mingw 在 Windows 上找不到 libpng 的 png.h答案

【问题标题】：mingw cannot find png.h for libpng on Windowsmingw 在 Windows 上找不到 libpng 的 png.h
【发布时间】：2020-05-18 05:23:28
【问题描述】：

我正在做一个需要我使用 CImg 的项目，而 CImg 又需要 libpng。我将 CLion 和 cmake 与 MinGW-W64 GCC-8.1.0 一起使用。我一直在关注这个答案 - https://stackoverflow.com/a/41956016/11382155 来设置它。

这就是我的 CMakeLists.txt 的样子

cmake_minimum_required(VERSION 3.15)
project(CImgProject)

set(CMAKE_CXX_STANDARD 14)

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

# You can alter these according to your needs, e.g if you don't need to display images - set(YOU_NEED_X11 0)
set(YOU_NEED_X11 1)
set(YOU_NEED_PNG 1)

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

if(${YOU_NEED_PNG} EQUAL 1)
    message(STATUS "Looking for libpng...")
    set(ZLIB_ROOT "CImg283/zlib-1.2.11")
    set(ZLIB_LIBRARY "CImg283/zlib-1.2.11")
    set(PNG_ROOT "CImg283/lpng1637")
    set(PNG_LIBRARY "CImg283/lpng1637")
    find_package(PNG REQUIRED)
    include_directories(${PNG_INCLUDE_DIR})
    target_link_libraries (CImgProject ${PNG_LIBRARY})
    target_compile_definitions(CImgProject PRIVATE cimg_use_png=1)
endif()

这是我的 main.cpp

#include "CImg283/CImg.h"

using namespace cimg_library;

int main() {
    CImg<unsigned char> img(640,400,1,3);         // Define a 640x400 color image with 8 bits per color component.
    img.fill(0);                                  // Set pixel values to 0 (color : black)
    unsigned char purple[] = { 255,0,255 };       // Define a purple color
    img.draw_text(100,100,"Hello World",purple);  // Draw a purple "Hello world" at coordinates (100,100).
    img.display("Window Title");                  // Display the image in a display window.
    img.save_png("test.png");                     // Save as PNG to prove we linked correctly
    return 0;
}

我遇到的问题是，当我点击构建时，我收到以下错误

====================[ Build | CImgProject | Debug ]=============================
"C:\Program Files\JetBrains\CLion 2019.1\bin\cmake\win\bin\cmake.exe" --build C:\Users\bhave\OneDrive\Desktop\untitled\cmake-build-debug --target CImgProject -- -j 6
Scanning dependencies of target CImgProject
[ 50%] Building CXX object CMakeFiles/CImgProject.dir/main.cpp.obj
In file included from C:\Users\bhave\OneDrive\Desktop\untitled\main.cpp:3:
C:\Users\bhave\OneDrive\Desktop\untitled\CImg283/CImg.h:447:10: fatal error: png.h: No such file or directory
 #include "png.h"
          ^~~~~~~
compilation terminated.
mingw32-make.exe[3]: *** [CMakeFiles\CImgProject.dir\build.make:63: CMakeFiles/CImgProject.dir/main.cpp.obj] Error 1
mingw32-make.exe[2]: *** [CMakeFiles\Makefile2:75: CMakeFiles/CImgProject.dir/all] Error 2
mingw32-make.exe[1]: *** [CMakeFiles\Makefile2:82: CMakeFiles/CImgProject.dir/rule] Error 2
mingw32-make.exe: *** [Makefile:117: CImgProject] Error 2

我不知道为什么当cmake能够找到libpng并且我检查了png.h确实存在时会弹出这个错误。

【问题讨论】：

您是否尝试过使用PNG_INCLUDE_DIRS 和PNG_LIBRARIES 而不是PNG_INCLUDE_DIR 和PNG_LIBRARY？根据 CMake docs，单数形式变量已过时。
@Dmitry：过时的变量仍然设置在current CMake code中。
@Dmitry 我尝试了你的建议，但没有解决问题。

标签： cmake clion libpng cimg

【解决方案1】：

我解决了这个问题

set(ZLIB_ROOT "CImg283/zlib-1.2.11")
set(ZLIB_LIBRARY "CImg283/zlib-1.2.11")
set(PNG_ROOT "CImg283/lpng1637")
set(PNG_LIBRARY "CImg283/lpng1637")

然后从https://packages.msys2.org/package/mingw-w64-x86_64-libpng 获取mingw-64 库分发并将文件放在我的mingw 分发中的正确位置。请务必将其放在 64 位安装中的两个 mingw 文件夹中。

【讨论】：