Method update

examples/keyboard/Keyboard.cpp:647–658

Fade out ouline

    // Fade out ouline
    void update(sf::Time frameTime)
    {
        const float ratio = m_remaining / duration;
        const float alpha = std::max(0.f, ratio * (2.f - ratio)) * 0.5f;

        sf::Color color = getOutlineColor();
        color.a         = static_cast<std::uint8_t>(255 * alpha);
        setOutlineColor(color);

        if (m_remaining > sf::Time::Zero)
            m_remaining -= frameTime;
    }

private:
    static constexpr sf::Time duration = sf::milliseconds(150);