QT Creator与命令行链接不同的库

Question

我有一个问题，我无法理解。 我想用openCV 3.1编写一个项目。我想在QT Creator环境中编写代码，因为我已经习惯了。我现在不需要任何QT特定功能，我正在使用Ubuntu 14.04。 问题是，无论何时我尝试在QT Creator内部构建，它都不会生成以下错误，但是如果从命令行构建，它将起作用。

10:57:36: Starting: "/usr/bin/cmake" --build . --target all 
Linking CXX executable arucoTest 
CMakeFiles/arucoTest.dir/PoseEstimator.cpp.o: In function `PoseEstimator::generateMarkers(std::string, int)': 
PoseEstimator.cpp:(.text+0x56): undefined reference to `cv::aruco::getPredefinedDictionary(cv::aruco::PREDEFINED_DICTIONARY_NAME)' 
PoseEstimator.cpp:(.text+0xb7): undefined reference to `cv::aruco::drawMarker(cv::Ptr<cv::aruco::Dictionary>&, int, int, cv::_OutputArray const&, int)' 
PoseEstimator.cpp:(.text+0x1a9): undefined reference to `cv::imwrite(cv::String const&, cv::_InputArray const&, std::vector<int, std::allocator<int> > const&)' 
CMakeFiles/arucoTest.dir/PoseEstimator.cpp.o: In function `cv::String::~String()': 
PoseEstimator.cpp:(.text._ZN2cv6StringD2Ev[_ZN2cv6StringD5Ev]+0x14): undefined reference to `cv::String::deallocate()' 
CMakeFiles/arucoTest.dir/PoseEstimator.cpp.o: In function `cv::String::String(std::string const&)': 
PoseEstimator.cpp:(.text._ZN2cv6StringC2ERKSs[_ZN2cv6StringC5ERKSs]+0x69): undefined reference to `cv::String::allocate(unsigned long)' 
collect2: error: ld returned 1 exit status 
make[2]: *** [arucoTest] Error 1 
make[1]: *** [CMakeFiles/arucoTest.dir/all] Error 2 
make: *** [all] Error 2 
10:57:36: The process "/usr/bin/cmake" exited with code 2. 

所以这是某种链接错误。当我检查我的CMake的文件和输出，我看到：

Running "/usr/bin/cmake /XYZ/arucoTest '-GCodeBlocks - Unix Makefiles'" in /XYZ/arucoTest/testbuild. 
-- OpenCV library status: 
--  version: 2.4.8 
--  libraries: opencv_videostab;opencv_video;opencv_ts;opencv_superres;opencv_stitching;opencv_photo;opencv_ocl;opencv_objdetect;opencv_ml;opencv_legacy;opencv_imgproc;opencv_highgui;opencv_gpu;opencv_flann;opencv_features2d;opencv_core;opencv_contrib;opencv_calib3d 
--  include path: /usr/include/opencv;/usr/include 
-- Configuring done 
-- Generating done 
-- Build files have been written to: /XYZ/arucoTest/testbuild 

正如你所看到的，它只是发现的OpenCV 2.4.8，我仍然需要，因为老ROS靛蓝项目。但是，如果我执行完全相同的cmake的文件，并从命令行构建，它完美的作品：

username@pc:/XYZ/arucoTest/build$ cmake .. 
-- The C compiler identification is GNU 4.8.4 
-- The CXX compiler identification is GNU 4.8.4 
-- Check for working C compiler: /usr/bin/cc 
-- Check for working C compiler: /usr/bin/cc -- works 
-- Detecting C compiler ABI info 
-- Detecting C compiler ABI info - done 
-- Check for working CXX compiler: /usr/bin/c++ 
-- Check for working CXX compiler: /usr/bin/c++ -- works 
-- Detecting CXX compiler ABI info 
-- Detecting CXX compiler ABI info - done 
-- OpenCV library status: 
--  version: 3.1.0 
--  libraries: opencv_xphoto;opencv_xobjdetect;opencv_ximgproc;opencv_xfeatures2d;opencv_tracking;opencv_text;opencv_surface_matching;opencv_structured_light;opencv_stereo;opencv_saliency;opencv_rgbd;opencv_reg;opencv_plot;opencv_optflow;opencv_line_descriptor;opencv_fuzzy;opencv_face;opencv_dpm;opencv_dnn;opencv_datasets;opencv_ccalib;opencv_bioinspired;opencv_bgsegm;opencv_aruco;opencv_viz;opencv_videostab;opencv_videoio;opencv_video;opencv_superres;opencv_stitching;opencv_shape;opencv_photo;opencv_objdetect;opencv_ml;opencv_imgproc;opencv_imgcodecs;opencv_highgui;opencv_flann;opencv_features2d;opencv_core;opencv_calib3d 
--  include path: /usr/local/include/opencv;/usr/local/include 
-- Configuring done 
-- Generating done 
-- Build files have been written to: /XYZ/arucoTest/build 
veith@roethlinLT:/XYZ/arucoTest/build$ make 
Scanning dependencies of target arucoTest 
[100%] Building CXX object CMakeFiles/arucoTest.dir/PoseEstimator.cpp.o 
Linking CXX executable arucoTest 
[100%] Built target arucoTest 

正如你可以看到我在建2个不同的文件夹，因为我发现，如果我在同一的CMake文件夹，它不起作用，即使我删除该文件夹中的所有内容，并再次从命令行重新制作。另外请注意，根据我从哪里启动cmake，它会找到2个不同的包含路径。

我的makefile看起来像这样（不是很疯狂），我对这两种情况都使用了完全相同的文件。

project(arucoTest) 
cmake_minimum_required(VERSION 2.8) 

find_package(OpenCV REQUIRED) 

message(STATUS "OpenCV library status:") 
message(STATUS " version: ${OpenCV_VERSION}") 
message(STATUS " libraries: ${OpenCV_LIBS}") 
message(STATUS " include path: ${OpenCV_INCLUDE_DIRS}") 

set(HEADER_LIST PoseEstimator.h) 
set(SRC_LIST PoseEstimator.cpp) 
add_executable(${PROJECT_NAME} ${SRC_LIST}) 
target_link_libraries(${PROJECT_NAME} ${OpenCV_LIBS}) 

使用ccmake和QT建立在检查窗口，我看到OpenCV_DIR变量被设置为2件不同的事情：在命令行：

OpenCV_DIR      /usr/local/share/OpenCV  

在QT创建者：

OpenCV_DIR       /ust/share/OpenCV 

如何将其设置为自动选择QT Creator中的正确文件夹？我真的不知道是什么原因造成的！ 谢谢！

Answer 1

缓存变量OpenCV_DIR通过搜索命令find_package（在配置模式）进行设置。尽管搜索机制是完全确定性的（在文档中有描述），但它使用了一些envorinment变量，这些变量在您的shell和QT Creator中可能会有所不同。

只是一个猜测，Qt Creator中可以设置CMAKE_PREFIX_PATH环境变量包含/usr目录，因此一个/usr/local下才发现/usr下安装。

对于选择特定的OpenCV安装，只需相应地设置OpenCV_DIR缓存变量并重新运行配置过程。