Animation Qt example

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Заголовочный файл
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QVector>
#include <QGraphicsItemAnimation>
#include <QGraphicsScene>
#include <QPushButton>
#include <QVBoxLayout>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void startAnimation();
    void finishAnimation();

private:
    // Methods
    void initialize();
    void initializeItemList();
    void setupAnimation();

private:
    Ui::MainWindow *ui;

    // UI items
    QVBoxLayout* m_mainLayout;
    QPushButton* m_startButton;

    // Graphics view items
    // Animation and items
    QGraphicsItemAnimation* m_animation;
    QVector<QGraphicsItem*> m_itemList;

    // Scene, view e.t.c.
    QGraphicsScene* m_scene;
    QGraphicsView *m_view;
    QTimeLine* m_timer;
};
#endif // MAINWINDOW_H

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Сурс файл
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

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

#include <QGraphicsEllipseItem>
#include <QGraphicsView>
#include <QRect>
#include <QTimeLine>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    showMaximized();

    // Inits for widgets
    m_startButton = new QPushButton(tr("Start animation"));
    m_startButton->setGeometry(QRect(QPoint(100, 100), QSize(200, 50)));
    connect(m_startButton, &QPushButton::pressed, this, &MainWindow::startAnimation);

    m_view = new QGraphicsView();
    m_view->setStyleSheet(
                "border-width: 2px; border-style: solid; border-color: darkblue; "
                );

    // Adding widgets to layout
    m_mainLayout = new QVBoxLayout(ui->centralwidget);
    m_mainLayout->addWidget(m_view);
    m_mainLayout->addWidget(m_startButton);
}

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

void MainWindow::startAnimation()
{
    initialize();

    if (m_itemList.size() != 0)
    {
        m_view->show();
        m_timer->start();
    }
}

void MainWindow::initialize()
{
    initializeItemList();

    m_timer = new QTimeLine(5000);
    m_timer->setFrameRange(0, 100);

    setupAnimation();

    m_scene = new QGraphicsScene();
    m_scene->setSceneRect(0, 0, width() - 100, height() - 50);
    ui->centralwidget->showMinimized();
    for (auto item : m_itemList)
    {
        m_scene->addItem(item);
    }

    m_view->setScene(m_scene);

    connect(m_timer, &QTimeLine::finished, this, &MainWindow::finishAnimation);
}

void MainWindow::initializeItemList()
{
    QGraphicsRectItem* redEllipse = new QGraphicsRectItem(width() / 2, height() / 2, 20, 20);
    redEllipse->setBrush(QBrush(QColor(Qt::red)));
    m_itemList.append(redEllipse);

    QGraphicsRectItem* blueEllipse = new QGraphicsRectItem(width() / 2, height() / 2, 20, 20);
    blueEllipse->setBrush(QBrush(QColor(Qt::blue)));
    m_itemList.append(blueEllipse);

    QGraphicsRectItem* greenEllipse = new QGraphicsRectItem(width() / 2, height() / 2, 20, 20);
    redEllipse->setBrush(QBrush(QColor(Qt::green)));
    m_itemList.append(greenEllipse);

    QGraphicsRectItem* yellowEllipse = new QGraphicsRectItem(width() / 2, height() / 2, 20, 20);
    blueEllipse->setBrush(QBrush(QColor(Qt::yellow)));
    m_itemList.append(yellowEllipse);
}

void MainWindow::setupAnimation()
{
    for (int itemNumber = 0; itemNumber < m_itemList.size(); itemNumber++)
    {
        QGraphicsItemAnimation *itemAnimation = new QGraphicsItemAnimation();
        itemAnimation->setTimeLine(m_timer);
        itemAnimation->setItem(m_itemList[itemNumber]);
        if (itemNumber == 0)
        {
            for (int index = 0; index < 200; index++)
            {
                itemAnimation->setPosAt(index / 200.0, QPointF(-index, -index));
            }
        }
        if (itemNumber == 1)
        {
            for (int index = 0; index < 200; index++)
            {
                itemAnimation->setPosAt(index / 200.0, QPointF(index, index));
            }
        }
        if (itemNumber == 2)
        {
            for (int index = 0; index < 200; index++)
            {
                itemAnimation->setPosAt(index / 200.0, QPointF(-index, index));
            }
        }
        if (itemNumber == 3)
        {
            for (int index = 0; index < 200; index++)
            {
                itemAnimation->setPosAt(index / 200.0, QPointF(index, -index));
            }
        }
    }
}

void MainWindow::finishAnimation()
{
    // Do smth when animation is finished
}