CMake/Help/manual/cmake-qt.7.rst

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.. cmake-manual-description: CMake Qt Features Reference
cmake-qt(7)
***********
.. only:: html
.. contents::
Introduction
============
CMake can find and use Qt 4 and Qt 5 libraries. The Qt 4 libraries are found
by the :module:`FindQt4` find-module shipped with CMake, whereas the
Qt 5 libraries are found using "Config-file Packages" shipped with Qt 5. See
:manual:`cmake-packages(7)` for more information about CMake packages, and
see `the Qt cmake manual <http://qt-project.org/doc/qt-5/cmake-manual.html>`_
for your Qt version.
Qt 4 and Qt 5 may be used together in the same
:manual:`CMake buildsystem <cmake-buildsystem(7)>`:
.. code-block:: cmake
cmake_minimum_required(VERSION 3.8.0 FATAL_ERROR)
project(Qt4And5)
set(CMAKE_AUTOMOC ON)
find_package(Qt5 COMPONENTS Widgets DBus REQUIRED)
add_executable(publisher publisher.cpp)
target_link_libraries(publisher Qt5::Widgets Qt5::DBus)
find_package(Qt4 REQUIRED)
add_executable(subscriber subscriber.cpp)
target_link_libraries(subscriber Qt4::QtGui Qt4::QtDBus)
A CMake target may not link to both Qt 4 and Qt 5. A diagnostic is issued if
this is attempted or results from transitive target dependency evaluation.
Qt Build Tools
==============
Qt relies on some bundled tools for code generation, such as ``moc`` for
meta-object code generation, ``uic`` for widget layout and population,
and ``rcc`` for virtual filesystem content generation. These tools may be
automatically invoked by :manual:`cmake(1)` if the appropriate conditions
are met. The automatic tool invocation may be used with both Qt 4 and Qt 5.
The tools are executed as part of a synthesized custom target generated by
CMake. Target dependencies may be added to that custom target by adding them
to the :prop_tgt:`AUTOGEN_TARGET_DEPENDS` target property.
AUTOMOC
^^^^^^^
The :prop_tgt:`AUTOMOC` target property controls whether :manual:`cmake(1)`
inspects the C++ files in the target to determine if they require ``moc`` to
be run, and to create rules to execute ``moc`` at the appropriate time.
If a macro from :prop_tgt:`AUTOMOC_MACRO_NAMES` is found in a header file,
``moc`` will be run on the file. The result will be put into a file named
according to ``moc_<basename>.cpp``.
If the macro is found in a C++ implementation
file, the moc output will be put into a file named according to
``<basename>.moc``, following the Qt conventions. The ``<basename>.moc`` must
be included by the user in the C++ implementation file with a preprocessor
``#include``.
Included ``moc_*.cpp`` and ``*.moc`` files will be generated in the
``<AUTOGEN_BUILD_DIR>/include`` directory which is
automatically added to the target's :prop_tgt:`INCLUDE_DIRECTORIES`.
* This differs from CMake 3.7 and below; see their documentation for details.
* For :prop_gbl:`multi configuration generators <GENERATOR_IS_MULTI_CONFIG>`,
the include directory is ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``.
* See :prop_tgt:`AUTOGEN_BUILD_DIR`.
Not included ``moc_<basename>.cpp`` files will be generated in custom
folders to avoid name collisions and included in a separate
``<AUTOGEN_BUILD_DIR>/mocs_compilation.cpp`` file which is compiled
into the target.
* See :prop_tgt:`AUTOGEN_BUILD_DIR`.
The ``moc`` command line will consume the :prop_tgt:`COMPILE_DEFINITIONS` and
:prop_tgt:`INCLUDE_DIRECTORIES` target properties from the target it is being
invoked for, and for the appropriate build configuration.
The :prop_tgt:`AUTOMOC` target property may be pre-set for all
following targets by setting the :variable:`CMAKE_AUTOMOC` variable. The
:prop_tgt:`AUTOMOC_MOC_OPTIONS` target property may be populated to set
options to pass to ``moc``. The :variable:`CMAKE_AUTOMOC_MOC_OPTIONS`
variable may be populated to pre-set the options for all following targets.
Additional macro names to search for can be added to :prop_tgt:`AUTOMOC_MACRO_NAMES`.
Additional ``moc`` dependency file names can be extracted from source code
by using :prop_tgt:`AUTOMOC_DEPEND_FILTERS`.
Source C++ files can be excluded from :prop_tgt:`AUTOMOC` processing by
enabling :prop_sf:`SKIP_AUTOMOC` or the broader :prop_sf:`SKIP_AUTOGEN`.
.. _`Qt AUTOUIC`:
AUTOUIC
^^^^^^^
The :prop_tgt:`AUTOUIC` target property controls whether :manual:`cmake(1)`
inspects the C++ files in the target to determine if they require ``uic`` to
be run, and to create rules to execute ``uic`` at the appropriate time.
If a preprocessor ``#include`` directive is found which matches
``<path>ui_<basename>.h``, and a ``<basename>.ui`` file exists,
then ``uic`` will be executed to generate the appropriate file.
The ``<basename>.ui`` file is searched for in the following places
1. ``<source_dir>/<basename>.ui``
2. ``<source_dir>/<path><basename>.ui``
3. ``<AUTOUIC_SEARCH_PATHS>/<basename>.ui``
4. ``<AUTOUIC_SEARCH_PATHS>/<path><basename>.ui``
where ``<source_dir>`` is the directory of the C++ file and
:prop_tgt:`AUTOUIC_SEARCH_PATHS` is a list of additional search paths.
The generated generated ``ui_*.h`` files are placed in the
``<AUTOGEN_BUILD_DIR>/include`` directory which is
automatically added to the target's :prop_tgt:`INCLUDE_DIRECTORIES`.
* This differs from CMake 3.7 and below; see their documentation for details.
* For :prop_gbl:`multi configuration generators <GENERATOR_IS_MULTI_CONFIG>`,
the include directory is ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``.
* See :prop_tgt:`AUTOGEN_BUILD_DIR`.
The :prop_tgt:`AUTOUIC` target property may be pre-set for all following
targets by setting the :variable:`CMAKE_AUTOUIC` variable. The
:prop_tgt:`AUTOUIC_OPTIONS` target property may be populated to set options
to pass to ``uic``. The :variable:`CMAKE_AUTOUIC_OPTIONS` variable may be
populated to pre-set the options for all following targets. The
:prop_sf:`AUTOUIC_OPTIONS` source file property may be set on the
``<basename>.ui`` file to set particular options for the file. This
overrides options from the :prop_tgt:`AUTOUIC_OPTIONS` target property.
A target may populate the :prop_tgt:`INTERFACE_AUTOUIC_OPTIONS` target
property with options that should be used when invoking ``uic``. This must be
consistent with the :prop_tgt:`AUTOUIC_OPTIONS` target property content of the
depender target. The :variable:`CMAKE_DEBUG_TARGET_PROPERTIES` variable may
be used to track the origin target of such
:prop_tgt:`INTERFACE_AUTOUIC_OPTIONS`. This means that a library which
provides an alternative translation system for Qt may specify options which
should be used when running ``uic``:
.. code-block:: cmake
add_library(KI18n klocalizedstring.cpp)
target_link_libraries(KI18n Qt5::Core)
# KI18n uses the tr2i18n() function instead of tr(). That function is
# declared in the klocalizedstring.h header.
set(autouic_options
-tr tr2i18n
-include klocalizedstring.h
)
set_property(TARGET KI18n APPEND PROPERTY
INTERFACE_AUTOUIC_OPTIONS ${autouic_options}
)
A consuming project linking to the target exported from upstream automatically
uses appropriate options when ``uic`` is run by :prop_tgt:`AUTOUIC`, as a
result of linking with the :prop_tgt:`IMPORTED` target:
.. code-block:: cmake
set(CMAKE_AUTOUIC ON)
# Uses a libwidget.ui file:
add_library(LibWidget libwidget.cpp)
target_link_libraries(LibWidget
KF5::KI18n
Qt5::Widgets
)
Source files can be excluded from :prop_tgt:`AUTOUIC` processing by
enabling :prop_sf:`SKIP_AUTOUIC` or the broader :prop_sf:`SKIP_AUTOGEN`.
.. _`Qt AUTORCC`:
AUTORCC
^^^^^^^
The :prop_tgt:`AUTORCC` target property controls whether :manual:`cmake(1)`
creates rules to execute ``rcc`` at the appropriate time on source files
which have the suffix ``.qrc``.
.. code-block:: cmake
add_executable(myexe main.cpp resource_file.qrc)
The :prop_tgt:`AUTORCC` target property may be pre-set for all following targets
by setting the :variable:`CMAKE_AUTORCC` variable. The
:prop_tgt:`AUTORCC_OPTIONS` target property may be populated to set options
to pass to ``rcc``. The :variable:`CMAKE_AUTORCC_OPTIONS` variable may be
populated to pre-set the options for all following targets. The
:prop_sf:`AUTORCC_OPTIONS` source file property may be set on the
``<name>.qrc`` file to set particular options for the file. This
overrides options from the :prop_tgt:`AUTORCC_OPTIONS` target property.
Source files can be excluded from :prop_tgt:`AUTORCC` processing by
enabling :prop_sf:`SKIP_AUTORCC` or the broader :prop_sf:`SKIP_AUTOGEN`.
Visual Studio Generators
========================
When using the :manual:`Visual Studio generators <cmake-generators(7)>`
CMake tries to use a ``PRE_BUILD``
:command:`custom command <add_custom_command>` instead
of a :command:`custom target <add_custom_target>` for autogen.
``PRE_BUILD`` can't be used when the autogen target depends on files.
This happens when
- :prop_tgt:`AUTOMOC` or :prop_tgt:`AUTOUIC` is enabled and the origin target
depends on :prop_sf:`GENERATED` files which aren't excluded from autogen by
:prop_sf:`SKIP_AUTOMOC`, :prop_sf:`SKIP_AUTOUIC`, :prop_sf:`SKIP_AUTOGEN`
or :policy:`CMP0071`
- :prop_tgt:`AUTORCC` is enabled and a ``.qrc`` file is listed in
the origin target sources
- :prop_tgt:`AUTOGEN_TARGET_DEPENDS` lists a source file
qtmain.lib on Windows
=====================
The Qt 4 and 5 :prop_tgt:`IMPORTED` targets for the QtGui libraries specify
that the qtmain.lib static library shipped with Qt will be linked by all
dependent executables which have the :prop_tgt:`WIN32_EXECUTABLE` enabled.
To disable this behavior, enable the ``Qt5_NO_LINK_QTMAIN`` target property for
Qt 5 based targets or ``QT4_NO_LINK_QTMAIN`` target property for Qt 4 based
targets.
.. code-block:: cmake
add_executable(myexe WIN32 main.cpp)
target_link_libraries(myexe Qt4::QtGui)
add_executable(myexe_no_qtmain WIN32 main_no_qtmain.cpp)
set_property(TARGET main_no_qtmain PROPERTY QT4_NO_LINK_QTMAIN ON)
target_link_libraries(main_no_qtmain Qt4::QtGui)