Qt unresolved external symbol after refactoring - c++

Question

I had a properly working Qt code with custom widget. Then I refractored a signal name and undo the action immediately. Since then I'm getting -
mainwindow.obj:-1: error: LNK2001: unresolved external symbol "protected: virtual void
__thiscall QWidget::mouseDoubleClicked(class QMouseEvent *)"
?mouseDoubleClicked#QWidget##MAEXPAVQMouseEvent###Z)
mouseDoubleClicked is the method which wmits the refractored signal. Although I undo the refractoring action but still it's giving this error. The same code did run bofe that.
I've tried cleaning and running qMake but no success. Even created a new project and copy pasted the file contents but still got the same error.
These are the files-
mainwindow.h
#pragma once;
#include <QMainWindow>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private:
Ui::MainWindow *ui;
};
myqtimagewidget.h
#pragma once
#include <QWidget>
#include <QImage>
#include <QPainter>
#include <QtGui/QMouseEvent>
#include "opencv2/opencv.hpp"
class MyQtImageWidget : public QWidget
{
Q_OBJECT
protected:
QImage qimage;
cv::Mat temp;
void paintEvent(QPaintEvent*);
void mouseDoubleClicked(QMouseEvent* event);
// void mousePressEvent(QMouseEvent *event);
public:
explicit MyQtImageWidget(QWidget *parent = 0) : QWidget(parent) {}
QSize sizeHint() const {return qimage.size(); }
QSize minimumSizeHint() const {return qimage.size(); }
signals:
void signalMouseMoved(QString);
public slots:
void showImage(const cv::Mat &image);
};
myqtimagewidget.cpp
#include "myqtimagewidget.h"
#include "opencv2/opencv.hpp"
using namespace cv;
void MyQtImageWidget::showImage(const Mat &image)
{
//resize image to fit widget. Maintains aspect ratio
int width = this->maximumWidth();
int hight = this->maximumHeight();
Mat rescaledImg;
if(image.cols > width || image.rows > hight)
{
// debug info --v
QString data = "Original dimention: " + QString::number(image.cols) + "x" + QString::number(image.rows);
qDebug(data.toStdString().c_str());
// debug info --^
double aspectRatio = (double)image.cols / (double)image.rows; // width / height
cv::Size2i newSize;
// debug info --v
qDebug(std::to_string(width).c_str());
qDebug(std::to_string(hight).c_str());
// debug info --^
if(image.cols >= image.rows)
{
newSize = cv::Size(width, width / aspectRatio);
}
else
{
newSize = cv::Size(hight * aspectRatio, hight);
}
cv::resize(image, rescaledImg, newSize, 1, 1);
// debug info --v
data = "Resized dimention: " + QString::number(rescaledImg.cols) + "x" + QString::number(rescaledImg.rows);
qDebug(data.toStdString().c_str());
// debug info --^
}
else
rescaledImg = image;
// Convert the image to the RGB888 format
switch (rescaledImg.type())
{
case CV_8UC1:
cvtColor(rescaledImg, temp, CV_GRAY2RGB);
break;
case CV_8UC3:
cvtColor(rescaledImg, temp, CV_BGR2RGB);
break;
}
// QImage needs the data to be stored continuously in memory
assert(temp.isContinuous());
// Assign OpenCV's image buffer to the QImage. Note that the bytesPerLine parameter
// (http://qt-project.org/doc/qt-4.8/qimage.html#QImage-6) is 3*width because each pixel
// has three bytes.
qimage = QImage(temp.data, temp.cols, temp.rows, temp.cols*3, QImage::Format_RGB888);
repaint();
}
void MyQtImageWidget::paintEvent(QPaintEvent *event)
{
// Display the image
QPainter painter(this);
painter.drawImage(QPoint(0,0), qimage);
painter.end();
}
void MyQtImageWidget::mouseDoubleClicked(QMouseEvent *event)
{
int x = event->pos().x(), y = event->pos().y();
QString data = "x: " + QString::number(x) + ", y: " + QString::number(y);
emit MyQtImageWidget::signalMouseMoved(data);
}
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "opencv2/opencv.hpp"
#include "myqtimagewidget.h"
using namespace cv;
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QString imageSrc = "E:\\Images\\Panorama\\Harshil3578_stitch.jpg";
Mat image = imread(imageSrc.toStdString(), IMREAD_COLOR);
}
MainWindow::~MainWindow()
{
delete ui;
}
In the GUI I have a widget promoted to MyQtImageWidget and connected to a QLabel.

Answer 1

Consider what the linker is telling you:
QWidget has a virtual method named mouseDoubleClicked.
That method is not implemented.
The problem is that QWidget does not have a virtual method named mouseDoubleClicked. My best guess is that during your refactoring, you somehow modified the header file for QWidget, renaming an existing virtual function to mouseDoubleClicked.
If that's the case, getting a fresh copy of qwidget.h (or re-installing Qt) should resolve the problem.