How to setup Qt and openCV on Windows
How to setup Qt and openCV on Windows
Introduction
This article shows how to install Qt, build OpenCV, and run a basic OpenCV example. This article assumes Windows 10 has just been installed.
This procedure requires close to 10GB of disk space:
Qt: 5.06GB opencv: 522MB opencv-Build: 3.95GB downloads:152MB
This article uses information from the following pages: http://docs.opencv.org/2.4/doc/tutorials/introduction/windows_install/windows_install.html?highlight=installation http://www.laganiere.name/opencvCookbook/chap1s1_2.shtml
Windows 10, Qt 5.9, OpenCV 3.2.0
This guide is actual for Qt 5.12.2 with MinGW 7.3.0 and OpenCV 4.0.1 too
Qt
Installation
Download the Qt installer from www.qt.io, then choose "Download now". This will then download qt-unified-windows-x86-2.0.5-online.exe. Execute the program, then choose the following settings:
Welcome to the Qt online installer: next Qt Account - your unified login to everything Qt: skip Setup-Qt: next installation folder: D:\Qt select components: Qt-Qt5.9-MingGW 5.3.0 32 bit select components: Qt-Tools-MinGW 5.3.0 License Agreement: agree and next start menu shortcuts: next ready to install: install
Testing
Run D:\Qt\Tools\QtCreator\bin\qtcreator.exe
File-New file or project-Qt Widgets Application-choose enter a name and a location: next select all kits: next Class information: MainWindow (defaults): Next Project management: Finish
Now a new project is made. Start debugging by choosing
Debug-Start Debugging-Start debugging (F5)
Now the Qt tab in the Windows taskbar should turn into a progress bar. After some time a new empty window should pop up. Stop debugging either by pressing the red cross in the top right of this new window, or choose
Debug-Stop debugging
Adjust Qt
When you need to add, remove or update a component of Qt, this can be done by running D:\Qt\MaintenanceTool.exe:
maintain Qt: Qt Account: Skip Setup Qt: Add or remove components: Next Select components: next :update
Cmake
Download cmake from cmake.org. In this guide, 3.7.2 is used. Start cmake-3.7.2-win64-x64.msi, then choose the following settinge:
Welcome to the CMake etup Wizzard: next End-User License Agreement: [X] Accept and next Install options: [X] Add CMake to the system PATH for all users, next Destination folder: C:\Program Files\CMake (default), next Ready to install CMake, Install
OpenCV
Getting OpenCV
Download openCV from sourceforge. In this guide, version 3.2.0 is used. Start opencv-3.2.0-vc14.exe and let it extract to d:\ . Now the folder d:\opencv is created.
Add minGW to the windows PATH variable
Open the control panel, System and Security, System, Advanced system settings, Environment Variables, System Variables, Variable Name: Path Variable value: ;D:\Qt\Tools\mingw530_32\bin
Compiling OpenCV
Start C:\Program Files\CMake\bin\cmake-gui.exe then choose the following settings:
Where is the source code: D:\opencv\sources where to build the binaries: D:\opencv-build
Then click Configure, let cmake create the build directory, and choose the following settings:
Specify the generator for this project: MinGW Makefiles Specify native compilers, next Compilers C: D:\Qt\Tools\mingw530_32\bin\gcc.exe Compilers C++: D:\Qt\Tools\mingw530_32\bin\g++.exe Finish
Check the box [X]WITH_QT
Check the box [X]WITH_OPENGL
set Qt5_DIR to D:\Qt\5.9\mingw53_32\lib\cmake\Qt5
Uncheck the box []ENABLE_PRECOMPILED_HEADERS
Then click configure again.
Set QT_MAKE_EXECUTABLE to D:\Qt\5.9\mingw53_32\bin\qmake.exe Set Qt5Concurrent_DIR to D:\Qt\5.9\mingw53_32\lib\cmake\Qt5Concurrent Set Qt5Core_DIR to D:\Qt\5.9\mingw53_32\lib\cmake\Qt5Core Set Qt5Gui_DIR to D:\Qt\5.9\mingw53_32\lib\cmake\Qt5Gui Set Qt5Test_DIR to D:\Qt\5.9\mingw53_32\lib\cmake\Qt5Test Set Qt5Widgets_DIR to D:\Qt\5.9\mingw53_32\lib\cmake\Qt5Widgets Set Qt5OpenGL_DIR to D:\Qt\5.9\mingw53_32\lib\cmake\Qt5OpenGL Set CMAKE_BUILD_TYPE to Release or RelWithDebInfo Set OPENCV_VS_VERSIONINFO_SKIP=1
Then click configure again Then click generate
Next open cmd, and type the following commands. To speed up the compile, the -j flag can be used to run multiple compile jobs simultaneously. On an 8 core CPU, you can set it to 8 or higher, so all cores are used. On a core i7-3770@3.4GHz with 8GB ram, the compile takes about 6 minutes.
d: cd d:\ cd opencv-build mingw32-make -j 8 mingw32-make install
If, in the file opencv/sources/modules/videoio/src/cap_dshow.cpp, you have the following error : 'sprintf_instead_use_StringCbPrintfA_or_StringCchPrintfA' was not declared in this scope ...
try this :put the following line: #define NO_DSHOW_STRSAFE, before the line : #include "DShow.h"
If you have the error: ‘nullptr’ was not declared in this scope..
try this: in cmake check the box ENABLE_CXX11
If, in the file modules\videoio\src\cap_msmf.cpp you have the error: using invalid field '{anonymous}::ComPtr<T>::p'..
try this: in cmake unchecking WITH_MSMF
Add OpenCV compiled libraries to the windows PATH variable
Open the control panel, System and Security, System, Advanced system settings, Environment Variables, System Variables, Variable Name: Path Variable value: ;D:\opencv-build\install\x86\mingw\bin
Compile and run the example
Run D:\Qt\Tools\QtCreator\bin\qtcreator.exe
File-New file or project-Qt Widgets Application-choose enter a name and a location: next select all kits: next Class information: MainWindow (defaults): Next Project management: Finish
Now a new project is made.
modify the .pro file like this:
#-------------------------------------------------
#
# Project created by QtCreator 2017-03-05T12:30:06
#
#-------------------------------------------------
QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = opencvtest
TEMPLATE = app
# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS
# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0
SOURCES += main.cpp\
mainwindow.cpp
HEADERS += mainwindow.h
FORMS += mainwindow.ui
INCLUDEPATH += D:\opencv\build\include
LIBS += D:\opencv-build\bin\libopencv_core320.dll
LIBS += D:\opencv-build\bin\libopencv_highgui320.dll
LIBS += D:\opencv-build\bin\libopencv_imgcodecs320.dll
LIBS += D:\opencv-build\bin\libopencv_imgproc320.dll
LIBS += D:\opencv-build\bin\libopencv_features2d320.dll
LIBS += D:\opencv-build\bin\libopencv_calib3d320.dll
# more correct variant, how set includepath and libs for mingw
# add system variable: OPENCV_SDK_DIR=D:/opencv/opencv-build/install
# read http://doc.qt.io/qt-5/qmake-variable-reference.html#libs
#INCLUDEPATH += $$(OPENCV_SDK_DIR)/include
#LIBS += -L$$(OPENCV_SDK_DIR)/x86/mingw/lib \
# -lopencv_core320 \
# -lopencv_highgui320 \
# -lopencv_imgcodecs320 \
# -lopencv_imgproc320 \
# -lopencv_features2d320 \
# -lopencv_calib3d320
and modify mainwindow.cpp like this:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
// read an image
cv::Mat image = cv::imread("f://1.jpg", 1);
// create image window named "My Image"
cv::namedWindow("My Image");
// show the image on window
cv::imshow("My Image", image);
}
MainWindow::~MainWindow()
{
delete ui;
}
Place an image with the name "1.img" in the root of F:\, then run the example. Now 2 windows should pop up. One with the image, and one with an empty window.