前言
QT里安装OpenCV环境过程比较复杂，如果网友们想要在QT里做OpenCV的开发，就需要耐心的跟着我列出来的操作步骤一步一步去安装环境，其中包含我在安装环境时遇到的坑，都已经在步骤中帮大家罗列出来，如有不懂的网友，可以评论或者私信我即可！
一、软件准备
1、Qt软件
2、CMake
3、OpenCV
二、环境搭建
1、安装QT：5.12.4版本（我用的版本）
（1）安装在D盘（任意选择一个盘）
（2）将QT环境变量添加到系统环境变量PATH中
注意的是需要将以下两个QT环境变量添加到系统PATH中：
D:\QTCreator_Windows\5.12.4\mingw73_64\bin
D:\QTCreator_Windows\Tools\mingw730_64\bin
2、安装CMake
官网：
https://cmake.org/files/
版本不作要求：
v3.12/（我用的版本）----cmake-3.12…4-win64-64.zip
（1）安装在D盘（任意选择一个盘，最好是与QT在一个盘里）
（2）将CMake环境变量添加到系统环境变量PATH中
D:\Opencv_Window\cmake-3.12.4-win64-x64\bin
3、安装opencv
官网：
https://opencv.org/releases
版本：
OpenCV-3.4.9（我用的版本）—选择Windows–自动开始下载.exe（opencv-3.4.9-vc14_vc15.exe）
（1）将opencv-3.4.9-vc14_vc15.exe放在D盘
（2）双击运行解压opencv-3.4.9-vc14_vc15.exe
会出现两个文件：
build文件：该文件为编译后Windows环境下编译好的可执行文件
sources文件：该文件为未编译过的源代码，要想在QT中运行opencv需要重新编译该文件里的代码（所以这时候就需要用前面下载好的CMake来重新编译opencv源码）
（3）cmake配置opencv
a、打开D:\Opencv_Window\cmake-3.12.4-win64-x64\bin\cmake-gui.exe
b、将opencv中的sources文件添加进来
where is the souce code：D:/Opencv_Window/opencv/sources
where is build the binaries：D:/Opencv_Window/opencv/rebuild_for_qt（注：rebuild_for_qt文件是我们自己建立的文件，用于存放编译后的代码）
c、点击configure开始配置
在弹出的界面中：
》Specify the generator for the project中选择：MinGw makefiles
》再选择：Specify native compilers
》点击next
在弹出的界面中
》C：选择QT路径下的GCC
即：D:/QTCreator_Windows/Tools/mingw730_64/bin/gcc.exe
》C++：选择QT路径下的G++
即：D:/QTCreator_Windows/Tools/mingw730_64/bin/g++.exe
》点击Finish开始配置
在点击Finish配置时出现：
由于找不到libwinpthread-1.dll，无法继续执行代码，重新安装可能会解决此问题
说明：QT的环境变量未添加到系统环境PATH中（我当时添加的时候是用了中文字符的冒号所以报错
》配置好出现Configuring done
》再次修改配置
ENABLE_CXX11（勾选）
WITH_OPENGL（勾选）
WITH_QT（勾选）
WITH_IPP（不勾选）
其他选择默认即可
》再次点击Configure
》又再一次点击Configure
然后选中Name下的CMAKE_CONFIGURATION_TYPES，将后面Value下的Debug给删除掉，只留下Release即可
》继续点击Configure
这时候会报错提示FFMPEG下载失败，无法连接到服务器，打开CMakeDownloadLog.txt查看详细信息----这会导致编译后的OpenCV无法用VideoCapture打开视频（报错内容：CMake Warning at cmake/OpenCVDownload.cmake:202 (message): FFMPEG: Download failed: 7;"Couldn't connect to server"For details please refer to the download log file: D:/Opencv_Window/opencv/rebuild_for_qt/CMakeDownloadLog.txt
Call Stack (most recent call first): 3rdparty/ffmpeg/ffmpeg.cmake:20 (ocv_download)cmake/OpenCVFindLibsVideo.cmake:227 (download_win_ffmpeg) CMakeLists.txt:683 (include)）
查看CMakeDownloadLog.txt需要以下3个文件：
opencv_ffmpeg.dll文件
opencv_ffmpeg_64.dll文件
ffmpeg_version.cmake文件
***************** 上面这个问题非常重要*****************
该问题解决如下：
（1）查看CMake编译后生成的D:\Opencv_Window\opencv\rebuild_for_qt\CMakeDownloadLog.txt文本，文本内容如下(解决方法就是我在文本内容注释的地方)：
#use_cache "D:/Opencv_Window/opencv/sources/.cache"
#do_copy "opencv_ffmpeg.dll" "168635a192fc2d2ae7d7d40150f0b349" "https://raw.githubusercontent.com/opencv/opencv_3rdparty/548e3c997a80d65f710b9048f1d33371e3a203ac/ffmpeg/opencv_ffmpeg.dll" "D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg"
//上面是说需要将缺省的“opencv_ffmpeg.dll”文件拷贝到“D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg”路径下
#missing "D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg/opencv_ffmpeg.dll"
#check_md5 "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/168635a192fc2d2ae7d7d40150f0b349-opencv_ffmpeg.dll"
//这一行是说可以将缺省的“opencv_ffmpeg.dll”文件以MD5编码命名（例如：168635a192fc2d2ae7d7d40150f0b349-opencv_ffmpeg.dll--该形式就是MD5编码命名，后面你只需要下载opencv_ffmpeg.dll文件然后在该文件前复制“168635a192fc2d2ae7d7d40150f0b349-”加上即可）之后拷贝到“D:/Opencv_Window/opencv/sources/.cache/ffmpeg/”路径下
#mismatch_md5 "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/168635a192fc2d2ae7d7d40150f0b349-opencv_ffmpeg.dll" "d41d8cd98f00b204e9800998ecf8427e"
#delete "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/168635a192fc2d2ae7d7d40150f0b349-opencv_ffmpeg.dll"
#cmake_download "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/168635a192fc2d2ae7d7d40150f0b349-opencv_ffmpeg.dll" "https://raw.githubusercontent.com/opencv/opencv_3rdparty/548e3c997a80d65f710b9048f1d33371e3a203ac/ffmpeg/opencv_ffmpeg.dll"
#try 1
# timeout on name lookup is not supported
# Trying 0.0.0.0...
# TCP_NODELAY set
# connect to 0.0.0.0 port 443 failed: Address not available
# Failed to connect to raw.githubusercontent.com port 443: Address not available
# Closing connection 0
#
#do_copy "opencv_ffmpeg_64.dll" "cbc25f8f2954475b127c7558558c18e6" "https://raw.githubusercontent.com/opencv/opencv_3rdparty/548e3c997a80d65f710b9048f1d33371e3a203ac/ffmpeg/opencv_ffmpeg_64.dll" "D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg"
//上面是说需要将缺省的“opencv_ffmpeg_64.dll”文件拷贝到“D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg”路径下
#missing "D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg/opencv_ffmpeg_64.dll"
#check_md5 "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/cbc25f8f2954475b127c7558558c18e6-opencv_ffmpeg_64.dll"
#mismatch_md5 "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/cbc25f8f2954475b127c7558558c18e6-opencv_ffmpeg_64.dll" "d41d8cd98f00b204e9800998ecf8427e"
//这一行是说可以将缺省的“opencv_ffmpeg.dll”文件以MD5编码命名之后拷贝到“D:/Opencv_Window/opencv/sources/.cache/ffmpeg/”路径下
#delete "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/cbc25f8f2954475b127c7558558c18e6-opencv_ffmpeg_64.dll"
#cmake_download "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/cbc25f8f2954475b127c7558558c18e6-opencv_ffmpeg_64.dll" "https://raw.githubusercontent.com/opencv/opencv_3rdparty/548e3c997a80d65f710b9048f1d33371e3a203ac/ffmpeg/opencv_ffmpeg_64.dll"
#try 1
# timeout on name lookup is not supported
# Trying 0.0.0.0...
# TCP_NODELAY set
# connect to 0.0.0.0 port 443 failed: Address not available
# Failed to connect to raw.githubusercontent.com port 443: Address not available
# Closing connection 0
#
#do_copy "ffmpeg_version.cmake" "3b90f67f4b429e77d3da36698cef700c" "https://raw.githubusercontent.com/opencv/opencv_3rdparty/548e3c997a80d65f710b9048f1d33371e3a203ac/ffmpeg/ffmpeg_version.cmake" "D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg"
//上面是说需要将缺省的“ffmpeg_version.cmake”文件拷贝到“D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg”路径下
#missing "D:/Opencv_Window/opencv/rebuild_for_qt/3rdparty/ffmpeg/ffmpeg_version.cmake"
#check_md5 "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/3b90f67f4b429e77d3da36698cef700c-ffmpeg_version.cmake"
#mismatch_md5 "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/3b90f67f4b429e77d3da36698cef700c-ffmpeg_version.cmake" "d41d8cd98f00b204e9800998ecf8427e"
//这一行是说可以将缺省的“ffmpeg_version.cmakel”文件以MD5编码命名之后拷贝到“D:/Opencv_Window/opencv/sources/.cache/ffmpeg/”路径下
#delete "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/3b90f67f4b429e77d3da36698cef700c-ffmpeg_version.cmake"
#cmake_download "D:/Opencv_Window/opencv/sources/.cache/ffmpeg/3b90f67f4b429e77d3da36698cef700c-ffmpeg_version.cmake" "https://raw.githubusercontent.com/opencv/opencv_3rdparty/548e3c997a80d65f710b9048f1d33371e3a203ac/ffmpeg/ffmpeg_version.cmake"
#try 1
# timeout on name lookup is not supported
# Trying 0.0.0.0...
# TCP_NODELAY set
# connect to 0.0.0.0 port 443 failed: Address not available
# Failed to connect to raw.githubusercontent.com port 443: Address not available
# Closing connection 0
#
（2）下载以下3个文件
opencv_ffmpeg.dll文件
下载链接：https://raw.githubusercontent.com
opencv_ffmpeg_64.dll文件
下载链接：https://raw.githubusercontent.com
ffmpeg_version.cmake文件
下载链接：https://raw.githubusercontent.com
（3）下载好上面3个文件之后，将3个文件以MD5命名方式（前面已经讲过）存入到“D:/Opencv_Window/opencv/sources/.cache/ffmpeg/”路径下即可
（4）在CMake中点击Configure即可，成功之后点击generate，解决该问题
4、编译安装opencv
（1）打开windows的CMD终端
使用命令切换到安装的opencv路径下刚刚编译好的的rebuild_for_qt文件夹
即：
>>D：
>>cd Opencv_Window\opencv\rebuild_for_qt
注：window下的盘符切换与Linux有区别，先输入“D:”切换到D盘，然后再使用cd命令具体切换到哪个目录
（2）输入命令编译opencv（编译需要10分钟左右）
即：
mingw32-make //输入之后等待编译完成
（3）编译完成之后，输入命令下载opencv库
即：
mingw32-make install //成功之后重新将编译好的opencv环境添加到系统PATH中
（4）添加新的opencv环境到PATH中
即：
将：
D:\Opencv_Window\opencv\rebuild_for_qt\bin
D:\Opencv_Window\opencv\rebuild_for_qt\install\x64\mingw\bin
添加到系统PATH中
三、配置QT工程验证opencv
1、使用QTCreator创建QT工程
2、在QT工程文件.pro中添加以下代码：文章来源：https://www.toymoban.com/news/detail-562505.html
INCLUDEPATH +=D:\Opencv_Window\opencv\rebuild_for_qt\install\include
D:\Opencv_Window\opencv\rebuild_for_qt\install\include\opencv
D:\Opencv_Window\opencv\rebuild_for_qt\install\include\opencv2
LIBS +=-L D:\Opencv_Window\opencv\rebuild_for_qt\install\x64\mingw\lib\libopencv_*.dll.a //意思是将编译好的所有opencv库添加到QT中
3、运行opencv代码，即成功运行文章来源地址https://www.toymoban.com/news/detail-562505.html
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
using namespace cv;
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Mat image = imread("the photo road!!!");//注意imread函数、waitkey函数都是属于cv命名空间里的内容，所以程序之前要添加using namespace cv
namedWindow("Display window",WINDOW_AUTOSIZE);
imshow("Display window",image);
waitKey(0);
Dialog w;
w.show();
return a.exec();
}
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