# H file #ifndef __HEADER_H #define __HEADER_H #include // include the actual base class namespace Ui { class inputImage; } // assumes that the Object name in Designer is CClassName class inputImage : public QWidget { Q_OBJECT // dont forget this public: inputImage( QWidget * parent ); // or whatever you need virtual ~inputImage(); public slots: // your slots go here signals: // your signals go here private: Ui::inputImage * fImpl; // oldschool naming convention.. sorry.. protected: void QWidget::mouseDoubleClickEvent ( QMouseEvent * event ); }; #endif # CPP file #include "stdafx.h" #include "qopencvwidget.h" #include "inputImage.h" #include "ui_opencvapplication.h" inputImage::inputImage( QWidget * parent ) : QWidget( parent ) { fImpl = new Ui::inputImage; fImpl->setupUi( this ); } inputImage::~inputImage() { } void QWidget::mouseDoubleClickEvent ( QMouseEvent * event ) { ui::openCVapplication.LoadImage(fImpl); }