Creating a dark overlay to apply on top of other widgets

saeid0034

Hi, I want to be able to create a dark overlay on top of other widgets that can be turned on or of with animation, so for I have this

OverlayWidget.h

#pragma once

#include <QObject>
#include <QFrame>
#include <QGraphicsOpacityEffect>
#include <QPropertyAnimation>
#include <QPaintEvent>
#include <QMouseEvent>

class OverlayWidget : public QWidget
{
    Q_OBJECT
public:
    explicit OverlayWidget(QWidget* parent = nullptr, const int duration = 370);
    void show(const bool& show = true);

signals:
    void pressed(); // used for close the overlay when its opened and user click on it

private:
    QGraphicsOpacityEffect fade_effect;
    QPropertyAnimation animation;

protected:
    void mousePressEvent(QMouseEvent* event);
    void paintEvent(QPaintEvent* event);
    bool eventFilter(QObject* obj, QEvent* ev) override;
    bool event(QEvent* ev) override;

private:
    void newParent();
};

OverlayWidget.cpp

#include "Overlay.h"
#include <QPainter>
#include <QDebug>

OverlayWidget::OverlayWidget(QWidget* parent, const int duration)
    : QWidget{ parent }
    , fade_effect(this)
    , animation(&fade_effect, "opacity")
{
    setPalette(Qt::transparent);
    setAttribute(Qt::WA_NoSystemBackground);
    newParent();
    // setStyleSheet("border-radius:8;");
    setGraphicsEffect(&fade_effect);
    animation.setStartValue(0.0);
    animation.setEndValue(1.0);
    animation.setEasingCurve(QEasingCurve::InOutQuint);
    animation.setDuration(duration);
    setVisible(false);
    setEnabled(false);
}

void OverlayWidget::newParent()
{
    if (!parent()) return;
    parent()->installEventFilter(this);
    raise();
}

bool OverlayWidget::eventFilter(QObject* obj, QEvent* ev)
{
    if (obj == parent()) {
        if (ev->type() == QEvent::Resize)
            resize(static_cast<QResizeEvent*>(ev)->size());
        else if (ev->type() == QEvent::ChildAdded)
            raise();
    }
    return QWidget::eventFilter(obj, ev);
}

bool OverlayWidget::event(QEvent* ev)
{
    if (ev->type() == QEvent::ParentAboutToChange) {
        if (parent()) parent()->removeEventFilter(this);
    }
    else if (ev->type() == QEvent::ParentChange)
        newParent();
    return QWidget::event(ev);
}

void OverlayWidget::show(const bool& show)
{
    animation.stop();
    animation.setStartValue(animation.currentValue());
    animation.setEndValue(show ? 1.0 : 0.0); // show or hide
    animation.start();
    if (show) {
        setVisible(true);
        setEnabled(true);
        setAttribute(Qt::WA_TransparentForMouseEvents, false);
    }
    else {
        // setVisible(false);
        setEnabled(false);
        setAttribute(Qt::WA_TransparentForMouseEvents);
    }
}

void OverlayWidget::paintEvent(QPaintEvent* event)
{
    Q_UNUSED(event);

    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.setBrush(QBrush(QColor(0, 0, 0, 150)));
    painter.setOpacity(50);
    painter.setPen(Qt::NoPen);
    painter.drawRoundedRect(rect(), 8.0, 8.0); // becasue my frame is round
}

void OverlayWidget::mousePressEvent(QMouseEvent* event)
{
    if (event->button() == Qt::LeftButton)
        emit pressed();
}

so far its work, but I think Im doing it very bad... any suggestion on how to improve it?

saeid0034

Here is the same question with a working example
https://codereview.stackexchange.com/questions/274781/qt-creating-a-dark-overlay-to-apply-on-top-of-other-widgets-with-animation