Qt Library Sample

In this project, a library is built with Qt and an output is provided that can be used in any other project. Cmake is used in this library.

MyLib Project
MyLibTest Project
Usage

MyLib Project

To build an exportable library, the following are required.

CMakeLists.txt

set(PROJECT_NAME "MyLib")
set(CMAKE_INSTALL_DIR "${CMAKE_CURRENT_SOURCE_DIR}/../Release")
set(CMAKE_INSTALL_BINDIR "${CMAKE_INSTALL_DIR}/bin")
set(CMAKE_INSTALL_INCLUDEDIR "${CMAKE_INSTALL_DIR}/include")
set(CMAKE_INSTALL_LIBDIR "${CMAKE_INSTALL_DIR}/lib")

set_target_properties(MyLib PROPERTIES OUTPUT_NAME "${PROJECT_NAME}")
install(TARGETS MyLib
RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
install(DIRECTORY / DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
FILE_PERMISSIONS
OWNER_READ OWNER_EXECUTE OWNER_WRITE
GROUP_READ GROUP_EXECUTE
WORLD_READ WORLD_EXECUTE
DIRECTORY_PERMISSIONS
OWNER_READ OWNER_EXECUTE OWNER_WRITE
GROUP_READ GROUP_EXECUTE GROUP_WRITE
WORLD_READ WORLD_EXECUTE
FILES_MATCHING PATTERN "*.h")

Note: It is possible to do the same for files of different types. In this section, it adds "*.h" extension files inside the project to the final Release folder of the library.

Now use "MYLIB_EXPORT" in classes for export.

class MYLIB_EXPORT MyLib
{
...
}

MyLibTest Project

To use the output of the "MyLib" library, follow the steps below.

CMakeLists.txt

set(MyLib_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../Release")
add_library(MyLib SHARED IMPORTED)
set_property(TARGET MyLib PROPERTY IMPORTED_LOCATION "${MyLib_PATH}/bin/MyLib.dll")
set_property(TARGET MyLib PROPERTY IMPORTED_IMPLIB "${MyLib_PATH}/lib/MyLib.lib")
target_include_directories(MyLib INTERFACE "${MyLib_PATH}/include")

Add "MyLib" in target_link_libraries.

target_link_libraries(MyLibTest Qt${QT_VERSION_MAJOR}::Core MyLib)

Now use library in main.cpp .

#include <QCoreApplication>
#include <mylib.h>
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
MyLib mylib;
mylib.Test_1();
mylib.Test_2();
return a.exec();
}

Usage

Step 1

After building the MyLib library, you must run the following command in that folder.

cmake --install ./

Note: That Cmake must be installed on your system before that.

Now you will have a folder called Release in the folder next to "MyLib", where the library outputs are placed.

Release Folder Structure

└── bin
| └── MyLib.dll
└── include
| ├── MyLib_global.h
| └── mylib.h
└── lib
└── MyLib.lib

Step 2

Now you can use this library by running the MyLibTest project using the Release folder.