How to override functionality for widgets hiding when losing mouse focus?

[Qtstarter121]

I need some kind of way to replace the existing functionality where a widget will hide automatically when a click occurs outside of it ( loses focus) with my own code to do something else instead.

[A Former User]

Hi, and welcome to the Qt forum.

widget will hide automatically when [...] loses focus [...]

You can override QWidget::focusOutEvent(QFocusEvent *event), see: focusOutEvent().

class MyPlainTextEdit : public QPlainTextEdit
{
    Q_OBJECT
public:
    explicit MyPlainTextEdit(QWidget *parent = nullptr);
protected:
    virtual void focusOutEvent(QFocusEvent *) override { hide(); }
};

[Qtstarter121]

Thank you. The problem is that I need to implement this in the eventFilter of my QMainWindow to filter for the correct object. I cannot implement this function for the object I need since there's no class implementation for that object, it's all part of my QMainWindow. How would I do this?

[A Former User]

Let's assume you have your MainWindow class and it contains the widget plainTextEdit.

myeventfilter.h

#ifndef MYEVENTFILTER_H
#define MYEVENTFILTER_H

#include <QObject>

class MyEventFilter : public QObject
{
    Q_OBJECT
public:
    MyEventFilter(QObject *parent = nullptr);
protected:
    virtual bool eventFilter(QObject *watched, QEvent *event) override;
};

#endif // MYEVENTFILTER_H

myeventfilter.cpp

#include "myeventfilter.h"
#include <QEvent>
#include <QWidget>

MyEventFilter::MyEventFilter(QObject *parent)
    : QObject(parent)
{
}

bool MyEventFilter::eventFilter(QObject *watched, QEvent *event)
{
    if (event->type() == QEvent::FocusOut) {
        auto widget = dynamic_cast<QWidget *>(watched);
        widget->hide();
        return true;
    } else {
        return QObject::eventFilter(watched, event);
    }
}

mainwindow.cpp

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

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    auto myEventFilter = new MyEventFilter(this);
    ui->plainTextEdit->installEventFilter(myEventFilter);
}

// ...

[Vinod Kuntoji]

@Qtstarter121 ,

Hi,

You can use,
yourWidget->setWindowFlags(Qt::Popup);
this will hide your widget when you click outside of it.