Qt Cross-Platform UI in C++

Qt is a cross-platform UI framework native to C++. It provides widgets, layouts, signals and slots, and is supported by CMake integration through qmake detection.

CMake Setup

When qmake is in the PATH, CMake detects Qt location automatically. Otherwise, specify the path explicitly:

cmake -S . -B build \
    -DCMAKE_BUILD_TYPE=Release \
    -DCMAKE_PREFIX_PATH=$QT6_DIR

Qt modules must be linked to executables via target_link_libraries:

add_executable(test_GearParamInput
    src/ui/tests/test_GearParamInput.cpp
    src/ui/OutputDirSelect.cpp)
target_link_libraries(test_GearParamInput
    PRIVATE Qt6::Widgets Qt6::Core Qt6::Gui)

MOC (Meta-Object Compiler)

For Qt’s signal/slot mechanism to work with QObject-derived classes, MOC must process the header files. All source files included in the executable should include only headers — never .cpp files — to ensure MOC runs correctly.

Using Qt Widgets

Each Qt class lives in its own header. Import the header for each widget used:

#include <QWidget>
#include <QFormLayout>

Each QWidget has a layout manager. Common layouts include QFormLayout, QVBoxLayout, and QHBoxLayout. Qt’s official documentation provides the definitive reference for widget properties, signals, and slot signatures.

References

• Qt in Cpp