Mouse Press/Release Events

**Vivek1982** · 22nd July 2014, 05:41

Dear All,

Im getting mouseevent at when i click the mouse on the GraphicsScene. Im getting the position/co-ordinate also, where as release event im getting the co-ordinate/positions. please Suggest me

Qt Code:

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#ifndef APP_H
#define APP_H
 
#include <QMainWindow>
#include <QGraphicsScene>
#include <QPoint>
#include <QMouseEvent>
 
protected:
void changeEvent(QEvent *e)
void mousePressEvent (QMouseEvent *e)
void mouseReleaseEvent (QMouseEvent *e)
 
private:
int x,x1,y,y1;
QPoint *point;
 
#endif

#ifndef APP_H
#define APP_H

#include <QMainWindow>
#include <QGraphicsScene>
#include <QPoint>
#include <QMouseEvent>

protected:
void changeEvent(QEvent *e)
void mousePressEvent (QMouseEvent *e)
void mouseReleaseEvent (QMouseEvent *e)

private:
int x,x1,y,y1;
QPoint *point;

#endif

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Qt Code:

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#include "app.h"
#include "ui_app.h"
 
APP::APP(QWidget *parent):
 
QMainWindow(parent),
ui(new Ui::APP)
{
ui->setupUi (this);
}
 
void APP::mousePressEvent(QMouseEvent *e)
{
QPoint point=e->pos();
x=point.x();
qDebug()<<x;
 
y=point.y();
qDebug()<<y
 
}
 
void APP::mouseReleaseEvent(QMouseEvent *e)
{
QPoint point=e->pos();
x1=point.x();
qDebug()<<x1;
 
y1=point.y();
qDebug()<<y1;
 
}

#include "app.h"
#include "ui_app.h"

APP::APP(QWidget *parent):

QMainWindow(parent),
ui(new Ui::APP)
{
ui->setupUi (this);
}

void APP::mousePressEvent(QMouseEvent *e)
{
QPoint point=e->pos();
x=point.x();
qDebug()<<x;

y=point.y();
qDebug()<<y

}

void APP::mouseReleaseEvent(QMouseEvent *e)
{
QPoint point=e->pos();
x1=point.x();
qDebug()<<x1;

y1=point.y();
qDebug()<<y1;

}

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Im getting x,y position data of Graphic scene when i click on scene, but not x1, y1 positions when i release mouse. By getting all co-ordinates i can draw line.

**stampede** · 22nd July 2014, 19:23

Call base class implementations of these event handlers after your class-specific code

Qt Code:

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void APP::mousePressEvent(QMouseEvent *e)
{
//... my code
    QMainWindow::mousePressEvent(e);
}
 
void APP::mouseReleaseEvent(QMouseEvent *e)
{
// ... my code
   QMainWindow::mouseReleaseEvent(e);
}

void APP::mousePressEvent(QMouseEvent *e)
{
//... my code
    QMainWindow::mousePressEvent(e);
}
 
void APP::mouseReleaseEvent(QMouseEvent *e)
{
// ... my code
   QMainWindow::mouseReleaseEvent(e);
}

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**Vivek1982** · 24th July 2014, 13:01

Hi..

I tried by calling base class, but still same result. Im getting only MousePressEvent Co-ordinates, but not the Co-ordinates where i released the Mouse. When I click mouse after dragging I get mouse click event co-ordinates.

**Vivek1982** · 4th August 2014, 10:16

Thanks alot for your replies. I got both the co-orodinates of Mouse on click and release events. Actually in my widget as QMainWindow. I have QGraphicsScene and QGraphicsView placed in my QMainWindow. scene has been created inside MainWindow.

Im getting mouse press and release event or positions on QMainWindow, whereas when i click on my GraphicScene area, im not getting press/release events on Scene. outside the graphicscene area im getting it..

How can i get the co-ordinates on graphicScene area.

**ChrisW67** · 4th August 2014, 21:16

If you want the click events when the mouse is over the QGraphicsView widget then you can either:

Reimplement and use the mouseClickEvent() and mouseReleaseEvent() of the QGraphicsView object.
Install an event filter on the QGraphicsView object.

**Vivek1982** · 5th August 2014, 13:35

Ya. I tried to implement both Mouse click and release events still the same release is not working on graphicsview.

Qt Code:

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#include <QtGui/QApplication>
#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

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Qt Code:

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#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include <QGraphicsView>
#include <QGraphicsScene>
#include <QGraphicsSceneMouseEvent>
#include <QPointF>
#include <QMouseEvent>
#include <QDebug>
namespace Ui {
    class MainWindow;
}
 
class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
protected:
    void changeEvent(QEvent *e);
protected:
      void mousePressEvent(QMouseEvent * e);
      void mouseReleaseEvent(QMouseEvent * e);
 
private:
    Ui::MainWindow *ui;
    QGraphicsView *view;
    QGraphicsScene *scene;
     QPointF *point,*point1;
     float x,y,x1,y1;
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QGraphicsView>
#include <QGraphicsScene>
#include <QGraphicsSceneMouseEvent>
#include <QPointF>
#include <QMouseEvent>
#include <QDebug>
namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();

protected:
    void changeEvent(QEvent *e);
protected:
      void mousePressEvent(QMouseEvent * e);
      void mouseReleaseEvent(QMouseEvent * e);

private:
    Ui::MainWindow *ui;
    QGraphicsView *view;
    QGraphicsScene *scene;
     QPointF *point,*point1;
     float x,y,x1,y1;
};

#endif // MAINWINDOW_H

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Qt Code:

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#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scene=new QGraphicsScene(0,0,740,400);
    ui->graphicsView->setScene(scene);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::changeEvent(QEvent *e)
{
    QMainWindow::changeEvent(e);
    switch (e->type()) {
    case QEvent::LanguageChange:
        ui->retranslateUi(this);
        break;
    default:
        break;
    }
 
}
 
void MainWindow::mousePressEvent(QMouseEvent *e)
    {
 
    if(e->MouseButtonPress)
    {
        qDebug("clicked");
        QPointF point= ui->graphicsView->mapFromScene(e->posF());
        x=point.x();
        qDebug()<<x;
        y= point.y();
        qDebug()<<y;
        qDebug()<<point;
 
    }
}
 
 
 
void MainWindow::mouseReleaseEvent(QMouseEvent *e)
    {
 
   if(e->MouseButtonRelease)
    {
        qDebug("released");
        QPointF point1= ui->graphicsView->mapFromScene(e->posF());
        x1=point1.x();
        qDebug()<<x1;
        y1= point1.y();
        qDebug()<<y1;
        qDebug()<<point1;
    }
 
    }

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scene=new QGraphicsScene(0,0,740,400);
    ui->graphicsView->setScene(scene);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::changeEvent(QEvent *e)
{
    QMainWindow::changeEvent(e);
    switch (e->type()) {
    case QEvent::LanguageChange:
        ui->retranslateUi(this);
        break;
    default:
        break;
    }

}

void MainWindow::mousePressEvent(QMouseEvent *e)
    {

    if(e->MouseButtonPress)
    {
        qDebug("clicked");
        QPointF point= ui->graphicsView->mapFromScene(e->posF());
        x=point.x();
        qDebug()<<x;
        y= point.y();
        qDebug()<<y;
        qDebug()<<point;
        
    }
}



void MainWindow::mouseReleaseEvent(QMouseEvent *e)
    {

   if(e->MouseButtonRelease)
    {
        qDebug("released");
        QPointF point1= ui->graphicsView->mapFromScene(e->posF());
        x1=point1.x();
        qDebug()<<x1;
        y1= point1.y();
        qDebug()<<y1;
        qDebug()<<point1;
    }

    }

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**anda_skoa** · 5th August 2014, 16:21

Originally Posted by Vivek1982

Ya. I tried to implement both Mouse click and release events still the same release is not working on graphicsview.

Instead of implementing the main window's event handler, you could try what ChrisW67 suggested.

Cheers,
_

**Vivek1982** · 6th August 2014, 09:03

I tried with event filter. i didnt get both press and release positions on GraphicsScene widget.I saw examples in
http://stackoverflow.com/questions/7...s-not-register

but still working on, how ever it is mouse press is okay.. but release pos is not coming.

**anda_skoa** · 6th August 2014, 12:52

Tried you implementing the graphicsview's eventhandlers?

Cheers,
_

**Vivek1982** · 7th August 2014, 04:52

Yes. reimplemented by sub class QGraphicsView and also calling event handlers of QGraphicsView. Im getting error like :-1: error: collect2: ld returned 1 exit status

Qt Code:

Switch view

#include <QDebug>
namespace Ui {
    class MainWindow;
}
 
class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
protected:
    void changeEvent(QEvent *e);
 
 
private:
    Ui::MainWindow *ui;
    QGraphicsView *view;
    QGraphicsScene *scene;
     QPointF *point,*point1;
     float x,y,x1,y1;
};
class MyGraphicsView : public QGraphicsView
{
   Q_OBJECT
public:
    MyGraphicsView(QWidget *parent=NULL);
    ~MyGraphicsView();
 
protected:
      void mousePressEvent(QGraphicsSceneMouseEvent * event);
      void mouseReleaseEvent(QGraphicsSceneMouseEvent * event);
 
};

#include <QDebug>
namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();

protected:
    void changeEvent(QEvent *e);


private:
    Ui::MainWindow *ui;
    QGraphicsView *view;
    QGraphicsScene *scene;
     QPointF *point,*point1;
     float x,y,x1,y1;
};
class MyGraphicsView : public QGraphicsView
{
   Q_OBJECT
public:
    MyGraphicsView(QWidget *parent=NULL);
    ~MyGraphicsView();

protected:
      void mousePressEvent(QGraphicsSceneMouseEvent * event);
      void mouseReleaseEvent(QGraphicsSceneMouseEvent * event);

};

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Qt Code:

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void MyGraphicsView::mousePressEvent(QGraphicsSceneMouseEvent *event)
    {
 
    if(event->MouseButtonPress)
    {
        qDebug("clicked");
        QPointF point= event->pos();//ui->graphicsView->mapFromScene(event->pos());
        //x=point.x();
        //qDebug()<<x;
        //y= point.y();
        //qDebug()<<y;
        qDebug()<<point;
 
    }
}
 
 
 
//void MainWindow::mouseReleaseEvent(QMouseEvent *event)
void MyGraphicsView::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
    {
 
   if(event->MouseButtonRelease)
    {
        qDebug("released");
        QPointF point1=event->pos();//ui->graphicsView->mapFromScene(event->pos());
        //x1=point1.x();
        //qDebug()<<x1;
        //y1= point1.y();
        //qDebug()<<y1;
        qDebug()<<point1;
    }
 
    }

void MyGraphicsView::mousePressEvent(QGraphicsSceneMouseEvent *event)
    {

    if(event->MouseButtonPress)
    {
        qDebug("clicked");
        QPointF point= event->pos();//ui->graphicsView->mapFromScene(event->pos());
        //x=point.x();
        //qDebug()<<x;
        //y= point.y();
        //qDebug()<<y;
        qDebug()<<point;

    }
}



//void MainWindow::mouseReleaseEvent(QMouseEvent *event)
void MyGraphicsView::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
    {

   if(event->MouseButtonRelease)
    {
        qDebug("released");
        QPointF point1=event->pos();//ui->graphicsView->mapFromScene(event->pos());
        //x1=point1.x();
        //qDebug()<<x1;
        //y1= point1.y();
        //qDebug()<<y1;
        qDebug()<<point1;
    }

    }

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**anda_skoa** · 7th August 2014, 07:26

Originally Posted by Vivek1982

Yes. reimplemented by sub class QGraphicsView and also calling event handlers of QGraphicsView. Im getting error like :-1: error: collect2: ld returned 1 exit status

You'll have to post the full error message, really.

Also it would help a lot if you implemented the event handler methods of QGraphicsView, not those of QGraphicsScene.
Unless your goal is to have methods that are never called, in which case that is of course fine.

Cheers,
_

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