Setting the Application Icon

To configure your application's icon, a resource file containing information about the icon is required. A resource file is a text file that contains information about the application resources, such as icons, cursors, fonts, and so on. For more information about resource files and what it can contain, see About Resource Files.

Once you have the .rc file, add information about the ICO file to it and use it to configure your application icon.

The following snippet demonstrates how the Qt Quick Demo - Photo Surface example application uses CMake to set up an application icon:

    set(app_icon_resource_windows "${CMAKE_CURRENT_SOURCE_DIR}/resources/photosurface.rc")
    qt_add_executable(photosurface main.cpp ${app_icon_resource_windows})

Notice that the set command, defines the app_icon_windows variable, which contains the path of the RC file. This variable is used with the add_executable command to set the application's icon.

If you are still using qmake to generate your makefiles, you need to add a single line to your .pro project file:

RC_ICONS = myappico.ico

Finally, regenerate your makefile and your application. The .exe file will now be represented by your icon in Explorer.

However, if you already have an .rc file, for example, with the name myapp.rc, which you want to reuse, the following two steps will be required. First, put a single line of text to the myapp.rc file:

IDI_ICON1               ICON    "myappico.ico"

Then, add this line to your myapp.pro file:

RC_FILE = myapp.rc

If you do not use qmake, the necessary steps are: first, create an .rc file and run the rc or windres program on the .rc file, then link your application with the resulting .res file.

To configure the application's icon, the Info.plist file generated by CMake must contain the icon information. This can be achieved by setting the .icns file name to the MACOSX_BUNDLE_ICON_FILE variable.

The following snippet demonstrates how the Qt Quick Demo - Photo Surface example application uses CMake to set up an application icon:

    # The MACOSX_BUNDLE_ICON_FILE variable is added to the Info.plist
    # generated by CMake. This variable contains the .icns file name,
    # without the path.
    set(MACOSX_BUNDLE_ICON_FILE photosurface.icns)

    # And the following tells CMake where to find and install the file itself.
    set(app_icon_macos "${CMAKE_CURRENT_SOURCE_DIR}/resources/photosurface.icns")
    set_source_files_properties(${app_icon_macos} PROPERTIES
           MACOSX_PACKAGE_LOCATION "Resources")

    qt_add_executable(photosurface MACOSX_BUNDLE main.cpp ${app_icon_macos})

Notice that the first set command defines the MACOSX_BUNDLE_ICON_FILE variable, which is required to add the icon file to the Info.plist file. The second set command defines the app_icon_macos variable with the absolute path to the icon file. This variable is then used to configure MACOSX_PACKAGE_LOCATION, which defines the icon file's install location. Finally, the add_executable uses the app_icon_macOS variable to set the application's icon.

If you are still using qmake to generate your makefiles, you only need to add a single line to your .pro project file. For example, if the name of your icon file is myapp.icns, and your project file is myapp.pro, add this line to myapp.pro:

ICON = myapp.icns

This will ensure that qmake puts your icons in the proper place and creates an Info.plist entry for the icon.

If you do not use qmake, you must do the following manually:

1. Create an Info.plist file for your application (using the PropertyListEditor, found in Developer/Applications).

2. Associate your .icns record with the CFBundleIconFile record in the Info.plist file (again, using the PropertyListEditor).

3. Copy the Info.plist file into your application bundle's Contents directory.

4. Copy the .icns file into your application bundle's Contents/Resources directory.

Application icons can be installed for use by all users, or on a per-user basis. A user currently logged into their KDE 4 desktop can discover these locations by using kde4-config, for example, by typing the following in a terminal window:

kde4-config --path icon

Applications using Qt 5 and KDE Frameworks 5 will find their icons in the list returned by this command:

qtpaths --locate-dirs GenericDataLocation icons

Typically, the list of colon-separated paths printed to stdout includes the user-specific icon path and the system-wide path. Beneath these directories, it should be possible to locate and install icons according to the conventions described in the Icon Theme Specification.

If you are developing exclusively for KDE, you may wish to take advantage of the KDE build system to configure your application. This ensures that your icons are installed in the appropriate locations for KDE.

The KDE developer website is at http://techbase.kde.org/.

Application icons are stored within a standard system-wide directory containing architecture-independent files. This location can be determined by using gnome-config, for example by typing the following in a terminal window:

gnome-config --datadir

The path printed on stdout refers to a location that should contain a directory called pixmaps; the directory structure within the pixmaps directory is described in the Icon Theme Specification.

If you are developing exclusively for GNOME, you may want to use the standard set of GNU Build Tools. For more information, see the Integration Guidelines section. This ensures that your icons are installed in the appropriate locations for GNOME.

The GNOME developer website, http://developer.gnome.org/, provides more insight into developing applications.