qmake Common Projects
This chapter describes how to set up qmake
project files for three common project types that are based on Qt. Although all kinds of projects use many of the same variables, each of them use project-specific variables to customize output files.
Platform-specific variables are not described here; we refer the reader to the Deploying Qt Applications document for information on issues such as building universal binaries for Mac OS X and handling Visual Studio manifest files.
Building an Application
The app Template
The app
template tells qmake
to generate a Makefile that will build an application. With this template, the type of application can be specified by adding one of the following options to the CONFIG
variable definition:
Option | Description |
---|---|
windows | The application is a Windows GUI application. |
console | app template only: the application is a Windows console application. |
When using this template the following qmake
system variables are recognized. You should use these in your .pro file to specify information about your application.
- HEADERS - A list of all the header files for the application.
- SOURCES - A list of all the source files for the application.
- FORMS - A list of all the UI files (created using
Qt Designer
) for the application. - LEXSOURCES - A list of all the lex source files for the application.
- YACCSOURCES - A list of all the yacc source files for the application.
- TARGET - Name of the executable for the application. This defaults to the name of the project file. (The extension, if any, is added automatically).
- DESTDIR - The directory in which the target executable is placed.
- DEFINES - A list of any additional pre-processor defines needed for the application.
- INCLUDEPATH - A list of any additional include paths needed for the application.
- DEPENDPATH - The dependency search path for the application.
- VPATH - The search path to find supplied files.
- DEF_FILE - Windows only: A .def file to be linked against for the application.
- RC_FILE - Windows only: A resource file for the application.
- RES_FILE - Windows only: A resource file to be linked against for the application.
You only need to use the system variables that you have values for, for instance, if you do not have any extra INCLUDEPATHs then you do not need to specify any, qmake
will add in the default ones needed. For instance, an example project file might look like this:
TEMPLATE = app DESTDIR = c:/helloapp HEADERS += hello.h SOURCES += hello.cpp SOURCES += main.cpp DEFINES += QT_DLL CONFIG += qt warn_on release
For items that are single valued, e.g. the template or the destination directory, we use "="; but for multi-valued items we use "+=" to add to the existing items of that type. Using "=" replaces the item's value with the new value, for example if we wrote DEFINES=QT_DLL
, all other definitions would be deleted.
Building a Library
The lib Template
The lib
template tells qmake
to generate a Makefile that will build a library. When using this template, in addition to the system variables mentioned above for the app
template the VERSION
variable is supported. You should use these in your .pro file to specify information about the library.
When using the lib
template, the following options can be added to the CONFIG
variable to determine the type of library that is built:
Option | Description |
---|---|
dll | The library is a shared library (dll). |
staticlib | The library is a static library. |
plugin | The library is a plugin; this also enables the dll option. |
The following option can also be defined to provide additional information about the library.
- VERSION - The version number of the target library, for example, 2.3.1.
The target file name for the library is platform-dependent. For example, on X11 and Mac OS X, the library name will be prefixed by lib
; on Windows, no prefix is added to the file name.
Building a Plugin
Plugins are built using the lib
template, as described in the previous section. This tells qmake
to generate a Makefile for the project that will build a plugin in a suitable form for each platform, usually in the form of a library. As with ordinary libraries, the VERSION
variable is used to specify information about the plugin.
- VERSION - The version number of the target library, for example, 2.3.1.
Building a Qt Designer Plugin
Qt Designer plugins are built using a specific set of configuration settings that depend on the way Qt was configured for your system. For convenience, these settings can be enabled by adding designer
to the project's CONFIG
variable. For example:
CONFIG += designer plugin
See the Qt Designer Examples for more examples of plugin-based projects.
Building and Installing in Debug and Release Modes
Sometimes, it is necessary to build a project in both debug and release modes. Although the CONFIG
variable can hold both debug
and release
options, the debug
option overrides the release
option.
Building in Both Modes
To enable a project to be built in both modes, you must add the debug_and_release
option to your project's CONFIG
definition:
CONFIG += debug_and_release CONFIG(debug, debug|release) { TARGET = debug_binary } else { TARGET = release_binary }
The scope in the above snippet modifies the build target in each mode to ensure that the resulting targets have different names. Providing different names for targets ensures that one will not overwrite the other.
When qmake
processes the project file, it will generate a Makefile rule to allow the project to be built in both modes. This can be invoked in the following way:
make all
The build_all
option can be added to the CONFIG
variable in the project file to ensure that the project is built in both modes by default:
CONFIG += build_all
This allows the Makefile to be processed using the default rule:
make
Installing in Both Modes
The build_all
option also ensures that both versions of the target will be installed when the installation rule is invoked:
make install
It is possible to customize the names of the build targets depending on the target platform. For example, a library or plugin may be named using a different convention on Windows to the one used on Unix platforms:
CONFIG(debug, debug|release) { mac: TARGET = $$join(TARGET,,,_debug) win32: TARGET = $$join(TARGET,,d) }
The default behavior in the above snippet is to modify the name used for the build target when building in debug mode. An else
clause could be added to the scope to do the same for release mode; left as it is, the target name remains unmodified.
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