solid examples for the commonly used API calls (most of which are simple, but still).