CMake - wxWidgets

CMake is released with a large set of source code that can be used to accomplish common tasks. One of this tasks is looking for a package used by your project.

For example, let's see how to look for the wxWidgets library. We can use the FIND_PACKAGE command for this purpose: CMake already knows how to handle wxWidgets.

Just add the following lines to CMakeLists.txt:

FIND_PACKAGE(wxWidgets REQUIRED html adv core base net aui xrc qa richtext )
INCLUDE(${wxWidgets_USE_FILE})

TARGET_LINK_LIBRARIES(myTarget ${wxWidgets_LIBRARIES})


The first line tells CMake to look for wxWidgets. The REQUIRED clause says that you require the specified modules.
The FIND_PACKAGE command executes some code and sets a number of variables if it finds the library.
The second line uses one of those variables to tell CMake where to look for include files.
The third line tells CMake how to link a target with wxWidgets.

Now let's see what happens when we run CMake from its GUI. Press Configure and you will probably see a number of red rows that need to be fixed. The rows content changes with the operating system.

Linux

I create two build folders, one for the debug configuration and one for the release one.

You need to look at the following variables:

• CMAKE_BUILD_TYPE: set it to Debug for a build folder and to Release for the other.
• wxWidgets_CONFIG_EXECUTABLE: it is the path to the wx-config script for the chosen copy of wxWidgets. For example, /usr/local/bin/wx-config for a library that has been installed, or /home/fulvio/wxSVN/buildgtk/wx-config for a library that has not been installed. In the library has not been installed you must point to the wx-config file in the folder with the right configuration (for example debug or not).
• wxWidgets_USE_DEBUG: check it if you want to use a debug version of the library.
• wxWIDGETS_USE_STATIC: check it if you ant to use a static version of the library.
• wxWidgets_USE_UNICODE: check it if you want to use the Unicode version of the library. If you are using version 2.9 or later this setting does not make sense any more (the llibrary is only Unicode): I leave it checked and everything works well.
• wxWidgets_wxrc_EXECUTABLE: this is probably a wxrc setting. Since I do not use it I left its value set to NOTFOUND.

OS X

I create two build folders, one for the debug configuration and one for the release one.

You need to look at the following variables:

• CMAKE_BUILD_TYPE: set it to Debug for a build folder and to Release for the other.
• CMAKE_OSX_ARCHITECTURES:  I set it to i386.
• CMAKE_OSX_DEPLOYMENT_TARGET: I leave this blank.
• wxWidgets_CONFIG_EXECUTABLE: it is the path to the wx-config script for the chosen copy of wxWidgets. For example /Users/fulvio/wxMac-2.8.10/buildgtk/wx-config for a library that has not been installed. In the library has not been installed you must point to the wx-config file in the folder with the right configuration (for example debug or not).
• wxWidgets_wxrc_EXECUTABLE: this is probably a wxrc setting. Since I do not use it I left its value set to NOTFOUND.

Windows

In Windows I create a single build folder. It will contain a Visual Studio project file with both a debug and a release configuration.

You need to look at the following variables:

• wxWidgets_CONFIGURATION: set to mswud, mswu or mswd. This is not very clear to me, but I set it to mswu and everything works well.
• wxWidgets_ROOT_DIR: it is the path to the root folder of the wxWidgets installation, for example E:/wxWidgets-2.8.10. If CMake does not find the path you need to set it manually and configure again.
• wxWidgets_LIB_DIR: it is the path of the folder that contains the libraries that will be linked to your program. Usually CMake can find this path by itself if it knows the root dir.
• wxWidgets_USE_REL_AND_DBG is a boolean value. Check it if you want to have a project with both a debug and a release configuration. You will probably check it.
• wxWidgets_wxrc_EXECUTABLE: this is probably a wxrc setting. Since I do not use it I left its value set to NOTFOUND.

As you can see configuring CMake to use your copy of wxWidgets is an easy task.
It is also easy to use different versions of wxWidgets with your project. Just build the different versions in different folders (do not install them in *nix), then create different build folders for the different wxWidgets versions. For each folder configure CMake to look for wxWidgets in the right folder, manually setting the required variables to the right value.