Building a QML application
In Building a C++ console application we showed the CMakeLists.txt file for a simple console application. We will now create a QML application that uses the Qt Quick module.
This is the full project file:
cmake_minimum_required(VERSION 3.16) project(hello VERSION 1.0 LANGUAGES CXX) find_package(Qt6 6.2 COMPONENTS Quick Gui REQUIRED) qt_standard_project_setup(REQUIRES 6.5) set(CMAKE_CXX_STANDARD 17) set(CMAKE_CXX_STANDARD_REQUIRED ON) qt_add_executable(myapp main.cpp ) qt_add_qml_module(myapp URI hello QML_FILES main.qml FramedImage.qml RESOURCES img/world.png ) target_link_libraries(myapp PRIVATE Qt6::Gui Qt6::Quick)
Let's walk through the changes we have made. In the find_package
call, we replace Core
with Quick
. This will locate the Qt6Quick
module and provide the Qt6::Quick
targets we later link against.
find_package(Qt6 6.2 COMPONENTS Quick Gui REQUIRED)
We call qt_standard_project_setup, and specify CMAKE_CXX_STANDARD, and CMAKE_CXX_STANDARD_REQUIRED
. By passing REQUIRES 6.5
to qt_standard_project_setup
, we opt-in to useful defaults for qt_add_qml_module. It enables all the Qt CMake policies up to version 6.5, in particular QTP0001 that defines a sane default resource prefix for QML modules.
qt_standard_project_setup(REQUIRES 6.5) set(CMAKE_CXX_STANDARD 17) set(CMAKE_CXX_STANDARD_REQUIRED ON)
Note that the application will still link against Qt6::Core
, because Qt6::Quick
depends on it.
qt_add_executable creates and finalizes an application target:
qt_add_executable(myapp main.cpp )
qt_add_qml_module passes the target of the executable, a URI, module version, and a list of QML files to ensure that myapp becomes a QML module. This places the QML files into qrc:/qt/qml/${URI}
in the resource file system. Moreover, qt_add_qml_module
ensures that qmlcachegen
runs. Additionally, it creates a myapp_qmllint
target, which runs qmllint
on the files in QML_FILES.
qt_add_qml_module(myapp URI hello QML_FILES main.qml FramedImage.qml RESOURCES img/world.png )
By adding the referenced resources, they get automatically added to the application under the same root path as the QML files – also in the resource file system. By keeping the path in the resource system consistent with the one in the source and build directory, we ensure that the image is always found, as it is resolved relative to FramedImage.qml. It refers to the image in the resource file system if we load main.qml from there, or to the one in the actual file system if we review it with the qml
tool.
In the target_link_libraries
command, we link against Qt6::Quick
instead of Qt6::Core
.
target_link_libraries(myapp PRIVATE Qt6::Gui Qt6::Quick)
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