How to animate a widget like discord 'zoom animation'

[Marcia3x]

How to create this kind of animation in qt?
I mean the 'zoom-out' animation when I click on the 'User Settings' button and at the Esc button
https://youtu.be/Z6Q-QUDLZ8E

The animation at a slower speed:
https://youtu.be/bcPs_kILo10

[jeremy_k]

https://doc.qt.io/qt-5/animation-overview.html

The video looks like a combination of opacity and scale animations.

[Marcia3x]

What properties is used to create scale?

[jsulm]

@Marcia3x In the link @jeremy_k gave you there is an example:

QPushButton button("Animated Button");
button.show();

QPropertyAnimation animation(&button, "geometry");
animation.setDuration(10000);
animation.setStartValue(QRect(0, 0, 100, 30));
animation.setEndValue(QRect(250, 250, 100, 30));

animation.start();

Just do not change x/y, only change width/height.

[Marcia3x]

@jsulm said in How to animate a widget like discord 'zoom animation':

@Marcia3x In the link @jeremy_k gave you there is an example:

QPushButton button("Animated Button");
button.show();

QPropertyAnimation animation(&button, "geometry");
animation.setDuration(10000);
animation.setStartValue(QRect(0, 0, 100, 30));
animation.setEndValue(QRect(250, 250, 100, 30));

animation.start();

Just do not change x/y, only change width/height.

After a lot of search and effort, I did something:

// stackedwidget.h
class StackedWidget : public QStackedWidget
{

    Q_OBJECT
public:

    enum QEasingCurve::Type m_animationtype = QEasingCurve::Type::OutQuart;
    int m_speed = 1000;
    int m_now;
    int m_next;
    bool animation_active = false;
    QPoint m_pnow;
    QParallelAnimationGroup* animgroup;

    StackedWidget(QWidget* parent) : QStackedWidget(parent)
    {
        QWidget* widget = new QWidget();
        QGridLayout* widget_layout = new QGridLayout();
	    widget->setLayout(widget_layout);

        QPushButton* button;
        for (size_t i = 0; i < 10; i++)
        {
            button = new QPushButton();
            button->setText("Button " + QString::number(i));
            button->setStyleSheet(R"(
	            background-color:  #3c3f45;
                border-radius: 4px;            
	            color: rgba(255, 255, 255, 0.4);
	            font-size: 15px;
	            font-weight: 600;	
            )");
            widget_layout->addWidget(button);
        }

        button->setText("Change Page");

        connect(button, &QPushButton::clicked, [=]
        {
            animimateToPage(1);
        });  



        QWidget* widget_2 = new QWidget();
        QGridLayout* widget_layout_2 = new QGridLayout();
	    widget_2->setLayout(widget_layout_2);

        for (size_t i = 0; i < 10; i++)
        {
            button = new QPushButton();
            button->setText("================ " + QString::number(i));
            button->setStyleSheet(R"(
	            background-color:  #3c3f45;
                border-radius: 4px;            
	            color: rgba(255, 255, 255, 0.4);
	            font-size: 15px;
	            font-weight: 600;	
            )");
            widget_layout_2->addWidget(button);
        }

        button->setText("return");
        
        connect(button, &QPushButton::clicked, [this]
        {
            animimateToPage(0);
        });  



        addWidget(widget);
        addWidget(widget_2);
    }



    void animimateToPage(int index)
    {

        if (animation_active)
            return;

        animation_active = true;

        int now = currentIndex();
        int next = indexOf(widget(index));

        int offsetx = frameRect().width();
        int offsety = frameRect().height();

        widget(next)->setGeometry(0, 0, offsetx, offsety);

        QPoint pnext = widget(next)->pos();
        QPoint pnow = widget(now)->pos();
        m_pnow = pnow;
        //widget(next)->move(pnext.x() - offsetx, pnext.y() - offsety);

        QRect rnext = widget(next)->geometry();
        QRect rnow = widget(now)->geometry();

        int addw = 300;
        int addh = 100;

        widget(next)->show();
        widget(next)->raise();

        QPropertyAnimation* animnow = new QPropertyAnimation(widget(now), "geometry");
        animnow->setDuration(m_speed);
        animnow->setEasingCurve(m_animationtype);
        animnow->setStartValue(QRect(0, 0, rnow.width(), rnow.height()));
        animnow->setEndValue(QRect(0, 0, rnow.width() - addw, rnow.height() - addh));

        QGraphicsOpacityEffect* animnow_op_eff = new QGraphicsOpacityEffect();
        widget(now)->setGraphicsEffect(animnow_op_eff);
        QPropertyAnimation* animnow_op = new QPropertyAnimation(animnow_op_eff, "opacity");
        animnow_op->setDuration(m_speed);
        animnow_op->setStartValue(1);
        animnow_op->setEndValue(0);



        QPropertyAnimation* animnext = new QPropertyAnimation(widget(next), "geometry");
        animnext->setDuration(m_speed);
        animnext->setEasingCurve(m_animationtype);
        animnext->setStartValue(QRect(0, 0, rnext.width() - addw, rnext.height() - addh));
        animnext->setEndValue(QRect(0, 0, rnext.width(), rnext.height()));

        QGraphicsOpacityEffect* animnext_op_eff = new QGraphicsOpacityEffect();
        animnext_op_eff->setOpacity(0);
        widget(next)->setGraphicsEffect(animnext_op_eff);
        QPropertyAnimation* animnext_op = new QPropertyAnimation(animnext_op_eff, "opacity");
        animnext_op->setDuration(m_speed);
        animnext_op->setStartValue(0);
        animnext_op->setEndValue(1);



        animgroup = new QParallelAnimationGroup;
        animgroup->addAnimation(animnow);
        animgroup->addAnimation(animnext);
        animgroup->addAnimation(animnow_op);
        animgroup->addAnimation(animnext_op);



        QObject::connect(animgroup, &QParallelAnimationGroup::finished, this, &StackedWidget::animationDoneSlot);
        m_next = next;
        m_now = now;
                
        animgroup->start(QAbstractAnimation::DeleteWhenStopped);
    }



    void animationDoneSlot()
    {
        setCurrentIndex(m_next);
        widget(m_now)->hide();
        widget(m_now)->move(m_pnow);

        widget(m_now)->setGraphicsEffect(nullptr);
        widget(m_next)->setGraphicsEffect(nullptr);

        animation_active = false;
    }
};

---

#include "stackedwidget.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    ui.setupUi(this);

    ui.centralWidget->setStyleSheet("#centralWidget { background-color: #36393f; }");

    QGridLayout* layout = new QGridLayout();
    ui.centralWidget->setLayout(layout);

    StackedWidget* stacked_widget = new StackedWidget(this);    
    layout->addWidget(stacked_widget);

    return;
}

I have added some random buttons which colors similar to those seen in discord just to help check if the
animation is 'correct'.

Result:

Looks like there's any kind of flickering in the animation, and I'm struggling with how to calculate the values to use in
start/end of the geometry animation.

The animation I'm referring to:
https://i.imgur.com/fC2cTCY.gif (i reduced the speed of the animation, also, click on the image to enlarge it)
https://imgur.com/a/nUuOGSn (default speed)