Qt Quick Ultralite is designed to serve as application front-end rendering engine. It is different from the classical Qt in a sense that its implementation does not use typical Qt libraries, such as Qt Core or Qt Gui. Hence Qt Quick Ultralite applications need to use standard C++ containers and classes instead of those from Qt. For example, instead of using QObject or QAbstractItemModel, Qt Quick Ultralite provides a simple C++ API to expose objects and models.

Applications that require non-graphical functionalities such as networking, filesystem access, locations, and multimedia need to either have their own implementation or leverage existing 3rd party libraries for respective platforms.

The QML code is compiled to C++. Since there is no JavaScript engine or garbage collection, only a subset of the language is allowed. This should be enough for the majority of use cases within Qt Quick Ultralite. When more advanced scripts are required, they can be exposed through C++ functions. Similarly, only a subset of the Qt Quick API is available.

The following topics describe the main differences between Qt Quick Ultralite and Qt Quick:

• API level differences
• Non-API level differences
• How to keep compatibility

If you believe that some important API is missing, contact Qt Professional Services.