I have been meaning to post this for a while, although no one’s asked me specifically about it.
A couple of years ago, while at Nokia, I wrote this post on QML and image providers for Qt 4.x.
While revising my latest book on Qt this fall, I learned that in Qt 5.x, the QDeclarativeImageProvider class is now the QQuickImageProvider class. The interface remains the same, so the guidance still stands — just replace one with the other.
If you want more details, stay tuned — my book should be out in the next couple of weeks, and I’ll post a link.