CMake link error resource file

JanW

Hi,

I'm setting up my environment for a C++/Qt Quick application (Windows VS2013 x64) with cmake. I'm having trouble to get a (shared) library be compiled and linked to my executable and using a resource file from it (just a simple qml file to test the setup).

I have set(CMAKE_AUTOMOC ON) and set(CMAKE_AUTORCC ON) in my root CMakeLists.txt
The CMakeLists.txt of my shared library is as follows (BEQMLResource.qrc is in the same directory as CMakeLists.txt):

    cmake_minimum_required(VERSION 3.2)
     
    if(UNIX)
        SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -std=gnu++11")
    endif()
     
    SET(QT_ROOT_DIR "C:/Qt/5.7/msvc2013_64/")
     
    set(QT_QMAKE_EXECUTABLE ${QT_ROOT_DIR}/bin/qmake)
     
    find_package(Qt5 COMPONENTS Quick Core Network Widgets Gui Qml Positioning PATHS ${QT_ROOT_DIR})
     
    project("BEQML")
    set(PROJECT_RESOURCES BEQMLResource.qrc)
    qt5_add_resources(BEQML_RESOURCES ${PROJECT_RESOURCES})
    file(GLOB BEQML_SRC_LIBRARY
    	"BEQMLLibrary.h" #contains dll import/export defines for windows.
    	"BEQMLLibraryInitializer.cpp" #dummy class with some functions so the library is created.
    	"BEQMLLibraryInitializer.h"
    )
    source_group("Library"		FILES ${BEQML_SRC_LIBRARY})
    add_library(BEQML SHARED ${BEQML_SRC_LIBRARY} ${BEQML_RESOURCES})
    target_include_directories(BEQML PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/../../BELibraries/)

When I compile the library, I get two linker errors in qrc_BEQMLResource.obje (unresolved external symbol for qRegisterResourceData and qUnregisterResourceData).
Any idea what can be wrong?
Kind regards,

Jan

ambershark

@JanW That indicates it isn't linking with Qt properly would be my guess.

Try adding the line: qt5_use_modules(${PROJECT_NAME} Core) after your add_library line.

JanW

Thanks, that already solved my first problem! The BEQML library is building without errors, but now I got a link error in my executable project: unresolved external symbol qInitResource_BEQMLResource.
The CMakeLists.txt from my exe project is as follows:

cmake_minimum_required(VERSION 3.2 FATAL_ERROR)

if(UNIX)
    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -std=gnu++11")
endif()

set(CMAKE_INCLUDE_CURRENT_DIR ON)

SET(QT_ROOT_DIR "C:/Qt/5.7/msvc2013_64/")

set(QT_QMAKE_EXECUTABLE ${QT_ROOT_DIR}/bin/qmake)

find_package(Qt5 COMPONENTS Quick Core Network Widgets Gui Qml Positioning PATHS ${QT_ROOT_DIR})

project("StormExe")

qt5_add_resources(RESOURCES StormExe.qrc)

file(GLOB STORMEXE_SRC_QML
	"QML/Main.qml"
)
file(GLOB STORMEXE_SRC_EXE
	"Main.cpp"
)

source_group("Exe"	FILES ${STORMEXE_SRC_EXE})
source_group("QML"	FILES ${STORMEXE_SRC_QML})

add_executable(Storm ${STORMEXE_SRC_EXE} ${RESOURCES} ${STORMEXE_SRC_QML})
qt5_use_modules(Storm Quick Core Network Widgets Gui Qml Positioning)

target_link_libraries(Storm BEQML)
target_include_directories(Storm PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/../../BELibraries/)

In my Main.cpp i have:

#include <QApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
	QApplication app(argc, argv);

	Q_INIT_RESOURCE(BEQMLResource);

	QQmlApplicationEngine engine;
	engine.load(QUrl(QStringLiteral("qrc:/Main.qml")));

	return app.exec();
}

Do I need to do something special to get access to the resources from the shared library?
Regards,

Jan

Btw, if i build as a static lib, everything works just fine...

JanW

Ok, found a workaround by exporting a custom method from the dll which calls the initialisation of the resource like this:

int BEQMLLibraryInitializer::init()
{
	extern int qInitResources_BEQMLResource();
	return qInitResources_BEQMLResource();
}

Is there a better way to do it?
Regards,

Jan

ambershark

@JanW This answers it better than I could:

http://stackoverflow.com/questions/14633454/how-can-i-embed-a-qt-resource-into-a-dll-file

Glad it's working for you now though. :)