Easiest and Fastest Way to implement gravity and jump (sfml)

float gravity = .3;

    sf::Event event;
    while (window.isOpen())
    {
        while (window.pollEvent(event))
        {
            if (event.type == sf::Event::Closed)
                window.close();

            if (event.type == sf::Event::KeyPressed)
            {
                if (event.key.code == sf::Keyboard::Space)
                {
                    velocity.y = -8;
                }
                if (event.key.code == sf::Keyboard::Right)
                {
                    velocity.x = 3;
                }
                else if (event.key.code == sf::Keyboard::Left)
                {
                    velocity.x = -3;
                }
            }
        }

        if (player.getPosition().y >= height / 2)
        {
            player.setPosition(player.getPosition().x, height / 2);
        }
        else
        {
            velocity.y += gravity;
        }

        window.clear(sf::Color::White); //Clear

        player.move(velocity);
        window.draw(player);

        window.display(); //Display
    }