error : definition is marked dllimport using lvgl_thorvg

[liquanqing]

Hi,
in windows, i use cmake with mingW compile successful except lvgl_thorvg;
but using LV_CONF_BUILD_DISABLE_THORVG_INTERNAL = ON to enable lvgl_thorvg ,
it compile error with "definition is marked dllimport ".
how can i fix it ?

[kisvegabor]

Last time we saw a dll import issue @kdschlosser investigated it. Kevin, do you know what can be the problem with ThorVG?

[kdschlosser]

Can you paste the compiler output into a post for me so I can see what is happening?

[liquanqing]

all api in thorvg are show error as follow :
lvgl-9.1.0\src\libs\thorvg\tvgCapi.cpp:63:20: error: function 'Tvg_Result tvg_canvas_destroy(Tvg_Canvas*)' definition is marked dllimport
[build] TVG_API Tvg_Result tvg_canvas_destroy(Tvg_Canvas* canvas)

lvgl-9.1.0\src\libs\thorvg\tvgCapi.cpp:498:20: error: function 'Tvg_Result tvg_shape_get_gradient(const Tvg_Paint*, Tvg_Gradient**)' definition is marked dllimport
[build] TVG_API Tvg_Result tvg_shape_get_gradient(const Tvg_Paint* paint, Tvg_Gradient** gradient)

[liquanqing]

and this is my cmake file written :
set(SDL2_RELEASE_DIR source/thirdparty/SDL2-devel-2.30.4-mingw)

find_package(SDL2 2.30.4 PATHS ${SDL2_RELEASE_DIR})

message(STATUS "SDL2_DIR = ${SDL2_DIR}")
message(STATUS "SDL2_INCLUDE_DIRS = ${SDL2_INCLUDE_DIRS}")
message(STATUS "SDL2_LIBDIR = ${SDL2_LIBDIR}")
message(STATUS "SDL2_BINDIR = ${SDL2_BINDIR}")
message(STATUS "SDL2_LIBRARIES = ${SDL2_LIBRARIES}")
message(STATUS "SDL2_FOUND = ${SDL2_FOUND}")

MESSAGE(STATUS "project_source" "${PROJECT_SOURCE_DIR}")

set(LVGL_SRC_DIR ${ROOT_PATH}/source/thirdparty/lvgl)
set(LVGL_VERSION 9.1.0)
set(LVGL_SIM_SRC_DIR ${CMAKE_CURRENT_SOURCE_DIR})
message(STATUS "LVGL path " ${LVGL_SRC_DIR}-${LVGL_VERSION})

option(LV_USE_DRAW_SDL "Use SDL draw unit" OFF)
option(LV_USE_LIBPNG "Use libpng to decode PNG" OFF)
option(LV_USE_LIBJPEG_TURBO "Use libjpeg turbo to decode JPEG" OFF)
option(LV_USE_FFMPEG "Use libffmpeg to display video using lv_ffmpeg" OFF)
option(LV_USE_FREETYPE "Use freetype lib" OFF)
option(LV_CONF_BUILD_DISABLE_THORVG_INTERNAL "Disable building thorvg library" OFF)

MESSAGE(STATUS "lvgl source dir: ${LVGL_SRC_DIR}-${LVGL_VERSION}")
add_subdirectory(${LVGL_SRC_DIR}-${LVGL_VERSION})

add_subdirectory(lvgl_sim_src)

in lvgl_sim_src directory 's CMakeLists.txt is :
message(STATUS "get ROOT_PATH" ${ROOT_PATH})
message(STATUS "cur path " ${CMAKE_CURRENT_SOURCE_DIR})

target_include_directories(lvgl PUBLIC ${CMAKE_CURRENT_SOURCE_DIR} ${LVGL_SRC_DIR}-${LVGL_VERSION} ${SDL2_INCLUDE_DIRS})
target_compile_options(lvgl PRIVATE -DLV_CONF_PATH=lv_conf.h)

add_executable(lvgl_main main.c mouse_cursor_icon.c)
target_link_directories(lvgl_main PRIVATE
${SDL2_LIBDIR})
target_include_directories(lvgl_main PUBLIC ${LVGL_SRC_DIR}-${LVGL_VERSION} ${SDL2_INCLUDE_DIRS})
target_link_libraries(lvgl_main lvgl lvgl::examples lvgl::demos lvgl::thorvg -lmingw32 ${SDL2_LIBRARIES} m pthread)

add_custom_command(TARGET lvgl_main POST_BUILD
COMMAND ${CMAKE_COMMAND} -E copy_if_different
${SDL2_BINDIR}/SDL2.dll $<TARGET_FILE_DIR:lvgl_main>)

[kdschlosser]

@kisvegabor

It's easy to locate the issue...

This is the compiler output

all api in thorvg are show error as follow :
lvgl-9.1.0\src\libs\thorvg\tvgCapi.cpp:63:20: error: function 'Tvg_Result tvg_canvas_destroy(Tvg_Canvas*)' definition is marked dllimport   << ------ RIGHT HERE
[build] TVG_API Tvg_Result tvg_canvas_destroy(Tvg_Canvas* canvas)

lvgl-9.1.0\src\libs\thorvg\tvgCapi.cpp:498:20: error: function 'Tvg_Result tvg_shape_get_gradient(const Tvg_Paint*, Tvg_Gradient**)' definition is marked dllimport   << ------ RIGHT HERE
[build] TVG_API Tvg_Result tvg_shape_get_gradient(const Tvg_Paint* paint, Tvg_Gradient** gradient)

searching for the function tvg_canvas_destroy we find the following..

thorvg_capi.h

TVG_API Tvg_Result tvg_canvas_destroy(Tvg_Canvas* canvas);

tvgCapi.cpp

TVG_API Tvg_Result tvg_canvas_destroy(Tvg_Canvas* canvas)
{
    if (!canvas) return TVG_RESULT_INVALID_ARGUMENT;
    delete(reinterpret_cast<Canvas*>(canvas));
    return TVG_RESULT_SUCCESS;
}

and when we look up what TVG_API is this is what is found in thorvg_capi.h

#ifndef TVG_STATIC
    #ifdef _WIN32
        #if TVG_BUILD
            #define TVG_API __declspec(dllexport)
        #else
            #define TVG_API __declspec(dllimport)
        #endif
    #elif (defined(__SUNPRO_C)  || defined(__SUNPRO_CC))
        #define TVG_API __global
    #else
        #if (defined(__GNUC__) && __GNUC__ >= 4) || defined(__INTEL_COMPILER)
            #define TVG_API __attribute__ ((visibility("default")))
        #else
            #define TVG_API
        #endif
    #endif
#else
    #define TVG_API
#endif

and there you have it. an undocumented macro.. TVG_BUILD needs to be set so that it will mark the functions as exports.

[kdschlosser]

@liquanqing

add -DTVG_BUILD=1 to your C and CPP compiler flags and that should do the trick.

[liquanqing]

i had add -DTVG_BUILD=1 and the error still happened, here is my modified :

message(STATUS "get ROOT_PATH" ${ROOT_PATH})
message(STATUS "cur path " ${CMAKE_CURRENT_SOURCE_DIR})

set(CMAKE_C_FLAGS "-DTVG_BUILD=1 ${CMAKE_C_FLAGS}")
set(CMAKE_CXX_FLAGS "-DTVG_BUILD=1 ${CMAKE_CXX_FLAGS}")

target_include_directories(lvgl PUBLIC  ${CMAKE_CURRENT_SOURCE_DIR} ${LVGL_SRC_DIR}-${LVGL_VERSION} ${SDL2_INCLUDE_DIRS})
target_compile_options(lvgl PRIVATE -DLV_CONF_PATH=lv_conf.h -DTVG_BUILD=1)

add_executable(lvgl_main main.c mouse_cursor_icon.c)
target_link_directories(lvgl_main PRIVATE 
                    ${SDL2_LIBDIR})
target_include_directories(lvgl_main PUBLIC ${LVGL_SRC_DIR}-${LVGL_VERSION} ${SDL2_INCLUDE_DIRS})
target_link_libraries(lvgl_main lvgl lvgl::examples lvgl::demos lvgl::thorvg -lmingw32 ${SDL2_LIBRARIES} m pthread)

add_custom_command(TARGET lvgl_main POST_BUILD
                    COMMAND ${CMAKE_COMMAND} -E copy_if_different
                    ${SDL2_BINDIR}/SDL2.dll $<TARGET_FILE_DIR:lvgl_main>)

[liquanqing]

@kdschlosser
i do a little change, and it worked.
target_compile_options(lvgl PUBLIC -DLV_CONF_PATH=lv_conf.h -DTVG_BUILD=1)
Thanks.

[liquanqing]

compiler is successful. and i run lvgl_main.exe vector_graphic and it maybe call some wrong.

[kdschlosser]

That is going to be in @kisvegabor 's court to help you. I know the build systems and documentation. LVGL's inner workings are not my strong area especially the vector graphics stuff.

[kisvegabor]

Awesome! Please try modifying this part to

target_compile_definitions(lvgl
    INTERFACE LV_ATTRIBUTE_EXTERN_DATA=__declspec\(dllimport\)
    PRIVATE LV_ATTRIBUTE_EXTERN_DATA=__declspec\(dllexport\)
    PRIVATE TVG_BUILD=1
)