Question

I am trying to implement a mouseover effect in Qt, but I don’t know how to use the event handlers. I have created a simple Qt Widget Application with a pushButton. I am able to bind an event handler to the MainWindow like so:

MainWindow::enterEvent(QEvent *event)
{
    ui->pushButton_3->setGraphicsEffect(effect);
}

This works, the graphicsEffect is applied to the pushButton. But I don’t understand how to bind the event handler to a single QObject. As far as I know is it not possible to use signals, because they only support click events and no mouseover events.

I am pretty new to Qt and I was not able to find any information I could understand.

Can anyone explain to me how to bind an event handler to a single QObject?

Thanks in advance.

Answer 1

I figured it out, in another way, by using the ‘Promote to …’ option in the QtCreator.
As also explained here: http://sector.ynet.sk/qt4-tutorial/customing-widgets.html

I added a class ‘MyPushButton”:

mypushbutton.h

#ifndef MYPUSHBUTTON_H
#define MYPUSHBUTTON_H

#include <QPushButton>
#include <QGraphicsDropShadowEffect>

class MyPushButton : public QPushButton
{
    Q_OBJECT
public:
    MyPushButton(QWidget *parent = 0);

private:
    void enterEvent(QEvent *e);
    void leaveEvent(QEvent *e);

    QGraphicsDropShadowEffect *effect;
};

#endif // MYPUSHBUTTON_H

mypushbutton.cpp

#include "mypushbutton.h"

MyPushButton::MyPushButton(QWidget *parent)
    :QPushButton(parent)
{
    effect = new QGraphicsDropShadowEffect();
    effect->setBlurRadius(5);
    effect->setEnabled(false);
    this->setGraphicsEffect(effect);
}

void MyPushButton::enterEvent(QEvent *event)
{
    if (this->isEnabled())
        effect->setEnabled(true);
}

void MyPushButton::leaveEvent(QEvent *event)
{
    if (this->isEnabled())
        effect->setEnabled(false);
}

and then I right clicked my QPushButton in the editor and I selected ‘Promote to …’ and I added MyPushButton as ‘Promoted class name’.

It works like a charm and is very easy to expand or customize as it works with any event.