Creating Project Files

The project file format used by qmake can be used to support both simple and fairly complex build systems. Simple project files use a straightforward declarative style, defining standard variables to indicate the source and header files that are used in the project. Complex projects may use control flow structures to fine-tune the build process.

The following sections describe the different types of elements used in project files.

Variables▲

HEADERS = mainwindow.h paintwidget.h

SOURCES = main.cpp mainwindow.cpp \
          paintwidget.cpp
CONFIG += console

TEMP_SOURCES = $$SOURCES

DEST = "Program Files"

win32:INCLUDEPATH += "C:/mylibs/extra headers"
unix:INCLUDEPATH += "/home/user/extra headers"

Comments▲

# Comments usually start at the beginning of a line, but they
# can also follow other content on the same line.

Built-in Functions and Control Flow▲

include(other.pro)

win32 {
    SOURCES += paintwidget_win.cpp
}

The TEMPLATE variable is used to define the type of project that will be built. If this is not declared in the project file, qmake assumes that an application should be built, and will generate an appropriate Makefile (or equivalent file) for the purpose.

The following table summarizes the types of projects available and describes the files that qmake will generate for each of them:

See Building Common Project Types for advice on writing project files for projects that use the app and lib templates.

When the subdirs template is used, qmake generates a Makefile to examine each specified subdirectory, process any project file it finds there, and run the platform's make tool on the newly-created Makefile. The SUBDIRS variable is used to contain a list of all the subdirectories to be processed.

The CONFIG variable specifies the options and features that the project should be configured with.

The project can be built in release mode or debug mode, or both. If debug and release are both specified, the last one takes effect. If you specify the debug_and_release option to build both the debug and release versions of a project, the Makefile that qmake generates includes a rule that builds both versions. This can be invoked in the following way:

make all

Adding the build_all option to the CONFIG variable makes this rule the default when building the project.

CONFIG(opengl) {
    message(Building with OpenGL support.)
} else {
    message(OpenGL support is not available.)
}

This enables different configurations to be defined for release and debug builds. For more information, see Using Scopes.

The following options define the type of project to be built.

The application and library project templates provide you with more specialized configuration options to fine tune the build process. The options are explained in detail in Building Common Project Types.

For example, if your application uses the Qt library and you want to build it in debug mode, your project file will contain the following line:

CONFIG += qt debug

If the CONFIG variable contains the qt value, qmake's support for Qt applications is enabled. This makes it possible to fine-tune which of the Qt modules are used by your application. This is achieved with the QT variable which can be used to declare the required extension modules. For example, we can enable the XML and network modules in the following way:

QT += network xml

QT = network xml # This will omit the core and gui modules.

If you want to build a project without the gui module, you need to exclude it with the "-=" operator. By default, QT contains both core and gui, so the following line will result in a minimal Qt project being built:

QT -= gui # Only the core module is used.

For a list of Qt modules that you can add to the QT variable, see QT.

qmake can be set up with extra configuration features that are specified in feature (.prf) files. These extra features often provide support for custom tools that are used during the build process. To add a feature to the build process, append the feature name (the stem of the feature filename) to the CONFIG variable.

For example, qmake can configure the build process to take advantage of external libraries that are supported by pkg-config, such as the D-Bus and ogg libraries, with the following lines:

CONFIG += link_pkgconfig
PKGCONFIG += ogg dbus-1

For more information about adding features, see Adding New Configuration Features.

If you are using other libraries in your project in addition to those supplied with Qt, you need to specify them in your project file.

The paths that qmake searches for libraries and the specific libraries to link against can be added to the list of values in the LIBS variable. You can specify the paths to the libraries or use the Unix-style notation for specifying libraries and paths.

For example, the following lines show how a library can be specified:

LIBS += -L/usr/local/lib -lmath

The paths containing header files can also be specified in a similar way using the INCLUDEPATH variable.

For example, to add several paths to be searched for header files:

INCLUDEPATH = c:/msdev/include d:/stl/include