How to add custom content to a CMake project? - cmake

We recently started switching over from using plain visual studio projects to using proper CMake files. Previously we would have the "Content" folder in the solution root folder to allow our executables to access content from it using a relative path like "../Tiles/tileset1.png".
How could we make sure CMake copies the files correctly, or in some other way makes sure that our executables are able to find the content folder while debugging from Visual Studio without manually setting the working directory?

I can think of a few different options:
Have CMake put all your executables in the same folder, as described in this question. Then you can use ../Tiles or ../../Tiles or whatever as you've been doing. Note, however, that you might want to consider setting this on a per-target basis instead of globally, e.g., using:
set_target_properties(
my_target
PROPERTIES
RUNTIME_OUTPUT_DIRECTORY
${CMAKE_BINARY_DIR}/bin
)
Setting CMAKE_RUNTIME_OUTPUT_DIRECTORY works fine, but some people consider it to be the 'old' way of doing it. (Depending on your needs, you might also want to set LIBRARY_OUTPUT_DIRECTORY, and possibly ARCHIVE_OUTPUT_DIRECTORY.)
Use an environmental variable (e.g., CONTENT_ROOT or some-such) to locate the resources. Hard-code a default that makes sense for production, but let developers override it for their particular work flow.
Look into cross-platform resource libaries (something like Qt's QRC files, but perhaps not tied to Qt).
Try the CMake modules listed in this FAQ answer to change Visual Studio's working/debugging directory.
Actually, a combination of 1 and 2 is probably your best bet...

Related

cmake: package config for installing arbitrary file dependencies for a target

I am creating a cmake package config file (a Foo-config.cmake) for a pre-existing .dll not created by cmake.
The annoying thing is that the .dll depends on some data files.
When a user consumes my package in his own cmake project, I want the INSTALL target to install both the .dll and data files to his specified install location. I don't want him to have to write extra install() rules to do that.
Is it good practice to write the install() rules directly in my Foo-config.cmake? Or is there a better way to do this, maybe with set_target_properties()? I just couldn't find the appropriate property for associating arbitrary file dependencies to a target.
In an alternate universe where this .dll didn't already exist and I had to create it myself using cmake, would I need to create a custom Foo-config.cmake, or is there something in cmake that can automatically generate it for me to achieve the same thing?
FWIW the .dll is an internal legacy library and is normally built by Visual Studio and uploaded in a .zip file to our internal artifactory. I want us to migrate away from manually pulling down .zip files from artifactory and manually integrating the files into Visual Studio projects.
I've since found that there are a couple different ways to do this:
In the config file, simply create one or more variables for the files/dirs you want to install. Then install those using install(FILES) and/or install(DIRECTORY). More info: https://stackoverflow.com/a/46361538/189341
Use file(GET_RUNTIME_DEPENDENCIES). More info:
https://discourse.cmake.org/t/installing-a-pre-built-module-and-its-various-dependencies/5227
How to use cmake file( GET_RUNTIME_DEPENDENCIES in an install statement?
Is it good practice to write the install() rules directly in my Foo-config.cmake?
No.
From 480 *-config.cmake and *Config.cmake files on my system none calls install().
Or is there a better way to do this, maybe with set_target_properties()?
No.
In an alternate universe where this .dll didn't already exist and I had to create it myself using cmake, would I need to create a custom Foo-config.cmake
No. This is unrelated to if you create a .dll or not. If .dll exists, there is no need to create Foo-config.cmake anyway. It is your choice that you want to (or make users to) use find_package.
is there something in cmake that can automatically generate it for me
No.
If you don't intent to support find_package features - VERSION OPTIONAL_COMPONENTS PATHS HINTS CONFIGS etc. - then just go with include(). find_package is just include() with some extra options.
If you want to have install() in your find_package, then just protect it with a variable, like if (FOO_DO_INSTALL) install(....) endif().

Force CMake to install targets to architecture-specific directories?

I'm currently having this issue with the Google Protobuf Library, but it is a recurring problem and will likely occur with many if not all 3rd-party packages that I want to build and install from source.
I'm developing for Windows, and we need to be able to generate both 32-bit and 64-bit versions of our DLLs. It was relatively straightforward to get CMake to install our own modules to architecture-specific subdirectories, e.g. D:\libraries\bin\i686 and d:\libraries\lib\i686 (and sim. for bin). But I'm having trouble achieving the same thing with 3rd-party libraries such as Protobuf.
I could, of course, use distinct CMAKE_INSTALL_PREFIX and CMAKE_PREFIX_PATH combinations (e.g. D:\libraries-i686 and D:\libraries-x86_64, and will probably end up doing just that, but it bothers me that there doesn't seem to be a better alternative. The docs for find_package() clearly show that the search procedure does attempt architecture-specific search paths, so why do the CMake files of popular libraries not generally seem to support installing to architecture-specific subdirectories?
Or could it be that it is just a matter of setting the right CMAKE_XXX variable?
Thanks to #arrowd for pointing me in the right direction, I now have my answer, though it is not exactly what I had hoped for.
CMAKE_LIBRARY_OUTPUT_DIRECTORY and CMAKE_RUNTIME_OUTPUT_DIRECTORY, however, specify the build output directories, not the install directories. As it turns out though, there are variables for the install directories too, called CMAKE_INSTALL_BINDIR and CMAKE_INSTALL_LIBDIR - they are actually plainly visible (along with plenty more) in the cmake-gui interface when "Advanced" is checked.
I tried setting those two manually (to bin\i686 and lib\i686), and it works: the Protobuf INSTALL target copies the files where I wanted to have them, i.e. where the CMake script of my consumer project will find them in an architecture-safe manner.
I'm not sure how I feel about this - I would have preferred something like a CMAKE_INSTALL_ARCHITECTURE or CMAKE_ARCHITECTURE_SUBDIR variable that CMake would automatically append to relevant install paths. The solution above requires overriding defaults that I would prefer to leave untouched.
Under the circumstances, my fallback approach might still be the better option. That approach however requires that the choice of architecture be made very early on, typically when running the script that initializes the CMake-specific environment variables that will be passed to cmake when configuring build directories. And it's worse when using cmake-gui, which requires the user to set all directories manually.
In the end, I'm still undecided.

MSBuild shared .targets file

I have several .csproj files that I will be importing a common .targets file into, to extend the build process. The projects are in different directories. The .targets file is in the solution directory. How do I refer to the location of the .targets file to import it? There's a solution directory property, but this doesn't work if the developer just builds a project. What do I do? I am using .NET 4.5 and Visual Studio 2015.
As you figured a project doesn't know about a solution it's contained in, and arguably it shouldn't. So there's not much you can do to programmatically figure out where, from the project's point of view, a totally unrelated file is situated. Apart from scanning the entire filesystem for it. There are some alternatives:
rely on a proper directory structure. You do this already anyway, since you use a solution which also needs to find projects in a fixed location. So suppose you have a main project dir with projectA/a.vcxproj, projectB/b.vcxproj and solutionDir/ab.sln and solutionDir/my.targets then in a and b just <Import Project="$(MSBuildProjectDirectory)..\solutionDir\my.targets"/>
require a property (or environment variable) which is set to the location of the targets file and then use <Import Project="$(SomeDir)\my.targets"/>
put your targets file in a 'known' msbuild location like the Importbefore/ImportAfter directories, mentioned here for instance.
I've used all of these at one point and in the end the first is in my opinion the better one: you just have to stick with a directory convention - you need that anyway for projects spanning mulriple directories or with common shared stuff - and that's it. For example we have a ton of common msbuild files and they're in a single repository. Starting a new project always comes down to creating a directory, cloning the common files dir and adding a new project dir. That can it turn easily be automated, also works well on typical CI servers. The second option is also doable, but it relies on a properly setup environment which is less 'self-contained' and gets really messy if developpers start entering the variable in the machines' global environment variable settings, and in the local ones, and so on. Similar problems with the third one but worse since now there's only one correct location.

Best way to access DLLs during development

I'm creating a development environment that should be easy to install on new systems. Therefore I created library packages (OpenCV, boost, Qt etc) all placed in a single folder (environment_folder) which is accessed by an environment variable by Visual Studio projects/solutions (so for a single compiler the whole folder can be copied and only the variable has to be set).
Now to execute the binary it needs access to the DLLs of those libraries.
I typically copy all needed DLLs to the binary directory, but that's neither nice nor pratical.
Another way would be to add all the libraries' pathes to the PATH variable, but that's a lot of work to perform while/after installing the library packages, so I would like to avoid it. Additionally it is error-prone when testing new versions of libraries for example.
A third way that comes in my mind would be to copy all the DLLs to a single package_bin folder, so only a single path has to be added to the PATH variable (which is additonally relative to the environment_folder), but I don't like that idea.
Is there any better way to do it?

Making my program compile on both windows and linux, what should I do about libraries?

I'm using CMake to generate my makefiles and VC solutions. I have my program running on linux just fine. I'm using a bunch of libraries, e.g. Lua. On my linux computer I just link to them and make sure in include the headers. All of the .so files are in some standard place. On Windows though I'm not sure what to do. Should I just include the entire Lua project into my own repository and link to that instead? Do I install Lua to some standard place like c:\program files\lua5.1 and link to that? Something else?
Your libraries can be in any place, you just need to say - where are they.
Before running cmake set up pathes of all your extern libs with some .bat file:
set LIBRARYPATH =path\to\your\library\
set include=%include%;%LIBRARYPATH%\include
set lib=%lib%;%LIBRARYPATH%\lib
Start cmd, run this .bat and then cmake should find all
I would provide a configuration field/variable for ccmake that the user can or must specify.
The mark_as_advanced can be used to make a custom variable only appear in the advanced mode. This would be suitable if you have a standard path (as you have mostly on windows). Yet, it still let's the user specify the value if needed.
Or you can simply set a variable the with the 'set' command if you don't want it in advanced.
Just make sure you check if the users entered a valid value.