Mouse move event problems

Siset

Hello,

I am using QT 5.14.1 (in visual studio, but I tried the same on QT creator 4.11 ). I am new in QT and I am trying to do something really basic, which consists in a graphic view object where I want to know the mouse position.

My code is as follows:
mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QGraphicsScene>
#include <QTextStream>
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
protected:
    void mouseMoveEvent(QMouseEvent* event);
    void mousePressEvent(QMouseEvent* event);
private:
    Ui::MainWindow *ui;
    QGraphicsScene* scene;
};
#endif // MAINWINDOW_H

mainwindow.cpp

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

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    scene=new QGraphicsScene(parent); //I have tried with this aswell
    ui->setupUi(this);
    ui->graphicsView->setMouseTracking(true);
    ui->graphicsView->setScene(scene);
    QTextStream cout(stdout);
    cout << "Something that appears on the standard output";
}

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

void MainWindow::mouseMoveEvent(QMouseEvent* event){
    QTextStream cout(stdout);
    cout << "aa";
}
void MainWindow::mousePressEvent(QMouseEvent* event){
    QTextStream cout(stdout);
    cout << "oo";
}

My Ui only contains the graphicView

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QGraphicsView" name="graphicsView">
    <property name="geometry">
     <rect>
      <x>180</x>
      <y>110</y>
      <width>256</width>
      <height>192</height>
     </rect>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>21</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

The problem is that I do not recieve "aaaaaaa" when I move the mouse over the graphicView (unless I press mouse outside and don't release mouse click). But I obtain "oo" each time I click with the mouse (everywhere not only in the GraphicView). What am I doing wrong?

Thanks in advanced,

ofmrew

@Siset The mouse move event is only triggered when the mouse button is pressed or mouse tracking has been set.

JonB

@Siset
Don't you have to set https://doc.qt.io/qt-5/qwidget.html#mouseTracking-prop (setMouseTracking(true)) for the MainWindow if you want MainWindow::mouseMoveEvent() to be called? You are only setting it for the graphicsView? (Or, if you want it there don't you have to do QGraphicsView::mouseMoveEvent()?)

See also perhaps https://forum.qt.io/topic/88459/qgraphicsview-mouse-move-event-not-work-to-me or https://stackoverflow.com/questions/21957314/mousemoveevent-in-qgraphicsview ?

Siset

@JonB I was confused on the usage of QGraphicsView::mouseMoveEvent(), I was not sure how this could work. But it does! :)

Thank @JonB and @ofmrew! Thank you very much.