I am trying to build an example qt-opencv project Hello_Qt_OpenCVthat is provided by Computer-Vision-with-OpenCV-3-and-Qt5. I use QtCreator4.5 with Qt5.7 and opencv3.2. Their configurations work fine with some other qt-opencv projects.
Building the project gives three issues:
File not found: mainwindow.obj: LNK2019: unresolved external symbol "void __cdecl cv::medianBlur(class cv::_InputArray const &,class cv::_OutputArray const &,int)" (?medianBlur@cv@@YAXAEBV_InputArray@1@AEBV_OutputArray@1@H@Z) referenced in function "private: void __cdecl MainWindow::on_outputPushButton_pressed(void)" (?on_outputPushButton_pressed@MainWindow@@AEAAXXZ)
File not found: mainwindow.obj: LNK2019: unresolved external symbol "void __cdecl cv::GaussianBlur(class cv::_InputArray const &,class cv::OutputArray const &,class cv::Size,double,double,int)" (?GaussianBlur@cv@@YAXAEBV_InputArray@1@AEBV_OutputArray@1@V?$Size_@H@1@NNH@Z) referenced in function "private: void __cdecl MainWindow::on_outputPushButton_pressed(void)" (?on_outputPushButton_pressed@MainWindow@@AEAAXXZ)
LNK1120: 2 unresolved externals release\Hello_Qt_OpenCV.exe:-1: error
I tried some suggestions at (File not found: mainwindow.obj by clean, run qmake and build, which however won't work in this case.
For your information, I post the mainwindow.cpp and mainwindow.h:
mainwindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
loadSettings();
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_inputPushButton_pressed()
{
QString fileName = QFileDialog::getOpenFileName(this, "Open Input Image", QDir::currentPath(), "Images (*.jpg *.png *.bmp)");
if(QFile::exists(fileName))
{
ui->inputLineEdit->setText(fileName);
}
}
void MainWindow::on_outputPushButton_pressed()
{
QString fileName = QFileDialog::getSaveFileName(this, "Select Output Image", QDir::currentPath(), "*.jpg;;*.png;;*.bmp");
if(!fileName.isEmpty())
{
ui->outputLineEdit->setText(fileName);
using namespace cv;
Mat inpImg, outImg;
inpImg = imread(ui->inputLineEdit->text().toStdString());
if(ui->medianBlurRadioButton->isChecked())
cv::medianBlur(inpImg, outImg, 5);
else if(ui->gaussianBlurRadioButton->isChecked())
cv::GaussianBlur(inpImg, outImg, Size(5, 5), 1.25);
imwrite(fileName.toStdString(), outImg);
if(ui->displayImageCheckBox->isChecked())
imshow("Output Image", outImg);
}
}
void MainWindow::closeEvent(QCloseEvent *event)
{
int result = QMessageBox::warning(this, "Exit", "Are you sure you want to close this program?", QMessageBox::Yes, QMessageBox::No);
if(result == QMessageBox::Yes)
{
saveSettings();
event->accept();
}
else
{
event->ignore();
}
}
void MainWindow::loadSettings()
{
QSettings settings("Packt", "Hello_OpenCV_Qt", this);
ui->inputLineEdit->setText(settings.value("inputLineEdit", "").toString());
ui->outputLineEdit->setText(settings.value("outputLineEdit", "").toString());
ui->medianBlurRadioButton->setChecked(settings.value("medianBlurRadioButton", true).toBool());
ui->gaussianBlurRadioButton->setChecked(settings.value("gaussianBlurRadioButton", false).toBool());
ui->displayImageCheckBox->setChecked(settings.value("displayImageCheckBox", false).toBool());
}
void MainWindow::saveSettings()
{
QSettings settings("Packt", "Hello_OpenCV_Qt", this);
settings.setValue("inputLineEdit", ui->inputLineEdit->text());
settings.setValue("outputLineEdit", ui->outputLineEdit->text());
settings.setValue("medianBlurRadioButton", ui->medianBlurRadioButton->isChecked());
settings.setValue("gaussianBlurRadioButton", ui->gaussianBlurRadioButton->isChecked());
settings.setValue("displayImageCheckBox", ui->displayImageCheckBox->isChecked());
}
mainwindow.h:
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QFileDialog>
#include <QDir>
#include <QFile>
#include <QCloseEvent>
#include <QMessageBox>
#include <QSettings>
#include "opencv2/opencv.hpp"
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
protected:
void closeEvent(QCloseEvent *event);
private slots:
void on_inputPushButton_pressed();
void on_outputPushButton_pressed();
private:
Ui::MainWindow *ui;
void loadSettings();
void saveSettings();
};
#endif // MAINWINDOW_H
You may also download the project files and give a quick run to see if the issues are related to the project itself.
