Qt 5 to Qt 6 Migration Services

Future-Ready Development Platform

By migrating to Qt 6, you're not only updating your codebase – you're investing in your application's future. The new framework provides continuous feature updates and improvements, and adjustments to changing platform requirements, ensuring your software remains competitive and capable.

Also, in an increasingly regulated software landscape, particularly with the European Cyber Resilience Act (CRA), upgrading helps organizations maintain compliance while focusing on innovation.

Improved Developer Tooling

Vastly improved developer tooling, particularly around QML, is another advantage coming with Qt 6. Tools like qmllint and the QML language server make QML developers more productive than ever. Combined with new QML language features this allows for faster, more expressive, and more maintainable QML code.

Better Performance and Modern Architecture

Qt 6 represents a significant leap forward in application development capabilities. The framework has been evolved according to modern development practices, for example by adoting the C++17 standard. A new rendering pipeline allows to take advantage of the platform's native graphics APIs as well as Vulkan to deliver improved performance, enabling more sophisticated and responsive user interfaces compare to older Qt versions.

Graphics and Rendering Considerations

Qt 6 introduces significant changes to graphics handling through the new Rendering Hardware Interface (RHI). This update requires careful attention to:

• Identify parts of the application that rely on OpenGL support
• Converting existing shader code to Vulkan-compatible GLSL
• Adapting to the new shader management system using the qsb tool
• Reviewing and updating any custom rendering implementations
• Testing graphics performance across different platforms and devices

Build System Evolution

One of the most significant changes in Qt 6 is the shift toward CMake as the recommended build system. While qmake remains available, it's considered deprecated in Qt 6, making CMake the clear choice for future-proofing your projects. This transition requires:

• Ensuring your compiler toolchain support C++17, which is mandatory for Qt 6
• Adapting your build system to build against Qt6, optionally while keeping support for Qt5 during a transition period
• Adapting your build- and deployment environment to support Qt6 (e.g. CI pipelines or Yocto builds)

Module and API Updates

The transition to Qt 6 involves several important changes to modules and APIs:

• Some modules have been removed or relocated (such as Qt Quick Controls 1 and Qt Script)
• Container classes have undergone significant updates
• The meta-object system has been enhanced
• String handling has been improved with new classes and methods

The Qt5Compat module is available to ease the transition, it is critical to see this as an interim temporary solution rather than a long-term fix.

Testing and Validation Strategy

A comprehensive testing strategy is crucial for a successful migration.

This should include:

• Systematic testing of all application features
• Performance benchmarking before and after migration
• Cross-platform compatibility verification
• User interface regression testing
• Validation of third-party integrations

Team Preparation and Training

Ensuring your development team is well-prepared for the migration is essential.

This includes:

• Familiarization with new Qt 6 features and APIs
• Training on CMake build system usage
• Understanding of modern C++ features (C++17)
• Knowledge of new debugging and profiling tools
• Expertise in using migration assistance tools like Clazy
• Find a complete overview of the available trainig courses
  on training.kdab.com