Lars Knoll announced the changes, as well as the intended goals and scope of Qt 5, on Qt Labs. There are four goals for Qt 5, and according to Knoll, to achieve these goals, it is needed to break binary compatibility; source compatibility will be maintained 'for the majority of cases'. Knoll promises the transition will be far less painful than the transition from Qt 3 to Qt 4. In any case, these are the four goals:
- Make better use of the GPU, allowing you to create smooth (and accelerated) graphics performance even with limited resources
- Make apps connected to the web be as powerful as possible, i.e. to embed and power up web content and services into any Qt app
- Reduce the complexity and amount of code required to maintain and implement a port.
The focus will be on X11/Wayland on Linux, Windows, and Mac; other platforms will be on thebackburner from within Nokia. "The goal of the Qt 5 project is to offer the best possible functionality on each platform, implying that Qt will begin to offer more differentiated functionality on some OS’s, while still offering efficient re-use for the absolute majority of the code across platforms," Knoll adds.
The remainder platforms currently supported by Qt will have to be added to Qt 5 by the community, which ought to be easier now since Qt is switching to open governance mode. "Qt 4 was mainly developed in-house in Trolltech and Nokia and the results were published to the developer community," Knoll writes, "Qt 5 we plan to develop in the open, as an open source project from the very start. There will not be any differences between developers working on Qt from inside Nokia or contributors from the outside."
The plan is to have a beta release somewhere at the end of 2011, with the final release hitting somewhere in 2012.