ladybird/Userland/Applications/Piano/TrackManager.cpp

/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * Copyright (c) 2019-2020, William McPherson <willmcpherson2@gmail.com>
 * Copyright (c) 2021, JJ Roberts-White <computerfido@gmail.com>
 * Copyright (c) 2022, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include "TrackManager.h"
#include "Applications/Piano/Music.h"
#include <AK/NonnullRefPtr.h>

TrackManager::TrackManager()
    : m_transport(make_ref_counted<DSP::Transport>(120, 4))
    , m_keyboard(make_ref_counted<DSP::Keyboard>(m_transport))
{
    add_track();
    m_tracks[m_current_track]->set_active(true);
}

void TrackManager::time_forward(int amount)
{
    int new_value = (static_cast<int>(m_transport->time()) + amount) % roll_length;

    if (new_value < 0) { // If the new time value is negative add roll_length to wrap around
        m_transport->set_time(roll_length + new_value);
    } else {
        m_transport->set_time(new_value);
    }
}

void TrackManager::fill_buffer(Span<Sample> buffer)
{
    memset(buffer.data(), 0, buffer_size);

    for (size_t i = 0; i < buffer.size(); ++i) {
        for (auto& track : m_tracks)
            track->fill_sample(buffer[i]);

        m_transport->set_time(m_transport->time() + 1);
        // FIXME: This should be handled automatically by Transport.
        if (m_transport->time() >= roll_length) {
            m_transport->set_time(0);
            if (!m_should_loop)
                break;
        }
    }

    memcpy(m_current_back_buffer.data(), buffer.data(), buffer_size);
    swap(m_current_front_buffer, m_current_back_buffer);
}

void TrackManager::reset()
{
    memset(m_front_buffer.data(), 0, buffer_size);
    memset(m_back_buffer.data(), 0, buffer_size);

    m_current_front_buffer = m_front_buffer.span();
    m_current_back_buffer = m_back_buffer.span();

    m_transport->set_time(0);

    for (auto& track : m_tracks) {
        track->reset();
        track->set_active(false);
    }
    m_tracks[m_current_track]->set_active(true);
}

void TrackManager::add_track()
{
    m_tracks.append(make<Track>(m_transport, m_keyboard));
}

int TrackManager::next_track_index() const
{
    auto next_track_index = m_current_track + 1;
    if (next_track_index >= m_tracks.size())
        return 0;
    else
        return next_track_index;
}