无法在 CLion (macOS) 上使用 CImg 打开 .png 文件

Question

我尝试过包含 libpng16/png.h 和 #define cimg_use_png，但它们都没有解决错误。另外，我在同一目录中有main.cpp、lenna.jpg 和CImg.h。

CMakeLists.txt：

cmake_minimum_required(VERSION 3.6)
project(HelloWorld)

set(CMAKE_CXX_STANDARD 17)

set(SOURCE_FILES main.cpp)
add_executable(HelloWorld ${SOURCE_FILES})

set(YOU_NEED_X11 1)
set(YOU_NEED_PNG 1)

if (${YOU_NEED_PNG} EQUAL 1)
    message(STATUS "Looking for libpng...")
    find_package(PNG REQUIRED)
    include_directories(${PNG_INCLUDE_DIR})
    target_link_libraries (HelloWorld ${PNG_LIBRARY})
    target_compile_definitions(HelloWorld PRIVATE cimg_use_png=1)
endif()

if (${YOU_NEED_X11} EQUAL 1)
    message(STATUS "Looking for X11...")
    find_package(X11 REQUIRED)
    include_directories(${X11_INCLUDE_DIR})
    target_link_libraries(HelloWorld ${X11_LIBRARIES})
else()
    target_compile_definitions(HelloWorld PRIVATE cimg_display=0)
endif()

main.cpp:

#include <iostream>
#include "CImg.h"

using namespace cimg_library;

int main() {

    CImg<unsigned char> img("lenna.png");

    int h = img.height();
    int w = img.width();
    int s = img.spectrum();

    std::cout << "h: " << h << " w: " << w << " s: " << s << std::endl;

    return 0;
}

错误：

[CImg] *** CImgIOException *** [instance(0,0,0,0,0x0,non-shared)] CImg<unsigned char>::load(): Failed to open file 'lenna.png'.
libc++abi.dylib: terminating with uncaught exception of type cimg_library::CImgIOException: [instance(0,0,0,0,0x0,non-shared)] CImg<unsigned char>::load(): Failed to open file 'lenna.png'.

Process finished with exit code 6

Answer 1

似乎找不到lenna.png。相对路径是相对于包含可执行文件的目录的。这意味着如果可执行文件位于cmake-build-debug/HelloWorld 并且您尝试打开lenna.png，则会打开位于cmake-build-debug/lenna.png 的文件。这意味着您应该手动将 lenna.png 复制到 cmake-build-debug（我不推荐这样做）或让 CMake 为您完成。

将此添加到您的 CMakeLists.txt 文件中。

add_custom_command(
      TARGET HelloWorld POST_BUILD
      COMMAND ${CMAKE_COMMAND} -E copy
              ${CMAKE_SOURCE_DIR}/lenna.png
              ${CMAKE_BINARY_DIR}/lenna.png
)

这将导致每次编译可执行文件时将lenna.png 复制到与您的可执行文件相同的目录中。