Vladest Software

Application Development with QML is simple and powerful. But Qt C++ can be more performant, offers many features and is less error-prone. This post shows you how to create apps that take advantage of both languages.

• How to Communicate between C++ and QML
  • Advantages of Coding in QML
  • When to Use C++ Instead
• How to Access a C++ Object from QML
  • Create a C++ Class in your V-Play Project
  • Implement the C++ Class for Usage with QML
  • Expose an Object to QML as a Context Property
  • Add a Class Property with Full QML Support
• How to Register your C++ Class as a QML Type
  • When to Use a Context Property and when a QML Object
  • Which Parameters Can you Pass between C++ and QML
  • Register and Use your C++ QML Type
  • Use a Property, Signal or Slot?
  • How to Start Long-running C++ Operations from QML
  • When to Derive from QQuickItem instead of QObject

How to Communicate between C++ and QML

It is important to choose the right language for different features of your app. Integrate C++ components with QML to take your mobile app development to the next level.

Advantages of Coding in QML

V-Play Engine for Qt-based mobile apps and games uses the power of Qt Quick (QML + Javascript). This declarative scripting language is so powerful that it saves up to 60% lines of code compared to other programming languages.

Coding in QML has several advantages over development with C++:

• Coding with QML + JavaScript is very easy to learn and allows to reduce the required amount of code a lot.
• Language concepts like states, signals or property bindings are a huge time-saver.
• QML makes adding animations simple. You can animate every property of your QML types with simple Animation components.
• QML is extensible and flexible. For example, you can extend objects with new properties and features in-line. No need to create a new re-usable type for small extensions.
• The QML Rendering Engine offers a great performance. The renderer uses C++ Qt and relies on a hardware accelerated scene graph. This makes it fast enough to power even high-performance games.

When to use C++ Instead

Qt app development with C++ has advantages as well. For some scenarios you need features that are only available with Qt C++. Also, C++ is fast and type-safe. This allows to provide the best possible performance for long-running and data-intense calculations.

For these examples, you would choose C++ over QML:

• Native C++ code is …read more

  Source:: https://v-play.net/cross-platform-development/how-to-expose-a-qt-cpp-class-with-signals-and-slots-to-qml